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* internals.h (strict __pthread_descr_struct): Add p_sem_avail.
	* semaphore.c: Handle spurious wakeups.

	* sysdeps/pthread/pthread.h: Add back PTHREAD_MUTX_FAST_NP as an alias
	for PTHREAD_MUTEX_ADAPTIVE_NP for source code compatibility.

	* pthread.c (__pthread_set_own_extricate): Use THREAD_GETMEM.
	(__pthread_wait_for_restart): Likewise.

	* condvar.c (pthread_cond_wait): Also check whether thread is
	cancelable before aborting loop.
	(pthread_cond_timedwait): Likewise.
This commit is contained in:
Ulrich Drepper 2000-07-26 02:18:41 +00:00
parent a956d04575
commit 9ec9e34ee3
6 changed files with 74 additions and 20 deletions

13
linuxthreads/ChangeLog

@ -1,5 +1,18 @@
2000-07-25 Ulrich Drepper <drepper@redhat.com>
* internals.h (strict __pthread_descr_struct): Add p_sem_avail.
* semaphore.c: Handle spurious wakeups.
* sysdeps/pthread/pthread.h: Add back PTHREAD_MUTX_FAST_NP as an alias
for PTHREAD_MUTEX_ADAPTIVE_NP for source code compatibility.
* pthread.c (__pthread_set_own_extricate): Use THREAD_GETMEM.
(__pthread_wait_for_restart): Likewise.
* condvar.c (pthread_cond_wait): Also check whether thread is
cancelable before aborting loop.
(pthread_cond_timedwait): Likewise.
* signals.c (pthread_sighandler): Remove special code to restrore
%gs on x86.
(pthread_sighandler_t): Likewise.

6
linuxthreads/condvar.c

@ -103,7 +103,8 @@ int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
{
suspend(self);
if (THREAD_GETMEM(self, p_condvar_avail) == 0
&& THREAD_GETMEM(self, p_woken_by_cancel) == 0)
&& (THREAD_GETMEM(self, p_woken_by_cancel) == 0
|| THREAD_GETMEM(self, p_cancelstate) != PTHREAD_CANCEL_ENABLE))
{
/* Count resumes that don't belong to us. */
spurious_wakeup_count++;
@ -196,7 +197,8 @@ pthread_cond_timedwait_relative(pthread_cond_t *cond,
}
if (THREAD_GETMEM(self, p_condvar_avail) == 0
&& THREAD_GETMEM(self, p_woken_by_cancel) == 0)
&& (THREAD_GETMEM(self, p_woken_by_cancel) == 0
|| THREAD_GETMEM(self, p_cancelstate) != PTHREAD_CANCEL_ENABLE))
{
/* Count resumes that don't belong to us. */
spurious_wakeup_count++;

1
linuxthreads/internals.h

@ -168,6 +168,7 @@ struct _pthread_descr_struct {
called on thread */
char p_woken_by_cancel; /* cancellation performed wakeup */
char p_condvar_avail; /* flag if conditional variable became avail */
char p_sem_avail; /* flag if semaphore became available */
pthread_extricate_if *p_extricate; /* See above */
pthread_readlock_info *p_readlock_list; /* List of readlock info structs */
pthread_readlock_info *p_readlock_free; /* Free list of structs */

8
linuxthreads/pthread.c

@ -868,9 +868,9 @@ weak_alias (__pthread_getconcurrency, pthread_getconcurrency)
void __pthread_set_own_extricate_if(pthread_descr self, pthread_extricate_if *peif)
{
__pthread_lock(self->p_lock, self);
__pthread_lock(THREAD_GETMEM(self, p_lock), self);
THREAD_SETMEM(self, p_extricate, peif);
__pthread_unlock(self->p_lock);
__pthread_unlock(THREAD_GETMEM (self, p_lock));
}
/* Primitives for controlling thread execution */
@ -881,10 +881,10 @@ void __pthread_wait_for_restart_signal(pthread_descr self)
sigprocmask(SIG_SETMASK, NULL, &mask); /* Get current signal mask */
sigdelset(&mask, __pthread_sig_restart); /* Unblock the restart signal */
THREAD_SETMEM(self, p_signal, 0);
do {
self->p_signal = 0;
sigsuspend(&mask); /* Wait for signal */
} while (self->p_signal !=__pthread_sig_restart );
} while (THREAD_GETMEM(self, p_signal) !=__pthread_sig_restart);
}
#if !__ASSUME_REALTIME_SIGNALS

