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pthread_barrier: Ensure the barrier is "idle" during destruction.

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If the serial thread tries to destroy barriers immediately, not all threads
may have exited yet. This takes care of that case.
This commit is contained in:
Augustin Cavalier 2023-06-12 23:46:11 -04:00
parent f79c7ae83e
commit 496e411397
1 changed files with 17 additions and 10 deletions
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27
src/system/libroot/posix/pthread/pthread_barrier.cpp
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@ -72,6 +72,21 @@ barrier_unlock(__haiku_std_int32* mutex)
}
static void
barrier_ensure_idle(pthread_barrier_t* barrier)
{
// waiter_count < 0 means other threads are still exiting.
// Loop (usually only one iteration needed) until this is no longer the case.
while (atomic_get((int32*)&barrier->waiter_count) < 0) {
status_t status = barrier_lock(&barrier->mutex);
if (status != B_OK)
return;
barrier_unlock(&barrier->mutex);
}
}
int
pthread_barrier_wait(pthread_barrier_t* barrier)
{
@ -81,15 +96,7 @@ pthread_barrier_wait(pthread_barrier_t* barrier)
if (barrier->waiter_max == 1)
return PTHREAD_BARRIER_SERIAL_THREAD;
// waiter_count < 0 means other threads are still exiting.
// Lock in a loop, if necessary, until this is no longer the case.
while (atomic_get((int32*)&barrier->waiter_count) < 0) {
status_t status = barrier_lock(&barrier->mutex);
if (status != B_OK)
return status;
barrier_unlock(&barrier->mutex);
}
barrier_ensure_idle(barrier);
if (atomic_add((int32*)&barrier->waiter_count, 1) == (barrier->waiter_max - 1)) {
// We are the last one in. Lock the barrier mutex.
@ -125,7 +132,7 @@ pthread_barrier_wait(pthread_barrier_t* barrier)
int
pthread_barrier_destroy(pthread_barrier_t* barrier)
{
// No dynamic resources to free
barrier_ensure_idle(barrier);
return B_OK;
}