/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2015, 2016 The FreeBSD Foundation
 * Copyright (c) 2004, David Xu <davidxu@freebsd.org>
 * Copyright (c) 2002, Jeffrey Roberson <jeff@freebsd.org>
 * All rights reserved.
 *
 * Portions of this software were developed by Konstantin Belousov
 * under sponsorship from the FreeBSD Foundation.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice unmodified, this list of conditions, and the following
 *    disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/cdefs.h>
#include "opt_umtx_profiling.h"

#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/fcntl.h>
#include <sys/file.h>
#include <sys/filedesc.h>
#include <sys/limits.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mman.h>
#include <sys/mutex.h>
#include <sys/priv.h>
#include <sys/proc.h>
#include <sys/resource.h>
#include <sys/resourcevar.h>
#include <sys/rwlock.h>
#include <sys/sbuf.h>
#include <sys/sched.h>
#include <sys/smp.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#include <sys/sysproto.h>
#include <sys/syscallsubr.h>
#include <sys/taskqueue.h>
#include <sys/time.h>
#include <sys/eventhandler.h>
#include <sys/umtx.h>
#include <sys/umtxvar.h>

#include <security/mac/mac_framework.h>

#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/pmap.h>
#include <vm/uma.h>
#include <vm/vm_map.h>
#include <vm/vm_object.h>

#include <machine/atomic.h>
#include <machine/cpu.h>

#include <compat/freebsd32/freebsd32.h>
#ifdef COMPAT_FREEBSD32
#include <compat/freebsd32/freebsd32_proto.h>
#endif

#define _UMUTEX_TRY             1
#define _UMUTEX_WAIT            2

#ifdef UMTX_PROFILING
#define UPROF_PERC_BIGGER(w, f, sw, sf)                                 \
        (((w) > (sw)) || ((w) == (sw) && (f) > (sf)))
#endif

#define UMTXQ_LOCKED_ASSERT(uc)         mtx_assert(&(uc)->uc_lock, MA_OWNED)
#ifdef INVARIANTS
#define UMTXQ_ASSERT_LOCKED_BUSY(key) do {                              \
        struct umtxq_chain *uc;                                         \
                                                                        \
        uc = umtxq_getchain(key);                                       \
        mtx_assert(&uc->uc_lock, MA_OWNED);                             \
        KASSERT(uc->uc_busy != 0, ("umtx chain is not busy"));          \
} while (0)
#else
#define UMTXQ_ASSERT_LOCKED_BUSY(key) do {} while (0)
#endif

/*
 * Don't propagate time-sharing priority, there is a security reason,
 * a user can simply introduce PI-mutex, let thread A lock the mutex,
 * and let another thread B block on the mutex, because B is
 * sleeping, its priority will be boosted, this causes A's priority to
 * be boosted via priority propagating too and will never be lowered even
 * if it is using 100%CPU, this is unfair to other processes.
 */

#define UPRI(td)        (((td)->td_user_pri >= PRI_MIN_TIMESHARE &&\
                          (td)->td_user_pri <= PRI_MAX_TIMESHARE) ?\
                         PRI_MAX_TIMESHARE : (td)->td_user_pri)

#define GOLDEN_RATIO_PRIME      2654404609U
#ifndef UMTX_CHAINS
#define UMTX_CHAINS             512
#endif
#define UMTX_SHIFTS             (__WORD_BIT - 9)

#define GET_SHARE(flags)        \
    (((flags) & USYNC_PROCESS_SHARED) == 0 ? THREAD_SHARE : PROCESS_SHARE)

#define BUSY_SPINS              200

struct umtx_copyops {
        int     (*copyin_timeout)(const void *uaddr, struct timespec *tsp);
        int     (*copyin_umtx_time)(const void *uaddr, size_t size,
            struct _umtx_time *tp);
        int     (*copyin_robust_lists)(const void *uaddr, size_t size,
            struct umtx_robust_lists_params *rbp);
        int     (*copyout_timeout)(void *uaddr, size_t size,
            struct timespec *tsp);
        const size_t    timespec_sz;
        const size_t    umtx_time_sz;
        const bool      compat32;
};

_Static_assert(sizeof(struct umutex) == sizeof(struct umutex32), "umutex32");
_Static_assert(__offsetof(struct umutex, m_spare[0]) ==
    __offsetof(struct umutex32, m_spare[0]), "m_spare32");

int umtx_shm_vnobj_persistent = 0;
SYSCTL_INT(_kern_ipc, OID_AUTO, umtx_vnode_persistent, CTLFLAG_RWTUN,
    &umtx_shm_vnobj_persistent, 0,
    "False forces destruction of umtx attached to file, on last close");
static int umtx_max_rb = 1000;
SYSCTL_INT(_kern_ipc, OID_AUTO, umtx_max_robust, CTLFLAG_RWTUN,
    &umtx_max_rb, 0,
    "Maximum number of robust mutexes allowed for each thread");

static uma_zone_t               umtx_pi_zone;
static struct umtxq_chain       umtxq_chains[2][UMTX_CHAINS];
static MALLOC_DEFINE(M_UMTX, "umtx", "UMTX queue memory");
static int                      umtx_pi_allocated;

static SYSCTL_NODE(_debug, OID_AUTO, umtx, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
    "umtx debug");
SYSCTL_INT(_debug_umtx, OID_AUTO, umtx_pi_allocated, CTLFLAG_RD,
    &umtx_pi_allocated, 0, "Allocated umtx_pi");
static int umtx_verbose_rb = 1;
SYSCTL_INT(_debug_umtx, OID_AUTO, robust_faults_verbose, CTLFLAG_RWTUN,
    &umtx_verbose_rb, 0,
    "");

#ifdef UMTX_PROFILING
static long max_length;
SYSCTL_LONG(_debug_umtx, OID_AUTO, max_length, CTLFLAG_RD, &max_length, 0, "max_length");
static SYSCTL_NODE(_debug_umtx, OID_AUTO, chains, CTLFLAG_RD | CTLFLAG_MPSAFE, 0,
    "umtx chain stats");
#endif

static inline void umtx_abs_timeout_init2(struct umtx_abs_timeout *timo,
    const struct _umtx_time *umtxtime);

static void umtx_shm_init(void);
static void umtxq_sysinit(void *);
static void umtxq_hash(struct umtx_key *key);
static int do_unlock_pp(struct thread *td, struct umutex *m, uint32_t flags,
    bool rb);
static void umtx_thread_cleanup(struct thread *td);
SYSINIT(umtx, SI_SUB_EVENTHANDLER+1, SI_ORDER_MIDDLE, umtxq_sysinit, NULL);

#define umtxq_signal(key, nwake)        umtxq_signal_queue((key), (nwake), UMTX_SHARED_QUEUE)

static struct mtx umtx_lock;

#ifdef UMTX_PROFILING
static void
umtx_init_profiling(void)
{
        struct sysctl_oid *chain_oid;
        char chain_name[10];
        int i;

        for (i = 0; i < UMTX_CHAINS; ++i) {
                snprintf(chain_name, sizeof(chain_name), "%d", i);
                chain_oid = SYSCTL_ADD_NODE(NULL,
                    SYSCTL_STATIC_CHILDREN(_debug_umtx_chains), OID_AUTO,
                    chain_name, CTLFLAG_RD | CTLFLAG_MPSAFE, NULL,
                    "umtx hash stats");
                SYSCTL_ADD_INT(NULL, SYSCTL_CHILDREN(chain_oid), OID_AUTO,
                    "max_length0", CTLFLAG_RD, &umtxq_chains[0][i].max_length, 0, NULL);
                SYSCTL_ADD_INT(NULL, SYSCTL_CHILDREN(chain_oid), OID_AUTO,
                    "max_length1", CTLFLAG_RD, &umtxq_chains[1][i].max_length, 0, NULL);
        }
}

static int
sysctl_debug_umtx_chains_peaks(SYSCTL_HANDLER_ARGS)
{
        char buf[512];
        struct sbuf sb;
        struct umtxq_chain *uc;
        u_int fract, i, j, tot, whole;
        u_int sf0, sf1, sf2, sf3, sf4;
        u_int si0, si1, si2, si3, si4;
        u_int sw0, sw1, sw2, sw3, sw4;

        sbuf_new(&sb, buf, sizeof(buf), SBUF_FIXEDLEN);
        for (i = 0; i < 2; i++) {
                tot = 0;
                for (j = 0; j < UMTX_CHAINS; ++j) {
                        uc = &umtxq_chains[i][j];
                        mtx_lock(&uc->uc_lock);
                        tot += uc->max_length;
                        mtx_unlock(&uc->uc_lock);
                }
                if (tot == 0)
                        sbuf_printf(&sb, "%u) Empty ", i);
                else {
                        sf0 = sf1 = sf2 = sf3 = sf4 = 0;
                        si0 = si1 = si2 = si3 = si4 = 0;
                        sw0 = sw1 = sw2 = sw3 = sw4 = 0;
                        for (j = 0; j < UMTX_CHAINS; j++) {
                                uc = &umtxq_chains[i][j];
                                mtx_lock(&uc->uc_lock);
                                whole = uc->max_length * 100;
                                mtx_unlock(&uc->uc_lock);
                                fract = (whole % tot) * 100;
                                if (UPROF_PERC_BIGGER(whole, fract, sw0, sf0)) {
                                        sf0 = fract;
                                        si0 = j;
                                        sw0 = whole;
                                } else if (UPROF_PERC_BIGGER(whole, fract, sw1,
                                    sf1)) {
                                        sf1 = fract;
                                        si1 = j;
                                        sw1 = whole;
                                } else if (UPROF_PERC_BIGGER(whole, fract, sw2,
                                    sf2)) {
                                        sf2 = fract;
                                        si2 = j;
                                        sw2 = whole;
                                } else if (UPROF_PERC_BIGGER(whole, fract, sw3,
                                    sf3)) {
                                        sf3 = fract;
                                        si3 = j;
                                        sw3 = whole;
                                } else if (UPROF_PERC_BIGGER(whole, fract, sw4,
                                    sf4)) {
                                        sf4 = fract;
                                        si4 = j;
                                        sw4 = whole;
                                }
                        }
                        sbuf_printf(&sb, "queue %u:\n", i);
                        sbuf_printf(&sb, "1st: %u.%u%% idx: %u\n", sw0 / tot,
                            sf0 / tot, si0);
                        sbuf_printf(&sb, "2nd: %u.%u%% idx: %u\n", sw1 / tot,
                            sf1 / tot, si1);
                        sbuf_printf(&sb, "3rd: %u.%u%% idx: %u\n", sw2 / tot,
                            sf2 / tot, si2);
                        sbuf_printf(&sb, "4th: %u.%u%% idx: %u\n", sw3 / tot,
                            sf3 / tot, si3);
                        sbuf_printf(&sb, "5th: %u.%u%% idx: %u\n", sw4 / tot,
                            sf4 / tot, si4);
                }
        }
        sbuf_trim(&sb);
        sbuf_finish(&sb);
        sysctl_handle_string(oidp, sbuf_data(&sb), sbuf_len(&sb), req);
        sbuf_delete(&sb);
        return (0);
}

static int
sysctl_debug_umtx_chains_clear(SYSCTL_HANDLER_ARGS)
{
        struct umtxq_chain *uc;
        u_int i, j;
        int clear, error;

        clear = 0;
        error = sysctl_handle_int(oidp, &clear, 0, req);
        if (error != 0 || req->newptr == NULL)
                return (error);

        if (clear != 0) {
                for (i = 0; i < 2; ++i) {
                        for (j = 0; j < UMTX_CHAINS; ++j) {
                                uc = &umtxq_chains[i][j];
                                mtx_lock(&uc->uc_lock);
                                uc->length = 0;
                                uc->max_length = 0;
                                mtx_unlock(&uc->uc_lock);
                        }
                }
        }
        return (0);
}

SYSCTL_PROC(_debug_umtx_chains, OID_AUTO, clear,
    CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 0,
    sysctl_debug_umtx_chains_clear, "I",
    "Clear umtx chains statistics");
SYSCTL_PROC(_debug_umtx_chains, OID_AUTO, peaks,
    CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, 0, 0,
    sysctl_debug_umtx_chains_peaks, "A",
    "Highest peaks in chains max length");
#endif

static void
umtxq_sysinit(void *arg __unused)
{
        int i, j;

        umtx_pi_zone = uma_zcreate("umtx pi", sizeof(struct umtx_pi),
                NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
        for (i = 0; i < 2; ++i) {
                for (j = 0; j < UMTX_CHAINS; ++j) {
                        mtx_init(&umtxq_chains[i][j].uc_lock, "umtxql", NULL,
                                 MTX_DEF | MTX_DUPOK);
                        LIST_INIT(&umtxq_chains[i][j].uc_queue[0]);
                        LIST_INIT(&umtxq_chains[i][j].uc_queue[1]);
                        LIST_INIT(&umtxq_chains[i][j].uc_spare_queue);
                        TAILQ_INIT(&umtxq_chains[i][j].uc_pi_list);
                        umtxq_chains[i][j].uc_busy = 0;
                        umtxq_chains[i][j].uc_waiters = 0;
#ifdef UMTX_PROFILING
                        umtxq_chains[i][j].length = 0;
                        umtxq_chains[i][j].max_length = 0;
#endif
                }
        }
#ifdef UMTX_PROFILING
        umtx_init_profiling();
#endif
        mtx_init(&umtx_lock, "umtx lock", NULL, MTX_DEF);
        umtx_shm_init();
}

struct umtx_q *
umtxq_alloc(void)
{
        struct umtx_q *uq;

        uq = malloc(sizeof(struct umtx_q), M_UMTX, M_WAITOK | M_ZERO);
        uq->uq_spare_queue = malloc(sizeof(struct umtxq_queue), M_UMTX,
            M_WAITOK | M_ZERO);
        TAILQ_INIT(&uq->uq_spare_queue->head);
        TAILQ_INIT(&uq->uq_pi_contested);
        uq->uq_inherited_pri = PRI_MAX;
        return (uq);
}

void
umtxq_free(struct umtx_q *uq)
{

        MPASS(uq->uq_spare_queue != NULL);
        free(uq->uq_spare_queue, M_UMTX);
        free(uq, M_UMTX);
}

static inline void
umtxq_hash(struct umtx_key *key)
{
        unsigned n;

        n = (uintptr_t)key->info.both.a + key->info.both.b;
        key->hash = ((n * GOLDEN_RATIO_PRIME) >> UMTX_SHIFTS) % UMTX_CHAINS;
}

struct umtxq_chain *
umtxq_getchain(struct umtx_key *key)
{

        if (key->type <= TYPE_SEM)
                return (&umtxq_chains[1][key->hash]);
        return (&umtxq_chains[0][key->hash]);
}

/*
 * Set chain to busy state when following operation
 * may be blocked (kernel mutex can not be used).
 */
void
umtxq_busy(struct umtx_key *key)
{
        struct umtxq_chain *uc;

        uc = umtxq_getchain(key);
        mtx_assert(&uc->uc_lock, MA_OWNED);
        if (uc->uc_busy) {
#ifdef SMP
                if (smp_cpus > 1) {
                        int count = BUSY_SPINS;
                        if (count > 0) {
                                umtxq_unlock(key);
                                while (uc->uc_busy && --count > 0)
                                        cpu_spinwait();
                                umtxq_lock(key);
                        }
                }
#endif
                while (uc->uc_busy) {
                        uc->uc_waiters++;
                        msleep(uc, &uc->uc_lock, 0, "umtxqb", 0);
                        uc->uc_waiters--;
                }
        }
        uc->uc_busy = 1;
}

/*
 * Unbusy a chain.
 */
void
umtxq_unbusy(struct umtx_key *key)
{
        struct umtxq_chain *uc;

        uc = umtxq_getchain(key);
        mtx_assert(&uc->uc_lock, MA_OWNED);
        KASSERT(uc->uc_busy != 0, ("not busy"));
        uc->uc_busy = 0;
        if (uc->uc_waiters)
                wakeup_one(uc);
}

void
umtxq_busy_unlocked(struct umtx_key *key)
{
        umtxq_lock(key);
        umtxq_busy(key);
        umtxq_unlock(key);
}

void
umtxq_unbusy_unlocked(struct umtx_key *key)
{
        umtxq_lock(key);
        umtxq_unbusy(key);
        umtxq_unlock(key);
}

static struct umtxq_queue *
umtxq_queue_lookup(struct umtx_key *key, int q)
{
        struct umtxq_queue *uh;
        struct umtxq_chain *uc;

        uc = umtxq_getchain(key);
        UMTXQ_LOCKED_ASSERT(uc);
        LIST_FOREACH(uh, &uc->uc_queue[q], link) {
                if (umtx_key_match(&uh->key, key))
                        return (uh);
        }

        return (NULL);
}

void
umtxq_insert_queue(struct umtx_q *uq, int q)
{
        struct umtxq_queue *uh;
        struct umtxq_chain *uc;

        uc = umtxq_getchain(&uq->uq_key);
        UMTXQ_LOCKED_ASSERT(uc);
        KASSERT((uq->uq_flags & UQF_UMTXQ) == 0, ("umtx_q is already on queue"));
        uh = umtxq_queue_lookup(&uq->uq_key, q);
        if (uh != NULL) {
                LIST_INSERT_HEAD(&uc->uc_spare_queue, uq->uq_spare_queue, link);
        } else {
                uh = uq->uq_spare_queue;
                uh->key = uq->uq_key;
                LIST_INSERT_HEAD(&uc->uc_queue[q], uh, link);
#ifdef UMTX_PROFILING
                uc->length++;
                if (uc->length > uc->max_length) {
                        uc->max_length = uc->length;
                        if (uc->max_length > max_length)
                                max_length = uc->max_length;
                }
#endif
        }
        uq->uq_spare_queue = NULL;

        TAILQ_INSERT_TAIL(&uh->head, uq, uq_link);
        uh->length++;
        uq->uq_flags |= UQF_UMTXQ;
        uq->uq_cur_queue = uh;
        return;
}

void
umtxq_remove_queue(struct umtx_q *uq, int q)
{
        struct umtxq_chain *uc;
        struct umtxq_queue *uh;

        uc = umtxq_getchain(&uq->uq_key);
        UMTXQ_LOCKED_ASSERT(uc);
        if (uq->uq_flags & UQF_UMTXQ) {
                uh = uq->uq_cur_queue;
                TAILQ_REMOVE(&uh->head, uq, uq_link);
                uh->length--;
                uq->uq_flags &= ~UQF_UMTXQ;
                if (TAILQ_EMPTY(&uh->head)) {
                        KASSERT(uh->length == 0,
                            ("inconsistent umtxq_queue length"));
#ifdef UMTX_PROFILING
                        uc->length--;
#endif
                        LIST_REMOVE(uh, link);
                } else {
                        uh = LIST_FIRST(&uc->uc_spare_queue);
                        KASSERT(uh != NULL, ("uc_spare_queue is empty"));
                        LIST_REMOVE(uh, link);
                }
                uq->uq_spare_queue = uh;
                uq->uq_cur_queue = NULL;
        }
}

/*
 * Check if there are multiple waiters
 */
int
umtxq_count(struct umtx_key *key)
{
        struct umtxq_queue *uh;

        UMTXQ_LOCKED_ASSERT(umtxq_getchain(key));
        uh = umtxq_queue_lookup(key, UMTX_SHARED_QUEUE);
        if (uh != NULL)
                return (uh->length);
        return (0);
}

/*
 * Check if there are multiple PI waiters and returns first
 * waiter.
 */
static int
umtxq_count_pi(struct umtx_key *key, struct umtx_q **first)
{
        struct umtxq_queue *uh;

        *first = NULL;
        UMTXQ_LOCKED_ASSERT(umtxq_getchain(key));
        uh = umtxq_queue_lookup(key, UMTX_SHARED_QUEUE);
        if (uh != NULL) {
                *first = TAILQ_FIRST(&uh->head);
                return (uh->length);
        }
        return (0);
}

/*
 * Wake up threads waiting on an userland object by a bit mask.
 */
int
umtxq_signal_mask(struct umtx_key *key, int n_wake, u_int bitset)
{
        struct umtxq_queue *uh;
        struct umtx_q *uq, *uq_temp;
        int ret;

        ret = 0;
        UMTXQ_LOCKED_ASSERT(umtxq_getchain(key));
        uh = umtxq_queue_lookup(key, UMTX_SHARED_QUEUE);
        if (uh == NULL)
                return (0);
        TAILQ_FOREACH_SAFE(uq, &uh->head, uq_link, uq_temp) {
                if ((uq->uq_bitset & bitset) == 0)
                        continue;
                umtxq_remove_queue(uq, UMTX_SHARED_QUEUE);
                wakeup_one(uq);
                if (++ret >= n_wake)
                        break;
        }
        return (ret);
}