62
linuxthreads/semaphore.c

@ -60,6 +60,7 @@ int __new_sem_wait(sem_t * sem)
volatile pthread_descr self = thread_self();
pthread_extricate_if extr;
int already_canceled = 0;
int spurious_wakeup_count;
/* Set up extrication interface */
extr.pu_object = sem;
@ -72,6 +73,7 @@ int __new_sem_wait(sem_t * sem)
return 0;
}
/* Register extrication interface */
THREAD_SETMEM(self, p_sem_avail, 0);
__pthread_set_own_extricate_if(self, &extr);
/* Enqueue only if not already cancelled. */
if (!(THREAD_GETMEM(self, p_canceled)
@ -87,7 +89,20 @@ int __new_sem_wait(sem_t * sem)
}
/* Wait for sem_post or cancellation, or fall through if already canceled */
suspend(self);
spurious_wakeup_count = 0;
while (1)
{
suspend(self);
if (THREAD_GETMEM(self, p_sem_avail) == 0
&& (THREAD_GETMEM(self, p_woken_by_cancel) == 0
|| THREAD_GETMEM(self, p_cancelstate) != PTHREAD_CANCEL_ENABLE))
{
/* Count resumes that don't belong to us. */
spurious_wakeup_count++;
continue;
}
break;
}
__pthread_set_own_extricate_if(self, 0);
/* Terminate only if the wakeup came from cancellation. */
@ -138,6 +153,8 @@ int __new_sem_post(sem_t * sem)
} else {
th = dequeue(&sem->__sem_waiting);
__pthread_unlock((struct _pthread_fastlock *) &sem->__sem_lock);
th->p_sem_avail = 1;
WRITE_MEMORY_BARRIER();
restart(th);
}
} else {
@ -195,6 +212,7 @@ int sem_timedwait(sem_t *sem, const struct timespec *abstime)
pthread_descr self = thread_self();
pthread_extricate_if extr;
int already_canceled = 0;
int spurious_wakeup_count;
__pthread_lock((struct _pthread_fastlock *) &sem->__sem_lock, self);
if (sem->__sem_value > 0) {
@ -215,6 +233,7 @@ int sem_timedwait(sem_t *sem, const struct timespec *abstime)
extr.pu_extricate_func = new_sem_extricate_func;
/* Register extrication interface */
THREAD_SETMEM(self, p_sem_avail, 0);
__pthread_set_own_extricate_if(self, &extr);
/* Enqueue only if not already cancelled. */
if (!(THREAD_GETMEM(self, p_canceled)
@ -229,24 +248,39 @@ int sem_timedwait(sem_t *sem, const struct timespec *abstime)
pthread_exit(PTHREAD_CANCELED);
}
if (timedsuspend(self, abstime) == 0) {
int was_on_queue;
spurious_wakeup_count = 0;
while (1)
{
if (timedsuspend(self, abstime) == 0) {
int was_on_queue;
/* __pthread_lock will queue back any spurious restarts that
may happen to it. */
/* __pthread_lock will queue back any spurious restarts that
may happen to it. */
__pthread_lock((struct _pthread_fastlock *)&sem->__sem_lock, self);
was_on_queue = remove_from_queue(&sem->__sem_waiting, self);
__pthread_unlock((struct _pthread_fastlock *)&sem->__sem_lock);
__pthread_lock((struct _pthread_fastlock *)&sem->__sem_lock, self);
was_on_queue = remove_from_queue(&sem->__sem_waiting, self);
__pthread_unlock((struct _pthread_fastlock *)&sem->__sem_lock);
if (was_on_queue) {
__pthread_set_own_extricate_if(self, 0);
return ETIMEDOUT;
if (was_on_queue) {
__pthread_set_own_extricate_if(self, 0);
return ETIMEDOUT;
}
/* Eat the outstanding restart() from the signaller */
suspend(self);
}
if (THREAD_GETMEM(self, p_sem_avail) == 0
&& (THREAD_GETMEM(self, p_woken_by_cancel) == 0
|| THREAD_GETMEM(self, p_cancelstate) != PTHREAD_CANCEL_ENABLE))
{
/* Count resumes that don't belong to us. */
spurious_wakeup_count++;
continue;
}
break;
}
/* Eat the outstanding restart() from the signaller */
suspend(self);
}
__pthread_set_own_extricate_if(self, 0);
/* Terminate only if the wakeup came from cancellation. */

4
linuxthreads/sysdeps/pthread/pthread.h

@ -88,6 +88,10 @@ enum
PTHREAD_MUTEX_ERRORCHECK = PTHREAD_MUTEX_ERRORCHECK_NP,
PTHREAD_MUTEX_DEFAULT = PTHREAD_MUTEX_NORMAL
#endif
#ifdef __USE_GNU
/* For compatibility. */
, PTHREAD_MUTEX_FAST_NP = PTHREAD_MUTEX_ADAPTIVE_NP
#endif
};
enum