Fix: compat_futex_noasync: don't override return value

[urcu.git] / urcu.c

diff --git a/urcu.c b/urcu.c
index e77306584d77f0fc012f6bfbae466452b3556b74..4702ba9aea4c1bc55f180b658c28bc56c03dec96 100644 (file)
--- a/urcu.c
+++ b/urcu.c
@@ -77,9 +77,10 @@
 # define membarrier(...)               -ENOSYS
 #endif
 
-#define MEMBARRIER_EXPEDITED           (1 << 0)
-#define MEMBARRIER_DELAYED             (1 << 1)
-#define MEMBARRIER_QUERY               (1 << 16)
+enum membarrier_cmd {
+       MEMBARRIER_CMD_QUERY = 0,
+       MEMBARRIER_CMD_SHARED = (1 << 0),
+};
 
 #ifdef RCU_MEMBARRIER
 static int init_done;
@@ -167,7 +168,7 @@ static void mutex_unlock(pthread_mutex_t *mutex)
 static void smp_mb_master(int group)
 {
        if (caa_likely(rcu_has_sys_membarrier))
-               (void) membarrier(MEMBARRIER_EXPEDITED);
+               (void) membarrier(MEMBARRIER_CMD_SHARED, 0);
        else
                cmm_smp_mb();
 }
@@ -499,6 +500,8 @@ void rcu_register_thread(void)
        assert(!(URCU_TLS(rcu_reader).ctr & RCU_GP_CTR_NEST_MASK));
 
        mutex_lock(&rcu_registry_lock);
+       assert(!URCU_TLS(rcu_reader).registered);
+       URCU_TLS(rcu_reader).registered = 1;
        rcu_init();     /* In case gcc does not support constructor attribute */
        cds_list_add(&URCU_TLS(rcu_reader).node, &registry);
        mutex_unlock(&rcu_registry_lock);
@@ -507,6 +510,8 @@ void rcu_register_thread(void)
 void rcu_unregister_thread(void)
 {
        mutex_lock(&rcu_registry_lock);
+       assert(URCU_TLS(rcu_reader).registered);
+       URCU_TLS(rcu_reader).registered = 0;
        cds_list_del(&URCU_TLS(rcu_reader).node);
        mutex_unlock(&rcu_registry_lock);
 }
@@ -514,11 +519,15 @@ void rcu_unregister_thread(void)
 #ifdef RCU_MEMBARRIER
 void rcu_init(void)
 {
+       int ret;
+
        if (init_done)
                return;
        init_done = 1;
-       if (!membarrier(MEMBARRIER_EXPEDITED | MEMBARRIER_QUERY))
+       ret = membarrier(MEMBARRIER_CMD_QUERY, 0);
+       if (ret >= 0 && (ret & MEMBARRIER_CMD_SHARED)) {
                rcu_has_sys_membarrier = 1;
+       }
 }
 #endif