/*
 * Wake up threads waiting on an userland object.
 */

static int
umtxq_signal_queue(struct umtx_key *key, int n_wake, int q)
{
        struct umtxq_queue *uh;
        struct umtx_q *uq;
        int ret;

        ret = 0;
        UMTXQ_LOCKED_ASSERT(umtxq_getchain(key));
        uh = umtxq_queue_lookup(key, q);
        if (uh != NULL) {
                while ((uq = TAILQ_FIRST(&uh->head)) != NULL) {
                        umtxq_remove_queue(uq, q);
                        wakeup(uq);
                        if (++ret >= n_wake)
                                return (ret);
                }
        }
        return (ret);
}

/*
 * Wake up specified thread.
 */
static inline void
umtxq_signal_thread(struct umtx_q *uq)
{

        UMTXQ_LOCKED_ASSERT(umtxq_getchain(&uq->uq_key));
        umtxq_remove(uq);
        wakeup(uq);
}

/*
 * Wake up a maximum of n_wake threads that are waiting on an userland
 * object identified by key. The remaining threads are removed from queue
 * identified by key and added to the queue identified by key2 (requeued).
 * The n_requeue specifies an upper limit on the number of threads that
 * are requeued to the second queue.
 */
int
umtxq_requeue(struct umtx_key *key, int n_wake, struct umtx_key *key2,
    int n_requeue)
{
        struct umtxq_queue *uh;
        struct umtx_q *uq, *uq_temp;
        int ret;

        ret = 0;
        UMTXQ_LOCKED_ASSERT(umtxq_getchain(key));
        UMTXQ_LOCKED_ASSERT(umtxq_getchain(key2));
        uh = umtxq_queue_lookup(key, UMTX_SHARED_QUEUE);
        if (uh == NULL)
                return (0);
        TAILQ_FOREACH_SAFE(uq, &uh->head, uq_link, uq_temp) {
                if (++ret <= n_wake) {
                        umtxq_remove(uq);
                        wakeup_one(uq);
                } else {
                        umtxq_remove(uq);
                        uq->uq_key = *key2;
                        umtxq_insert(uq);
                        if (ret - n_wake == n_requeue)
                                break;
                }
        }
        return (ret);
}

static inline int
tstohz(const struct timespec *tsp)
{
        struct timeval tv;

        TIMESPEC_TO_TIMEVAL(&tv, tsp);
        return tvtohz(&tv);
}

void
umtx_abs_timeout_init(struct umtx_abs_timeout *timo, int clockid,
    int absolute, const struct timespec *timeout)
{

        timo->clockid = clockid;
        if (!absolute) {
                timo->is_abs_real = false;
                kern_clock_gettime(curthread, timo->clockid, &timo->cur);
                timespecadd(&timo->cur, timeout, &timo->end);
        } else {
                timo->end = *timeout;
                timo->is_abs_real = clockid == CLOCK_REALTIME ||
                    clockid == CLOCK_REALTIME_FAST ||
                    clockid == CLOCK_REALTIME_PRECISE ||
                    clockid == CLOCK_TAI ||
                    clockid == CLOCK_SECOND;
        }
}

static void
umtx_abs_timeout_init2(struct umtx_abs_timeout *timo,
    const struct _umtx_time *umtxtime)
{

        umtx_abs_timeout_init(timo, umtxtime->_clockid,
            (umtxtime->_flags & UMTX_ABSTIME) != 0, &umtxtime->_timeout);
}

static void
umtx_abs_timeout_enforce_min(sbintime_t *sbt)
{
        sbintime_t when, mint;

        mint = curproc->p_umtx_min_timeout;
        if (__predict_false(mint != 0)) {
                when = sbinuptime() + mint;
                if (*sbt < when)
                        *sbt = when;
        }
}

static int
umtx_abs_timeout_getsbt(struct umtx_abs_timeout *timo, sbintime_t *sbt,
    int *flags)
{
        struct bintime bt, bbt;
        struct timespec tts;
        sbintime_t rem;

        switch (timo->clockid) {

        /* Clocks that can be converted into absolute time. */
        case CLOCK_REALTIME:
        case CLOCK_REALTIME_PRECISE:
        case CLOCK_REALTIME_FAST:
        case CLOCK_MONOTONIC:
        case CLOCK_MONOTONIC_PRECISE:
        case CLOCK_MONOTONIC_FAST:
        case CLOCK_UPTIME:
        case CLOCK_UPTIME_PRECISE:
        case CLOCK_UPTIME_FAST:
        case CLOCK_SECOND:
                timespec2bintime(&timo->end, &bt);
                switch (timo->clockid) {
                case CLOCK_REALTIME:
                case CLOCK_REALTIME_PRECISE:
                case CLOCK_REALTIME_FAST:
                case CLOCK_SECOND:
                        getboottimebin(&bbt);
                        bintime_sub(&bt, &bbt);
                        break;
                }
                if (bt.sec < 0)
                        return (ETIMEDOUT);
                if (bt.sec >= (SBT_MAX >> 32)) {
                        *sbt = 0;
                        *flags = 0;
                        return (0);
                }
                *sbt = bttosbt(bt);
                umtx_abs_timeout_enforce_min(sbt);

                /*
                 * Check if the absolute time should be aligned to
                 * avoid firing multiple timer events in non-periodic
                 * timer mode.
                 */
                switch (timo->clockid) {
                case CLOCK_REALTIME_FAST:
                case CLOCK_MONOTONIC_FAST:
                case CLOCK_UPTIME_FAST:
                        rem = *sbt % tc_tick_sbt;
                        if (__predict_true(rem != 0))
                                *sbt += tc_tick_sbt - rem;
                        break;
                case CLOCK_SECOND:
                        rem = *sbt % SBT_1S;
                        if (__predict_true(rem != 0))
                                *sbt += SBT_1S - rem;
                        break;
                }
                *flags = C_ABSOLUTE;
                return (0);

        /* Clocks that has to be periodically polled. */
        case CLOCK_VIRTUAL:
        case CLOCK_PROF:
        case CLOCK_THREAD_CPUTIME_ID:
        case CLOCK_PROCESS_CPUTIME_ID:
        case CLOCK_TAI: /* Boot time is not necessarily stable in TAI */
        default:
                kern_clock_gettime(curthread, timo->clockid, &timo->cur);
                if (timespeccmp(&timo->end, &timo->cur, <=))
                        return (ETIMEDOUT);
                timespecsub(&timo->end, &timo->cur, &tts);
                *sbt = tick_sbt * tstohz(&tts);
                *flags = C_HARDCLOCK;
                return (0);
        }
}

static uint32_t
umtx_unlock_val(uint32_t flags, bool rb)
{

        if (rb)
                return (UMUTEX_RB_OWNERDEAD);
        else if ((flags & UMUTEX_NONCONSISTENT) != 0)
                return (UMUTEX_RB_NOTRECOV);
        else
                return (UMUTEX_UNOWNED);

}

/*
 * Put thread into sleep state, before sleeping, check if
 * thread was removed from umtx queue.
 */
int
umtxq_sleep(struct umtx_q *uq, const char *wmesg,
    struct umtx_abs_timeout *timo)
{
        struct umtxq_chain *uc;
        sbintime_t sbt = 0;
        int error, flags = 0;

        uc = umtxq_getchain(&uq->uq_key);
        UMTXQ_LOCKED_ASSERT(uc);
        for (;;) {
                if (!(uq->uq_flags & UQF_UMTXQ)) {
                        error = 0;
                        break;
                }
                if (timo != NULL) {
                        if (timo->is_abs_real)
                                curthread->td_rtcgen =
                                    atomic_load_acq_int(&rtc_generation);
                        error = umtx_abs_timeout_getsbt(timo, &sbt, &flags);
                        if (error != 0)
                                break;
                }
                error = msleep_sbt(uq, &uc->uc_lock, PCATCH | PDROP, wmesg,
                    sbt, 0, flags);
                uc = umtxq_getchain(&uq->uq_key);
                mtx_lock(&uc->uc_lock);
                if (error == EINTR || error == ERESTART)
                        break;
                if (error == EWOULDBLOCK && (flags & C_ABSOLUTE) != 0) {
                        error = ETIMEDOUT;
                        break;
                }
        }

        curthread->td_rtcgen = 0;
        return (error);
}

/*
 * Convert userspace address into unique logical address.
 */
int
umtx_key_get(const void *addr, int type, int share, struct umtx_key *key)
{
        struct thread *td = curthread;
        vm_map_t map;
        vm_map_entry_t entry;
        vm_pindex_t pindex;
        vm_prot_t prot;
        boolean_t wired;

        key->type = type;
        if (share == THREAD_SHARE) {
                key->shared = 0;
                key->info.private.vs = td->td_proc->p_vmspace;
                key->info.private.addr = (uintptr_t)addr;
        } else {
                MPASS(share == PROCESS_SHARE || share == AUTO_SHARE);
                map = &td->td_proc->p_vmspace->vm_map;
                if (vm_map_lookup(&map, (vm_offset_t)addr, VM_PROT_WRITE,
                    &entry, &key->info.shared.object, &pindex, &prot,
                    &wired) != KERN_SUCCESS) {
                        return (EFAULT);
                }

                if ((share == PROCESS_SHARE) ||
                    (share == AUTO_SHARE &&
                     VM_INHERIT_SHARE == entry->inheritance)) {
                        key->shared = 1;
                        key->info.shared.offset = (vm_offset_t)addr -
                            entry->start + entry->offset;
                        vm_object_reference(key->info.shared.object);
                } else {
                        key->shared = 0;
                        key->info.private.vs = td->td_proc->p_vmspace;
                        key->info.private.addr = (uintptr_t)addr;
                }
                vm_map_lookup_done(map, entry);
        }

        umtxq_hash(key);
        return (0);
}

/*
 * Release key.
 */
void
umtx_key_release(struct umtx_key *key)
{
        if (key->shared)
                vm_object_deallocate(key->info.shared.object);
}

#ifdef COMPAT_FREEBSD10
/*
 * Lock a umtx object.
 */
static int
do_lock_umtx(struct thread *td, struct umtx *umtx, u_long id,
    const struct timespec *timeout)
{
        struct umtx_abs_timeout timo;
        struct umtx_q *uq;
        u_long owner;
        u_long old;
        int error = 0;

        uq = td->td_umtxq;
        if (timeout != NULL)
                umtx_abs_timeout_init(&timo, CLOCK_REALTIME, 0, timeout);

        /*
         * Care must be exercised when dealing with umtx structure. It
         * can fault on any access.
         */
        for (;;) {
                /*
                 * Try the uncontested case.  This should be done in userland.
                 */
                owner = casuword(&umtx->u_owner, UMTX_UNOWNED, id);

                /* The acquire succeeded. */
                if (owner == UMTX_UNOWNED)
                        return (0);

                /* The address was invalid. */
                if (owner == -1)
                        return (EFAULT);

                /* If no one owns it but it is contested try to acquire it. */
                if (owner == UMTX_CONTESTED) {
                        owner = casuword(&umtx->u_owner,
                            UMTX_CONTESTED, id | UMTX_CONTESTED);

                        if (owner == UMTX_CONTESTED)
                                return (0);

                        /* The address was invalid. */
                        if (owner == -1)
                                return (EFAULT);

                        error = thread_check_susp(td, false);
                        if (error != 0)
                                break;

                        /* If this failed the lock has changed, restart. */
                        continue;
                }

                /*
                 * If we caught a signal, we have retried and now
                 * exit immediately.
                 */
                if (error != 0)
                        break;

                if ((error = umtx_key_get(umtx, TYPE_SIMPLE_LOCK,
                        AUTO_SHARE, &uq->uq_key)) != 0)
                        return (error);

                umtxq_lock(&uq->uq_key);
                umtxq_busy(&uq->uq_key);
                umtxq_insert(uq);
                umtxq_unbusy(&uq->uq_key);
                umtxq_unlock(&uq->uq_key);

                /*
                 * Set the contested bit so that a release in user space
                 * knows to use the system call for unlock.  If this fails
                 * either some one else has acquired the lock or it has been
                 * released.
                 */
                old = casuword(&umtx->u_owner, owner, owner | UMTX_CONTESTED);

                /* The address was invalid. */
                if (old == -1) {
                        umtxq_lock(&uq->uq_key);
                        umtxq_remove(uq);
                        umtxq_unlock(&uq->uq_key);
                        umtx_key_release(&uq->uq_key);
                        return (EFAULT);
                }

                /*
                 * We set the contested bit, sleep. Otherwise the lock changed
                 * and we need to retry or we lost a race to the thread
                 * unlocking the umtx.
                 */
                umtxq_lock(&uq->uq_key);
                if (old == owner)
                        error = umtxq_sleep(uq, "umtx", timeout == NULL ? NULL :
                            &timo);
                umtxq_remove(uq);
                umtxq_unlock(&uq->uq_key);
                umtx_key_release(&uq->uq_key);

                if (error == 0)
                        error = thread_check_susp(td, false);
        }

        if (timeout == NULL) {
                /* Mutex locking is restarted if it is interrupted. */
                if (error == EINTR)
                        error = ERESTART;
        } else {
                /* Timed-locking is not restarted. */
                if (error == ERESTART)
                        error = EINTR;
        }
        return (error);
}

/*
 * Unlock a umtx object.
 */
static int
do_unlock_umtx(struct thread *td, struct umtx *umtx, u_long id)
{
        struct umtx_key key;
        u_long owner;
        u_long old;
        int error;
        int count;

        /*
         * Make sure we own this mtx.
         */
        owner = fuword(__DEVOLATILE(u_long *, &umtx->u_owner));
        if (owner == -1)
                return (EFAULT);

        if ((owner & ~UMTX_CONTESTED) != id)
                return (EPERM);

        /* This should be done in userland */
        if ((owner & UMTX_CONTESTED) == 0) {
                old = casuword(&umtx->u_owner, owner, UMTX_UNOWNED);
                if (old == -1)
                        return (EFAULT);
                if (old == owner)
                        return (0);
                owner = old;
        }

        /* We should only ever be in here for contested locks */
        if ((error = umtx_key_get(umtx, TYPE_SIMPLE_LOCK, AUTO_SHARE,
            &key)) != 0)
                return (error);

        umtxq_lock(&key);
        umtxq_busy(&key);
        count = umtxq_count(&key);
        umtxq_unlock(&key);

        /*
         * When unlocking the umtx, it must be marked as unowned if
         * there is zero or one thread only waiting for it.
         * Otherwise, it must be marked as contested.
         */
        old = casuword(&umtx->u_owner, owner,
            count <= 1 ? UMTX_UNOWNED : UMTX_CONTESTED);
        umtxq_lock(&key);
        umtxq_signal(&key,1);
        umtxq_unbusy(&key);
        umtxq_unlock(&key);
        umtx_key_release(&key);
        if (old == -1)
                return (EFAULT);
        if (old != owner)
                return (EINVAL);
        return (0);
}

#ifdef COMPAT_FREEBSD32

/*
 * Lock a umtx object.
 */
static int
do_lock_umtx32(struct thread *td, uint32_t *m, uint32_t id,
        const struct timespec *timeout)
{
        struct umtx_abs_timeout timo;
        struct umtx_q *uq;
        uint32_t owner;
        uint32_t old;
        int error = 0;

        uq = td->td_umtxq;

        if (timeout != NULL)
                umtx_abs_timeout_init(&timo, CLOCK_REALTIME, 0, timeout);

        /*
         * Care must be exercised when dealing with umtx structure. It
         * can fault on any access.
         */
        for (;;) {
                /*
                 * Try the uncontested case.  This should be done in userland.
                 */
                owner = casuword32(m, UMUTEX_UNOWNED, id);

                /* The acquire succeeded. */
                if (owner == UMUTEX_UNOWNED)
                        return (0);

                /* The address was invalid. */
                if (owner == -1)
                        return (EFAULT);

                /* If no one owns it but it is contested try to acquire it. */
                if (owner == UMUTEX_CONTESTED) {
                        owner = casuword32(m,
                            UMUTEX_CONTESTED, id | UMUTEX_CONTESTED);
                        if (owner == UMUTEX_CONTESTED)
                                return (0);

                        /* The address was invalid. */
                        if (owner == -1)
                                return (EFAULT);

                        error = thread_check_susp(td, false);
                        if (error != 0)
                                break;

                        /* If this failed the lock has changed, restart. */
                        continue;
                }

                /*
                 * If we caught a signal, we have retried and now
                 * exit immediately.
                 */
                if (error != 0)
                        return (error);

                if ((error = umtx_key_get(m, TYPE_SIMPLE_LOCK,
                        AUTO_SHARE, &uq->uq_key)) != 0)
                        return (error);

                umtxq_lock(&uq->uq_key);
                umtxq_busy(&uq->uq_key);
                umtxq_insert(uq);
                umtxq_unbusy(&uq->uq_key);
                umtxq_unlock(&uq->uq_key);

                /*
                 * Set the contested bit so that a release in user space
                 * knows to use the system call for unlock.  If this fails
                 * either some one else has acquired the lock or it has been
                 * released.
                 */
                old = casuword32(m, owner, owner | UMUTEX_CONTESTED);

                /* The address was invalid. */
                if (old == -1) {
                        umtxq_lock(&uq->uq_key);
                        umtxq_remove(uq);
                        umtxq_unlock(&uq->uq_key);
                        umtx_key_release(&uq->uq_key);
                        return (EFAULT);
                }

                /*
                 * We set the contested bit, sleep. Otherwise the lock changed
                 * and we need to retry or we lost a race to the thread
                 * unlocking the umtx.
                 */
                umtxq_lock(&uq->uq_key);
                if (old == owner)
                        error = umtxq_sleep(uq, "umtx", timeout == NULL ?
                            NULL : &timo);
                umtxq_remove(uq);
                umtxq_unlock(&uq->uq_key);
                umtx_key_release(&uq->uq_key);

                if (error == 0)
                        error = thread_check_susp(td, false);
        }

        if (timeout == NULL) {
                /* Mutex locking is restarted if it is interrupted. */
                if (error == EINTR)
                        error = ERESTART;
        } else {
                /* Timed-locking is not restarted. */
                if (error == ERESTART)
                        error = EINTR;
        }
        return (error);
}

/*
 * Unlock a umtx object.
 */
static int
do_unlock_umtx32(struct thread *td, uint32_t *m, uint32_t id)
{
        struct umtx_key key;
        uint32_t owner;
        uint32_t old;
        int error;
        int count;

        /*
         * Make sure we own this mtx.
         */
        owner = fuword32(m);
        if (owner == -1)
                return (EFAULT);

        if ((owner & ~UMUTEX_CONTESTED) != id)
                return (EPERM);

        /* This should be done in userland */
        if ((owner & UMUTEX_CONTESTED) == 0) {
                old = casuword32(m, owner, UMUTEX_UNOWNED);
                if (old == -1)
                        return (EFAULT);
                if (old == owner)
                        return (0);
                owner = old;
        }

        /* We should only ever be in here for contested locks */
        if ((error = umtx_key_get(m, TYPE_SIMPLE_LOCK, AUTO_SHARE,
                &key)) != 0)
                return (error);

        umtxq_lock(&key);
        umtxq_busy(&key);
        count = umtxq_count(&key);
        umtxq_unlock(&key);

        /*
         * When unlocking the umtx, it must be marked as unowned if
         * there is zero or one thread only waiting for it.
         * Otherwise, it must be marked as contested.
         */
        old = casuword32(m, owner,
                count <= 1 ? UMUTEX_UNOWNED : UMUTEX_CONTESTED);
        umtxq_lock(&key);
        umtxq_signal(&key,1);
        umtxq_unbusy(&key);
        umtxq_unlock(&key);
        umtx_key_release(&key);
        if (old == -1)
                return (EFAULT);
        if (old != owner)
                return (EINVAL);
        return (0);
}
#endif  /* COMPAT_FREEBSD32 */
#endif  /* COMPAT_FREEBSD10 */

/*
 * Fetch and compare value, sleep on the address if value is not changed.
 */
static int
do_wait(struct thread *td, void *addr, u_long id,
    struct _umtx_time *timeout, int compat32, int is_private)
{
        struct umtx_abs_timeout timo;
        struct umtx_q *uq;
        u_long tmp;
        uint32_t tmp32;
        int error = 0;

        uq = td->td_umtxq;
        if ((error = umtx_key_get(addr, TYPE_SIMPLE_WAIT,
            is_private ? THREAD_SHARE : AUTO_SHARE, &uq->uq_key)) != 0)
                return (error);

        if (timeout != NULL)
                umtx_abs_timeout_init2(&timo, timeout);

        umtxq_lock(&uq->uq_key);
        umtxq_insert(uq);
        umtxq_unlock(&uq->uq_key);
        if (compat32 == 0) {
                error = fueword(addr, &tmp);
                if (error != 0)
                        error = EFAULT;
        } else {
                error = fueword32(addr, &tmp32);
                if (error == 0)
                        tmp = tmp32;
                else
                        error = EFAULT;
        }
        umtxq_lock(&uq->uq_key);
        if (error == 0) {
                if (tmp == id)
                        error = umtxq_sleep(uq, "uwait", timeout == NULL ?
                            NULL : &timo);
                if ((uq->uq_flags & UQF_UMTXQ) == 0)
                        error = 0;
                else
                        umtxq_remove(uq);
        } else if ((uq->uq_flags & UQF_UMTXQ) != 0) {
                umtxq_remove(uq);
        }
        umtxq_unlock(&uq->uq_key);
        umtx_key_release(&uq->uq_key);
        if (error == ERESTART)
                error = EINTR;
        return (error);
}

