X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=src%2Furcu.c;h=f5a32317813a1290139e77c397d7d19db73b46c4;hb=440c99a97ddff4d611eb3001ff0d5c2daf0bdc88;hp=e64432f8bb7034cf3ef63cacc03aca7884133b74;hpb=70469b43316ecc8d6053550504858ad8a8ef9b16;p=urcu.git

diff --git a/src/urcu.c b/src/urcu.c
index e64432f..f5a3231 100644
--- a/src/urcu.c
+++ b/src/urcu.c
@@ -94,8 +94,6 @@ static int urcu_memb_has_sys_membarrier_private_expedited;
  * uninitialized variable.
  */
 int urcu_memb_has_sys_membarrier = 0;
-URCU_ATTR_ALIAS("urcu_memb_has_sys_membarrier")
-extern int rcu_has_sys_membarrier_memb;
 #endif
 
 void __attribute__((constructor)) rcu_init(void);
@@ -105,8 +103,6 @@ void __attribute__((constructor)) rcu_init(void);
 void rcu_init(void)
 {
 }
-URCU_ATTR_ALIAS(urcu_stringify(rcu_init))
-void alias_rcu_init(void);
 #endif
 
 #ifdef RCU_SIGNAL
@@ -132,15 +128,12 @@ static pthread_mutex_t rcu_gp_lock = PTHREAD_MUTEX_INITIALIZER;
  */
 static pthread_mutex_t rcu_registry_lock = PTHREAD_MUTEX_INITIALIZER;
 struct urcu_gp rcu_gp = { .ctr = URCU_GP_COUNT };
-URCU_ATTR_ALIAS(urcu_stringify(rcu_gp))
-extern struct urcu_gp alias_rcu_gp;
 
 /*
  * Written to only by each individual reader. Read by both the reader and the
  * writers.
  */
 DEFINE_URCU_TLS(struct urcu_reader, rcu_reader);
-DEFINE_URCU_TLS_ALIAS(struct urcu_reader, rcu_reader, alias_rcu_reader);
 
 static CDS_LIST_HEAD(registry);
 
@@ -266,17 +259,25 @@ static void wait_gp(void)
 	smp_mb_master();
 	/* Temporarily unlock the registry lock. */
 	mutex_unlock(&rcu_registry_lock);
-	if (uatomic_read(&rcu_gp.futex) != -1)
-		goto end;
-	while (futex_async(&rcu_gp.futex, FUTEX_WAIT, -1,
-			NULL, NULL, 0)) {
+	while (uatomic_read(&rcu_gp.futex) == -1) {
+		if (!futex_async(&rcu_gp.futex, FUTEX_WAIT, -1, NULL, NULL, 0)) {
+			/*
+			 * Prior queued wakeups queued by unrelated code
+			 * using the same address can cause futex wait to
+			 * return 0 even through the futex value is still
+			 * -1 (spurious wakeups). Check the value again
+			 * in user-space to validate whether it really
+			 * differs from -1.
+			 */
+			continue;
+		}
 		switch (errno) {
-		case EWOULDBLOCK:
+		case EAGAIN:
 			/* Value already changed. */
 			goto end;
 		case EINTR:
 			/* Retry if interrupted by signal. */
-			break;	/* Get out of switch. */
+			break;	/* Get out of switch. Check again. */
 		default:
 			/* Unexpected error. */
 			urcu_die(errno);
@@ -516,8 +517,6 @@ out:
 	 */
 	urcu_wake_all_waiters(&waiters);
 }
-URCU_ATTR_ALIAS(urcu_stringify(synchronize_rcu))
-void alias_synchronize_rcu();
 
 /*
  * library wrappers to be used by non-LGPL compatible source code.
@@ -527,22 +526,16 @@ void rcu_read_lock(void)
 {
 	_rcu_read_lock();
 }
-URCU_ATTR_ALIAS(urcu_stringify(rcu_read_lock))
-void alias_rcu_read_lock();
 
 void rcu_read_unlock(void)
 {
 	_rcu_read_unlock();
 }
-URCU_ATTR_ALIAS(urcu_stringify(rcu_read_unlock))
-void alias_rcu_read_unlock();
 
 int rcu_read_ongoing(void)
 {
 	return _rcu_read_ongoing();
 }
-URCU_ATTR_ALIAS(urcu_stringify(rcu_read_ongoing))
-void alias_rcu_read_ongoing();
 
 void rcu_register_thread(void)
 {
@@ -557,8 +550,6 @@ void rcu_register_thread(void)
 	cds_list_add(&URCU_TLS(rcu_reader).node, &registry);
 	mutex_unlock(&rcu_registry_lock);
 }
-URCU_ATTR_ALIAS(urcu_stringify(rcu_register_thread))
-void alias_rcu_register_thread();
 
 void rcu_unregister_thread(void)
 {
@@ -568,8 +559,6 @@ void rcu_unregister_thread(void)
 	cds_list_del(&URCU_TLS(rcu_reader).node);
 	mutex_unlock(&rcu_registry_lock);
 }
-URCU_ATTR_ALIAS(urcu_stringify(rcu_unregister_thread))
-void alias_rcu_unregister_thread();
 
 #ifdef RCU_MEMBARRIER
 
@@ -617,8 +606,6 @@ void rcu_init(void)
 	init_done = 1;
 	rcu_sys_membarrier_init();
 }
-URCU_ATTR_ALIAS(urcu_stringify(rcu_init))
-void alias_rcu_init(void);
 #endif
 
 #ifdef RCU_SIGNAL
@@ -660,8 +647,6 @@ void rcu_init(void)
 	if (ret)
 		urcu_die(errno);
 }
-URCU_ATTR_ALIAS(urcu_stringify(rcu_init))
-void alias_rcu_init(void);
 
 void rcu_exit(void)
 {
@@ -674,13 +659,10 @@ void rcu_exit(void)
 	 * assert(cds_list_empty(&registry));
 	 */
 }
-URCU_ATTR_ALIAS(urcu_stringify(rcu_exit))
-void alias_rcu_exit(void);
 
 #endif /* #ifdef RCU_SIGNAL */
 
 DEFINE_RCU_FLAVOR(rcu_flavor);
-DEFINE_RCU_FLAVOR_ALIAS(rcu_flavor, alias_rcu_flavor);
 
 #include "urcu-call-rcu-impl.h"
 #include "urcu-defer-impl.h"