From 7b7f43bed134db6a0da34282fffcbf0af10d4613 Mon Sep 17 00:00:00 2001 From: Ulrich Drepper Date: Sun, 26 Jul 2009 13:00:04 -0700 Subject: [PATCH] Memory ordering in pthread_mutex_{,timed}lock. All commits should have happened before the mutex lock is taken. Therefore use the _rel variant of the cmpxchg atomic op. --- nptl/ChangeLog | 7 +++++++ nptl/pthread_mutex_lock.c | 12 ++++++------ nptl/pthread_mutex_timedlock.c | 12 ++++++------ 3 files changed, 19 insertions(+), 12 deletions(-) diff --git a/nptl/ChangeLog b/nptl/ChangeLog index cb9ec53cd1..222112161a 100644 --- a/nptl/ChangeLog +++ b/nptl/ChangeLog @@ -1,3 +1,10 @@ +2009-07-26 Ulrich Drepper + + [BZ #10418] + * pthread_mutex_lock.c (pthread_mutex_lock): Use _rel instead of of + _acq variants of cmpxchg. + * pthread_mutex_timedlock.c (pthread_mutex_timedlock): Likewise. + 2009-07-23 Ulrich Drepper * sysdeps/x86_64/configure.in: New file. diff --git a/nptl/pthread_mutex_lock.c b/nptl/pthread_mutex_lock.c index 406e588fdb..a0ff881faf 100644 --- a/nptl/pthread_mutex_lock.c +++ b/nptl/pthread_mutex_lock.c @@ -1,4 +1,4 @@ -/* Copyright (C) 2002-2007, 2008 Free Software Foundation, Inc. +/* Copyright (C) 2002-2007, 2008, 2009 Free Software Foundation, Inc. This file is part of the GNU C Library. Contributed by Ulrich Drepper , 2002. @@ -160,7 +160,7 @@ __pthread_mutex_lock_full (pthread_mutex_t *mutex) #endif newval - = atomic_compare_and_exchange_val_acq (&mutex->__data.__lock, + = atomic_compare_and_exchange_val_rel (&mutex->__data.__lock, newval, oldval); if (newval != oldval) @@ -285,7 +285,7 @@ __pthread_mutex_lock_full (pthread_mutex_t *mutex) #ifdef NO_INCR newval |= FUTEX_WAITERS; #endif - oldval = atomic_compare_and_exchange_val_acq (&mutex->__data.__lock, + oldval = atomic_compare_and_exchange_val_rel (&mutex->__data.__lock, newval, 0); if (oldval != 0) @@ -420,7 +420,7 @@ __pthread_mutex_lock_full (pthread_mutex_t *mutex) oldprio = ceiling; oldval - = atomic_compare_and_exchange_val_acq (&mutex->__data.__lock, + = atomic_compare_and_exchange_val_rel (&mutex->__data.__lock, #ifdef NO_INCR ceilval | 2, #else @@ -434,7 +434,7 @@ __pthread_mutex_lock_full (pthread_mutex_t *mutex) do { oldval - = atomic_compare_and_exchange_val_acq (&mutex->__data.__lock, + = atomic_compare_and_exchange_val_rel (&mutex->__data.__lock, ceilval | 2, ceilval | 1); @@ -445,7 +445,7 @@ __pthread_mutex_lock_full (pthread_mutex_t *mutex) lll_futex_wait (&mutex->__data.__lock, ceilval | 2, PTHREAD_MUTEX_PSHARED (mutex)); } - while (atomic_compare_and_exchange_val_acq (&mutex->__data.__lock, + while (atomic_compare_and_exchange_val_rel (&mutex->__data.__lock, ceilval | 2, ceilval) != ceilval); } diff --git a/nptl/pthread_mutex_timedlock.c b/nptl/pthread_mutex_timedlock.c index 8d0db79d58..2c6ff114da 100644 --- a/nptl/pthread_mutex_timedlock.c +++ b/nptl/pthread_mutex_timedlock.c @@ -1,4 +1,4 @@ -/* Copyright (C) 2002-2007, 2008 Free Software Foundation, Inc. +/* Copyright (C) 2002-2007, 2008, 2009 Free Software Foundation, Inc. This file is part of the GNU C Library. Contributed by Ulrich Drepper , 2002. @@ -126,7 +126,7 @@ pthread_mutex_timedlock (mutex, abstime) int newval = id | (oldval & FUTEX_WAITERS); newval - = atomic_compare_and_exchange_val_acq (&mutex->__data.__lock, + = atomic_compare_and_exchange_val_rel (&mutex->__data.__lock, newval, oldval); if (newval != oldval) { @@ -246,7 +246,7 @@ pthread_mutex_timedlock (mutex, abstime) } } - oldval = atomic_compare_and_exchange_val_acq (&mutex->__data.__lock, + oldval = atomic_compare_and_exchange_val_rel (&mutex->__data.__lock, id, 0); if (oldval != 0) @@ -404,7 +404,7 @@ pthread_mutex_timedlock (mutex, abstime) oldprio = ceiling; oldval - = atomic_compare_and_exchange_val_acq (&mutex->__data.__lock, + = atomic_compare_and_exchange_val_rel (&mutex->__data.__lock, ceilval | 1, ceilval); if (oldval == ceilval) @@ -413,7 +413,7 @@ pthread_mutex_timedlock (mutex, abstime) do { oldval - = atomic_compare_and_exchange_val_acq (&mutex->__data.__lock, + = atomic_compare_and_exchange_val_rel (&mutex->__data.__lock, ceilval | 2, ceilval | 1); @@ -456,7 +456,7 @@ pthread_mutex_timedlock (mutex, abstime) PTHREAD_MUTEX_PSHARED (mutex)); } } - while (atomic_compare_and_exchange_val_acq (&mutex->__data.__lock, + while (atomic_compare_and_exchange_val_rel (&mutex->__data.__lock, ceilval | 2, ceilval) != ceilval); }