From 9c4a51972f5de318f3786938949b8320a385fef1 Mon Sep 17 00:00:00 2001 From: Ulrich Drepper Date: Thu, 24 May 2001 07:25:43 +0000 Subject: Update. 2001-05-01 Kaz Kylheku Memory barrier overhaul following line by line inspection. * mutex.c (pthread_once): Missing memory barriers added. * pthread.c (__pthread_wait_for_restart_signal, __pthread_timedsuspend_new, __pthread_restart_new): Added memory barriers ``just in case'' and for documentary value. * spinlock.c (__pthread_release): New inline function for releasing spinlock, to complement __pthread_acquire. Includes memory barrier prior to assignment to spinlock, and __asm __volatile dance to prevent reordering or optimization of the spinlock access. * spinlock.c (__pthread_unlock, __pthread_alt_lock, __pthread_alt_timedlock, __pthread_alt_unlock, __pthread_compare_and_swap): Updated to use new __pthread_release instead of updating spinlock directly. * spinlock.c (__pthread_lock, __pthread_unlock, wait_node_alloc, wait_node_free, wait_node_dequeue, __pthread_alt_lock, __pthread_alt_timedlock, __pthread_alt_unlock, __pthread_acquire): Memory barrier overhaul. Lots of missing memory barriers added, a couple needless ones removed. * spinlock.c (__pthread_compare_and_swap): testandset optimization removed, just calls __pthread_acquire, which has the new read barrier in it before its testandset. --- linuxthreads/mutex.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'linuxthreads/mutex.c') diff --git a/linuxthreads/mutex.c b/linuxthreads/mutex.c index 3ad27942af..3c97ea7d66 100644 --- a/linuxthreads/mutex.c +++ b/linuxthreads/mutex.c @@ -285,7 +285,10 @@ int __pthread_once(pthread_once_t * once_control, void (*init_routine)(void)) int state_changed; /* Test without locking first for speed */ - if (*once_control == DONE) return 0; + if (*once_control == DONE) { + READ_MEMORY_BARRIER(); + return 0; + } /* Lock and test again */ state_changed = 0; @@ -310,6 +313,7 @@ int __pthread_once(pthread_once_t * once_control, void (*init_routine)(void)) init_routine(); pthread_cleanup_pop(0); pthread_mutex_lock(&once_masterlock); + WRITE_MEMORY_BARRIER(); *once_control = DONE; state_changed = 1; } -- cgit v1.2.3