X-Git-Url: https://git.lttng.org/?p=urcu.git;a=blobdiff_plain;f=urcu.c;h=4702ba9aea4c1bc55f180b658c28bc56c03dec96;hp=94d1131e3dba6df7982a33def88f6ec3908c2bf2;hb=6ef5ddc9b4e136e250f3c5f292f847e6849e6200;hpb=8999a9ee7abe868caf8f5327d8b2e8b8b44ee87d

diff --git a/urcu.c b/urcu.c
index 94d1131..4702ba9 100644
--- 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();
 }
@@ -236,9 +237,22 @@ static void wait_gp(void)
 {
 	/* Read reader_gp before read futex */
 	smp_mb_master(RCU_MB_GROUP);
-	if (uatomic_read(&rcu_gp.futex) == -1)
-		futex_async(&rcu_gp.futex, FUTEX_WAIT, -1,
-		      NULL, NULL, 0);
+	if (uatomic_read(&rcu_gp.futex) != -1)
+		return;
+	while (futex_async(&rcu_gp.futex, FUTEX_WAIT, -1,
+			NULL, NULL, 0)) {
+		switch (errno) {
+		case EWOULDBLOCK:
+			/* Value already changed. */
+			return;
+		case EINTR:
+			/* Retry if interrupted by signal. */
+			break;	/* Get out of switch. */
+		default:
+			/* Unexpected error. */
+			urcu_die(errno);
+		}
+	}
 }
 
 /*
@@ -486,6 +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);
@@ -494,6 +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);
 }
@@ -501,11 +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