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| author | H.J. Lu <hjl.tools@gmail.com> | 2021-11-12 11:47:42 -0800 |
|---|---|---|
| committer | Sunil K Pandey <skpgkp2@gmail.com> | 2022-09-28 07:33:49 -0700 |
| commit | 6bcfbee7277e4faa4b693bd965931f0d1883005d (patch) | |
| tree | 194b55b2b510c5f3b076cbe125b2d3535907bd82 | |
| parent | a6b81f605dfba8650ea1f80122f41eb8e6c73dc7 (diff) | |
| download | glibc-6bcfbee7277e4faa4b693bd965931f0d1883005d.tar glibc-6bcfbee7277e4faa4b693bd965931f0d1883005d.tar.gz glibc-6bcfbee7277e4faa4b693bd965931f0d1883005d.tar.bz2 glibc-6bcfbee7277e4faa4b693bd965931f0d1883005d.zip | |
Move assignment out of the CAS condition
Update
commit 49302b8fdf9103b6fc0a398678668a22fa19574c
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.
and
commit 0b82747dc48d5bf0871bdc6da8cb6eec1256355f
Author: H.J. Lu <hjl.tools@gmail.com>
Date: Thu Nov 11 06:31:51 2021 -0800
Avoid extra load with CAS in __pthread_mutex_lock_full [BZ #28537]
Replace boolean CAS with value CAS to avoid the extra load.
by moving assignment out of the CAS condition.
(cherry picked from commit 120ac6d238825452e8024e2f627da33b2508dfd3)
| -rw-r--r-- | nptl/pthread_mutex_lock.c | 7 | ||||
| -rw-r--r-- | nptl/pthread_mutex_timedlock.c | 7 |
2 files changed, 6 insertions, 8 deletions
diff --git a/nptl/pthread_mutex_lock.c b/nptl/pthread_mutex_lock.c index 9f40928cc6..49901ffa0a 100644 --- a/nptl/pthread_mutex_lock.c +++ b/nptl/pthread_mutex_lock.c @@ -305,10 +305,9 @@ __pthread_mutex_lock_full (pthread_mutex_t *mutex) meantime. */ if ((oldval & FUTEX_WAITERS) == 0) { - int val; - if ((val = atomic_compare_and_exchange_val_acq - (&mutex->__data.__lock, oldval | FUTEX_WAITERS, - oldval)) != oldval) + int val = atomic_compare_and_exchange_val_acq + (&mutex->__data.__lock, oldval | FUTEX_WAITERS, oldval); + if (val != oldval) { oldval = val; continue; diff --git a/nptl/pthread_mutex_timedlock.c b/nptl/pthread_mutex_timedlock.c index 90cede9446..2e5506db06 100644 --- a/nptl/pthread_mutex_timedlock.c +++ b/nptl/pthread_mutex_timedlock.c @@ -234,10 +234,9 @@ __pthread_mutex_clocklock_common (pthread_mutex_t *mutex, meantime. */ if ((oldval & FUTEX_WAITERS) == 0) { - int val; - if ((val = atomic_compare_and_exchange_val_acq - (&mutex->__data.__lock, oldval | FUTEX_WAITERS, - oldval)) != oldval) + int val = atomic_compare_and_exchange_val_acq + (&mutex->__data.__lock, oldval | FUTEX_WAITERS, oldval); + if (val != oldval) { oldval = val; continue; |