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Simplify code, fix a thread cancellation bug in sem_wait and sem_timedwait.

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This commit is contained in:
David Xu 2007-11-23 05:42:52 +00:00
parent 4c8e514bdc
commit da4410f25f
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=173856
1 changed files with 15 additions and 21 deletions
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36
lib/libthr/thread/thr_sem.c
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@ -199,19 +199,17 @@ _sem_wait(sem_t *sem)
_pthread_testcancel();
do {
atomic_add_int(&(*sem)->nwaiters, 1);
while ((val = (*sem)->count) > 0) {
if (atomic_cmpset_acq_int(&(*sem)->count, val, val - 1)) {
atomic_add_int(&(*sem)->nwaiters, -1);
if (atomic_cmpset_acq_int(&(*sem)->count, val, val - 1))
return (0);
}
}
atomic_add_int(&(*sem)->nwaiters, 1);
THR_CLEANUP_PUSH(curthread, sem_cancel_handler, sem);
_thr_cancel_enter(curthread);
retval = _thr_umtx_wait_uint(&(*sem)->count, 0, NULL);
atomic_add_int(&(*sem)->nwaiters, -1);
_thr_cancel_leave(curthread);
THR_CLEANUP_POP(curthread, 0);
atomic_add_int(&(*sem)->nwaiters, -1);
} while (retval == 0);
errno = retval;
return (-1);
@ -242,35 +240,37 @@ _sem_timedwait(sem_t * __restrict sem,
*/
_pthread_testcancel();
do {
atomic_add_int(&(*sem)->nwaiters, 1);
while ((val = (*sem)->count) > 0) {
if (atomic_cmpset_acq_int(&(*sem)->count, val, val - 1)) {
atomic_add_int(&(*sem)->nwaiters, -1);
if (atomic_cmpset_acq_int(&(*sem)->count, val, val - 1))
return (0);
}
}
if (abstime == NULL) {
atomic_add_int(&(*sem)->nwaiters, -1);
errno = EINVAL;
return (-1);
}
THR_CLEANUP_PUSH(curthread, sem_cancel_handler, sem);
clock_gettime(CLOCK_REALTIME, &ts);
TIMESPEC_SUB(&ts2, abstime, &ts);
atomic_add_int(&(*sem)->nwaiters, 1);
THR_CLEANUP_PUSH(curthread, sem_cancel_handler, sem);
_thr_cancel_enter(curthread);
retval = _thr_umtx_wait_uint(&(*sem)->count, 0, &ts2);
atomic_add_int(&(*sem)->nwaiters, -1);
_thr_cancel_leave(curthread);
THR_CLEANUP_POP(curthread, 0);
atomic_add_int(&(*sem)->nwaiters, -1);
} while (retval == 0);
errno = retval;
return (-1);
}
/*
* sem_post() is required to be safe to call from within
* signal handlers, these code should work as that.
*/
int
_sem_post(sem_t *sem)
{
int val, retval = 0;
int retval = 0;
if (sem_check_validity(sem) != 0)
return (-1);
@ -278,16 +278,10 @@ _sem_post(sem_t *sem)
if ((*sem)->syssem != 0)
return (ksem_post((*sem)->semid));
/*
* sem_post() is required to be safe to call from within
* signal handlers, these code should work as that.
*/
do {
val = (*sem)->count;
} while (!atomic_cmpset_rel_int(&(*sem)->count, val, val + 1));
atomic_add_rel_int(&(*sem)->count, 1);
if ((*sem)->nwaiters) {
retval = _thr_umtx_wake(&(*sem)->count, val + 1);
retval = _thr_umtx_wake(&(*sem)->count, 1);
if (retval > 0)
retval = 0;
}