glibc/SOURCES/glibc-upstream-2.34-331.patch
2023-05-09 05:53:24 +00:00

34 lines
1.1 KiB
Diff

commit ed8300c054cae4aeb0bbfa043f5fccc91a4adbf5
Author: H.J. Lu <hjl.tools@gmail.com>
Date: Thu Nov 11 06:54:01 2021 -0800
Avoid extra load with CAS in __pthread_mutex_clocklock_common [BZ #28537]
Replace boolean CAS with value CAS to avoid the extra load.
Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
(cherry picked from commit 49302b8fdf9103b6fc0a398678668a22fa19574c)
diff --git a/nptl/pthread_mutex_timedlock.c b/nptl/pthread_mutex_timedlock.c
index 11ad7005d07afc6e..90cede9446e33fcf 100644
--- a/nptl/pthread_mutex_timedlock.c
+++ b/nptl/pthread_mutex_timedlock.c
@@ -234,12 +234,12 @@ __pthread_mutex_clocklock_common (pthread_mutex_t *mutex,
meantime. */
if ((oldval & FUTEX_WAITERS) == 0)
{
- if (atomic_compare_and_exchange_bool_acq (&mutex->__data.__lock,
- oldval | FUTEX_WAITERS,
- oldval)
- != 0)
+ int val;
+ if ((val = atomic_compare_and_exchange_val_acq
+ (&mutex->__data.__lock, oldval | FUTEX_WAITERS,
+ oldval)) != oldval)
{
- oldval = mutex->__data.__lock;
+ oldval = val;
continue;
}
oldval |= FUTEX_WAITERS;