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/*
* This file is part of the SPL: Solaris Porting Layer.
*
* Copyright (c) 2008 Lawrence Livermore National Security, LLC.
* Produced at Lawrence Livermore National Laboratory
* Written by:
* Brian Behlendorf <behlendorf1@llnl.gov>,
* Herb Wartens <wartens2@llnl.gov>,
* Jim Garlick <garlick@llnl.gov>
* UCRL-CODE-235197
*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include <sys/condvar.h>
#ifdef DEBUG_SUBSYSTEM
#undef DEBUG_SUBSYSTEM
#endif
#define DEBUG_SUBSYSTEM S_CONDVAR
void
__cv_init(kcondvar_t *cvp, char *name, kcv_type_t type, void *arg)
{
int flags = KM_SLEEP;
ENTRY;
ASSERT(cvp);
ASSERT(name);
ASSERT(type == CV_DEFAULT);
ASSERT(arg == NULL);
cvp->cv_magic = CV_MAGIC;
init_waitqueue_head(&cvp->cv_event);
spin_lock_init(&cvp->cv_lock);
atomic_set(&cvp->cv_waiters, 0);
cvp->cv_mutex = NULL;
cvp->cv_name = NULL;
cvp->cv_name_size = strlen(name) + 1;
/* We may be called when there is a non-zero preempt_count or
* interrupts are disabled is which case we must not sleep.
*/
if (current_thread_info()->preempt_count || irqs_disabled())
flags = KM_NOSLEEP;
cvp->cv_name = kmem_alloc(cvp->cv_name_size, flags);
if (cvp->cv_name)
strcpy(cvp->cv_name, name);
EXIT;
}
EXPORT_SYMBOL(__cv_init);
void
__cv_destroy(kcondvar_t *cvp)
{
ENTRY;
ASSERT(cvp);
ASSERT(cvp->cv_magic == CV_MAGIC);
spin_lock(&cvp->cv_lock);
ASSERT(atomic_read(&cvp->cv_waiters) == 0);
ASSERT(!waitqueue_active(&cvp->cv_event));
if (cvp->cv_name)
kmem_free(cvp->cv_name, cvp->cv_name_size);
spin_unlock(&cvp->cv_lock);
memset(cvp, CV_POISON, sizeof(*cvp));
EXIT;
}
EXPORT_SYMBOL(__cv_destroy);
void
__cv_wait(kcondvar_t *cvp, kmutex_t *mp)
{
DEFINE_WAIT(wait);
ENTRY;
ASSERT(cvp);
ASSERT(mp);
ASSERT(cvp->cv_magic == CV_MAGIC);
spin_lock(&cvp->cv_lock);
ASSERT(mutex_owned(mp));
if (cvp->cv_mutex == NULL)
cvp->cv_mutex = mp;
/* Ensure the same mutex is used by all callers */
ASSERT(cvp->cv_mutex == mp);
spin_unlock(&cvp->cv_lock);
prepare_to_wait_exclusive(&cvp->cv_event, &wait,
TASK_UNINTERRUPTIBLE);
atomic_inc(&cvp->cv_waiters);
/* Mutex should be dropped after prepare_to_wait() this
* ensures we're linked in to the waiters list and avoids the
* race where 'cvp->cv_waiters > 0' but the list is empty. */
mutex_exit(mp);
schedule();
mutex_enter(mp);
atomic_dec(&cvp->cv_waiters);
finish_wait(&cvp->cv_event, &wait);
EXIT;
}
EXPORT_SYMBOL(__cv_wait);
/* 'expire_time' argument is an absolute wall clock time in jiffies.
* Return value is time left (expire_time - now) or -1 if timeout occurred.
*/
clock_t
__cv_timedwait(kcondvar_t *cvp, kmutex_t *mp, clock_t expire_time)
{
DEFINE_WAIT(wait);
clock_t time_left;
ENTRY;
ASSERT(cvp);
ASSERT(mp);
ASSERT(cvp->cv_magic == CV_MAGIC);
spin_lock(&cvp->cv_lock);
ASSERT(mutex_owned(mp));
if (cvp->cv_mutex == NULL)
cvp->cv_mutex = mp;
/* Ensure the same mutex is used by all callers */
ASSERT(cvp->cv_mutex == mp);
spin_unlock(&cvp->cv_lock);
/* XXX - Does not handle jiffie wrap properly */
time_left = expire_time - jiffies;
if (time_left <= 0)
RETURN(-1);
prepare_to_wait_exclusive(&cvp->cv_event, &wait,
TASK_UNINTERRUPTIBLE);
atomic_inc(&cvp->cv_waiters);
/* Mutex should be dropped after prepare_to_wait() this
* ensures we're linked in to the waiters list and avoids the
* race where 'cvp->cv_waiters > 0' but the list is empty. */
mutex_exit(mp);
time_left = schedule_timeout(time_left);
mutex_enter(mp);
atomic_dec(&cvp->cv_waiters);
finish_wait(&cvp->cv_event, &wait);
RETURN(time_left > 0 ? time_left : -1);
}
EXPORT_SYMBOL(__cv_timedwait);
void
__cv_signal(kcondvar_t *cvp)
{
ENTRY;
ASSERT(cvp);
ASSERT(cvp->cv_magic == CV_MAGIC);
/* All waiters are added with WQ_FLAG_EXCLUSIVE so only one
* waiter will be set runable with each call to wake_up().
* Additionally wake_up() holds a spin_lock assoicated with
* the wait queue to ensure we don't race waking up processes. */
if (atomic_read(&cvp->cv_waiters) > 0)
wake_up(&cvp->cv_event);
EXIT;
}
EXPORT_SYMBOL(__cv_signal);
void
__cv_broadcast(kcondvar_t *cvp)
{
ASSERT(cvp);
ASSERT(cvp->cv_magic == CV_MAGIC);
ENTRY;
/* Wake_up_all() will wake up all waiters even those which
* have the WQ_FLAG_EXCLUSIVE flag set. */
if (atomic_read(&cvp->cv_waiters) > 0)
wake_up_all(&cvp->cv_event);
EXIT;
}
EXPORT_SYMBOL(__cv_broadcast);
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