/*
 * Wake up threads sleeping on the specified address.
 */
int
kern_umtx_wake(struct thread *td, void *uaddr, int n_wake, int is_private)
{
        struct umtx_key key;
        int ret;

        if ((ret = umtx_key_get(uaddr, TYPE_SIMPLE_WAIT,
            is_private ? THREAD_SHARE : AUTO_SHARE, &key)) != 0)
                return (ret);
        umtxq_lock(&key);
        umtxq_signal(&key, n_wake);
        umtxq_unlock(&key);
        umtx_key_release(&key);
        return (0);
}

/*
 * Lock PTHREAD_PRIO_NONE protocol POSIX mutex.
 */
static int
do_lock_normal(struct thread *td, struct umutex *m, uint32_t flags,
    struct _umtx_time *timeout, int mode)
{
        struct umtx_abs_timeout timo;
        struct umtx_q *uq;
        uint32_t owner, old, id;
        int error, rv;

        id = td->td_tid;
        uq = td->td_umtxq;
        error = 0;
        if (timeout != NULL)
                umtx_abs_timeout_init2(&timo, timeout);

        /*
         * Care must be exercised when dealing with umtx structure. It
         * can fault on any access.
         */
        for (;;) {
                rv = fueword32(&m->m_owner, &owner);
                if (rv == -1)
                        return (EFAULT);
                if (mode == _UMUTEX_WAIT) {
                        if (owner == UMUTEX_UNOWNED ||
                            owner == UMUTEX_CONTESTED ||
                            owner == UMUTEX_RB_OWNERDEAD ||
                            owner == UMUTEX_RB_NOTRECOV)
                                return (0);
                } else {
                        /*
                         * Robust mutex terminated.  Kernel duty is to
                         * return EOWNERDEAD to the userspace.  The
                         * umutex.m_flags UMUTEX_NONCONSISTENT is set
                         * by the common userspace code.
                         */
                        if (owner == UMUTEX_RB_OWNERDEAD) {
                                rv = casueword32(&m->m_owner,
                                    UMUTEX_RB_OWNERDEAD, &owner,
                                    id | UMUTEX_CONTESTED);
                                if (rv == -1)
                                        return (EFAULT);
                                if (rv == 0) {
                                        MPASS(owner == UMUTEX_RB_OWNERDEAD);
                                        return (EOWNERDEAD); /* success */
                                }
                                MPASS(rv == 1);
                                rv = thread_check_susp(td, false);
                                if (rv != 0)
                                        return (rv);
                                continue;
                        }
                        if (owner == UMUTEX_RB_NOTRECOV)
                                return (ENOTRECOVERABLE);

                        /*
                         * Try the uncontested case.  This should be
                         * done in userland.
                         */
                        rv = casueword32(&m->m_owner, UMUTEX_UNOWNED,
                            &owner, id);
                        /* The address was invalid. */
                        if (rv == -1)
                                return (EFAULT);

                        /* The acquire succeeded. */
                        if (rv == 0) {
                                MPASS(owner == UMUTEX_UNOWNED);
                                return (0);
                        }

                        /*
                         * If no one owns it but it is contested try
                         * to acquire it.
                         */
                        MPASS(rv == 1);
                        if (owner == UMUTEX_CONTESTED) {
                                rv = casueword32(&m->m_owner,
                                    UMUTEX_CONTESTED, &owner,
                                    id | UMUTEX_CONTESTED);
                                /* The address was invalid. */
                                if (rv == -1)
                                        return (EFAULT);
                                if (rv == 0) {
                                        MPASS(owner == UMUTEX_CONTESTED);
                                        return (0);
                                }
                                if (rv == 1) {
                                        rv = thread_check_susp(td, false);
                                        if (rv != 0)
                                                return (rv);
                                }

                                /*
                                 * If this failed the lock has
                                 * changed, restart.
                                 */
                                continue;
                        }

                        /* rv == 1 but not contested, likely store failure */
                        rv = thread_check_susp(td, false);
                        if (rv != 0)
                                return (rv);
                }

                if (mode == _UMUTEX_TRY)
                        return (EBUSY);

                /*
                 * If we caught a signal, we have retried and now
                 * exit immediately.
                 */
                if (error != 0)
                        return (error);

                if ((error = umtx_key_get(m, TYPE_NORMAL_UMUTEX,
                    GET_SHARE(flags), &uq->uq_key)) != 0)
                        return (error);

                umtxq_lock(&uq->uq_key);
                umtxq_busy(&uq->uq_key);
                umtxq_insert(uq);
                umtxq_unlock(&uq->uq_key);

                /*
                 * Set the contested bit so that a release in user space
                 * knows to use the system call for unlock.  If this fails
                 * either some one else has acquired the lock or it has been
                 * released.
                 */
                rv = casueword32(&m->m_owner, owner, &old,
                    owner | UMUTEX_CONTESTED);

                /* The address was invalid or casueword failed to store. */
                if (rv == -1 || rv == 1) {
                        umtxq_lock(&uq->uq_key);
                        umtxq_remove(uq);
                        umtxq_unbusy(&uq->uq_key);
                        umtxq_unlock(&uq->uq_key);
                        umtx_key_release(&uq->uq_key);
                        if (rv == -1)
                                return (EFAULT);
                        if (rv == 1) {
                                rv = thread_check_susp(td, false);
                                if (rv != 0)
                                        return (rv);
                        }
                        continue;
                }

                /*
                 * We set the contested bit, sleep. Otherwise the lock changed
                 * and we need to retry or we lost a race to the thread
                 * unlocking the umtx.
                 */
                umtxq_lock(&uq->uq_key);
                umtxq_unbusy(&uq->uq_key);
                MPASS(old == owner);
                error = umtxq_sleep(uq, "umtxn", timeout == NULL ?
                    NULL : &timo);
                umtxq_remove(uq);
                umtxq_unlock(&uq->uq_key);
                umtx_key_release(&uq->uq_key);

                if (error == 0)
                        error = thread_check_susp(td, false);
        }

        return (0);
}

/*
 * Unlock PTHREAD_PRIO_NONE protocol POSIX mutex.
 */
static int
do_unlock_normal(struct thread *td, struct umutex *m, uint32_t flags, bool rb)
{
        struct umtx_key key;
        uint32_t owner, old, id, newlock;
        int error, count;

        id = td->td_tid;

again:
        /*
         * Make sure we own this mtx.
         */
        error = fueword32(&m->m_owner, &owner);
        if (error == -1)
                return (EFAULT);

        if ((owner & ~UMUTEX_CONTESTED) != id)
                return (EPERM);

        newlock = umtx_unlock_val(flags, rb);
        if ((owner & UMUTEX_CONTESTED) == 0) {
                error = casueword32(&m->m_owner, owner, &old, newlock);
                if (error == -1)
                        return (EFAULT);
                if (error == 1) {
                        error = thread_check_susp(td, false);
                        if (error != 0)
                                return (error);
                        goto again;
                }
                MPASS(old == owner);
                return (0);
        }

        /* We should only ever be in here for contested locks */
        if ((error = umtx_key_get(m, TYPE_NORMAL_UMUTEX, GET_SHARE(flags),
            &key)) != 0)
                return (error);

        umtxq_lock(&key);
        umtxq_busy(&key);
        count = umtxq_count(&key);
        umtxq_unlock(&key);

        /*
         * When unlocking the umtx, it must be marked as unowned if
         * there is zero or one thread only waiting for it.
         * Otherwise, it must be marked as contested.
         */
        if (count > 1)
                newlock |= UMUTEX_CONTESTED;
        error = casueword32(&m->m_owner, owner, &old, newlock);
        umtxq_lock(&key);
        umtxq_signal(&key, 1);
        umtxq_unbusy(&key);
        umtxq_unlock(&key);
        umtx_key_release(&key);
        if (error == -1)
                return (EFAULT);
        if (error == 1) {
                if (old != owner)
                        return (EINVAL);
                error = thread_check_susp(td, false);
                if (error != 0)
                        return (error);
                goto again;
        }
        return (0);
}

/*
 * Check if the mutex is available and wake up a waiter,
 * only for simple mutex.
 */
static int
do_wake_umutex(struct thread *td, struct umutex *m)
{
        struct umtx_key key;
        uint32_t owner;
        uint32_t flags;
        int error;
        int count;

again:
        error = fueword32(&m->m_owner, &owner);
        if (error == -1)
                return (EFAULT);

        if ((owner & ~UMUTEX_CONTESTED) != 0 && owner != UMUTEX_RB_OWNERDEAD &&
            owner != UMUTEX_RB_NOTRECOV)
                return (0);

        error = fueword32(&m->m_flags, &flags);
        if (error == -1)
                return (EFAULT);

        /* We should only ever be in here for contested locks */
        if ((error = umtx_key_get(m, TYPE_NORMAL_UMUTEX, GET_SHARE(flags),
            &key)) != 0)
                return (error);

        umtxq_lock(&key);
        umtxq_busy(&key);
        count = umtxq_count(&key);
        umtxq_unlock(&key);

        if (count <= 1 && owner != UMUTEX_RB_OWNERDEAD &&
            owner != UMUTEX_RB_NOTRECOV) {
                error = casueword32(&m->m_owner, UMUTEX_CONTESTED, &owner,
                    UMUTEX_UNOWNED);
                if (error == -1) {
                        error = EFAULT;
                } else if (error == 1) {
                        umtxq_lock(&key);
                        umtxq_unbusy(&key);
                        umtxq_unlock(&key);
                        umtx_key_release(&key);
                        error = thread_check_susp(td, false);
                        if (error != 0)
                                return (error);
                        goto again;
                }
        }

        umtxq_lock(&key);
        if (error == 0 && count != 0) {
                MPASS((owner & ~UMUTEX_CONTESTED) == 0 ||
                    owner == UMUTEX_RB_OWNERDEAD ||
                    owner == UMUTEX_RB_NOTRECOV);
                umtxq_signal(&key, 1);
        }
        umtxq_unbusy(&key);
        umtxq_unlock(&key);
        umtx_key_release(&key);
        return (error);
}

/*
 * Check if the mutex has waiters and tries to fix contention bit.
 */
static int
do_wake2_umutex(struct thread *td, struct umutex *m, uint32_t flags)
{
        struct umtx_key key;
        uint32_t owner, old;
        int type;
        int error;
        int count;

        switch (flags & (UMUTEX_PRIO_INHERIT | UMUTEX_PRIO_PROTECT |
            UMUTEX_ROBUST)) {
        case 0:
        case UMUTEX_ROBUST:
                type = TYPE_NORMAL_UMUTEX;
                break;
        case UMUTEX_PRIO_INHERIT:
                type = TYPE_PI_UMUTEX;
                break;
        case (UMUTEX_PRIO_INHERIT | UMUTEX_ROBUST):
                type = TYPE_PI_ROBUST_UMUTEX;
                break;
        case UMUTEX_PRIO_PROTECT:
                type = TYPE_PP_UMUTEX;
                break;
        case (UMUTEX_PRIO_PROTECT | UMUTEX_ROBUST):
                type = TYPE_PP_ROBUST_UMUTEX;
                break;
        default:
                return (EINVAL);
        }
        if ((error = umtx_key_get(m, type, GET_SHARE(flags), &key)) != 0)
                return (error);

        owner = 0;
        umtxq_lock(&key);
        umtxq_busy(&key);
        count = umtxq_count(&key);
        umtxq_unlock(&key);

        error = fueword32(&m->m_owner, &owner);
        if (error == -1)
                error = EFAULT;

        /*
         * Only repair contention bit if there is a waiter, this means
         * the mutex is still being referenced by userland code,
         * otherwise don't update any memory.
         */
        while (error == 0 && (owner & UMUTEX_CONTESTED) == 0 &&
            (count > 1 || (count == 1 && (owner & ~UMUTEX_CONTESTED) != 0))) {
                error = casueword32(&m->m_owner, owner, &old,
                    owner | UMUTEX_CONTESTED);
                if (error == -1) {
                        error = EFAULT;
                        break;
                }
                if (error == 0) {
                        MPASS(old == owner);
                        break;
                }
                owner = old;
                error = thread_check_susp(td, false);
        }

        umtxq_lock(&key);
        if (error == EFAULT) {
                umtxq_signal(&key, INT_MAX);
        } else if (count != 0 && ((owner & ~UMUTEX_CONTESTED) == 0 ||
            owner == UMUTEX_RB_OWNERDEAD || owner == UMUTEX_RB_NOTRECOV))
                umtxq_signal(&key, 1);
        umtxq_unbusy(&key);
        umtxq_unlock(&key);
        umtx_key_release(&key);
        return (error);
}

struct umtx_pi *
umtx_pi_alloc(int flags)
{
        struct umtx_pi *pi;

        pi = uma_zalloc(umtx_pi_zone, M_ZERO | flags);
        if (pi == NULL)
                return (NULL);

        TAILQ_INIT(&pi->pi_blocked);
        atomic_add_int(&umtx_pi_allocated, 1);
        return (pi);
}

void
umtx_pi_free(struct umtx_pi *pi)
{
        uma_zfree(umtx_pi_zone, pi);
        atomic_add_int(&umtx_pi_allocated, -1);
}

/*
 * Adjust the thread's position on a pi_state after its priority has been
 * changed.
 */
static int
umtx_pi_adjust_thread(struct umtx_pi *pi, struct thread *td)
{
        struct umtx_q *uq, *uq1, *uq2;
        struct thread *td1;

        mtx_assert(&umtx_lock, MA_OWNED);
        if (pi == NULL)
                return (0);

        uq = td->td_umtxq;

        /*
         * Check if the thread needs to be moved on the blocked chain.
         * It needs to be moved if either its priority is lower than
         * the previous thread or higher than the next thread.
         */
        uq1 = TAILQ_PREV(uq, umtxq_head, uq_lockq);
        uq2 = TAILQ_NEXT(uq, uq_lockq);
        if ((uq1 != NULL && UPRI(td) < UPRI(uq1->uq_thread)) ||
            (uq2 != NULL && UPRI(td) > UPRI(uq2->uq_thread))) {
                /*
                 * Remove thread from blocked chain and determine where
                 * it should be moved to.
                 */
                TAILQ_REMOVE(&pi->pi_blocked, uq, uq_lockq);
                TAILQ_FOREACH(uq1, &pi->pi_blocked, uq_lockq) {
                        td1 = uq1->uq_thread;
                        MPASS(td1->td_proc->p_magic == P_MAGIC);
                        if (UPRI(td1) > UPRI(td))
                                break;
                }

                if (uq1 == NULL)
                        TAILQ_INSERT_TAIL(&pi->pi_blocked, uq, uq_lockq);
                else
                        TAILQ_INSERT_BEFORE(uq1, uq, uq_lockq);
        }
        return (1);
}

static struct umtx_pi *
umtx_pi_next(struct umtx_pi *pi)
{
        struct umtx_q *uq_owner;

        if (pi->pi_owner == NULL)
                return (NULL);
        uq_owner = pi->pi_owner->td_umtxq;
        if (uq_owner == NULL)
                return (NULL);
        return (uq_owner->uq_pi_blocked);
}

/*
 * Floyd's Cycle-Finding Algorithm.
 */
static bool
umtx_pi_check_loop(struct umtx_pi *pi)
{
        struct umtx_pi *pi1;    /* fast iterator */

        mtx_assert(&umtx_lock, MA_OWNED);
        if (pi == NULL)
                return (false);
        pi1 = pi;
        for (;;) {
                pi = umtx_pi_next(pi);
                if (pi == NULL)
                        break;
                pi1 = umtx_pi_next(pi1);
                if (pi1 == NULL)
                        break;
                pi1 = umtx_pi_next(pi1);
                if (pi1 == NULL)
                        break;
                if (pi == pi1)
                        return (true);
        }
        return (false);
}

/*
 * Propagate priority when a thread is blocked on POSIX
 * PI mutex.
 */
static void
umtx_propagate_priority(struct thread *td)
{
        struct umtx_q *uq;
        struct umtx_pi *pi;
        int pri;

        mtx_assert(&umtx_lock, MA_OWNED);
        pri = UPRI(td);
        uq = td->td_umtxq;
        pi = uq->uq_pi_blocked;
        if (pi == NULL)
                return;
        if (umtx_pi_check_loop(pi))
                return;

        for (;;) {
                td = pi->pi_owner;
                if (td == NULL || td == curthread)
                        return;

                MPASS(td->td_proc != NULL);
                MPASS(td->td_proc->p_magic == P_MAGIC);

                thread_lock(td);
                if (td->td_lend_user_pri > pri)
                        sched_lend_user_prio(td, pri);
                else {
                        thread_unlock(td);
                        break;
                }
                thread_unlock(td);

                /*
                 * Pick up the lock that td is blocked on.
                 */
                uq = td->td_umtxq;
                pi = uq->uq_pi_blocked;
                if (pi == NULL)
                        break;
                /* Resort td on the list if needed. */
                umtx_pi_adjust_thread(pi, td);
        }
}

/*
 * Unpropagate priority for a PI mutex when a thread blocked on
 * it is interrupted by signal or resumed by others.
 */
static void
umtx_repropagate_priority(struct umtx_pi *pi)
{
        struct umtx_q *uq, *uq_owner;
        struct umtx_pi *pi2;
        int pri;

        mtx_assert(&umtx_lock, MA_OWNED);

        if (umtx_pi_check_loop(pi))
                return;
        while (pi != NULL && pi->pi_owner != NULL) {
                pri = PRI_MAX;
                uq_owner = pi->pi_owner->td_umtxq;

                TAILQ_FOREACH(pi2, &uq_owner->uq_pi_contested, pi_link) {
                        uq = TAILQ_FIRST(&pi2->pi_blocked);
                        if (uq != NULL) {
                                if (pri > UPRI(uq->uq_thread))
                                        pri = UPRI(uq->uq_thread);
                        }
                }

                if (pri > uq_owner->uq_inherited_pri)
                        pri = uq_owner->uq_inherited_pri;
                thread_lock(pi->pi_owner);
                sched_lend_user_prio(pi->pi_owner, pri);
                thread_unlock(pi->pi_owner);
                if ((pi = uq_owner->uq_pi_blocked) != NULL)
                        umtx_pi_adjust_thread(pi, uq_owner->uq_thread);
        }
}

/*
 * Insert a PI mutex into owned list.
 */
static void
umtx_pi_setowner(struct umtx_pi *pi, struct thread *owner)
{
        struct umtx_q *uq_owner;

        uq_owner = owner->td_umtxq;
        mtx_assert(&umtx_lock, MA_OWNED);
        MPASS(pi->pi_owner == NULL);
        pi->pi_owner = owner;
        TAILQ_INSERT_TAIL(&uq_owner->uq_pi_contested, pi, pi_link);
}

/*
 * Disown a PI mutex, and remove it from the owned list.
 */
static void
umtx_pi_disown(struct umtx_pi *pi)
{

        mtx_assert(&umtx_lock, MA_OWNED);
        TAILQ_REMOVE(&pi->pi_owner->td_umtxq->uq_pi_contested, pi, pi_link);
        pi->pi_owner = NULL;
}

/*
 * Claim ownership of a PI mutex.
 */
int
umtx_pi_claim(struct umtx_pi *pi, struct thread *owner)
{
        struct umtx_q *uq;
        int pri;

        mtx_lock(&umtx_lock);
        if (pi->pi_owner == owner) {
                mtx_unlock(&umtx_lock);
                return (0);
        }

        if (pi->pi_owner != NULL) {
                /*
                 * userland may have already messed the mutex, sigh.
                 */
                mtx_unlock(&umtx_lock);
                return (EPERM);
        }
        umtx_pi_setowner(pi, owner);
        uq = TAILQ_FIRST(&pi->pi_blocked);
        if (uq != NULL) {
                pri = UPRI(uq->uq_thread);
                thread_lock(owner);
                if (pri < UPRI(owner))
                        sched_lend_user_prio(owner, pri);
                thread_unlock(owner);
        }
        mtx_unlock(&umtx_lock);
        return (0);
}

/*
 * Adjust a thread's order position in its blocked PI mutex,
 * this may result new priority propagating process.
 */
void
umtx_pi_adjust(struct thread *td, u_char oldpri)
{
        struct umtx_q *uq;
        struct umtx_pi *pi;

        uq = td->td_umtxq;
        mtx_lock(&umtx_lock);
        /*
         * Pick up the lock that td is blocked on.
         */
        pi = uq->uq_pi_blocked;
        if (pi != NULL) {
                umtx_pi_adjust_thread(pi, td);
                umtx_repropagate_priority(pi);
        }
        mtx_unlock(&umtx_lock);
}

