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From: Wilco Dijkstra <wilco@sourceware.org>
To: glibc-cvs@sourceware.org
Subject: [glibc] Use C11 atomics instead of atomic_and/or
Date: Fri, 23 Sep 2022 15:01:04 +0000 (GMT)	[thread overview]
Message-ID: <20220923150104.99C353857B8D@sourceware.org> (raw)

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=8114b95cef10a5a1fc3e529ab8b3a75f56fe889a

commit 8114b95cef10a5a1fc3e529ab8b3a75f56fe889a
Author: Wilco Dijkstra <wdijkstr@arm.com>
Date:   Thu Sep 22 15:27:20 2022 +0100

    Use C11 atomics instead of atomic_and/or
    
    Remove the 4 uses of atomic_and and atomic_or with atomic_fetch_and_acquire
    and atomic_fetch_or_acquire. This is preserves existing implied semantics,
    however relaxed MO on FUTEX_OWNER_DIED accesses may be correct.
    
    Passes regress on AArch64.
    
    Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

Diff:
---
 nptl/pthread_create.c          | 2 +-
 nptl/pthread_mutex_lock.c      | 2 +-
 nptl/pthread_mutex_timedlock.c | 2 +-
 nptl/pthread_mutex_trylock.c   | 2 +-
 4 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/nptl/pthread_create.c b/nptl/pthread_create.c
index ee29cb375d..59d8df8cd7 100644
--- a/nptl/pthread_create.c
+++ b/nptl/pthread_create.c
@@ -539,7 +539,7 @@ start_thread (void *arg)
 # endif
 	  this->__list.__next = NULL;
 
-	  atomic_or (&this->__lock, FUTEX_OWNER_DIED);
+	  atomic_fetch_or_acquire (&this->__lock, FUTEX_OWNER_DIED);
 	  futex_wake ((unsigned int *) &this->__lock, 1,
 		      /* XYZ */ FUTEX_SHARED);
 	}
diff --git a/nptl/pthread_mutex_lock.c b/nptl/pthread_mutex_lock.c
index 6e767a8724..439b1e6391 100644
--- a/nptl/pthread_mutex_lock.c
+++ b/nptl/pthread_mutex_lock.c
@@ -462,7 +462,7 @@ __pthread_mutex_lock_full (pthread_mutex_t *mutex)
 
 	if (__glibc_unlikely (oldval & FUTEX_OWNER_DIED))
 	  {
-	    atomic_and (&mutex->__data.__lock, ~FUTEX_OWNER_DIED);
+	    atomic_fetch_and_acquire (&mutex->__data.__lock, ~FUTEX_OWNER_DIED);
 
 	    /* We got the mutex.  */
 	    mutex->__data.__count = 1;
diff --git a/nptl/pthread_mutex_timedlock.c b/nptl/pthread_mutex_timedlock.c
index 0fcaabfb48..af70a60528 100644
--- a/nptl/pthread_mutex_timedlock.c
+++ b/nptl/pthread_mutex_timedlock.c
@@ -392,7 +392,7 @@ __pthread_mutex_clocklock_common (pthread_mutex_t *mutex,
 
 	if (__glibc_unlikely (oldval & FUTEX_OWNER_DIED))
 	  {
-	    atomic_and (&mutex->__data.__lock, ~FUTEX_OWNER_DIED);
+	    atomic_fetch_and_acquire (&mutex->__data.__lock, ~FUTEX_OWNER_DIED);
 
 	    /* We got the mutex.  */
 	    mutex->__data.__count = 1;
diff --git a/nptl/pthread_mutex_trylock.c b/nptl/pthread_mutex_trylock.c
index 8a7de8e598..50524942a7 100644
--- a/nptl/pthread_mutex_trylock.c
+++ b/nptl/pthread_mutex_trylock.c
@@ -308,7 +308,7 @@ ___pthread_mutex_trylock (pthread_mutex_t *mutex)
 
 	if (__glibc_unlikely (oldval & FUTEX_OWNER_DIED))
 	  {
-	    atomic_and (&mutex->__data.__lock, ~FUTEX_OWNER_DIED);
+	    atomic_fetch_and_acquire (&mutex->__data.__lock, ~FUTEX_OWNER_DIED);
 
 	    /* We got the mutex.  */
 	    mutex->__data.__count = 1;

                 reply	other threads:[~2022-09-23 15:01 UTC|newest]

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