/*      $NetBSD: sleepq.c,v 1.28 2023/10/13 18:23:54 ad Exp $   */

/*
 * Copyright (c) 2008 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: sleepq.c,v 1.28 2023/10/13 18:23:54 ad Exp $");

#include <sys/param.h>
#include <sys/condvar.h>
#include <sys/mutex.h>
#include <sys/once.h>
#include <sys/queue.h>
#include <sys/sleepq.h>
#include <sys/syncobj.h>
#include <sys/atomic.h>

#include <rump-sys/kern.h>

syncobj_t sleep_syncobj;

void
sleepq_init(sleepq_t *sq)
{

        LIST_INIT(sq);
        cv_init(&sq->sq_cv, "sleepq");
}

void
sleepq_destroy(sleepq_t *sq)
{

        cv_destroy(&sq->sq_cv);
}

int
sleepq_enter(sleepq_t *sq, lwp_t *l, kmutex_t *mp)
{
        int nlocks;

        lwp_lock(l);
        if (mp != NULL) {
                lwp_unlock_to(l, mp);
        }
        if ((nlocks = l->l_blcnt) != 0) {
                KERNEL_UNLOCK_ALL(NULL, NULL);
        }
        return nlocks;
}

void
sleepq_enqueue(sleepq_t *sq, wchan_t wc, const char *wmsg, syncobj_t *sob,
    bool catch_p)
{
        struct lwp *l = curlwp;

        l->l_wchan = wc;
        l->l_wmesg = wmsg;
        l->l_sleepq = sq;
        LIST_INSERT_HEAD(sq, l, l_sleepchain);
}

int
sleepq_block(int timo, bool catch, syncobj_t *syncobj __unused, int nlocks)
{
        struct lwp *l = curlwp;
        int error = 0;
        kmutex_t *mp = l->l_mutex;

        while (l->l_wchan) {
                l->l_mutex = mp; /* keep sleepq lock until woken up */
                error = cv_timedwait(&l->l_sleepq->sq_cv, mp, timo);
                if (error == EWOULDBLOCK || error == EINTR) {
                        if (l->l_wchan) {
                                LIST_REMOVE(l, l_sleepchain);
                                l->l_wchan = NULL;
                                l->l_wmesg = NULL;
                        }
                }
        }
        mutex_spin_exit(mp);

        if (nlocks)
                KERNEL_LOCK(nlocks, curlwp);

        return error;
}

void
sleepq_wake(sleepq_t *sq, wchan_t wchan, u_int expected, kmutex_t *mp)
{
        struct lwp *l, *l_next;
        bool found = false;

        for (l = LIST_FIRST(sq); l; l = l_next) {
                l_next = LIST_NEXT(l, l_sleepchain);
                if (l->l_wchan == wchan) {
                        found = true;
                        l->l_wchan = NULL;
                        l->l_wmesg = NULL;
                        LIST_REMOVE(l, l_sleepchain);
                        if (--expected == 0)
                                break;
                }
        }
        if (found)
                cv_broadcast(&sq->sq_cv);

        mutex_spin_exit(mp);
}

void
sleepq_unsleep(struct lwp *l, bool cleanup)
{

        l->l_wchan = NULL;
        l->l_wmesg = NULL;
        LIST_REMOVE(l, l_sleepchain);
        cv_broadcast(&l->l_sleepq->sq_cv);

        if (cleanup) {
                mutex_spin_exit(l->l_mutex);
        }
}

void
sleepq_remove(sleepq_t *sq, struct lwp *l, bool wakeup)
{

        sleepq_unsleep(l, false);
}

/*
 * Thread scheduler handles priorities.  Therefore no action here.
 * (maybe do something if we're deperate?)
 */
void
sleepq_changepri(struct lwp *l, pri_t pri)
{

}

void
sleepq_lendpri(struct lwp *l, pri_t pri)
{

}

struct lwp *
syncobj_noowner(wchan_t wc)
{

        return NULL;
}

void
lwp_unlock_to(struct lwp *l, kmutex_t *new)
{
        kmutex_t *old;

        KASSERT(mutex_owned(l->l_mutex));

        old = l->l_mutex;
        atomic_store_release(&l->l_mutex, new);
        mutex_spin_exit(old);
}

void
lwp_lock(lwp_t *l)
{
        kmutex_t *old = atomic_load_consume(&l->l_mutex);

        mutex_spin_enter(old);
        while (__predict_false(atomic_load_relaxed(&l->l_mutex) != old)) {
                mutex_spin_exit(old);
                old = atomic_load_consume(&l->l_mutex);
                mutex_spin_enter(old);
        }
}

void
lwp_unlock(lwp_t *l)
{

        mutex_spin_exit(l->l_mutex);
}

void
lwp_changepri(lwp_t *l, pri_t pri)
{

        /* fuck */
}

void
lwp_lendpri(lwp_t *l, pri_t pri)
{

        /* you */
}

pri_t
lwp_eprio(lwp_t *l)
{

        /* Antti */
        return l->l_priority;
}