/*
 * Sleep on a PI mutex.
 */
int
umtxq_sleep_pi(struct umtx_q *uq, struct umtx_pi *pi, uint32_t owner,
    const char *wmesg, struct umtx_abs_timeout *timo, bool shared)
{
        struct thread *td, *td1;
        struct umtx_q *uq1;
        int error, pri;
#ifdef INVARIANTS
        struct umtxq_chain *uc;

        uc = umtxq_getchain(&pi->pi_key);
#endif
        error = 0;
        td = uq->uq_thread;
        KASSERT(td == curthread, ("inconsistent uq_thread"));
        UMTXQ_LOCKED_ASSERT(umtxq_getchain(&uq->uq_key));
        KASSERT(uc->uc_busy != 0, ("umtx chain is not busy"));
        umtxq_insert(uq);
        mtx_lock(&umtx_lock);
        if (pi->pi_owner == NULL) {
                mtx_unlock(&umtx_lock);
                td1 = tdfind(owner, shared ? -1 : td->td_proc->p_pid);
                mtx_lock(&umtx_lock);
                if (td1 != NULL) {
                        if (pi->pi_owner == NULL)
                                umtx_pi_setowner(pi, td1);
                        PROC_UNLOCK(td1->td_proc);
                }
        }

        TAILQ_FOREACH(uq1, &pi->pi_blocked, uq_lockq) {
                pri = UPRI(uq1->uq_thread);
                if (pri > UPRI(td))
                        break;
        }

        if (uq1 != NULL)
                TAILQ_INSERT_BEFORE(uq1, uq, uq_lockq);
        else
                TAILQ_INSERT_TAIL(&pi->pi_blocked, uq, uq_lockq);

        uq->uq_pi_blocked = pi;
        thread_lock(td);
        td->td_flags |= TDF_UPIBLOCKED;
        thread_unlock(td);
        umtx_propagate_priority(td);
        mtx_unlock(&umtx_lock);
        umtxq_unbusy(&uq->uq_key);

        error = umtxq_sleep(uq, wmesg, timo);
        umtxq_remove(uq);

        mtx_lock(&umtx_lock);
        uq->uq_pi_blocked = NULL;
        thread_lock(td);
        td->td_flags &= ~TDF_UPIBLOCKED;
        thread_unlock(td);
        TAILQ_REMOVE(&pi->pi_blocked, uq, uq_lockq);
        umtx_repropagate_priority(pi);
        mtx_unlock(&umtx_lock);
        umtxq_unlock(&uq->uq_key);

        return (error);
}

/*
 * Add reference count for a PI mutex.
 */
void
umtx_pi_ref(struct umtx_pi *pi)
{

        UMTXQ_LOCKED_ASSERT(umtxq_getchain(&pi->pi_key));
        pi->pi_refcount++;
}

/*
 * Decrease reference count for a PI mutex, if the counter
 * is decreased to zero, its memory space is freed.
 */
void
umtx_pi_unref(struct umtx_pi *pi)
{
        struct umtxq_chain *uc;

        uc = umtxq_getchain(&pi->pi_key);
        UMTXQ_LOCKED_ASSERT(uc);
        KASSERT(pi->pi_refcount > 0, ("invalid reference count"));
        if (--pi->pi_refcount == 0) {
                mtx_lock(&umtx_lock);
                if (pi->pi_owner != NULL)
                        umtx_pi_disown(pi);
                KASSERT(TAILQ_EMPTY(&pi->pi_blocked),
                        ("blocked queue not empty"));
                mtx_unlock(&umtx_lock);
                TAILQ_REMOVE(&uc->uc_pi_list, pi, pi_hashlink);
                umtx_pi_free(pi);
        }
}

/*
 * Find a PI mutex in hash table.
 */
struct umtx_pi *
umtx_pi_lookup(struct umtx_key *key)
{
        struct umtxq_chain *uc;
        struct umtx_pi *pi;

        uc = umtxq_getchain(key);
        UMTXQ_LOCKED_ASSERT(uc);

        TAILQ_FOREACH(pi, &uc->uc_pi_list, pi_hashlink) {
                if (umtx_key_match(&pi->pi_key, key)) {
                        return (pi);
                }
        }
        return (NULL);
}

/*
 * Insert a PI mutex into hash table.
 */
void
umtx_pi_insert(struct umtx_pi *pi)
{
        struct umtxq_chain *uc;

        uc = umtxq_getchain(&pi->pi_key);
        UMTXQ_LOCKED_ASSERT(uc);
        TAILQ_INSERT_TAIL(&uc->uc_pi_list, pi, pi_hashlink);
}

/*
 * Drop a PI mutex and wakeup a top waiter.
 */
int
umtx_pi_drop(struct thread *td, struct umtx_key *key, bool rb, int *count)
{
        struct umtx_q *uq_first, *uq_first2, *uq_me;
        struct umtx_pi *pi, *pi2;
        int pri;

        UMTXQ_ASSERT_LOCKED_BUSY(key);
        *count = umtxq_count_pi(key, &uq_first);
        if (uq_first != NULL) {
                mtx_lock(&umtx_lock);
                pi = uq_first->uq_pi_blocked;
                KASSERT(pi != NULL, ("pi == NULL?"));
                if (pi->pi_owner != td && !(rb && pi->pi_owner == NULL)) {
                        mtx_unlock(&umtx_lock);
                        /* userland messed the mutex */
                        return (EPERM);
                }
                uq_me = td->td_umtxq;
                if (pi->pi_owner == td)
                        umtx_pi_disown(pi);
                /* get highest priority thread which is still sleeping. */
                uq_first = TAILQ_FIRST(&pi->pi_blocked);
                while (uq_first != NULL &&
                    (uq_first->uq_flags & UQF_UMTXQ) == 0) {
                        uq_first = TAILQ_NEXT(uq_first, uq_lockq);
                }
                pri = PRI_MAX;
                TAILQ_FOREACH(pi2, &uq_me->uq_pi_contested, pi_link) {
                        uq_first2 = TAILQ_FIRST(&pi2->pi_blocked);
                        if (uq_first2 != NULL) {
                                if (pri > UPRI(uq_first2->uq_thread))
                                        pri = UPRI(uq_first2->uq_thread);
                        }
                }
                thread_lock(td);
                sched_lend_user_prio(td, pri);
                thread_unlock(td);
                mtx_unlock(&umtx_lock);
                if (uq_first)
                        umtxq_signal_thread(uq_first);
        } else {
                pi = umtx_pi_lookup(key);
                /*
                 * A umtx_pi can exist if a signal or timeout removed the
                 * last waiter from the umtxq, but there is still
                 * a thread in do_lock_pi() holding the umtx_pi.
                 */
                if (pi != NULL) {
                        /*
                         * The umtx_pi can be unowned, such as when a thread
                         * has just entered do_lock_pi(), allocated the
                         * umtx_pi, and unlocked the umtxq.
                         * If the current thread owns it, it must disown it.
                         */
                        mtx_lock(&umtx_lock);
                        if (pi->pi_owner == td)
                                umtx_pi_disown(pi);
                        mtx_unlock(&umtx_lock);
                }
        }
        return (0);
}

/*
 * Lock a PI mutex.
 */
static int
do_lock_pi(struct thread *td, struct umutex *m, uint32_t flags,
    struct _umtx_time *timeout, int try)
{
        struct umtx_abs_timeout timo;
        struct umtx_q *uq;
        struct umtx_pi *pi, *new_pi;
        uint32_t id, old_owner, owner, old;
        int error, rv;

        id = td->td_tid;
        uq = td->td_umtxq;

        if ((error = umtx_key_get(m, (flags & UMUTEX_ROBUST) != 0 ?
            TYPE_PI_ROBUST_UMUTEX : TYPE_PI_UMUTEX, GET_SHARE(flags),
            &uq->uq_key)) != 0)
                return (error);

        if (timeout != NULL)
                umtx_abs_timeout_init2(&timo, timeout);

        umtxq_lock(&uq->uq_key);
        pi = umtx_pi_lookup(&uq->uq_key);
        if (pi == NULL) {
                new_pi = umtx_pi_alloc(M_NOWAIT);
                if (new_pi == NULL) {
                        umtxq_unlock(&uq->uq_key);
                        new_pi = umtx_pi_alloc(M_WAITOK);
                        umtxq_lock(&uq->uq_key);
                        pi = umtx_pi_lookup(&uq->uq_key);
                        if (pi != NULL) {
                                umtx_pi_free(new_pi);
                                new_pi = NULL;
                        }
                }
                if (new_pi != NULL) {
                        new_pi->pi_key = uq->uq_key;
                        umtx_pi_insert(new_pi);
                        pi = new_pi;
                }
        }
        umtx_pi_ref(pi);
        umtxq_unlock(&uq->uq_key);

        /*
         * Care must be exercised when dealing with umtx structure.  It
         * can fault on any access.
         */
        for (;;) {
                /*
                 * Try the uncontested case.  This should be done in userland.
                 */
                rv = casueword32(&m->m_owner, UMUTEX_UNOWNED, &owner, id);
                /* The address was invalid. */
                if (rv == -1) {
                        error = EFAULT;
                        break;
                }
                /* The acquire succeeded. */
                if (rv == 0) {
                        MPASS(owner == UMUTEX_UNOWNED);
                        error = 0;
                        break;
                }

                if (owner == UMUTEX_RB_NOTRECOV) {
                        error = ENOTRECOVERABLE;
                        break;
                }

                /*
                 * Nobody owns it, but the acquire failed. This can happen
                 * with ll/sc atomics.
                 */
                if (owner == UMUTEX_UNOWNED) {
                        error = thread_check_susp(td, true);
                        if (error != 0)
                                break;
                        continue;
                }

                /*
                 * Avoid overwriting a possible error from sleep due
                 * to the pending signal with suspension check result.
                 */
                if (error == 0) {
                        error = thread_check_susp(td, true);
                        if (error != 0)
                                break;
                }

                /* If no one owns it but it is contested try to acquire it. */
                if (owner == UMUTEX_CONTESTED || owner == UMUTEX_RB_OWNERDEAD) {
                        old_owner = owner;
                        rv = casueword32(&m->m_owner, owner, &owner,
                            id | UMUTEX_CONTESTED);
                        /* The address was invalid. */
                        if (rv == -1) {
                                error = EFAULT;
                                break;
                        }
                        if (rv == 1) {
                                if (error == 0) {
                                        error = thread_check_susp(td, true);
                                        if (error != 0)
                                                break;
                                }

                                /*
                                 * If this failed the lock could
                                 * changed, restart.
                                 */
                                continue;
                        }

                        MPASS(rv == 0);
                        MPASS(owner == old_owner);
                        umtxq_lock(&uq->uq_key);
                        umtxq_busy(&uq->uq_key);
                        error = umtx_pi_claim(pi, td);
                        umtxq_unbusy(&uq->uq_key);
                        umtxq_unlock(&uq->uq_key);
                        if (error != 0) {
                                /*
                                 * Since we're going to return an
                                 * error, restore the m_owner to its
                                 * previous, unowned state to avoid
                                 * compounding the problem.
                                 */
                                (void)casuword32(&m->m_owner,
                                    id | UMUTEX_CONTESTED, old_owner);
                        }
                        if (error == 0 && old_owner == UMUTEX_RB_OWNERDEAD)
                                error = EOWNERDEAD;
                        break;
                }

                if ((owner & ~UMUTEX_CONTESTED) == id) {
                        error = EDEADLK;
                        break;
                }

                if (try != 0) {
                        error = EBUSY;
                        break;
                }

                /*
                 * If we caught a signal, we have retried and now
                 * exit immediately.
                 */
                if (error != 0)
                        break;

                umtxq_busy_unlocked(&uq->uq_key);

                /*
                 * Set the contested bit so that a release in user space
                 * knows to use the system call for unlock.  If this fails
                 * either some one else has acquired the lock or it has been
                 * released.
                 */
                rv = casueword32(&m->m_owner, owner, &old, owner |
                    UMUTEX_CONTESTED);

                /* The address was invalid. */
                if (rv == -1) {
                        umtxq_unbusy_unlocked(&uq->uq_key);
                        error = EFAULT;
                        break;
                }
                if (rv == 1) {
                        umtxq_unbusy_unlocked(&uq->uq_key);
                        error = thread_check_susp(td, true);
                        if (error != 0)
                                break;

                        /*
                         * The lock changed and we need to retry or we
                         * lost a race to the thread unlocking the
                         * umtx.  Note that the UMUTEX_RB_OWNERDEAD
                         * value for owner is impossible there.
                         */
                        continue;
                }

                umtxq_lock(&uq->uq_key);

                /* We set the contested bit, sleep. */
                MPASS(old == owner);
                error = umtxq_sleep_pi(uq, pi, owner & ~UMUTEX_CONTESTED,
                    "umtxpi", timeout == NULL ? NULL : &timo,
                    (flags & USYNC_PROCESS_SHARED) != 0);
                if (error != 0)
                        continue;

                error = thread_check_susp(td, false);
                if (error != 0)
                        break;
        }

        umtxq_lock(&uq->uq_key);
        umtx_pi_unref(pi);
        umtxq_unlock(&uq->uq_key);

        umtx_key_release(&uq->uq_key);
        return (error);
}

/*
 * Unlock a PI mutex.
 */
static int
do_unlock_pi(struct thread *td, struct umutex *m, uint32_t flags, bool rb)
{
        struct umtx_key key;
        uint32_t id, new_owner, old, owner;
        int count, error;

        id = td->td_tid;

usrloop:
        /*
         * Make sure we own this mtx.
         */
        error = fueword32(&m->m_owner, &owner);
        if (error == -1)
                return (EFAULT);

        if ((owner & ~UMUTEX_CONTESTED) != id)
                return (EPERM);

        new_owner = umtx_unlock_val(flags, rb);

        /* This should be done in userland */
        if ((owner & UMUTEX_CONTESTED) == 0) {
                error = casueword32(&m->m_owner, owner, &old, new_owner);
                if (error == -1)
                        return (EFAULT);
                if (error == 1) {
                        error = thread_check_susp(td, true);
                        if (error != 0)
                                return (error);
                        goto usrloop;
                }
                if (old == owner)
                        return (0);
                owner = old;
        }

        /* We should only ever be in here for contested locks */
        if ((error = umtx_key_get(m, (flags & UMUTEX_ROBUST) != 0 ?
            TYPE_PI_ROBUST_UMUTEX : TYPE_PI_UMUTEX, GET_SHARE(flags),
            &key)) != 0)
                return (error);

        umtxq_lock(&key);
        umtxq_busy(&key);
        error = umtx_pi_drop(td, &key, rb, &count);
        if (error != 0) {
                umtxq_unbusy(&key);
                umtxq_unlock(&key);
                umtx_key_release(&key);
                /* userland messed the mutex */
                return (error);
        }
        umtxq_unlock(&key);

        /*
         * When unlocking the umtx, it must be marked as unowned if
         * there is zero or one thread only waiting for it.
         * Otherwise, it must be marked as contested.
         */

        if (count > 1)
                new_owner |= UMUTEX_CONTESTED;
again:
        error = casueword32(&m->m_owner, owner, &old, new_owner);
        if (error == 1) {
                error = thread_check_susp(td, false);
                if (error == 0)
                        goto again;
        }
        umtxq_unbusy_unlocked(&key);
        umtx_key_release(&key);
        if (error == -1)
                return (EFAULT);
        if (error == 0 && old != owner)
                return (EINVAL);
        return (error);
}

/*
 * Lock a PP mutex.
 */
static int
do_lock_pp(struct thread *td, struct umutex *m, uint32_t flags,
    struct _umtx_time *timeout, int try)
{
        struct umtx_abs_timeout timo;
        struct umtx_q *uq, *uq2;
        struct umtx_pi *pi;
        uint32_t ceiling;
        uint32_t owner, id;
        int error, pri, old_inherited_pri, new_pri, rv;
        bool su;

        id = td->td_tid;
        uq = td->td_umtxq;
        if ((error = umtx_key_get(m, (flags & UMUTEX_ROBUST) != 0 ?
            TYPE_PP_ROBUST_UMUTEX : TYPE_PP_UMUTEX, GET_SHARE(flags),
            &uq->uq_key)) != 0)
                return (error);

        if (timeout != NULL)
                umtx_abs_timeout_init2(&timo, timeout);

        su = (priv_check(td, PRIV_SCHED_RTPRIO) == 0);
        for (;;) {
                old_inherited_pri = uq->uq_inherited_pri;
                umtxq_busy_unlocked(&uq->uq_key);

                rv = fueword32(&m->m_ceilings[0], &ceiling);
                if (rv == -1) {
                        error = EFAULT;
                        goto out;
                }
                ceiling = RTP_PRIO_MAX - ceiling;
                if (ceiling > RTP_PRIO_MAX) {
                        error = EINVAL;
                        goto out;
                }
                new_pri = PRI_MIN_REALTIME + ceiling;

                if (td->td_base_user_pri < new_pri) {
                        error = EINVAL;
                        goto out;
                }
                if (su) {
                        mtx_lock(&umtx_lock);
                        if (new_pri < uq->uq_inherited_pri) {
                                uq->uq_inherited_pri = new_pri;
                                thread_lock(td);
                                if (new_pri < UPRI(td))
                                        sched_lend_user_prio(td, new_pri);
                                thread_unlock(td);
                        }
                        mtx_unlock(&umtx_lock);
                }

                rv = casueword32(&m->m_owner, UMUTEX_CONTESTED, &owner,
                    id | UMUTEX_CONTESTED);
                /* The address was invalid. */
                if (rv == -1) {
                        error = EFAULT;
                        break;
                }
                if (rv == 0) {
                        MPASS(owner == UMUTEX_CONTESTED);
                        error = 0;
                        break;
                }
                /* rv == 1 */
                if (owner == UMUTEX_RB_OWNERDEAD) {
                        rv = casueword32(&m->m_owner, UMUTEX_RB_OWNERDEAD,
                            &owner, id | UMUTEX_CONTESTED);
                        if (rv == -1) {
                                error = EFAULT;
                                break;
                        }
                        if (rv == 0) {
                                MPASS(owner == UMUTEX_RB_OWNERDEAD);
                                error = EOWNERDEAD; /* success */
                                break;
                        }

                        /*
                         *  rv == 1, only check for suspension if we
                         *  did not already catched a signal.  If we
                         *  get an error from the check, the same
                         *  condition is checked by the umtxq_sleep()
                         *  call below, so we should obliterate the
                         *  error to not skip the last loop iteration.
                         */
                        if (error == 0) {
                                error = thread_check_susp(td, false);
                                if (error == 0 && try == 0) {
                                        umtxq_unbusy_unlocked(&uq->uq_key);
                                        continue;
                                }
                                error = 0;
                        }
                } else if (owner == UMUTEX_RB_NOTRECOV) {
                        error = ENOTRECOVERABLE;
                } else if (owner == UMUTEX_CONTESTED) {
                        /* Spurious failure, retry. */
                        umtxq_unbusy_unlocked(&uq->uq_key);
                        continue;
                }

                if (try != 0)
                        error = EBUSY;

                /*
                 * If we caught a signal, we have retried and now
                 * exit immediately.
                 */
                if (error != 0)
                        break;

                umtxq_lock(&uq->uq_key);
                umtxq_insert(uq);
                umtxq_unbusy(&uq->uq_key);
                error = umtxq_sleep(uq, "umtxpp", timeout == NULL ?
                    NULL : &timo);
                umtxq_remove(uq);
                umtxq_unlock(&uq->uq_key);

                mtx_lock(&umtx_lock);
                uq->uq_inherited_pri = old_inherited_pri;
                pri = PRI_MAX;
                TAILQ_FOREACH(pi, &uq->uq_pi_contested, pi_link) {
                        uq2 = TAILQ_FIRST(&pi->pi_blocked);
                        if (uq2 != NULL) {
                                if (pri > UPRI(uq2->uq_thread))
                                        pri = UPRI(uq2->uq_thread);
                        }
                }
                if (pri > uq->uq_inherited_pri)
                        pri = uq->uq_inherited_pri;
                thread_lock(td);
                sched_lend_user_prio(td, pri);
                thread_unlock(td);
                mtx_unlock(&umtx_lock);
        }

        if (error != 0 && error != EOWNERDEAD) {
                mtx_lock(&umtx_lock);
                uq->uq_inherited_pri = old_inherited_pri;
                pri = PRI_MAX;
                TAILQ_FOREACH(pi, &uq->uq_pi_contested, pi_link) {
                        uq2 = TAILQ_FIRST(&pi->pi_blocked);
                        if (uq2 != NULL) {
                                if (pri > UPRI(uq2->uq_thread))
                                        pri = UPRI(uq2->uq_thread);
                        }
                }
                if (pri > uq->uq_inherited_pri)
                        pri = uq->uq_inherited_pri;
                thread_lock(td);
                sched_lend_user_prio(td, pri);
                thread_unlock(td);
                mtx_unlock(&umtx_lock);
        }

out:
        umtxq_unbusy_unlocked(&uq->uq_key);
        umtx_key_release(&uq->uq_key);
        return (error);
}

