From ca37f880abe1c8e3464fd646fd8b89171d8fca0c Mon Sep 17 00:00:00 2001 From: "H.J. Lu" Date: Thu, 11 Nov 2021 06:31:51 -0800 Subject: [PATCH] Avoid extra load with CAS in __pthread_mutex_lock_full [BZ #28537] Replace boolean CAS with value CAS to avoid the extra load. Reviewed-by: Szabolcs Nagy (cherry picked from commit 0b82747dc48d5bf0871bdc6da8cb6eec1256355f) --- nptl/pthread_mutex_lock.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/nptl/pthread_mutex_lock.c b/nptl/pthread_mutex_lock.c index 29cc143e..60ada70d 100644 --- a/nptl/pthread_mutex_lock.c +++ b/nptl/pthread_mutex_lock.c @@ -292,12 +292,12 @@ __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; -- GitLab