/*      $NetBSD: locks.c,v 1.88 2023/11/02 10:31:55 martin Exp $        */

/*
 * Copyright (c) 2007-2011 Antti Kantee.  All Rights Reserved.
 *
 * 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, 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 OR CONTRIBUTORS 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>
__KERNEL_RCSID(0, "$NetBSD: locks.c,v 1.88 2023/11/02 10:31:55 martin Exp $");

#include <sys/param.h>
#include <sys/kmem.h>
#include <sys/mutex.h>
#include <sys/rwlock.h>

#include <rump-sys/kern.h>

#include <rump/rumpuser.h>

#ifdef LOCKDEBUG
const int rump_lockdebug = 1;
#else
const int rump_lockdebug = 0;
#endif

/*
 * Simple lockdebug.  If it's compiled in, it's always active.
 * Currently available only for mtx/rwlock.
 */
#ifdef LOCKDEBUG
#include <sys/lockdebug.h>

static lockops_t mutex_spin_lockops = {
        .lo_name = "mutex",
        .lo_type = LOCKOPS_SPIN,
        .lo_dump = NULL,
};
static lockops_t mutex_adaptive_lockops = {
        .lo_name = "mutex",
        .lo_type = LOCKOPS_SLEEP,
        .lo_dump = NULL,
};
static lockops_t rw_lockops = {
        .lo_name = "rwlock",
        .lo_type = LOCKOPS_SLEEP,
        .lo_dump = NULL,
};

#define ALLOCK(lock, ops, return_address)               \
        lockdebug_alloc(__func__, __LINE__, lock, ops,  \
            return_address)
#define FREELOCK(lock)                                  \
        lockdebug_free(__func__, __LINE__, lock)
#define WANTLOCK(lock, shar)                            \
        lockdebug_wantlock(__func__, __LINE__, lock,    \
            (uintptr_t)__builtin_return_address(0), shar)
#define LOCKED(lock, shar)                              \
        lockdebug_locked(__func__, __LINE__, lock, NULL,\
            (uintptr_t)__builtin_return_address(0), shar)
#define UNLOCKED(lock, shar)                            \
        lockdebug_unlocked(__func__, __LINE__, lock,    \
            (uintptr_t)__builtin_return_address(0), shar)
#define BARRIER(lock, slp)                              \
        lockdebug_barrier(__func__, __LINE__, lock, slp)
#else
#define ALLOCK(a, b, c) do {} while (0)
#define FREELOCK(a)     do {} while (0)
#define WANTLOCK(a, b)  do {} while (0)
#define LOCKED(a, b)    do {} while (0)
#define UNLOCKED(a, b)  do {} while (0)
#define BARRIER(a, b)   do {} while (0)
#endif

/*
 * We map locks to pthread routines.  The difference between kernel
 * and rumpuser routines is that while the kernel uses static
 * storage, rumpuser allocates the object from the heap.  This
 * indirection is necessary because we don't know the size of
 * pthread objects here.  It is also beneficial, since we can
 * be easily compatible with the kernel ABI because all kernel
 * objects regardless of machine architecture are always at least
 * the size of a pointer.  The downside, of course, is a performance
 * penalty.
 */

#define RUMPMTX(mtx) (*(struct rumpuser_mtx *const *)(mtx))

void
_mutex_init(kmutex_t *mtx, kmutex_type_t type, int ipl,
    uintptr_t return_address)
{
        int ruflags = RUMPUSER_MTX_KMUTEX;
        int isspin;

        CTASSERT(sizeof(kmutex_t) >= sizeof(void *));

        /*
         * Try to figure out if the caller wanted a spin mutex or
         * not with this easy set of conditionals.  The difference
         * between a spin mutex and an adaptive mutex for a rump
         * kernel is that the hypervisor does not relinquish the
         * rump kernel CPU context for a spin mutex.  The
         * hypervisor itself may block even when "spinning".
         */
        if (type == MUTEX_SPIN) {
                isspin = 1;
        } else if (ipl == IPL_NONE || ipl == IPL_SOFTCLOCK ||
            ipl == IPL_SOFTBIO || ipl == IPL_SOFTNET ||
            ipl == IPL_SOFTSERIAL) {
                isspin = 0;
        } else {
                isspin = 1;
        }

        if (isspin)
                ruflags |= RUMPUSER_MTX_SPIN;
        rumpuser_mutex_init((struct rumpuser_mtx **)mtx, ruflags);
        if (isspin)
                ALLOCK(mtx, &mutex_spin_lockops, return_address);
        else
                ALLOCK(mtx, &mutex_adaptive_lockops, return_address);
}