/*
 * Unlock a PP mutex.
 */
static int
do_unlock_pp(struct thread *td, struct umutex *m, uint32_t flags, bool rb)
{
        struct umtx_key key;
        struct umtx_q *uq, *uq2;
        struct umtx_pi *pi;
        uint32_t id, owner, rceiling;
        int error, pri, new_inherited_pri;
        bool su;

        id = td->td_tid;
        uq = td->td_umtxq;
        su = (priv_check(td, PRIV_SCHED_RTPRIO) == 0);

        /*
         * Make sure we own this mtx.
         */
        error = fueword32(&m->m_owner, &owner);
        if (error == -1)
                return (EFAULT);

        if ((owner & ~UMUTEX_CONTESTED) != id)
                return (EPERM);

        error = copyin(&m->m_ceilings[1], &rceiling, sizeof(uint32_t));
        if (error != 0)
                return (error);

        if (rceiling == -1)
                new_inherited_pri = PRI_MAX;
        else {
                rceiling = RTP_PRIO_MAX - rceiling;
                if (rceiling > RTP_PRIO_MAX)
                        return (EINVAL);
                new_inherited_pri = PRI_MIN_REALTIME + rceiling;
        }

        if ((error = umtx_key_get(m, (flags & UMUTEX_ROBUST) != 0 ?
            TYPE_PP_ROBUST_UMUTEX : TYPE_PP_UMUTEX, GET_SHARE(flags),
            &key)) != 0)
                return (error);
        umtxq_busy_unlocked(&key);

        /*
         * For priority protected mutex, always set unlocked state
         * to UMUTEX_CONTESTED, so that userland always enters kernel
         * to lock the mutex, it is necessary because thread priority
         * has to be adjusted for such mutex.
         */
        error = suword32(&m->m_owner, umtx_unlock_val(flags, rb) |
            UMUTEX_CONTESTED);

        umtxq_lock(&key);
        if (error == 0)
                umtxq_signal(&key, 1);
        umtxq_unbusy(&key);
        umtxq_unlock(&key);

        if (error == -1)
                error = EFAULT;
        else {
                mtx_lock(&umtx_lock);
                if (su || new_inherited_pri == PRI_MAX)
                        uq->uq_inherited_pri = new_inherited_pri;
                pri = PRI_MAX;
                TAILQ_FOREACH(pi, &uq->uq_pi_contested, pi_link) {
                        uq2 = TAILQ_FIRST(&pi->pi_blocked);
                        if (uq2 != NULL) {
                                if (pri > UPRI(uq2->uq_thread))
                                        pri = UPRI(uq2->uq_thread);
                        }
                }
                if (pri > uq->uq_inherited_pri)
                        pri = uq->uq_inherited_pri;
                thread_lock(td);
                sched_lend_user_prio(td, pri);
                thread_unlock(td);
                mtx_unlock(&umtx_lock);
        }
        umtx_key_release(&key);
        return (error);
}

static int
do_set_ceiling(struct thread *td, struct umutex *m, uint32_t ceiling,
    uint32_t *old_ceiling)
{
        struct umtx_q *uq;
        uint32_t flags, id, owner, save_ceiling;
        int error, rv, rv1;

        error = fueword32(&m->m_flags, &flags);
        if (error == -1)
                return (EFAULT);
        if ((flags & UMUTEX_PRIO_PROTECT) == 0)
                return (EINVAL);
        if (ceiling > RTP_PRIO_MAX)
                return (EINVAL);
        id = td->td_tid;
        uq = td->td_umtxq;
        if ((error = umtx_key_get(m, (flags & UMUTEX_ROBUST) != 0 ?
            TYPE_PP_ROBUST_UMUTEX : TYPE_PP_UMUTEX, GET_SHARE(flags),
            &uq->uq_key)) != 0)
                return (error);
        for (;;) {
                umtxq_busy_unlocked(&uq->uq_key);

                rv = fueword32(&m->m_ceilings[0], &save_ceiling);
                if (rv == -1) {
                        error = EFAULT;
                        break;
                }

                rv = casueword32(&m->m_owner, UMUTEX_CONTESTED, &owner,
                    id | UMUTEX_CONTESTED);
                if (rv == -1) {
                        error = EFAULT;
                        break;
                }

                if (rv == 0) {
                        MPASS(owner == UMUTEX_CONTESTED);
                        rv = suword32(&m->m_ceilings[0], ceiling);
                        rv1 = suword32(&m->m_owner, UMUTEX_CONTESTED);
                        error = (rv == 0 && rv1 == 0) ? 0: EFAULT;
                        break;
                }

                if ((owner & ~UMUTEX_CONTESTED) == id) {
                        rv = suword32(&m->m_ceilings[0], ceiling);
                        error = rv == 0 ? 0 : EFAULT;
                        break;
                }

                if (owner == UMUTEX_RB_OWNERDEAD) {
                        error = EOWNERDEAD;
                        break;
                } else if (owner == UMUTEX_RB_NOTRECOV) {
                        error = ENOTRECOVERABLE;
                        break;
                } else if (owner == UMUTEX_CONTESTED) {
                        /* Spurious failure, retry. */
                        umtxq_unbusy_unlocked(&uq->uq_key);
                        continue;
                }

                /*
                 * If we caught a signal, we have retried and now
                 * exit immediately.
                 */
                if (error != 0)
                        break;

                /*
                 * We set the contested bit, sleep. Otherwise the lock changed
                 * and we need to retry or we lost a race to the thread
                 * unlocking the umtx.
                 */
                umtxq_lock(&uq->uq_key);
                umtxq_insert(uq);
                umtxq_unbusy(&uq->uq_key);
                error = umtxq_sleep(uq, "umtxpp", NULL);
                umtxq_remove(uq);
                umtxq_unlock(&uq->uq_key);
        }
        umtxq_lock(&uq->uq_key);
        if (error == 0)
                umtxq_signal(&uq->uq_key, INT_MAX);
        umtxq_unbusy(&uq->uq_key);
        umtxq_unlock(&uq->uq_key);
        umtx_key_release(&uq->uq_key);
        if (error == 0 && old_ceiling != NULL) {
                rv = suword32(old_ceiling, save_ceiling);
                error = rv == 0 ? 0 : EFAULT;
        }
        return (error);
}

/*
 * Lock a userland POSIX mutex.
 */
static int
do_lock_umutex(struct thread *td, struct umutex *m,
    struct _umtx_time *timeout, int mode)
{
        uint32_t flags;
        int error;

        error = fueword32(&m->m_flags, &flags);
        if (error == -1)
                return (EFAULT);

        switch (flags & (UMUTEX_PRIO_INHERIT | UMUTEX_PRIO_PROTECT)) {
        case 0:
                error = do_lock_normal(td, m, flags, timeout, mode);
                break;
        case UMUTEX_PRIO_INHERIT:
                error = do_lock_pi(td, m, flags, timeout, mode);
                break;
        case UMUTEX_PRIO_PROTECT:
                error = do_lock_pp(td, m, flags, timeout, mode);
                break;
        default:
                return (EINVAL);
        }
        if (timeout == NULL) {
                if (error == EINTR && mode != _UMUTEX_WAIT)
                        error = ERESTART;
        } else {
                /* Timed-locking is not restarted. */
                if (error == ERESTART)
                        error = EINTR;
        }
        return (error);
}

/*
 * Unlock a userland POSIX mutex.
 */
static int
do_unlock_umutex(struct thread *td, struct umutex *m, bool rb)
{
        uint32_t flags;
        int error;

        error = fueword32(&m->m_flags, &flags);
        if (error == -1)
                return (EFAULT);

        switch (flags & (UMUTEX_PRIO_INHERIT | UMUTEX_PRIO_PROTECT)) {
        case 0:
                return (do_unlock_normal(td, m, flags, rb));
        case UMUTEX_PRIO_INHERIT:
                return (do_unlock_pi(td, m, flags, rb));
        case UMUTEX_PRIO_PROTECT:
                return (do_unlock_pp(td, m, flags, rb));
        }

        return (EINVAL);
}

static int
do_cv_wait(struct thread *td, struct ucond *cv, struct umutex *m,
    struct timespec *timeout, u_long wflags)
{
        struct umtx_abs_timeout timo;
        struct umtx_q *uq;
        uint32_t flags, clockid, hasw;
        int error;

        uq = td->td_umtxq;
        error = fueword32(&cv->c_flags, &flags);
        if (error == -1)
                return (EFAULT);
        error = umtx_key_get(cv, TYPE_CV, GET_SHARE(flags), &uq->uq_key);
        if (error != 0)
                return (error);

        if ((wflags & CVWAIT_CLOCKID) != 0) {
                error = fueword32(&cv->c_clockid, &clockid);
                if (error == -1) {
                        umtx_key_release(&uq->uq_key);
                        return (EFAULT);
                }
                if ((clockid < CLOCK_REALTIME ||
                    clockid >= CLOCK_THREAD_CPUTIME_ID) &&
                    clockid != CLOCK_TAI) {
                        /* hmm, only HW clock id will work. */
                        umtx_key_release(&uq->uq_key);
                        return (EINVAL);
                }
        } else {
                clockid = CLOCK_REALTIME;
        }

        umtxq_lock(&uq->uq_key);
        umtxq_busy(&uq->uq_key);
        umtxq_insert(uq);
        umtxq_unlock(&uq->uq_key);

        /*
         * Set c_has_waiters to 1 before releasing user mutex, also
         * don't modify cache line when unnecessary.
         */
        error = fueword32(&cv->c_has_waiters, &hasw);
        if (error == 0 && hasw == 0)
                error = suword32(&cv->c_has_waiters, 1);
        if (error != 0) {
                umtxq_lock(&uq->uq_key);
                umtxq_remove(uq);
                umtxq_unbusy(&uq->uq_key);
                error = EFAULT;
                goto out;
        }

        umtxq_unbusy_unlocked(&uq->uq_key);

        error = do_unlock_umutex(td, m, false);

        if (timeout != NULL)
                umtx_abs_timeout_init(&timo, clockid,
                    (wflags & CVWAIT_ABSTIME) != 0, timeout);

        umtxq_lock(&uq->uq_key);
        if (error == 0) {
                error = umtxq_sleep(uq, "ucond", timeout == NULL ?
                    NULL : &timo);
        }

        if ((uq->uq_flags & UQF_UMTXQ) == 0)
                error = 0;
        else {
                /*
                 * This must be timeout,interrupted by signal or
                 * surprious wakeup, clear c_has_waiter flag when
                 * necessary.
                 */
                umtxq_busy(&uq->uq_key);
                if ((uq->uq_flags & UQF_UMTXQ) != 0) {
                        int oldlen = uq->uq_cur_queue->length;
                        umtxq_remove(uq);
                        if (oldlen == 1) {
                                umtxq_unlock(&uq->uq_key);
                                if (suword32(&cv->c_has_waiters, 0) != 0 &&
                                    error == 0)
                                        error = EFAULT;
                                umtxq_lock(&uq->uq_key);
                        }
                }
                umtxq_unbusy(&uq->uq_key);
                if (error == ERESTART)
                        error = EINTR;
        }
out:
        umtxq_unlock(&uq->uq_key);
        umtx_key_release(&uq->uq_key);
        return (error);
}

/*
 * Signal a userland condition variable.
 */
static int
do_cv_signal(struct thread *td, struct ucond *cv)
{
        struct umtx_key key;
        int error, cnt, nwake;
        uint32_t flags;

        error = fueword32(&cv->c_flags, &flags);
        if (error == -1)
                return (EFAULT);
        if ((error = umtx_key_get(cv, TYPE_CV, GET_SHARE(flags), &key)) != 0)
                return (error);
        umtxq_lock(&key);
        umtxq_busy(&key);
        cnt = umtxq_count(&key);
        nwake = umtxq_signal(&key, 1);
        if (cnt <= nwake) {
                umtxq_unlock(&key);
                error = suword32(&cv->c_has_waiters, 0);
                if (error == -1)
                        error = EFAULT;
                umtxq_lock(&key);
        }
        umtxq_unbusy(&key);
        umtxq_unlock(&key);
        umtx_key_release(&key);
        return (error);
}

static int
do_cv_broadcast(struct thread *td, struct ucond *cv)
{
        struct umtx_key key;
        int error;
        uint32_t flags;

        error = fueword32(&cv->c_flags, &flags);
        if (error == -1)
                return (EFAULT);
        if ((error = umtx_key_get(cv, TYPE_CV, GET_SHARE(flags), &key)) != 0)
                return (error);

        umtxq_lock(&key);
        umtxq_busy(&key);
        umtxq_signal(&key, INT_MAX);
        umtxq_unlock(&key);

        error = suword32(&cv->c_has_waiters, 0);
        if (error == -1)
                error = EFAULT;

        umtxq_unbusy_unlocked(&key);

        umtx_key_release(&key);
        return (error);
}

static int
do_rw_rdlock(struct thread *td, struct urwlock *rwlock, long fflag,
    struct _umtx_time *timeout)
{
        struct umtx_abs_timeout timo;
        struct umtx_q *uq;
        uint32_t flags, wrflags;
        int32_t state, oldstate;
        int32_t blocked_readers;
        int error, error1, rv;

        uq = td->td_umtxq;
        error = fueword32(&rwlock->rw_flags, &flags);
        if (error == -1)
                return (EFAULT);
        error = umtx_key_get(rwlock, TYPE_RWLOCK, GET_SHARE(flags), &uq->uq_key);
        if (error != 0)
                return (error);

        if (timeout != NULL)
                umtx_abs_timeout_init2(&timo, timeout);

        wrflags = URWLOCK_WRITE_OWNER;
        if (!(fflag & URWLOCK_PREFER_READER) && !(flags & URWLOCK_PREFER_READER))
                wrflags |= URWLOCK_WRITE_WAITERS;

        for (;;) {
                rv = fueword32(&rwlock->rw_state, &state);
                if (rv == -1) {
                        umtx_key_release(&uq->uq_key);
                        return (EFAULT);
                }

                /* try to lock it */
                while (!(state & wrflags)) {
                        if (__predict_false(URWLOCK_READER_COUNT(state) ==
                            URWLOCK_MAX_READERS)) {
                                umtx_key_release(&uq->uq_key);
                                return (EAGAIN);
                        }
                        rv = casueword32(&rwlock->rw_state, state,
                            &oldstate, state + 1);
                        if (rv == -1) {
                                umtx_key_release(&uq->uq_key);
                                return (EFAULT);
                        }
                        if (rv == 0) {
                                MPASS(oldstate == state);
                                umtx_key_release(&uq->uq_key);
                                return (0);
                        }
                        error = thread_check_susp(td, true);
                        if (error != 0)
                                break;
                        state = oldstate;
                }

                if (error)
                        break;

                /* grab monitor lock */
                umtxq_busy_unlocked(&uq->uq_key);

                /*
                 * re-read the state, in case it changed between the try-lock above
                 * and the check below
                 */
                rv = fueword32(&rwlock->rw_state, &state);
                if (rv == -1)
                        error = EFAULT;

                /* set read contention bit */
                while (error == 0 && (state & wrflags) &&
                    !(state & URWLOCK_READ_WAITERS)) {
                        rv = casueword32(&rwlock->rw_state, state,
                            &oldstate, state | URWLOCK_READ_WAITERS);
                        if (rv == -1) {
                                error = EFAULT;
                                break;
                        }
                        if (rv == 0) {
                                MPASS(oldstate == state);
                                goto sleep;
                        }
                        state = oldstate;
                        error = thread_check_susp(td, false);
                        if (error != 0)
                                break;
                }
                if (error != 0) {
                        umtxq_unbusy_unlocked(&uq->uq_key);
                        break;
                }

                /* state is changed while setting flags, restart */
                if (!(state & wrflags)) {
                        umtxq_unbusy_unlocked(&uq->uq_key);
                        error = thread_check_susp(td, true);
                        if (error != 0)
                                break;
                        continue;
                }

sleep:
                /*
                 * Contention bit is set, before sleeping, increase
                 * read waiter count.
                 */
                rv = fueword32(&rwlock->rw_blocked_readers,
                    &blocked_readers);
                if (rv == 0)
                        rv = suword32(&rwlock->rw_blocked_readers,
                            blocked_readers + 1);
                if (rv == -1) {
                        umtxq_unbusy_unlocked(&uq->uq_key);
                        error = EFAULT;
                        break;
                }

                while (state & wrflags) {
                        umtxq_lock(&uq->uq_key);
                        umtxq_insert(uq);
                        umtxq_unbusy(&uq->uq_key);

                        error = umtxq_sleep(uq, "urdlck", timeout == NULL ?
                            NULL : &timo);

                        umtxq_busy(&uq->uq_key);
                        umtxq_remove(uq);
                        umtxq_unlock(&uq->uq_key);
                        if (error)
                                break;
                        rv = fueword32(&rwlock->rw_state, &state);
                        if (rv == -1) {
                                error = EFAULT;
                                break;
                        }
                }

                /* decrease read waiter count, and may clear read contention bit */
                rv = fueword32(&rwlock->rw_blocked_readers,
                    &blocked_readers);
                if (rv == 0)
                        rv = suword32(&rwlock->rw_blocked_readers,
                            blocked_readers - 1);
                if (rv == -1) {
                        umtxq_unbusy_unlocked(&uq->uq_key);
                        error = EFAULT;
                        break;
                }
                if (blocked_readers == 1) {
                        rv = fueword32(&rwlock->rw_state, &state);
                        if (rv == -1) {
                                umtxq_unbusy_unlocked(&uq->uq_key);
                                error = EFAULT;
                                break;
                        }
                        for (;;) {
                                rv = casueword32(&rwlock->rw_state, state,
                                    &oldstate, state & ~URWLOCK_READ_WAITERS);
                                if (rv == -1) {
                                        error = EFAULT;
                                        break;
                                }
                                if (rv == 0) {
                                        MPASS(oldstate == state);
                                        break;
                                }
                                state = oldstate;
                                error1 = thread_check_susp(td, false);
                                if (error1 != 0) {
                                        if (error == 0)
                                                error = error1;
                                        break;
                                }
                        }
                }

                umtxq_unbusy_unlocked(&uq->uq_key);
                if (error != 0)
                        break;
        }
        umtx_key_release(&uq->uq_key);
        if (error == ERESTART)
                error = EINTR;
        return (error);
}

static int
do_rw_wrlock(struct thread *td, struct urwlock *rwlock, struct _umtx_time *timeout)
{
        struct umtx_abs_timeout timo;
        struct umtx_q *uq;
        uint32_t flags;
        int32_t state, oldstate;
        int32_t blocked_writers;
        int32_t blocked_readers;
        int error, error1, rv;

        uq = td->td_umtxq;
        error = fueword32(&rwlock->rw_flags, &flags);
        if (error == -1)
                return (EFAULT);
        error = umtx_key_get(rwlock, TYPE_RWLOCK, GET_SHARE(flags), &uq->uq_key);
        if (error != 0)
                return (error);

        if (timeout != NULL)
                umtx_abs_timeout_init2(&timo, timeout);

        blocked_readers = 0;
        for (;;) {
                rv = fueword32(&rwlock->rw_state, &state);
                if (rv == -1) {
                        umtx_key_release(&uq->uq_key);
                        return (EFAULT);
                }
                while ((state & URWLOCK_WRITE_OWNER) == 0 &&
                    URWLOCK_READER_COUNT(state) == 0) {
                        rv = casueword32(&rwlock->rw_state, state,
                            &oldstate, state | URWLOCK_WRITE_OWNER);
                        if (rv == -1) {
                                umtx_key_release(&uq->uq_key);
                                return (EFAULT);
                        }
                        if (rv == 0) {
                                MPASS(oldstate == state);
                                umtx_key_release(&uq->uq_key);
                                return (0);
                        }
                        state = oldstate;
                        error = thread_check_susp(td, true);
                        if (error != 0)
                                break;
                }

                if (error) {
                        if ((state & (URWLOCK_WRITE_OWNER |
                            URWLOCK_WRITE_WAITERS)) == 0 &&
                            blocked_readers != 0) {
                                umtxq_lock(&uq->uq_key);
                                umtxq_busy(&uq->uq_key);
                                umtxq_signal_queue(&uq->uq_key, INT_MAX,
                                    UMTX_SHARED_QUEUE);
                                umtxq_unbusy(&uq->uq_key);
                                umtxq_unlock(&uq->uq_key);
                        }

                        break;
                }

                /* grab monitor lock */
                umtxq_busy_unlocked(&uq->uq_key);

