/*
 * This file and its contents are supplied under the terms of the
 * Common Development and Distribution License ("CDDL"), version 1.0.
 * You may only use this file in accordance with the terms of version
 * 1.0 of the CDDL.
 *
 * A full copy of the text of the CDDL should have accompanied this
 * source.  A copy of the CDDL is also available via the Internet at
 * http://www.illumos.org/license/CDDL.
 */

/*
 * Copyright 2018 Nexenta Systems, Inc.  All rights reserved.
 * Copyright 2017 RackTop Systems.
 */

/*
 * mutex(9f)
 */

/* This is the API we're emulating */
#include <sys/mutex.h>

#include <sys/errno.h>
#include <sys/debug.h>
#include <sys/thread.h>

int     _lwp_mutex_lock(lwp_mutex_t *);
int     _lwp_mutex_unlock(lwp_mutex_t *);
int     _lwp_mutex_trylock(lwp_mutex_t *);

extern clock_t ddi_get_lbolt(void);

/* See: head/synch.h ERRORCHECKMUTEX */
static const lwp_mutex_t default_mutex =
        {{0, 0, 0, {USYNC_THREAD|LOCK_ERRORCHECK}, _MUTEX_MAGIC},
        {{{0, 0, 0, 0, 0, 0, 0, 0}}}, 0};

/* ARGSUSED */
void
kmutex_init(kmutex_t *mp, char *name, kmutex_type_t typ, void *arg)
{
        mp->m_lock = default_mutex;
        mp->m_owner = _KTHREAD_INVALID;
}

/* ARGSUSED */
void
kmutex_destroy(kmutex_t *mp)
{
        mp->m_owner = _KTHREAD_INVALID;
}

void
kmutex_enter(kmutex_t *mp)
{
        kthread_t *t = _curthread();

        VERIFY(mp->m_owner != t);
        VERIFY(0 == _lwp_mutex_lock(&mp->m_lock));
        mp->m_owner = t;
}

int
mutex_tryenter(kmutex_t *mp)
{
        int rc;

        rc = _lwp_mutex_trylock(&mp->m_lock);
        if (rc == 0) {
                mp->m_owner = _curthread();
                return (1);
        }
        return (0);
}

void
kmutex_exit(kmutex_t *mp)
{
        ASSERT(mp->m_owner == _curthread());
        mp->m_owner = _KTHREAD_INVALID;
        (void) _lwp_mutex_unlock(&mp->m_lock);
}

/*
 * Returns the kthread_t * of the owner.
 */
void *
mutex_owner(const kmutex_t *mp)
{
        return (mp->m_owner);
}

int
mutex_owned(const kmutex_t *mp)
{
        void *t = _curthread();
        return (t == mp->m_owner);
}