diff mbox series

Move assignment out of the CAS condition

Message ID 20211112202256.1591340-1-hjl.tools@gmail.com
State Committed
Commit 120ac6d238825452e8024e2f627da33b2508dfd3
Headers
Series Move assignment out of the CAS condition |

Checks

Context Check Description
dj/TryBot-apply_patch success Patch applied to master at the time it was sent
dj/TryBot-32bit success Build for i686

Commit Message

H.J. Lu Nov. 12, 2021, 8:22 p.m. UTC 
  Update

commit 49302b8fdf9103b6fc0a398678668a22fa19574c
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.

and

commit 0b82747dc48d5bf0871bdc6da8cb6eec1256355f
Author: H.J. Lu <hjl.tools@gmail.com>
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.
---
 nptl/pthread_mutex_lock.c      | 7 +++----
 nptl/pthread_mutex_timedlock.c | 7 +++----
 2 files changed, 6 insertions(+), 8 deletions(-)

Comments

Andreas Schwab Nov. 15, 2021, 1:42 p.m. UTC | #1 
Ok.

Andreas.
Sunil Pandey Sept. 11, 2022, 8:21 p.m. UTC | #2 
On Mon, Nov 15, 2021 at 5:42 AM Andreas Schwab <schwab@linux-m68k.org> wrote:
>
> Ok.
>
> Andreas.
>
> --
> Andreas Schwab, schwab@linux-m68k.org
> GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510  2552 DF73 E780 A9DA AEC1
> "And now for something completely different."

I would like to backport this patch to release branch 2.33 and 2.34.

Any comments/suggestions or objections on this.

commit 120ac6d238825452e8024e2f627da33b2508dfd3
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Fri Nov 12 11:47:42 2021 -0800

    Move assignment out of the CAS condition
Noah Goldstein Sept. 29, 2022, 12:09 a.m. UTC | #3 
On Sun, Sep 11, 2022 at 4:22 PM Sunil Pandey via Libc-stable
<libc-stable@sourceware.org> wrote:
>
> On Mon, Nov 15, 2021 at 5:42 AM Andreas Schwab <schwab@linux-m68k.org> wrote:
> >
> > Ok.
> >
> > Andreas.
> >
> > --
> > Andreas Schwab, schwab@linux-m68k.org
> > GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510  2552 DF73 E780 A9DA AEC1
> > "And now for something completely different."
>
> I would like to backport this patch to release branch 2.33 and 2.34.
>
> Any comments/suggestions or objections on this.
>
> commit 120ac6d238825452e8024e2f627da33b2508dfd3
> Author: H.J. Lu <hjl.tools@gmail.com>
> Date:   Fri Nov 12 11:47:42 2021 -0800
>
>     Move assignment out of the CAS condition

Fine by me.
diff mbox series

Patch

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;