                /*
                 * Re-read the state, in case it changed between the
                 * try-lock above and the check below.
                 */
                rv = fueword32(&rwlock->rw_state, &state);
                if (rv == -1)
                        error = EFAULT;

                while (error == 0 && ((state & URWLOCK_WRITE_OWNER) ||
                    URWLOCK_READER_COUNT(state) != 0) &&
                    (state & URWLOCK_WRITE_WAITERS) == 0) {
                        rv = casueword32(&rwlock->rw_state, state,
                            &oldstate, state | URWLOCK_WRITE_WAITERS);
                        if (rv == -1) {
                                error = EFAULT;
                                break;
                        }
                        if (rv == 0) {
                                MPASS(oldstate == state);
                                goto sleep;
                        }
                        state = oldstate;
                        error = thread_check_susp(td, false);
                        if (error != 0)
                                break;
                }
                if (error != 0) {
                        umtxq_unbusy_unlocked(&uq->uq_key);
                        break;
                }

                if ((state & URWLOCK_WRITE_OWNER) == 0 &&
                    URWLOCK_READER_COUNT(state) == 0) {
                        umtxq_unbusy_unlocked(&uq->uq_key);
                        error = thread_check_susp(td, false);
                        if (error != 0)
                                break;
                        continue;
                }
sleep:
                rv = fueword32(&rwlock->rw_blocked_writers,
                    &blocked_writers);
                if (rv == 0)
                        rv = suword32(&rwlock->rw_blocked_writers,
                            blocked_writers + 1);
                if (rv == -1) {
                        umtxq_unbusy_unlocked(&uq->uq_key);
                        error = EFAULT;
                        break;
                }

                while ((state & URWLOCK_WRITE_OWNER) ||
                    URWLOCK_READER_COUNT(state) != 0) {
                        umtxq_lock(&uq->uq_key);
                        umtxq_insert_queue(uq, UMTX_EXCLUSIVE_QUEUE);
                        umtxq_unbusy(&uq->uq_key);

                        error = umtxq_sleep(uq, "uwrlck", timeout == NULL ?
                            NULL : &timo);

                        umtxq_busy(&uq->uq_key);
                        umtxq_remove_queue(uq, UMTX_EXCLUSIVE_QUEUE);
                        umtxq_unlock(&uq->uq_key);
                        if (error)
                                break;
                        rv = fueword32(&rwlock->rw_state, &state);
                        if (rv == -1) {
                                error = EFAULT;
                                break;
                        }
                }

                rv = fueword32(&rwlock->rw_blocked_writers,
                    &blocked_writers);
                if (rv == 0)
                        rv = suword32(&rwlock->rw_blocked_writers,
                            blocked_writers - 1);
                if (rv == -1) {
                        umtxq_unbusy_unlocked(&uq->uq_key);
                        error = EFAULT;
                        break;
                }
                if (blocked_writers == 1) {
                        rv = fueword32(&rwlock->rw_state, &state);
                        if (rv == -1) {
                                umtxq_unbusy_unlocked(&uq->uq_key);
                                error = EFAULT;
                                break;
                        }
                        for (;;) {
                                rv = casueword32(&rwlock->rw_state, state,
                                    &oldstate, state & ~URWLOCK_WRITE_WAITERS);
                                if (rv == -1) {
                                        error = EFAULT;
                                        break;
                                }
                                if (rv == 0) {
                                        MPASS(oldstate == state);
                                        break;
                                }
                                state = oldstate;
                                error1 = thread_check_susp(td, false);
                                /*
                                 * We are leaving the URWLOCK_WRITE_WAITERS
                                 * behind, but this should not harm the
                                 * correctness.
                                 */
                                if (error1 != 0) {
                                        if (error == 0)
                                                error = error1;
                                        break;
                                }
                        }
                        rv = fueword32(&rwlock->rw_blocked_readers,
                            &blocked_readers);
                        if (rv == -1) {
                                umtxq_unbusy_unlocked(&uq->uq_key);
                                error = EFAULT;
                                break;
                        }
                } else
                        blocked_readers = 0;

                umtxq_unbusy_unlocked(&uq->uq_key);
        }

        umtx_key_release(&uq->uq_key);
        if (error == ERESTART)
                error = EINTR;
        return (error);
}

static int
do_rw_unlock(struct thread *td, struct urwlock *rwlock)
{
        struct umtx_q *uq;
        uint32_t flags;
        int32_t state, oldstate;
        int error, rv, q, count;

        uq = td->td_umtxq;
        error = fueword32(&rwlock->rw_flags, &flags);
        if (error == -1)
                return (EFAULT);
        error = umtx_key_get(rwlock, TYPE_RWLOCK, GET_SHARE(flags), &uq->uq_key);
        if (error != 0)
                return (error);

        error = fueword32(&rwlock->rw_state, &state);
        if (error == -1) {
                error = EFAULT;
                goto out;
        }
        if (state & URWLOCK_WRITE_OWNER) {
                for (;;) {
                        rv = casueword32(&rwlock->rw_state, state,
                            &oldstate, state & ~URWLOCK_WRITE_OWNER);
                        if (rv == -1) {
                                error = EFAULT;
                                goto out;
                        }
                        if (rv == 1) {
                                state = oldstate;
                                if (!(oldstate & URWLOCK_WRITE_OWNER)) {
                                        error = EPERM;
                                        goto out;
                                }
                                error = thread_check_susp(td, true);
                                if (error != 0)
                                        goto out;
                        } else
                                break;
                }
        } else if (URWLOCK_READER_COUNT(state) != 0) {
                for (;;) {
                        rv = casueword32(&rwlock->rw_state, state,
                            &oldstate, state - 1);
                        if (rv == -1) {
                                error = EFAULT;
                                goto out;
                        }
                        if (rv == 1) {
                                state = oldstate;
                                if (URWLOCK_READER_COUNT(oldstate) == 0) {
                                        error = EPERM;
                                        goto out;
                                }
                                error = thread_check_susp(td, true);
                                if (error != 0)
                                        goto out;
                        } else
                                break;
                }
        } else {
                error = EPERM;
                goto out;
        }

        count = 0;

        if (!(flags & URWLOCK_PREFER_READER)) {
                if (state & URWLOCK_WRITE_WAITERS) {
                        count = 1;
                        q = UMTX_EXCLUSIVE_QUEUE;
                } else if (state & URWLOCK_READ_WAITERS) {
                        count = INT_MAX;
                        q = UMTX_SHARED_QUEUE;
                }
        } else {
                if (state & URWLOCK_READ_WAITERS) {
                        count = INT_MAX;
                        q = UMTX_SHARED_QUEUE;
                } else if (state & URWLOCK_WRITE_WAITERS) {
                        count = 1;
                        q = UMTX_EXCLUSIVE_QUEUE;
                }
        }

        if (count) {
                umtxq_lock(&uq->uq_key);
                umtxq_busy(&uq->uq_key);
                umtxq_signal_queue(&uq->uq_key, count, q);
                umtxq_unbusy(&uq->uq_key);
                umtxq_unlock(&uq->uq_key);
        }
out:
        umtx_key_release(&uq->uq_key);
        return (error);
}

#if defined(COMPAT_FREEBSD9) || defined(COMPAT_FREEBSD10)
static int
do_sem_wait(struct thread *td, struct _usem *sem, struct _umtx_time *timeout)
{
        struct umtx_abs_timeout timo;
        struct umtx_q *uq;
        uint32_t flags, count, count1;
        int error, rv, rv1;

        uq = td->td_umtxq;
        error = fueword32(&sem->_flags, &flags);
        if (error == -1)
                return (EFAULT);
        error = umtx_key_get(sem, TYPE_SEM, GET_SHARE(flags), &uq->uq_key);
        if (error != 0)
                return (error);

        if (timeout != NULL)
                umtx_abs_timeout_init2(&timo, timeout);

again:
        umtxq_lock(&uq->uq_key);
        umtxq_busy(&uq->uq_key);
        umtxq_insert(uq);
        umtxq_unlock(&uq->uq_key);
        rv = casueword32(&sem->_has_waiters, 0, &count1, 1);
        if (rv != -1)
                rv1 = fueword32(&sem->_count, &count);
        if (rv == -1 || rv1 == -1 || count != 0 || (rv == 1 && count1 == 0)) {
                if (rv == 0)
                        rv = suword32(&sem->_has_waiters, 0);
                umtxq_lock(&uq->uq_key);
                umtxq_unbusy(&uq->uq_key);
                umtxq_remove(uq);
                umtxq_unlock(&uq->uq_key);
                if (rv == -1 || rv1 == -1) {
                        error = EFAULT;
                        goto out;
                }
                if (count != 0) {
                        error = 0;
                        goto out;
                }
                MPASS(rv == 1 && count1 == 0);
                rv = thread_check_susp(td, true);
                if (rv == 0)
                        goto again;
                error = rv;
                goto out;
        }
        umtxq_lock(&uq->uq_key);
        umtxq_unbusy(&uq->uq_key);

        error = umtxq_sleep(uq, "usem", timeout == NULL ? NULL : &timo);

        if ((uq->uq_flags & UQF_UMTXQ) == 0)
                error = 0;
        else {
                umtxq_remove(uq);
                /* A relative timeout cannot be restarted. */
                if (error == ERESTART && timeout != NULL &&
                    (timeout->_flags & UMTX_ABSTIME) == 0)
                        error = EINTR;
        }
        umtxq_unlock(&uq->uq_key);
out:
        umtx_key_release(&uq->uq_key);
        return (error);
}

/*
 * Signal a userland semaphore.
 */
static int
do_sem_wake(struct thread *td, struct _usem *sem)
{
        struct umtx_key key;
        int error, cnt;
        uint32_t flags;

        error = fueword32(&sem->_flags, &flags);
        if (error == -1)
                return (EFAULT);
        if ((error = umtx_key_get(sem, TYPE_SEM, GET_SHARE(flags), &key)) != 0)
                return (error);
        umtxq_lock(&key);
        umtxq_busy(&key);
        cnt = umtxq_count(&key);
        if (cnt > 0) {
                /*
                 * Check if count is greater than 0, this means the memory is
                 * still being referenced by user code, so we can safely
                 * update _has_waiters flag.
                 */
                if (cnt == 1) {
                        umtxq_unlock(&key);
                        error = suword32(&sem->_has_waiters, 0);
                        umtxq_lock(&key);
                        if (error == -1)
                                error = EFAULT;
                }
                umtxq_signal(&key, 1);
        }
        umtxq_unbusy(&key);
        umtxq_unlock(&key);
        umtx_key_release(&key);
        return (error);
}
#endif

static int
do_sem2_wait(struct thread *td, struct _usem2 *sem, struct _umtx_time *timeout)
{
        struct umtx_abs_timeout timo;
        struct umtx_q *uq;
        uint32_t count, flags;
        int error, rv;

        uq = td->td_umtxq;
        flags = fuword32(&sem->_flags);
        if (timeout != NULL)
                umtx_abs_timeout_init2(&timo, timeout);

again:
        error = umtx_key_get(sem, TYPE_SEM, GET_SHARE(flags), &uq->uq_key);
        if (error != 0)
                return (error);
        umtxq_lock(&uq->uq_key);
        umtxq_busy(&uq->uq_key);
        umtxq_insert(uq);
        umtxq_unlock(&uq->uq_key);
        rv = fueword32(&sem->_count, &count);
        if (rv == -1) {
                umtxq_lock(&uq->uq_key);
                umtxq_unbusy(&uq->uq_key);
                umtxq_remove(uq);
                umtxq_unlock(&uq->uq_key);
                umtx_key_release(&uq->uq_key);
                return (EFAULT);
        }
        for (;;) {
                if (USEM_COUNT(count) != 0) {
                        umtxq_lock(&uq->uq_key);
                        umtxq_unbusy(&uq->uq_key);
                        umtxq_remove(uq);
                        umtxq_unlock(&uq->uq_key);
                        umtx_key_release(&uq->uq_key);
                        return (0);
                }
                if (count == USEM_HAS_WAITERS)
                        break;
                rv = casueword32(&sem->_count, 0, &count, USEM_HAS_WAITERS);
                if (rv == 0)
                        break;
                umtxq_lock(&uq->uq_key);
                umtxq_unbusy(&uq->uq_key);
                umtxq_remove(uq);
                umtxq_unlock(&uq->uq_key);
                umtx_key_release(&uq->uq_key);
                if (rv == -1)
                        return (EFAULT);
                rv = thread_check_susp(td, true);
                if (rv != 0)
                        return (rv);
                goto again;
        }
        umtxq_lock(&uq->uq_key);
        umtxq_unbusy(&uq->uq_key);

        error = umtxq_sleep(uq, "usem", timeout == NULL ? NULL : &timo);

        if ((uq->uq_flags & UQF_UMTXQ) == 0)
                error = 0;
        else {
                umtxq_remove(uq);
                if (timeout != NULL && (timeout->_flags & UMTX_ABSTIME) == 0) {
                        /* A relative timeout cannot be restarted. */
                        if (error == ERESTART)
                                error = EINTR;
                        if (error == EINTR) {
                                kern_clock_gettime(curthread, timo.clockid,
                                    &timo.cur);
                                timespecsub(&timo.end, &timo.cur,
                                    &timeout->_timeout);
                        }
                }
        }
        umtxq_unlock(&uq->uq_key);
        umtx_key_release(&uq->uq_key);
        return (error);
}

/*
 * Signal a userland semaphore.
 */
static int
do_sem2_wake(struct thread *td, struct _usem2 *sem)
{
        struct umtx_key key;
        int error, cnt, rv;
        uint32_t count, flags;

        rv = fueword32(&sem->_flags, &flags);
        if (rv == -1)
                return (EFAULT);
        if ((error = umtx_key_get(sem, TYPE_SEM, GET_SHARE(flags), &key)) != 0)
                return (error);
        umtxq_lock(&key);
        umtxq_busy(&key);
        cnt = umtxq_count(&key);
        if (cnt > 0) {
                /*
                 * If this was the last sleeping thread, clear the waiters
                 * flag in _count.
                 */
                if (cnt == 1) {
                        umtxq_unlock(&key);
                        rv = fueword32(&sem->_count, &count);
                        while (rv != -1 && count & USEM_HAS_WAITERS) {
                                rv = casueword32(&sem->_count, count, &count,
                                    count & ~USEM_HAS_WAITERS);
                                if (rv == 1) {
                                        rv = thread_check_susp(td, false);
                                        if (rv != 0)
                                                break;
                                }
                        }
                        if (rv == -1)
                                error = EFAULT;
                        else if (rv > 0) {
                                error = rv;
                        }
                        umtxq_lock(&key);
                }

                umtxq_signal(&key, 1);
        }
        umtxq_unbusy(&key);
        umtxq_unlock(&key);
        umtx_key_release(&key);
        return (error);
}

#ifdef COMPAT_FREEBSD10
int
freebsd10__umtx_lock(struct thread *td, struct freebsd10__umtx_lock_args *uap)
{
        return (do_lock_umtx(td, uap->umtx, td->td_tid, 0));
}

int
freebsd10__umtx_unlock(struct thread *td,
    struct freebsd10__umtx_unlock_args *uap)
{
        return (do_unlock_umtx(td, uap->umtx, td->td_tid));
}
#endif

inline int
umtx_copyin_timeout(const void *uaddr, struct timespec *tsp)
{
        int error;

        error = copyin(uaddr, tsp, sizeof(*tsp));
        if (error == 0) {
                if (!timespecvalid_interval(tsp))
                        error = EINVAL;
        }
        return (error);
}

static inline int
umtx_copyin_umtx_time(const void *uaddr, size_t size, struct _umtx_time *tp)
{
        int error;

        if (size <= sizeof(tp->_timeout)) {
                tp->_clockid = CLOCK_REALTIME;
                tp->_flags = 0;
                error = copyin(uaddr, &tp->_timeout, sizeof(tp->_timeout));
        } else
                error = copyin(uaddr, tp, sizeof(*tp));
        if (error != 0)
                return (error);
        if (!timespecvalid_interval(&tp->_timeout))
                return (EINVAL);
        return (0);
}

static int
umtx_copyin_robust_lists(const void *uaddr, size_t size,
    struct umtx_robust_lists_params *rb)
{

        if (size > sizeof(*rb))
                return (EINVAL);
        return (copyin(uaddr, rb, size));
}

static int
umtx_copyout_timeout(void *uaddr, size_t sz, struct timespec *tsp)
{

        /*
         * Should be guaranteed by the caller, sz == uaddr1 - sizeof(_umtx_time)
         * and we're only called if sz >= sizeof(timespec) as supplied in the
         * copyops.
         */
        KASSERT(sz >= sizeof(*tsp),
            ("umtx_copyops specifies incorrect sizes"));

        return (copyout(tsp, uaddr, sizeof(*tsp)));
}

#ifdef COMPAT_FREEBSD10
static int
__umtx_op_lock_umtx(struct thread *td, struct _umtx_op_args *uap,
    const struct umtx_copyops *ops)
{
        struct timespec *ts, timeout;
        int error;

        /* Allow a null timespec (wait forever). */
        if (uap->uaddr2 == NULL)
                ts = NULL;
        else {
                error = ops->copyin_timeout(uap->uaddr2, &timeout);
                if (error != 0)
                        return (error);
                ts = &timeout;
        }
#ifdef COMPAT_FREEBSD32
        if (ops->compat32)
                return (do_lock_umtx32(td, uap->obj, uap->val, ts));
#endif
        return (do_lock_umtx(td, uap->obj, uap->val, ts));
}

static int
__umtx_op_unlock_umtx(struct thread *td, struct _umtx_op_args *uap,
    const struct umtx_copyops *ops)
{
#ifdef COMPAT_FREEBSD32
        if (ops->compat32)
                return (do_unlock_umtx32(td, uap->obj, uap->val));
#endif
        return (do_unlock_umtx(td, uap->obj, uap->val));
}
#endif  /* COMPAT_FREEBSD10 */

#if !defined(COMPAT_FREEBSD10)
static int
__umtx_op_unimpl(struct thread *td __unused, struct _umtx_op_args *uap __unused,
    const struct umtx_copyops *ops __unused)
{
        return (EOPNOTSUPP);
}
#endif  /* COMPAT_FREEBSD10 */

static int
__umtx_op_wait(struct thread *td, struct _umtx_op_args *uap,
    const struct umtx_copyops *ops)
{
        struct _umtx_time timeout, *tm_p;
        int error;

        if (uap->uaddr2 == NULL)
                tm_p = NULL;
        else {
                error = ops->copyin_umtx_time(
                    uap->uaddr2, (size_t)uap->uaddr1, &timeout);
                if (error != 0)
                        return (error);
                tm_p = &timeout;
        }
        return (do_wait(td, uap->obj, uap->val, tm_p, ops->compat32, 0));
}

static int
__umtx_op_wait_uint(struct thread *td, struct _umtx_op_args *uap,
    const struct umtx_copyops *ops)
{
        struct _umtx_time timeout, *tm_p;
        int error;

        if (uap->uaddr2 == NULL)
                tm_p = NULL;
        else {
                error = ops->copyin_umtx_time(
                    uap->uaddr2, (size_t)uap->uaddr1, &timeout);
                if (error != 0)
                        return (error);
                tm_p = &timeout;
        }
        return (do_wait(td, uap->obj, uap->val, tm_p, 1, 0));
}

static int
__umtx_op_wait_uint_private(struct thread *td, struct _umtx_op_args *uap,
    const struct umtx_copyops *ops)
{
        struct _umtx_time *tm_p, timeout;
        int error;

        if (uap->uaddr2 == NULL)
                tm_p = NULL;
        else {
                error = ops->copyin_umtx_time(
                    uap->uaddr2, (size_t)uap->uaddr1, &timeout);
                if (error != 0)
                        return (error);
                tm_p = &timeout;
        }
        return (do_wait(td, uap->obj, uap->val, tm_p, 1, 1));
}

static int
__umtx_op_wake(struct thread *td, struct _umtx_op_args *uap,
    const struct umtx_copyops *ops __unused)
{

        return (kern_umtx_wake(td, uap->obj, uap->val, 0));
}

#define BATCH_SIZE      128
static int
__umtx_op_nwake_private_native(struct thread *td, struct _umtx_op_args *uap)
{
        char *uaddrs[BATCH_SIZE], **upp;
        int count, error, i, pos, tocopy;

        upp = (char **)uap->obj;
        error = 0;
        for (count = uap->val, pos = 0; count > 0; count -= tocopy,
            pos += tocopy) {
                tocopy = MIN(count, BATCH_SIZE);
                error = copyin(upp + pos, uaddrs, tocopy * sizeof(char *));
                if (error != 0)
                        break;
                for (i = 0; i < tocopy; ++i) {
                        kern_umtx_wake(td, uaddrs[i], INT_MAX, 1);
                }
                maybe_yield();
        }
        return (error);
}

static int
__umtx_op_nwake_private_compat32(struct thread *td, struct _umtx_op_args *uap)
{
        uint32_t uaddrs[BATCH_SIZE], *upp;
        int count, error, i, pos, tocopy;

        upp = (uint32_t *)uap->obj;
        error = 0;
        for (count = uap->val, pos = 0; count > 0; count -= tocopy,
            pos += tocopy) {
                tocopy = MIN(count, BATCH_SIZE);
                error = copyin(upp + pos, uaddrs, tocopy * sizeof(uint32_t));
                if (error != 0)
                        break;
                for (i = 0; i < tocopy; ++i) {
                        kern_umtx_wake(td, (void *)(uintptr_t)uaddrs[i],
                            INT_MAX, 1);
                }
                maybe_yield();
        }
        return (error);
}

static int
__umtx_op_nwake_private(struct thread *td, struct _umtx_op_args *uap,
    const struct umtx_copyops *ops)
{

        if (ops->compat32)
                return (__umtx_op_nwake_private_compat32(td, uap));
        return (__umtx_op_nwake_private_native(td, uap));
}

static int
__umtx_op_wake_private(struct thread *td, struct _umtx_op_args *uap,
    const struct umtx_copyops *ops __unused)
{

        return (kern_umtx_wake(td, uap->obj, uap->val, 1));
}

static int
__umtx_op_lock_umutex(struct thread *td, struct _umtx_op_args *uap,
   const struct umtx_copyops *ops)
{
        struct _umtx_time *tm_p, timeout;
        int error;

