From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 1039) id 4EAA93857C5E; Mon, 15 Nov 2021 13:51:18 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 4EAA93857C5E Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit From: H.J. Lu To: glibc-cvs@sourceware.org Subject: [glibc] Move assignment out of the CAS condition X-Act-Checkin: glibc X-Git-Author: H.J. Lu X-Git-Refname: refs/heads/master X-Git-Oldrev: cbcd65c8b526555d9b98628338973f91f74002ad X-Git-Newrev: 120ac6d238825452e8024e2f627da33b2508dfd3 Message-Id: <20211115135118.4EAA93857C5E@sourceware.org> Date: Mon, 15 Nov 2021 13:51:18 +0000 (GMT) X-BeenThere: glibc-cvs@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Glibc-cvs mailing list List-Unsubscribe: , List-Archive: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 15 Nov 2021 13:51:18 -0000 https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=120ac6d238825452e8024e2f627da33b2508dfd3 commit 120ac6d238825452e8024e2f627da33b2508dfd3 Author: H.J. Lu Date: Fri Nov 12 11:47:42 2021 -0800 Move assignment out of the CAS condition Update commit 49302b8fdf9103b6fc0a398678668a22fa19574c Author: H.J. Lu 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 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. Diff: --- nptl/pthread_mutex_lock.c | 7 +++---- 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;