void
mutex_init(kmutex_t *mtx, kmutex_type_t type, int ipl)
{

        _mutex_init(mtx, type, ipl, (uintptr_t)__builtin_return_address(0));
}

void
mutex_destroy(kmutex_t *mtx)
{

        FREELOCK(mtx);
        rumpuser_mutex_destroy(RUMPMTX(mtx));
}

void
mutex_enter(kmutex_t *mtx)
{

        WANTLOCK(mtx, 0);
        if (!rumpuser_mutex_spin_p(RUMPMTX(mtx)))
                BARRIER(mtx, 1);
        rumpuser_mutex_enter(RUMPMTX(mtx));
        LOCKED(mtx, false);
}

void
mutex_spin_enter(kmutex_t *mtx)
{

        KASSERT(rumpuser_mutex_spin_p(RUMPMTX(mtx)));
        WANTLOCK(mtx, 0);
        rumpuser_mutex_enter_nowrap(RUMPMTX(mtx));
        LOCKED(mtx, false);
}

int
mutex_tryenter(kmutex_t *mtx)
{
        int error;

        error = rumpuser_mutex_tryenter(RUMPMTX(mtx));
        if (error == 0) {
                WANTLOCK(mtx, 0);
                LOCKED(mtx, false);
        }
        return error == 0;
}

void
mutex_exit(kmutex_t *mtx)
{

#ifndef LOCKDEBUG
        KASSERT(mutex_owned(mtx));
#endif
        UNLOCKED(mtx, false);
        rumpuser_mutex_exit(RUMPMTX(mtx));
}
__strong_alias(mutex_spin_exit,mutex_exit);

int
mutex_ownable(const kmutex_t *mtx)
{

#ifdef LOCKDEBUG
        WANTLOCK(mtx, -1);
#endif
        return 1;
}

int
mutex_owned(const kmutex_t *mtx)
{
        struct lwp *l;

        rumpuser_mutex_owner(RUMPMTX(mtx), &l);
        return l == curlwp;
}

#define RUMPRW(rw) (*(struct rumpuser_rw **)(rw))

/* reader/writer locks */

static enum rumprwlock
krw2rumprw(const krw_t op)
{

        switch (op) {
        case RW_READER:
                return RUMPUSER_RW_READER;
        case RW_WRITER:
                return RUMPUSER_RW_WRITER;
        default:
                panic("unknown rwlock type");
        }
}

void
_rw_init(krwlock_t *rw, uintptr_t return_address)
{

        CTASSERT(sizeof(krwlock_t) >= sizeof(void *));

        rumpuser_rw_init((struct rumpuser_rw **)rw);
        ALLOCK(rw, &rw_lockops, return_address);
}

void
rw_init(krwlock_t *rw)
{

        _rw_init(rw, (uintptr_t)__builtin_return_address(0));
}

void
rw_destroy(krwlock_t *rw)
{

        FREELOCK(rw);
        rumpuser_rw_destroy(RUMPRW(rw));
}

void
rw_enter(krwlock_t *rw, const krw_t op)
{

        WANTLOCK(rw, op == RW_READER);
        BARRIER(rw, 1);
        rumpuser_rw_enter(krw2rumprw(op), RUMPRW(rw));
        LOCKED(rw, op == RW_READER);
}

int
rw_tryenter(krwlock_t *rw, const krw_t op)
{
        int error;

        error = rumpuser_rw_tryenter(krw2rumprw(op), RUMPRW(rw));
        if (error == 0) {
                WANTLOCK(rw, op == RW_READER);
                LOCKED(rw, op == RW_READER);
        }
        return error == 0;
}

void
rw_exit(krwlock_t *rw)
{

#ifdef LOCKDEBUG
        bool shared = !rw_write_held(rw);

        if (shared)
                KASSERT(rw_read_held(rw));
        UNLOCKED(rw, shared);
#endif
        rumpuser_rw_exit(RUMPRW(rw));
}

int
rw_tryupgrade(krwlock_t *rw)
{
        int rv;

        rv = rumpuser_rw_tryupgrade(RUMPRW(rw));
        if (rv == 0) {
                UNLOCKED(rw, 1);
                WANTLOCK(rw, 0);
                LOCKED(rw, 0);
        }
        return rv == 0;
}

void
rw_downgrade(krwlock_t *rw)
{

        rumpuser_rw_downgrade(RUMPRW(rw));
        UNLOCKED(rw, 0);
        WANTLOCK(rw, 1);
        LOCKED(rw, 1);
}

