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/* Copyright (C) 2008 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by David Bartley <dtbartle@csclub.uwaterloo.ca>, 2008.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
#include <inline-syscall.h>
#include <pthreadP.h>
#include <synch.h>
#include <errno.h>
DECLARE_INLINE_SYSCALL (int, lwp_cond_wait, cond_t *cv, mutex_t *mp,
struct timespec *tsp, int check_park);
struct _condvar_cleanup_buffer
{
int oldtype;
cond_t *cond;
mutex_t *mutex;
int recursive;
uint8_t old_mutex_rcount;
};
void
__attribute__ ((visibility ("hidden")))
__condvar_cleanup (void *arg)
{
struct _condvar_cleanup_buffer *cbuffer =
(struct _condvar_cleanup_buffer *) arg;
mutex_t *mutex = cbuffer->mutex;
/* Note: we don't whether the mutex was unlocked by the kernel or not. */
int errval = 0;
while (1)
{
if (MUTEX_IS_OWNER (mutex))
{
/* The lock is held by us (we didn't get signaled). */
break;
}
else
{
/* The mutex was unlocked so we claim it, */
errval = mutex_lock (mutex);
break;
}
}
/* Restore the mutex_rcount. */
if (errval == 0)
mutex->mutex_rcount = cbuffer->old_mutex_rcount;
/* The condition variable is no longer using the mutex. */
atomic_decrement (&mutex->mutex_cond_waiters);
}
int
__cond_reltimedwait_internal (cond, mutex, reltime, cancel)
cond_t *cond;
mutex_t *mutex;
struct timespec *reltime;
int cancel;
{
struct _pthread_cleanup_buffer buffer;
struct _condvar_cleanup_buffer cbuffer = {
.recursive = 0
};
/* Reject invalid timeouts. */
if (PAST_TIMESPEC (reltime))
return ETIME;
else if (INVALID_TIMESPEC (reltime))
return EINVAL;
if ((mutex->mutex_type & LOCK_ERRORCHECK) && MUTEX_NOT_OWNER (mutex))
{
/* Error checking: lock not held by this thread. */
return EPERM;
}
else if ((mutex->mutex_type & LOCK_RECURSIVE) && MUTEX_IS_OWNER (mutex) &&
mutex->mutex_rcount > 0)
{
/* Recursively held lock. XXX: Using recursive mutexes with condition
variables is undefined; we do what sun's libc does, namely fully
release the lock. */
cbuffer.recursive = 1;
cbuffer.old_mutex_rcount = mutex->mutex_rcount;
mutex->mutex_rcount = 0;
}
/* Mark the mutex as still in use. */
atomic_increment (&mutex->mutex_cond_waiters);
/* Prepare structure passed to cancellation handler. */
cbuffer.cond = cond;
cbuffer.mutex = mutex;
if (cancel)
{
/* Before we block we enable cancellation. Therefore we have to
install a cancellation handler. */
__pthread_cleanup_push (&buffer, __condvar_cleanup, &cbuffer);
/* Enable asynchronous cancellation. Required by the standard. */
cbuffer.oldtype = __pthread_enable_asynccancel ();
}
int errval = INLINE_SYSCALL (lwp_cond_wait, 4, cond, mutex, reltime, 1);
if (cancel)
{
/* Disable asynchronous cancellation. */
__pthread_disable_asynccancel (cbuffer.oldtype);
/* The cancellation handling is back to normal, remove the handler. */
__pthread_cleanup_pop (&buffer, 0);
}
/* Re-acquire the lock. The docs say we must always re-acquire so we don't
use __mutex_timedlock. Note that even if the above wait fails the kernel
always unlocks the mutex. */
int errval2 = mutex_lock (mutex);
if (errval2 == EOWNERDEAD)
errval = errval2;
else if (errval == 0)
errval = errval2;
/* Restore the mutex_rcount. */
if ((errval2 == 0 || errval2 == EOWNERDEAD) && cbuffer.recursive)
mutex->mutex_rcount = cbuffer.old_mutex_rcount;
/* The condition variable is no longer using the mutex. */
atomic_decrement (&mutex->mutex_cond_waiters);
return errval;
}
int cond_reltimedwait (cond, mutex, reltime)
cond_t *cond;
mutex_t *mutex;
struct timespec *reltime;
{
return __cond_reltimedwait_internal (cond, mutex, reltime, 1);
}
weak_alias (cond_reltimedwait, _lwp_cond_reltimedwait)
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