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| author | H.J. Lu <hjl.tools@gmail.com> | 2021-11-12 11:47:42 -0800 |
|---|---|---|
| committer | H.J. Lu <hjl.tools@gmail.com> | 2021-11-15 05:50:56 -0800 |
| commit | 120ac6d238825452e8024e2f627da33b2508dfd3 (patch) | |
| tree | 4215cb357a961543c55aa8bbe5ef754d212be1e8 | |
| parent | cbcd65c8b526555d9b98628338973f91f74002ad (diff) | |
| download | glibc-120ac6d238825452e8024e2f627da33b2508dfd3.tar.gz glibc-120ac6d238825452e8024e2f627da33b2508dfd3.tar.xz glibc-120ac6d238825452e8024e2f627da33b2508dfd3.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.
| -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 762059b230..47b88a6b5b 100644 --- a/nptl/pthread_mutex_lock.c +++ b/nptl/pthread_mutex_lock.c @@ -304,10 +304,9 @@ __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 f763cfc7fa..791a2b54b1 100644 --- a/nptl/pthread_mutex_timedlock.c +++ b/nptl/pthread_mutex_timedlock.c @@ -233,10 +233,9 @@ __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; |