From c8d3877e48c4f57381d72eaf8d016bff12ce2d7c Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Fri, 16 Feb 2018 10:04:18 +0100 Subject: membarrier: introduce qemu/sys_membarrier.h This new header file provides heavy-weight "global" memory barriers that enforce memory ordering on each running thread belonging to the current process. For now, use a dummy implementation that issues memory barriers on both sides (matching what QEMU has been doing so far). Signed-off-by: Paolo Bonzini --- util/rcu.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) (limited to 'util') diff --git a/util/rcu.c b/util/rcu.c index 7366dc50dd..5676c22bd1 100644 --- a/util/rcu.c +++ b/util/rcu.c @@ -93,10 +93,10 @@ static void wait_for_readers(void) } /* Here, order the stores to index->waiting before the loads of - * index->ctr. Pairs with smp_mb() in rcu_read_unlock(), + * index->ctr. Pairs with smp_mb_placeholder() in rcu_read_unlock(), * ensuring that the loads of index->ctr are sequentially consistent. */ - smp_mb(); + smp_mb_global(); QLIST_FOREACH_SAFE(index, ®istry, node, tmp) { if (!rcu_gp_ongoing(&index->ctr)) { @@ -145,9 +145,9 @@ void synchronize_rcu(void) qemu_mutex_lock(&rcu_sync_lock); /* Write RCU-protected pointers before reading p_rcu_reader->ctr. - * Pairs with smp_mb() in rcu_read_lock(). + * Pairs with smp_mb_placeholder() in rcu_read_lock(). */ - smp_mb(); + smp_mb_global(); qemu_mutex_lock(&rcu_registry_lock); if (!QLIST_EMPTY(®istry)) { @@ -376,6 +376,7 @@ static void rcu_init_child(void) static void __attribute__((__constructor__)) rcu_init(void) { + smp_mb_global_init(); #ifdef CONFIG_POSIX pthread_atfork(rcu_init_lock, rcu_init_unlock, rcu_init_child); #endif -- cgit v1.2.3-55-g7522