diff options
Diffstat (limited to 'util/rcu.c')
| -rw-r--r-- | util/rcu.c | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/util/rcu.c b/util/rcu.c index f4d09c8304..7366dc50dd 100644 --- a/util/rcu.c +++ b/util/rcu.c @@ -92,8 +92,9 @@ static void wait_for_readers(void) atomic_set(&index->waiting, true); } - /* Here, order the stores to index->waiting before the - * loads of index->ctr. + /* Here, order the stores to index->waiting before the loads of + * index->ctr. Pairs with smp_mb() in rcu_read_unlock(), + * ensuring that the loads of index->ctr are sequentially consistent. */ smp_mb(); @@ -142,8 +143,13 @@ static void wait_for_readers(void) void synchronize_rcu(void) { qemu_mutex_lock(&rcu_sync_lock); - qemu_mutex_lock(&rcu_registry_lock); + /* Write RCU-protected pointers before reading p_rcu_reader->ctr. + * Pairs with smp_mb() in rcu_read_lock(). + */ + smp_mb(); + + qemu_mutex_lock(&rcu_registry_lock); if (!QLIST_EMPTY(®istry)) { /* In either case, the atomic_mb_set below blocks stores that free * old RCU-protected pointers. |