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From: Sunil Pandey <skpgkp2@sourceware.org> To: glibc-cvs@sourceware.org Subject: [glibc/users/skpgkp2/2.33/master] Avoid extra load with CAS in __pthread_mutex_clocklock_common [BZ #28537] Date: Wed, 28 Sep 2022 21:45:37 +0000 (GMT) [thread overview] Message-ID: <20220928214537.A4DD73858406@sourceware.org> (raw) https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=e6f492033f524670855c08bef56b89419457c380 commit e6f492033f524670855c08bef56b89419457c380 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: --- nptl/pthread_mutex_timedlock.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/nptl/pthread_mutex_timedlock.c b/nptl/pthread_mutex_timedlock.c index 8428ebca0f..541ec18938 100644 --- a/nptl/pthread_mutex_timedlock.c +++ b/nptl/pthread_mutex_timedlock.c @@ -247,12 +247,12 @@ __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;
next reply other threads:[~2022-09-28 21:45 UTC|newest] Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-09-28 21:45 Sunil Pandey [this message] -- strict thread matches above, loose matches on Subject: below -- 2022-09-29 18:41 Sunil Pandey 2022-09-28 19:11 Sunil Pandey
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