        /* Allow a null timespec (wait forever). */
        if (uap->uaddr2 == NULL)
                tm_p = NULL;
        else {
                error = ops->copyin_umtx_time(
                    uap->uaddr2, (size_t)uap->uaddr1, &timeout);
                if (error != 0)
                        return (error);
                tm_p = &timeout;
        }
        return (do_lock_umutex(td, uap->obj, tm_p, 0));
}

static int
__umtx_op_trylock_umutex(struct thread *td, struct _umtx_op_args *uap,
    const struct umtx_copyops *ops __unused)
{

        return (do_lock_umutex(td, uap->obj, NULL, _UMUTEX_TRY));
}

static int
__umtx_op_wait_umutex(struct thread *td, struct _umtx_op_args *uap,
    const struct umtx_copyops *ops)
{
        struct _umtx_time *tm_p, timeout;
        int error;

        /* Allow a null timespec (wait forever). */
        if (uap->uaddr2 == NULL)
                tm_p = NULL;
        else {
                error = ops->copyin_umtx_time(
                    uap->uaddr2, (size_t)uap->uaddr1, &timeout);
                if (error != 0)
                        return (error);
                tm_p = &timeout;
        }
        return (do_lock_umutex(td, uap->obj, tm_p, _UMUTEX_WAIT));
}

static int
__umtx_op_wake_umutex(struct thread *td, struct _umtx_op_args *uap,
    const struct umtx_copyops *ops __unused)
{

        return (do_wake_umutex(td, uap->obj));
}

static int
__umtx_op_unlock_umutex(struct thread *td, struct _umtx_op_args *uap,
    const struct umtx_copyops *ops __unused)
{

        return (do_unlock_umutex(td, uap->obj, false));
}

static int
__umtx_op_set_ceiling(struct thread *td, struct _umtx_op_args *uap,
    const struct umtx_copyops *ops __unused)
{

        return (do_set_ceiling(td, uap->obj, uap->val, uap->uaddr1));
}

static int
__umtx_op_cv_wait(struct thread *td, struct _umtx_op_args *uap,
    const struct umtx_copyops *ops)
{
        struct timespec *ts, timeout;
        int error;

        /* Allow a null timespec (wait forever). */
        if (uap->uaddr2 == NULL)
                ts = NULL;
        else {
                error = ops->copyin_timeout(uap->uaddr2, &timeout);
                if (error != 0)
                        return (error);
                ts = &timeout;
        }
        return (do_cv_wait(td, uap->obj, uap->uaddr1, ts, uap->val));
}

static int
__umtx_op_cv_signal(struct thread *td, struct _umtx_op_args *uap,
    const struct umtx_copyops *ops __unused)
{

        return (do_cv_signal(td, uap->obj));
}

static int
__umtx_op_cv_broadcast(struct thread *td, struct _umtx_op_args *uap,
    const struct umtx_copyops *ops __unused)
{

        return (do_cv_broadcast(td, uap->obj));
}

static int
__umtx_op_rw_rdlock(struct thread *td, struct _umtx_op_args *uap,
    const struct umtx_copyops *ops)
{
        struct _umtx_time timeout;
        int error;

        /* Allow a null timespec (wait forever). */
        if (uap->uaddr2 == NULL) {
                error = do_rw_rdlock(td, uap->obj, uap->val, 0);
        } else {
                error = ops->copyin_umtx_time(uap->uaddr2,
                   (size_t)uap->uaddr1, &timeout);
                if (error != 0)
                        return (error);
                error = do_rw_rdlock(td, uap->obj, uap->val, &timeout);
        }
        return (error);
}

static int
__umtx_op_rw_wrlock(struct thread *td, struct _umtx_op_args *uap,
    const struct umtx_copyops *ops)
{
        struct _umtx_time timeout;
        int error;

        /* Allow a null timespec (wait forever). */
        if (uap->uaddr2 == NULL) {
                error = do_rw_wrlock(td, uap->obj, 0);
        } else {
                error = ops->copyin_umtx_time(uap->uaddr2,
                   (size_t)uap->uaddr1, &timeout);
                if (error != 0)
                        return (error);

                error = do_rw_wrlock(td, uap->obj, &timeout);
        }
        return (error);
}

static int
__umtx_op_rw_unlock(struct thread *td, struct _umtx_op_args *uap,
    const struct umtx_copyops *ops __unused)
{

        return (do_rw_unlock(td, uap->obj));
}

#if defined(COMPAT_FREEBSD9) || defined(COMPAT_FREEBSD10)
static int
__umtx_op_sem_wait(struct thread *td, struct _umtx_op_args *uap,
    const struct umtx_copyops *ops)
{
        struct _umtx_time *tm_p, timeout;
        int error;

        /* Allow a null timespec (wait forever). */
        if (uap->uaddr2 == NULL)
                tm_p = NULL;
        else {
                error = ops->copyin_umtx_time(
                    uap->uaddr2, (size_t)uap->uaddr1, &timeout);
                if (error != 0)
                        return (error);
                tm_p = &timeout;
        }
        return (do_sem_wait(td, uap->obj, tm_p));
}

static int
__umtx_op_sem_wake(struct thread *td, struct _umtx_op_args *uap,
    const struct umtx_copyops *ops __unused)
{

        return (do_sem_wake(td, uap->obj));
}
#endif

static int
__umtx_op_wake2_umutex(struct thread *td, struct _umtx_op_args *uap,
    const struct umtx_copyops *ops __unused)
{

        return (do_wake2_umutex(td, uap->obj, uap->val));
}

static int
__umtx_op_sem2_wait(struct thread *td, struct _umtx_op_args *uap,
    const struct umtx_copyops *ops)
{
        struct _umtx_time *tm_p, timeout;
        size_t uasize;
        int error;

        /* Allow a null timespec (wait forever). */
        if (uap->uaddr2 == NULL) {
                uasize = 0;
                tm_p = NULL;
        } else {
                uasize = (size_t)uap->uaddr1;
                error = ops->copyin_umtx_time(uap->uaddr2, uasize, &timeout);
                if (error != 0)
                        return (error);
                tm_p = &timeout;
        }
        error = do_sem2_wait(td, uap->obj, tm_p);
        if (error == EINTR && uap->uaddr2 != NULL &&
            (timeout._flags & UMTX_ABSTIME) == 0 &&
            uasize >= ops->umtx_time_sz + ops->timespec_sz) {
                error = ops->copyout_timeout(
                    (void *)((uintptr_t)uap->uaddr2 + ops->umtx_time_sz),
                    uasize - ops->umtx_time_sz, &timeout._timeout);
                if (error == 0) {
                        error = EINTR;
                }
        }

        return (error);
}

static int
__umtx_op_sem2_wake(struct thread *td, struct _umtx_op_args *uap,
    const struct umtx_copyops *ops __unused)
{

        return (do_sem2_wake(td, uap->obj));
}

#define USHM_OBJ_UMTX(o)                                                \
    ((struct umtx_shm_obj_list *)(&(o)->umtx_data))

#define USHMF_LINKED            0x0001
struct umtx_shm_reg {
        TAILQ_ENTRY(umtx_shm_reg) ushm_reg_link;
        LIST_ENTRY(umtx_shm_reg) ushm_obj_link;
        struct umtx_key         ushm_key;
        struct ucred            *ushm_cred;
        struct shmfd            *ushm_obj;
        u_int                   ushm_refcnt;
        u_int                   ushm_flags;
};

LIST_HEAD(umtx_shm_obj_list, umtx_shm_reg);
TAILQ_HEAD(umtx_shm_reg_head, umtx_shm_reg);

static uma_zone_t umtx_shm_reg_zone;
static struct umtx_shm_reg_head umtx_shm_registry[UMTX_CHAINS];
static struct mtx umtx_shm_lock;
static struct umtx_shm_reg_head umtx_shm_reg_delfree =
    TAILQ_HEAD_INITIALIZER(umtx_shm_reg_delfree);

static void umtx_shm_free_reg(struct umtx_shm_reg *reg);

static void
umtx_shm_reg_delfree_tq(void *context __unused, int pending __unused)
{
        struct umtx_shm_reg_head d;
        struct umtx_shm_reg *reg, *reg1;

        TAILQ_INIT(&d);
        mtx_lock(&umtx_shm_lock);
        TAILQ_CONCAT(&d, &umtx_shm_reg_delfree, ushm_reg_link);
        mtx_unlock(&umtx_shm_lock);
        TAILQ_FOREACH_SAFE(reg, &d, ushm_reg_link, reg1) {
                TAILQ_REMOVE(&d, reg, ushm_reg_link);
                umtx_shm_free_reg(reg);
        }
}

static struct task umtx_shm_reg_delfree_task =
    TASK_INITIALIZER(0, umtx_shm_reg_delfree_tq, NULL);

/*
 * Returns 0 if a SHM with the passed key is found in the registry, in which
 * case it is returned through 'oreg'.  Otherwise, returns an error among ESRCH
 * (no corresponding SHM; ESRCH was chosen for compatibility, ENOENT would have
 * been preferable) or EOVERFLOW (there is a corresponding SHM, but reference
 * count would overflow, so can't return it), in which case '*oreg' is left
 * unchanged.
 */
static int
umtx_shm_find_reg_locked(const struct umtx_key *key,
    struct umtx_shm_reg **const oreg)
{
        struct umtx_shm_reg *reg;
        struct umtx_shm_reg_head *reg_head;

        KASSERT(key->shared, ("umtx_p_find_rg: private key"));
        mtx_assert(&umtx_shm_lock, MA_OWNED);
        reg_head = &umtx_shm_registry[key->hash];
        TAILQ_FOREACH(reg, reg_head, ushm_reg_link) {
                KASSERT(reg->ushm_key.shared,
                    ("non-shared key on reg %p %d", reg, reg->ushm_key.shared));
                if (reg->ushm_key.info.shared.object ==
                    key->info.shared.object &&
                    reg->ushm_key.info.shared.offset ==
                    key->info.shared.offset) {
                        KASSERT(reg->ushm_key.type == TYPE_SHM, ("TYPE_USHM"));
                        KASSERT(reg->ushm_refcnt != 0,
                            ("reg %p refcnt 0 onlist", reg));
                        KASSERT((reg->ushm_flags & USHMF_LINKED) != 0,
                            ("reg %p not linked", reg));
                        /*
                         * Don't let overflow happen, just deny a new reference
                         * (this is additional protection against some reference
                         * count leak, which is known not to be the case at the
                         * time of this writing).
                         */
                        if (__predict_false(reg->ushm_refcnt == UINT_MAX))
                                return (EOVERFLOW);
                        reg->ushm_refcnt++;
                        *oreg = reg;
                        return (0);
                }
        }
        return (ESRCH);
}

/*
 * Calls umtx_shm_find_reg_unlocked() under the 'umtx_shm_lock'.
 */
static int
umtx_shm_find_reg(const struct umtx_key *key, struct umtx_shm_reg **const oreg)
{
        int error;

        mtx_lock(&umtx_shm_lock);
        error = umtx_shm_find_reg_locked(key, oreg);
        mtx_unlock(&umtx_shm_lock);
        return (error);
}

static void
umtx_shm_free_reg(struct umtx_shm_reg *reg)
{

        chgumtxcnt(reg->ushm_cred->cr_ruidinfo, -1, 0);
        crfree(reg->ushm_cred);
        shm_drop(reg->ushm_obj);
        uma_zfree(umtx_shm_reg_zone, reg);
}

static bool
umtx_shm_unref_reg_locked(struct umtx_shm_reg *reg, bool linked_ref)
{
        mtx_assert(&umtx_shm_lock, MA_OWNED);
        KASSERT(reg->ushm_refcnt != 0, ("ushm_reg %p refcnt 0", reg));

        if (linked_ref) {
                if ((reg->ushm_flags & USHMF_LINKED) == 0)
                        /*
                         * The reference tied to USHMF_LINKED has already been
                         * released concurrently.
                         */
                        return (false);

                TAILQ_REMOVE(&umtx_shm_registry[reg->ushm_key.hash], reg,
                    ushm_reg_link);
                LIST_REMOVE(reg, ushm_obj_link);
                reg->ushm_flags &= ~USHMF_LINKED;
        }

        reg->ushm_refcnt--;
        return (reg->ushm_refcnt == 0);
}

static void
umtx_shm_unref_reg(struct umtx_shm_reg *reg, bool linked_ref)
{
        vm_object_t object;
        bool dofree;

        if (linked_ref) {
                /*
                 * Note: This may be executed multiple times on the same
                 * shared-memory VM object in presence of concurrent callers
                 * because 'umtx_shm_lock' is not held all along in umtx_shm()
                 * and here.
                 */
                object = reg->ushm_obj->shm_object;
                VM_OBJECT_WLOCK(object);
                vm_object_set_flag(object, OBJ_UMTXDEAD);
                VM_OBJECT_WUNLOCK(object);
        }
        mtx_lock(&umtx_shm_lock);
        dofree = umtx_shm_unref_reg_locked(reg, linked_ref);
        mtx_unlock(&umtx_shm_lock);
        if (dofree)
                umtx_shm_free_reg(reg);
}

void
umtx_shm_object_init(vm_object_t object)
{

        LIST_INIT(USHM_OBJ_UMTX(object));
}

void
umtx_shm_object_terminated(vm_object_t object)
{
        struct umtx_shm_reg *reg, *reg1;
        bool dofree;

        if (LIST_EMPTY(USHM_OBJ_UMTX(object)))
                return;

        dofree = false;
        mtx_lock(&umtx_shm_lock);
        LIST_FOREACH_SAFE(reg, USHM_OBJ_UMTX(object), ushm_obj_link, reg1) {
                if (umtx_shm_unref_reg_locked(reg, true)) {
                        TAILQ_INSERT_TAIL(&umtx_shm_reg_delfree, reg,
                            ushm_reg_link);
                        dofree = true;
                }
        }
        mtx_unlock(&umtx_shm_lock);
        if (dofree)
                taskqueue_enqueue(taskqueue_thread, &umtx_shm_reg_delfree_task);
}

static int
umtx_shm_create_reg(struct thread *td, const struct umtx_key *key,
    struct umtx_shm_reg **res)
{
        struct shmfd *shm;
        struct umtx_shm_reg *reg, *reg1;
        struct ucred *cred;
        int error;

        error = umtx_shm_find_reg(key, res);
        if (error != ESRCH) {
                /*
                 * Either no error occured, and '*res' was filled, or EOVERFLOW
                 * was returned, indicating a reference count limit, and we
                 * won't create a duplicate registration.  In both cases, we are
                 * done.
                 */
                return (error);
        }
        /* No entry, we will create one. */

        cred = td->td_ucred;
        if (!chgumtxcnt(cred->cr_ruidinfo, 1, lim_cur(td, RLIMIT_UMTXP)))
                return (ENOMEM);
        shm = shm_alloc(td->td_ucred, O_RDWR, false);
        if (shm == NULL) {
                chgumtxcnt(cred->cr_ruidinfo, -1, 0);
                return (ENOMEM);
        }
        reg = uma_zalloc(umtx_shm_reg_zone, M_WAITOK | M_ZERO);
        bcopy(key, &reg->ushm_key, sizeof(*key));
        reg->ushm_obj = shm;
        reg->ushm_cred = crhold(cred);
        error = shm_dotruncate(reg->ushm_obj, PAGE_SIZE);
        if (error != 0) {
                umtx_shm_free_reg(reg);
                return (error);
        }
        mtx_lock(&umtx_shm_lock);
        /* Re-lookup as 'umtx_shm_lock' has been temporarily released. */
        error = umtx_shm_find_reg_locked(key, &reg1);
        switch (error) {
        case 0:
                mtx_unlock(&umtx_shm_lock);
                umtx_shm_free_reg(reg);
                *res = reg1;
                return (0);
        case ESRCH:
                break;
        default:
                mtx_unlock(&umtx_shm_lock);
                umtx_shm_free_reg(reg);
                return (error);
        }
        TAILQ_INSERT_TAIL(&umtx_shm_registry[key->hash], reg, ushm_reg_link);
        LIST_INSERT_HEAD(USHM_OBJ_UMTX(key->info.shared.object), reg,
            ushm_obj_link);
        reg->ushm_flags = USHMF_LINKED;
        /*
         * This is one reference for the registry and the list of shared
         * mutexes referenced by the VM object containing the lock pointer, and
         * another for the caller, which it will free after use.  So, one of
         * these is tied to the presence of USHMF_LINKED.
         */
        reg->ushm_refcnt = 2;
        mtx_unlock(&umtx_shm_lock);
        *res = reg;
        return (0);
}

static int
umtx_shm_alive(struct thread *td, void *addr)
{
        vm_map_t map;
        vm_map_entry_t entry;
        vm_object_t object;
        vm_pindex_t pindex;
        vm_prot_t prot;
        int res, ret;
        boolean_t wired;

        map = &td->td_proc->p_vmspace->vm_map;
        res = vm_map_lookup(&map, (uintptr_t)addr, VM_PROT_READ, &entry,
            &object, &pindex, &prot, &wired);
        if (res != KERN_SUCCESS)
                return (EFAULT);
        if (object == NULL)
                ret = EINVAL;
        else
                ret = (object->flags & OBJ_UMTXDEAD) != 0 ? ENOTTY : 0;
        vm_map_lookup_done(map, entry);
        return (ret);
}

static void
umtx_shm_init(void)
{
        int i;

        umtx_shm_reg_zone = uma_zcreate("umtx_shm", sizeof(struct umtx_shm_reg),
            NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
        mtx_init(&umtx_shm_lock, "umtxshm", NULL, MTX_DEF);
        for (i = 0; i < nitems(umtx_shm_registry); i++)
                TAILQ_INIT(&umtx_shm_registry[i]);
}

static int
umtx_shm(struct thread *td, void *addr, u_int flags)
{
        struct umtx_key key;
        struct umtx_shm_reg *reg;
        struct file *fp;
        int error, fd;

        if (__bitcount(flags & (UMTX_SHM_CREAT | UMTX_SHM_LOOKUP |
            UMTX_SHM_DESTROY| UMTX_SHM_ALIVE)) != 1)
                return (EINVAL);
        if ((flags & UMTX_SHM_ALIVE) != 0)
                return (umtx_shm_alive(td, addr));
        error = umtx_key_get(addr, TYPE_SHM, PROCESS_SHARE, &key);
        if (error != 0)
                return (error);
        KASSERT(key.shared == 1, ("non-shared key"));
        error = (flags & UMTX_SHM_CREAT) != 0 ?
            umtx_shm_create_reg(td, &key, &reg) :
            umtx_shm_find_reg(&key, &reg);
        umtx_key_release(&key);
        if (error != 0)
                return (error);
        KASSERT(reg != NULL, ("no reg"));
        if ((flags & UMTX_SHM_DESTROY) != 0) {
                umtx_shm_unref_reg(reg, true);
        } else {
#if 0
#ifdef MAC
                error = mac_posixshm_check_open(td->td_ucred,
                    reg->ushm_obj, FFLAGS(O_RDWR));
                if (error == 0)
#endif
                        error = shm_access(reg->ushm_obj, td->td_ucred,
                            FFLAGS(O_RDWR));
                if (error == 0)
#endif
                        error = falloc_caps(td, &fp, &fd, O_CLOEXEC, NULL);
                if (error == 0) {
                        shm_hold(reg->ushm_obj);
                        finit(fp, FFLAGS(O_RDWR), DTYPE_SHM, reg->ushm_obj,
                            &shm_ops);
                        td->td_retval[0] = fd;
                        fdrop(fp, td);
                }
        }
        umtx_shm_unref_reg(reg, false);
        return (error);
}

static int
__umtx_op_shm(struct thread *td, struct _umtx_op_args *uap,
    const struct umtx_copyops *ops __unused)
{

        return (umtx_shm(td, uap->uaddr1, uap->val));
}

static int
__umtx_op_robust_lists(struct thread *td, struct _umtx_op_args *uap,
    const struct umtx_copyops *ops)
{
        struct umtx_robust_lists_params rb;
        int error;

        if (ops->compat32) {
                if ((td->td_pflags2 & TDP2_COMPAT32RB) == 0 &&
                    (td->td_rb_list != 0 || td->td_rbp_list != 0 ||
                    td->td_rb_inact != 0))
                        return (EBUSY);
        } else if ((td->td_pflags2 & TDP2_COMPAT32RB) != 0) {
                return (EBUSY);
        }

        bzero(&rb, sizeof(rb));
        error = ops->copyin_robust_lists(uap->uaddr1, uap->val, &rb);
        if (error != 0)
                return (error);

        if (ops->compat32)
                td->td_pflags2 |= TDP2_COMPAT32RB;

        td->td_rb_list = rb.robust_list_offset;
        td->td_rbp_list = rb.robust_priv_list_offset;
        td->td_rb_inact = rb.robust_inact_offset;
        return (0);
}

static int
__umtx_op_get_min_timeout(struct thread *td, struct _umtx_op_args *uap,
    const struct umtx_copyops *ops)
{
        long val;
        int error, val1;

        val = sbttons(td->td_proc->p_umtx_min_timeout);
        if (ops->compat32) {
                val1 = (int)val;
                error = copyout(&val1, uap->uaddr1, sizeof(val1));
        } else {
                error = copyout(&val, uap->uaddr1, sizeof(val));
        }
        return (error);
}

static int
__umtx_op_set_min_timeout(struct thread *td, struct _umtx_op_args *uap,
    const struct umtx_copyops *ops)
{
        if (uap->val < 0)
                return (EINVAL);
        td->td_proc->p_umtx_min_timeout = nstosbt(uap->val);
        return (0);
}

