[glibc/users/skpgkp2/2.33/master] Avoid extra load with CAS in __pthread_mutex_clocklock_common [BZ #28537]

[Sunil Pandey <skpgkp2@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=0ec276739a22c0305263941b5213e8c368269ec0

commit 0ec276739a22c0305263941b5213e8c368269ec0
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;