diff options
Diffstat (limited to 'linuxthreads/semaphore.c')
| -rw-r--r-- | linuxthreads/semaphore.c | 62 |
1 files changed, 48 insertions, 14 deletions
diff --git a/linuxthreads/semaphore.c b/linuxthreads/semaphore.c index a772ea5091..e5afce43eb 100644 --- a/linuxthreads/semaphore.c +++ b/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. */ |