int
rw_read_held(krwlock_t *rw)
{
        int rv;

        rumpuser_rw_held(RUMPUSER_RW_READER, RUMPRW(rw), &rv);
        return rv;
}

int
rw_write_held(krwlock_t *rw)
{
        int rv;

        rumpuser_rw_held(RUMPUSER_RW_WRITER, RUMPRW(rw), &rv);
        return rv;
}

int
rw_lock_held(krwlock_t *rw)
{

        return rw_read_held(rw) || rw_write_held(rw);
}

krw_t
rw_lock_op(krwlock_t *rw)
{

        return rw_write_held(rw) ? RW_WRITER : RW_READER;
}

/* curriculum vitaes */

#define RUMPCV(cv) (*(struct rumpuser_cv **)(cv))

void
cv_init(kcondvar_t *cv, const char *msg)
{

        CTASSERT(sizeof(kcondvar_t) >= sizeof(void *));

        rumpuser_cv_init((struct rumpuser_cv **)cv);
}

void
cv_destroy(kcondvar_t *cv)
{

        rumpuser_cv_destroy(RUMPCV(cv));
}

static int
docvwait(kcondvar_t *cv, kmutex_t *mtx, struct timespec *ts)
{
        struct lwp *l = curlwp;
        int rv;

        if (__predict_false(l->l_flag & LW_RUMP_QEXIT)) {
                /*
                 * yield() here, someone might want the cpu
                 * to set a condition.  otherwise we'll just
                 * loop forever.
                 */
                yield();
                return EINTR;
        }

        UNLOCKED(mtx, false);

        l->l_sched.info = cv;
        rv = 0;
        if (ts) {
                if (rumpuser_cv_timedwait(RUMPCV(cv), RUMPMTX(mtx),
                    ts->tv_sec, ts->tv_nsec))
                        rv = EWOULDBLOCK;
        } else {
                rumpuser_cv_wait(RUMPCV(cv), RUMPMTX(mtx));
        }

        LOCKED(mtx, false);

        /*
         * Check for QEXIT.  if so, we need to wait here until we
         * are allowed to exit.
         */
        if (__predict_false(l->l_flag & LW_RUMP_QEXIT)) {
                struct proc *p = l->l_proc;

                mutex_exit(mtx); /* drop and retake later */

                mutex_enter(p->p_lock);
                while ((p->p_sflag & PS_RUMP_LWPEXIT) == 0) {
                        /* avoid recursion */
                        rumpuser_cv_wait(RUMPCV(&p->p_waitcv),
                            RUMPMTX(p->p_lock));
                }
                KASSERT(p->p_sflag & PS_RUMP_LWPEXIT);
                mutex_exit(p->p_lock);

                /* ok, we can exit and remove "reference" to l->l_sched.info */

                mutex_enter(mtx);
                rv = EINTR;
        }
        l->l_sched.info = NULL;

        return rv;
}

void
cv_wait(kcondvar_t *cv, kmutex_t *mtx)
{

        if (__predict_false(rump_threads == 0))
                panic("cv_wait without threads");
        (void) docvwait(cv, mtx, NULL);
}

int
cv_wait_sig(kcondvar_t *cv, kmutex_t *mtx)
{

        if (__predict_false(rump_threads == 0))
                panic("cv_wait without threads");
        return docvwait(cv, mtx, NULL);
}

int
cv_timedwait(kcondvar_t *cv, kmutex_t *mtx, int ticks)
{
        struct timespec ts;
        extern int hz;
        int rv;

        if (ticks == 0) {
                rv = cv_wait_sig(cv, mtx);
        } else {
                ts.tv_sec = ticks / hz;
                ts.tv_nsec = (ticks % hz) * (1000000000/hz);
                rv = docvwait(cv, mtx, &ts);
        }

        return rv;
}
__strong_alias(cv_timedwait_sig,cv_timedwait);

void
cv_signal(kcondvar_t *cv)
{

        rumpuser_cv_signal(RUMPCV(cv));
}

void
cv_broadcast(kcondvar_t *cv)
{

        rumpuser_cv_broadcast(RUMPCV(cv));
}

bool
cv_has_waiters(kcondvar_t *cv)
{
        int rv;

        rumpuser_cv_has_waiters(RUMPCV(cv), &rv);
        return rv != 0;
}

/* this is not much of an attempt, but ... */
bool
cv_is_valid(kcondvar_t *cv)
{

        return RUMPCV(cv) != NULL;
}