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Avoid extra load with CAS in __pthread_mutex_lock_full [BZ #28537]

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Replace boolean CAS with value CAS to avoid the extra load.

Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
This commit is contained in:
H.J. Lu 2021-11-11 06:31:51 -08:00
parent 6c1e3c0fd0
commit 0b82747dc4
1 changed files with 5 additions and 5 deletions
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10
nptl/pthread_mutex_lock.c
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@ -297,12 +297,12 @@ __pthread_mutex_lock_full (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;