From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 7852) id 5ED2F385742A; Wed, 28 Sep 2022 19:10:56 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 5ED2F385742A DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1664392256; bh=peqgTVBej4H5pdp34jqz838TmKNDJlfOGJbQdUfcN0o=; h=From:To:Subject:Date:From; b=fbhUmwSMuURekfoG52RAGKCMeq6OqzkbD9m50EbR4zrlaQLlqdDP12I7T/d8+Z2em NEnAHa8zg+3kpsdAo0SpxsoKCSCfo61Dg1+JYYVi5k29HGQwuNywnjOQdhL/Sj3Y6R zZlKdmtJaZwjQPZS62j+IbuBmfQFypoJodgLaL8Q= Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit From: Sunil Pandey To: glibc-cvs@sourceware.org Subject: [glibc/users/skpgkp2/2.33/master] Avoid extra load with CAS in __pthread_mutex_lock_full [BZ #28537] X-Act-Checkin: glibc X-Git-Author: H.J. Lu X-Git-Refname: refs/heads/users/skpgkp2/2.33/master X-Git-Oldrev: 4f2167e4319e7b1cebe0f0f14a2f0db9da24971e X-Git-Newrev: b62b86cf12fa1484d1952bedb2856860030d6cc0 Message-Id: <20220928191056.5ED2F385742A@sourceware.org> Date: Wed, 28 Sep 2022 19:10:56 +0000 (GMT) List-Id: https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=b62b86cf12fa1484d1952bedb2856860030d6cc0 commit b62b86cf12fa1484d1952bedb2856860030d6cc0 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. Reviewed-by: Szabolcs Nagy (cherry picked from commit 0b82747dc48d5bf0871bdc6da8cb6eec1256355f) Diff: --- 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 319658adc4..0fd7467b97 100644 --- a/nptl/pthread_mutex_lock.c +++ b/nptl/pthread_mutex_lock.c @@ -289,12 +289,12 @@ __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;