#if defined(__i386__) || defined(__amd64__)
/*
 * Provide the standard 32-bit definitions for x86, since native/compat32 use a
 * 32-bit time_t there.  Other architectures just need the i386 definitions
 * along with their standard compat32.
 */
struct timespecx32 {
        int64_t                 tv_sec;
        int32_t                 tv_nsec;
};

struct umtx_timex32 {
        struct  timespecx32     _timeout;
        uint32_t                _flags;
        uint32_t                _clockid;
};

#ifndef __i386__
#define timespeci386    timespec32
#define umtx_timei386   umtx_time32
#endif
#else /* !__i386__ && !__amd64__ */
/* 32-bit architectures can emulate i386, so define these almost everywhere. */
struct timespeci386 {
        int32_t                 tv_sec;
        int32_t                 tv_nsec;
};

struct umtx_timei386 {
        struct  timespeci386    _timeout;
        uint32_t                _flags;
        uint32_t                _clockid;
};

#if defined(__LP64__)
#define timespecx32     timespec32
#define umtx_timex32    umtx_time32
#endif
#endif

static int
umtx_copyin_robust_lists32(const void *uaddr, size_t size,
    struct umtx_robust_lists_params *rbp)
{
        struct umtx_robust_lists_params_compat32 rb32;
        int error;

        if (size > sizeof(rb32))
                return (EINVAL);
        bzero(&rb32, sizeof(rb32));
        error = copyin(uaddr, &rb32, size);
        if (error != 0)
                return (error);
        CP(rb32, *rbp, robust_list_offset);
        CP(rb32, *rbp, robust_priv_list_offset);
        CP(rb32, *rbp, robust_inact_offset);
        return (0);
}

#ifndef __i386__
static inline int
umtx_copyin_timeouti386(const void *uaddr, struct timespec *tsp)
{
        struct timespeci386 ts32;
        int error;

        error = copyin(uaddr, &ts32, sizeof(ts32));
        if (error == 0) {
                if (!timespecvalid_interval(&ts32))
                        error = EINVAL;
                else {
                        CP(ts32, *tsp, tv_sec);
                        CP(ts32, *tsp, tv_nsec);
                }
        }
        return (error);
}

static inline int
umtx_copyin_umtx_timei386(const void *uaddr, size_t size, struct _umtx_time *tp)
{
        struct umtx_timei386 t32;
        int error;

        t32._clockid = CLOCK_REALTIME;
        t32._flags   = 0;
        if (size <= sizeof(t32._timeout))
                error = copyin(uaddr, &t32._timeout, sizeof(t32._timeout));
        else
                error = copyin(uaddr, &t32, sizeof(t32));
        if (error != 0)
                return (error);
        if (!timespecvalid_interval(&t32._timeout))
                return (EINVAL);
        TS_CP(t32, *tp, _timeout);
        CP(t32, *tp, _flags);
        CP(t32, *tp, _clockid);
        return (0);
}

static int
umtx_copyout_timeouti386(void *uaddr, size_t sz, struct timespec *tsp)
{
        struct timespeci386 remain32 = {
                .tv_sec = tsp->tv_sec,
                .tv_nsec = tsp->tv_nsec,
        };

        /*
         * Should be guaranteed by the caller, sz == uaddr1 - sizeof(_umtx_time)
         * and we're only called if sz >= sizeof(timespec) as supplied in the
         * copyops.
         */
        KASSERT(sz >= sizeof(remain32),
            ("umtx_copyops specifies incorrect sizes"));

        return (copyout(&remain32, uaddr, sizeof(remain32)));
}
#endif /* !__i386__ */

#if defined(__i386__) || defined(__LP64__)
static inline int
umtx_copyin_timeoutx32(const void *uaddr, struct timespec *tsp)
{
        struct timespecx32 ts32;
        int error;

        error = copyin(uaddr, &ts32, sizeof(ts32));
        if (error == 0) {
                if (!timespecvalid_interval(&ts32))
                        error = EINVAL;
                else {
                        CP(ts32, *tsp, tv_sec);
                        CP(ts32, *tsp, tv_nsec);
                }
        }
        return (error);
}

static inline int
umtx_copyin_umtx_timex32(const void *uaddr, size_t size, struct _umtx_time *tp)
{
        struct umtx_timex32 t32;
        int error;

        t32._clockid = CLOCK_REALTIME;
        t32._flags   = 0;
        if (size <= sizeof(t32._timeout))
                error = copyin(uaddr, &t32._timeout, sizeof(t32._timeout));
        else
                error = copyin(uaddr, &t32, sizeof(t32));
        if (error != 0)
                return (error);
        if (!timespecvalid_interval(&t32._timeout))
                return (EINVAL);
        TS_CP(t32, *tp, _timeout);
        CP(t32, *tp, _flags);
        CP(t32, *tp, _clockid);
        return (0);
}

static int
umtx_copyout_timeoutx32(void *uaddr, size_t sz, struct timespec *tsp)
{
        struct timespecx32 remain32 = {
                .tv_sec = tsp->tv_sec,
                .tv_nsec = tsp->tv_nsec,
        };

        /*
         * Should be guaranteed by the caller, sz == uaddr1 - sizeof(_umtx_time)
         * and we're only called if sz >= sizeof(timespec) as supplied in the
         * copyops.
         */
        KASSERT(sz >= sizeof(remain32),
            ("umtx_copyops specifies incorrect sizes"));

        return (copyout(&remain32, uaddr, sizeof(remain32)));
}
#endif /* __i386__ || __LP64__ */

typedef int (*_umtx_op_func)(struct thread *td, struct _umtx_op_args *uap,
    const struct umtx_copyops *umtx_ops);

static const _umtx_op_func op_table[] = {
#ifdef COMPAT_FREEBSD10
        [UMTX_OP_LOCK]          = __umtx_op_lock_umtx,
        [UMTX_OP_UNLOCK]        = __umtx_op_unlock_umtx,
#else
        [UMTX_OP_LOCK]          = __umtx_op_unimpl,
        [UMTX_OP_UNLOCK]        = __umtx_op_unimpl,
#endif
        [UMTX_OP_WAIT]          = __umtx_op_wait,
        [UMTX_OP_WAKE]          = __umtx_op_wake,
        [UMTX_OP_MUTEX_TRYLOCK] = __umtx_op_trylock_umutex,
        [UMTX_OP_MUTEX_LOCK]    = __umtx_op_lock_umutex,
        [UMTX_OP_MUTEX_UNLOCK]  = __umtx_op_unlock_umutex,
        [UMTX_OP_SET_CEILING]   = __umtx_op_set_ceiling,
        [UMTX_OP_CV_WAIT]       = __umtx_op_cv_wait,
        [UMTX_OP_CV_SIGNAL]     = __umtx_op_cv_signal,
        [UMTX_OP_CV_BROADCAST]  = __umtx_op_cv_broadcast,
        [UMTX_OP_WAIT_UINT]     = __umtx_op_wait_uint,
        [UMTX_OP_RW_RDLOCK]     = __umtx_op_rw_rdlock,
        [UMTX_OP_RW_WRLOCK]     = __umtx_op_rw_wrlock,
        [UMTX_OP_RW_UNLOCK]     = __umtx_op_rw_unlock,
        [UMTX_OP_WAIT_UINT_PRIVATE] = __umtx_op_wait_uint_private,
        [UMTX_OP_WAKE_PRIVATE]  = __umtx_op_wake_private,
        [UMTX_OP_MUTEX_WAIT]    = __umtx_op_wait_umutex,
        [UMTX_OP_MUTEX_WAKE]    = __umtx_op_wake_umutex,
#if defined(COMPAT_FREEBSD9) || defined(COMPAT_FREEBSD10)
        [UMTX_OP_SEM_WAIT]      = __umtx_op_sem_wait,
        [UMTX_OP_SEM_WAKE]      = __umtx_op_sem_wake,
#else
        [UMTX_OP_SEM_WAIT]      = __umtx_op_unimpl,
        [UMTX_OP_SEM_WAKE]      = __umtx_op_unimpl,
#endif
        [UMTX_OP_NWAKE_PRIVATE] = __umtx_op_nwake_private,
        [UMTX_OP_MUTEX_WAKE2]   = __umtx_op_wake2_umutex,
        [UMTX_OP_SEM2_WAIT]     = __umtx_op_sem2_wait,
        [UMTX_OP_SEM2_WAKE]     = __umtx_op_sem2_wake,
        [UMTX_OP_SHM]           = __umtx_op_shm,
        [UMTX_OP_ROBUST_LISTS]  = __umtx_op_robust_lists,
        [UMTX_OP_GET_MIN_TIMEOUT] = __umtx_op_get_min_timeout,
        [UMTX_OP_SET_MIN_TIMEOUT] = __umtx_op_set_min_timeout,
};

static const struct umtx_copyops umtx_native_ops = {
        .copyin_timeout = umtx_copyin_timeout,
        .copyin_umtx_time = umtx_copyin_umtx_time,
        .copyin_robust_lists = umtx_copyin_robust_lists,
        .copyout_timeout = umtx_copyout_timeout,
        .timespec_sz = sizeof(struct timespec),
        .umtx_time_sz = sizeof(struct _umtx_time),
};

#ifndef __i386__
static const struct umtx_copyops umtx_native_opsi386 = {
        .copyin_timeout = umtx_copyin_timeouti386,
        .copyin_umtx_time = umtx_copyin_umtx_timei386,
        .copyin_robust_lists = umtx_copyin_robust_lists32,
        .copyout_timeout = umtx_copyout_timeouti386,
        .timespec_sz = sizeof(struct timespeci386),
        .umtx_time_sz = sizeof(struct umtx_timei386),
        .compat32 = true,
};
#endif

#if defined(__i386__) || defined(__LP64__)
/* i386 can emulate other 32-bit archs, too! */
static const struct umtx_copyops umtx_native_opsx32 = {
        .copyin_timeout = umtx_copyin_timeoutx32,
        .copyin_umtx_time = umtx_copyin_umtx_timex32,
        .copyin_robust_lists = umtx_copyin_robust_lists32,
        .copyout_timeout = umtx_copyout_timeoutx32,
        .timespec_sz = sizeof(struct timespecx32),
        .umtx_time_sz = sizeof(struct umtx_timex32),
        .compat32 = true,
};

#ifdef COMPAT_FREEBSD32
#ifdef __amd64__
#define umtx_native_ops32       umtx_native_opsi386
#else
#define umtx_native_ops32       umtx_native_opsx32
#endif
#endif /* COMPAT_FREEBSD32 */
#endif /* __i386__ || __LP64__ */

#define UMTX_OP__FLAGS  (UMTX_OP__32BIT | UMTX_OP__I386)

static int
kern__umtx_op(struct thread *td, void *obj, int op, unsigned long val,
    void *uaddr1, void *uaddr2, const struct umtx_copyops *ops)
{
        struct _umtx_op_args uap = {
                .obj = obj,
                .op = op & ~UMTX_OP__FLAGS,
                .val = val,
                .uaddr1 = uaddr1,
                .uaddr2 = uaddr2
        };

        if ((uap.op >= nitems(op_table)))
                return (EINVAL);
        return ((*op_table[uap.op])(td, &uap, ops));
}

int
sys__umtx_op(struct thread *td, struct _umtx_op_args *uap)
{
        static const struct umtx_copyops *umtx_ops;

        umtx_ops = &umtx_native_ops;
#ifdef __LP64__
        if ((uap->op & (UMTX_OP__32BIT | UMTX_OP__I386)) != 0) {
                if ((uap->op & UMTX_OP__I386) != 0)
                        umtx_ops = &umtx_native_opsi386;
                else
                        umtx_ops = &umtx_native_opsx32;
        }
#elif !defined(__i386__)
        /* We consider UMTX_OP__32BIT a nop on !i386 ILP32. */
        if ((uap->op & UMTX_OP__I386) != 0)
                umtx_ops = &umtx_native_opsi386;
#else
        /* Likewise, UMTX_OP__I386 is a nop on i386. */
        if ((uap->op & UMTX_OP__32BIT) != 0)
                umtx_ops = &umtx_native_opsx32;
#endif
        return (kern__umtx_op(td, uap->obj, uap->op, uap->val, uap->uaddr1,
            uap->uaddr2, umtx_ops));
}

#ifdef COMPAT_FREEBSD32
#ifdef COMPAT_FREEBSD10
int
freebsd10_freebsd32__umtx_lock(struct thread *td,
    struct freebsd10_freebsd32__umtx_lock_args *uap)
{
        return (do_lock_umtx32(td, (uint32_t *)uap->umtx, td->td_tid, NULL));
}

int
freebsd10_freebsd32__umtx_unlock(struct thread *td,
    struct freebsd10_freebsd32__umtx_unlock_args *uap)
{
        return (do_unlock_umtx32(td, (uint32_t *)uap->umtx, td->td_tid));
}
#endif /* COMPAT_FREEBSD10 */

int
freebsd32__umtx_op(struct thread *td, struct freebsd32__umtx_op_args *uap)
{

        return (kern__umtx_op(td, uap->obj, uap->op, uap->val, uap->uaddr1,
            uap->uaddr2, &umtx_native_ops32));
}
#endif /* COMPAT_FREEBSD32 */

void
umtx_thread_init(struct thread *td)
{

        td->td_umtxq = umtxq_alloc();
        td->td_umtxq->uq_thread = td;
}

void
umtx_thread_fini(struct thread *td)
{

        umtxq_free(td->td_umtxq);
}

/*
 * It will be called when new thread is created, e.g fork().
 */
void
umtx_thread_alloc(struct thread *td)
{
        struct umtx_q *uq;

        uq = td->td_umtxq;
        uq->uq_inherited_pri = PRI_MAX;

        KASSERT(uq->uq_flags == 0, ("uq_flags != 0"));
        KASSERT(uq->uq_thread == td, ("uq_thread != td"));
        KASSERT(uq->uq_pi_blocked == NULL, ("uq_pi_blocked != NULL"));
        KASSERT(TAILQ_EMPTY(&uq->uq_pi_contested), ("uq_pi_contested is not empty"));
}

/*
 * exec() hook.
 *
 * Clear robust lists for all process' threads, not delaying the
 * cleanup to thread exit, since the relevant address space is
 * destroyed right now.
 */
void
umtx_exec(struct proc *p)
{
        struct thread *td;

        KASSERT(p == curproc, ("need curproc"));
        KASSERT((p->p_flag & P_HADTHREADS) == 0 ||
            (p->p_flag & P_STOPPED_SINGLE) != 0,
            ("curproc must be single-threaded"));
        /*
         * There is no need to lock the list as only this thread can be
         * running.
         */
        FOREACH_THREAD_IN_PROC(p, td) {
                KASSERT(td == curthread ||
                    ((td->td_flags & TDF_BOUNDARY) != 0 && TD_IS_SUSPENDED(td)),
                    ("running thread %p %p", p, td));
                umtx_thread_cleanup(td);
                td->td_rb_list = td->td_rbp_list = td->td_rb_inact = 0;
        }

        p->p_umtx_min_timeout = 0;
}

/*
 * thread exit hook.
 */
void
umtx_thread_exit(struct thread *td)
{

        umtx_thread_cleanup(td);
}

static int
umtx_read_uptr(struct thread *td, uintptr_t ptr, uintptr_t *res, bool compat32)
{
        u_long res1;
        uint32_t res32;
        int error;

        if (compat32) {
                error = fueword32((void *)ptr, &res32);
                if (error == 0)
                        res1 = res32;
        } else {
                error = fueword((void *)ptr, &res1);
        }
        if (error == 0)
                *res = res1;
        else
                error = EFAULT;
        return (error);
}

static void
umtx_read_rb_list(struct thread *td, struct umutex *m, uintptr_t *rb_list,
    bool compat32)
{
        struct umutex32 m32;

        if (compat32) {
                memcpy(&m32, m, sizeof(m32));
                *rb_list = m32.m_rb_lnk;
        } else {
                *rb_list = m->m_rb_lnk;
        }
}

static int
umtx_handle_rb(struct thread *td, uintptr_t rbp, uintptr_t *rb_list, bool inact,
    bool compat32)
{
        struct umutex m;
        int error;

        KASSERT(td->td_proc == curproc, ("need current vmspace"));
        error = copyin((void *)rbp, &m, sizeof(m));
        if (error != 0)
                return (error);
        if (rb_list != NULL)
                umtx_read_rb_list(td, &m, rb_list, compat32);
        if ((m.m_flags & UMUTEX_ROBUST) == 0)
                return (EINVAL);
        if ((m.m_owner & ~UMUTEX_CONTESTED) != td->td_tid)
                /* inact is cleared after unlock, allow the inconsistency */
                return (inact ? 0 : EINVAL);
        return (do_unlock_umutex(td, (struct umutex *)rbp, true));
}

static void
umtx_cleanup_rb_list(struct thread *td, uintptr_t rb_list, uintptr_t *rb_inact,
    const char *name, bool compat32)
{
        int error, i;
        uintptr_t rbp;
        bool inact;

        if (rb_list == 0)
                return;
        error = umtx_read_uptr(td, rb_list, &rbp, compat32);
        for (i = 0; error == 0 && rbp != 0 && i < umtx_max_rb; i++) {
                if (rbp == *rb_inact) {
                        inact = true;
                        *rb_inact = 0;
                } else
                        inact = false;
                error = umtx_handle_rb(td, rbp, &rbp, inact, compat32);
        }
        if (i == umtx_max_rb && umtx_verbose_rb) {
                uprintf("comm %s pid %d: reached umtx %smax rb %d\n",
                    td->td_proc->p_comm, td->td_proc->p_pid, name, umtx_max_rb);
        }
        if (error != 0 && umtx_verbose_rb) {
                uprintf("comm %s pid %d: handling %srb error %d\n",
                    td->td_proc->p_comm, td->td_proc->p_pid, name, error);
        }
}

/*
 * Clean up umtx data.
 */
static void
umtx_thread_cleanup(struct thread *td)
{
        struct umtx_q *uq;
        struct umtx_pi *pi;
        uintptr_t rb_inact;
        bool compat32;

        /*
         * Disown pi mutexes.
         */
        uq = td->td_umtxq;
        if (uq != NULL) {
                if (uq->uq_inherited_pri != PRI_MAX ||
                    !TAILQ_EMPTY(&uq->uq_pi_contested)) {
                        mtx_lock(&umtx_lock);
                        uq->uq_inherited_pri = PRI_MAX;
                        while ((pi = TAILQ_FIRST(&uq->uq_pi_contested)) != NULL) {
                                pi->pi_owner = NULL;
                                TAILQ_REMOVE(&uq->uq_pi_contested, pi, pi_link);
                        }
                        mtx_unlock(&umtx_lock);
                }
                sched_lend_user_prio_cond(td, PRI_MAX);
        }

        compat32 = (td->td_pflags2 & TDP2_COMPAT32RB) != 0;
        td->td_pflags2 &= ~TDP2_COMPAT32RB;

        if (td->td_rb_inact == 0 && td->td_rb_list == 0 && td->td_rbp_list == 0)
                return;

        /*
         * Handle terminated robust mutexes.  Must be done after
         * robust pi disown, otherwise unlock could see unowned
         * entries.
         */
        rb_inact = td->td_rb_inact;
        if (rb_inact != 0)
                (void)umtx_read_uptr(td, rb_inact, &rb_inact, compat32);
        umtx_cleanup_rb_list(td, td->td_rb_list, &rb_inact, "", compat32);
        umtx_cleanup_rb_list(td, td->td_rbp_list, &rb_inact, "priv ", compat32);
        if (rb_inact != 0)
                (void)umtx_handle_rb(td, rb_inact, NULL, true, compat32);
}