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Redesigned how cancellation unblocks a thread from internal cancellation points (sem_wait, pthread_join, pthread_cond_{wait,timedwait}). Cancellation won't eat a signal in any of these functions (*required* by POSIX and Single Unix Spec!).

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2000-01-03  Kaz Kylheku  <kaz@ashi.footprints.net>

	Redesigned how cancellation unblocks a thread from internal
	cancellation points (sem_wait, pthread_join,
	pthread_cond_{wait,timedwait}).
	Cancellation won't eat a signal in any of these functions
	(*required* by POSIX and Single Unix Spec!).
	* condvar.c: spontaneous wakeup on pthread_cond_timedwait won't eat a
	simultaneous condition variable signal (not required by POSIX
	or Single Unix Spec, but nice).
	* spinlock.c: __pthread_lock queues back any received restarts
	that don't belong to it instead of assuming ownership of lock
	upon any restart; fastlock can no longer be acquired by two threads
	simultaneously.
	* restart.h: restarts queue even on kernels that don't have
	queued real time signals (2.0, early 2.1), thanks to atomic counter,
	avoiding a rare race condition in pthread_cond_timedwait.
This commit is contained in:
Ulrich Drepper
2000-01-05 02:09:12 +00:00
parent f19f2b3443
commit 1d2fc9b3c5
14 changed files with 719 additions and 107 deletions
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24
linuxthreads/oldsemaphore.c
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@@ -68,13 +68,29 @@ int __old_sem_init(old_sem_t *sem, int pshared, unsigned int value)
return 0;
}
/* Function called by pthread_cancel to remove the thread from
waiting inside __old_sem_wait. Here we simply unconditionally
indicate that the thread is to be woken, by returning 1. */
static int old_sem_extricate_func(void *obj, pthread_descr th)
{
return 1;
}
int __old_sem_wait(old_sem_t * sem)
{
long oldstatus, newstatus;
volatile pthread_descr self = thread_self();
pthread_descr * th;
pthread_extricate_if extr;
/* Set up extrication interface */
extr.pu_object = 0;
extr.pu_extricate_func = old_sem_extricate_func;
while (1) {
/* Register extrication interface */
__pthread_set_own_extricate_if(self, &extr);
do {
oldstatus = sem->sem_status;
if ((oldstatus & 1) && (oldstatus != 1))
@@ -85,11 +101,15 @@ int __old_sem_wait(old_sem_t * sem)
}
}
while (! sem_compare_and_swap(sem, oldstatus, newstatus));
if (newstatus & 1)
if (newstatus & 1) {
/* We got the semaphore. */
__pthread_set_own_extricate_if(self, 0);
return 0;
}
/* Wait for sem_post or cancellation */
suspend_with_cancellation(self);
suspend(self);
__pthread_set_own_extricate_if(self, 0);
/* This is a cancellation point */
if (self->p_canceled && self->p_cancelstate == PTHREAD_CANCEL_ENABLE) {
/* Remove ourselves from the waiting list if we're still on it */