X-Git-Url: https://git.liburcu.org/?a=blobdiff_plain;f=src%2Furcu-qsbr.c;h=5572d39da65f1030510274b0618e301e893cfbcd;hb=9803f7dab4c8caa1c911e9e37d4ab1f89a27dfbe;hp=346748b2176dfe9fb2917a1769cdc28483da9b19;hpb=4477a87021ffbfbfdb2a2084d05a084171343d36;p=urcu.git

diff --git a/src/urcu-qsbr.c b/src/urcu-qsbr.c
index 346748b..5572d39 100644
--- a/src/urcu-qsbr.c
+++ b/src/urcu-qsbr.c
@@ -23,6 +23,7 @@
  * IBM's contributions to this file may be relicensed under LGPLv2 or later.
  */
 
+#define URCU_NO_COMPAT_IDENTIFIERS
 #define _LGPL_SOURCE
 #include <stdio.h>
 #include <pthread.h>
@@ -43,6 +44,7 @@
 
 #include "urcu-die.h"
 #include "urcu-wait.h"
+#include "urcu-utils.h"
 
 #define URCU_API_MAP
 /* Do not #define _LGPL_SOURCE to ensure we can emit the wrapper symbols */
@@ -68,7 +70,7 @@ static pthread_mutex_t rcu_gp_lock = PTHREAD_MUTEX_INITIALIZER;
  */
 static pthread_mutex_t rcu_registry_lock = PTHREAD_MUTEX_INITIALIZER;
 struct urcu_gp urcu_qsbr_gp = { .ctr = URCU_QSBR_GP_ONLINE };
-__attribute__((alias("urcu_qsbr_gp"))) extern struct urcu_gp rcu_gp_qsbr;
+URCU_ATTR_ALIAS("urcu_qsbr_gp") extern struct urcu_gp rcu_gp_qsbr;
 
 /*
  * Active attempts to check for reader Q.S. before calling futex().
@@ -80,8 +82,7 @@ __attribute__((alias("urcu_qsbr_gp"))) extern struct urcu_gp rcu_gp_qsbr;
  * writers.
  */
 DEFINE_URCU_TLS(struct urcu_qsbr_reader, urcu_qsbr_reader);
-__attribute__((alias("urcu_qsbr_reader")))
-extern struct urcu_qsbr_reader rcu_reader_qsbr;
+DEFINE_URCU_TLS_ALIAS(struct urcu_qsbr_reader, urcu_qsbr_reader, rcu_reader_qsbr);
 
 static CDS_LIST_HEAD(registry);
 
@@ -124,17 +125,25 @@ static void wait_gp(void)
 {
 	/* Read reader_gp before read futex */
 	cmm_smp_rmb();
-	if (uatomic_read(&urcu_qsbr_gp.futex) != -1)
-		return;
-	while (futex_noasync(&urcu_qsbr_gp.futex, FUTEX_WAIT, -1,
-			NULL, NULL, 0)) {
+	while (uatomic_read(&urcu_qsbr_gp.futex) == -1) {
+		if (!futex_noasync(&urcu_qsbr_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. */
 			return;
 		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);
@@ -430,7 +439,7 @@ gp_end:
 		cmm_smp_mb();
 }
 #endif  /* !(CAA_BITS_PER_LONG < 64) */
-__attribute__((alias("urcu_qsbr_synchronize_rcu")))
+URCU_ATTR_ALIAS("urcu_qsbr_synchronize_rcu")
 void synchronize_rcu_qsbr();
 
 /*
@@ -441,40 +450,40 @@ void urcu_qsbr_read_lock(void)
 {
 	_urcu_qsbr_read_lock();
 }
-__attribute__((alias("urcu_qsbr_read_lock"))) void rcu_read_lock_qsbr();
+URCU_ATTR_ALIAS("urcu_qsbr_read_lock") void rcu_read_lock_qsbr();
 
 void urcu_qsbr_read_unlock(void)
 {
 	_urcu_qsbr_read_unlock();
 }
-__attribute__((alias("urcu_qsbr_read_unlock"))) void rcu_read_unlock_qsbr();
+URCU_ATTR_ALIAS("urcu_qsbr_read_unlock") void rcu_read_unlock_qsbr();
 
 int urcu_qsbr_read_ongoing(void)
 {
 	return _urcu_qsbr_read_ongoing();
 }
-__attribute__((alias("urcu_qsbr_read_ongoing")))
+URCU_ATTR_ALIAS("urcu_qsbr_read_ongoing")
 void rcu_read_ongoing_qsbr();
 
 void urcu_qsbr_quiescent_state(void)
 {
 	_urcu_qsbr_quiescent_state();
 }
-__attribute__((alias("urcu_qsbr_quiescent_state")))
+URCU_ATTR_ALIAS("urcu_qsbr_quiescent_state")
 void rcu_quiescent_state_qsbr();
 
 void urcu_qsbr_thread_offline(void)
 {
 	_urcu_qsbr_thread_offline();
 }
-__attribute__((alias("urcu_qsbr_thread_offline")))
+URCU_ATTR_ALIAS("urcu_qsbr_thread_offline")
 void rcu_thread_offline_qsbr();
 
 void urcu_qsbr_thread_online(void)
 {
 	_urcu_qsbr_thread_online();
 }
-__attribute__((alias("urcu_qsbr_thread_online")))
+URCU_ATTR_ALIAS("urcu_qsbr_thread_online")
 void rcu_thread_online_qsbr();
 
 void urcu_qsbr_register_thread(void)
@@ -489,7 +498,7 @@ void urcu_qsbr_register_thread(void)
 	mutex_unlock(&rcu_registry_lock);
 	_urcu_qsbr_thread_online();
 }
-__attribute__((alias("urcu_qsbr_register_thread")))
+URCU_ATTR_ALIAS("urcu_qsbr_register_thread")
 void rcu_register_thread_qsbr();
 
 void urcu_qsbr_unregister_thread(void)
@@ -505,7 +514,7 @@ void urcu_qsbr_unregister_thread(void)
 	cds_list_del(&URCU_TLS(urcu_qsbr_reader).node);
 	mutex_unlock(&rcu_registry_lock);
 }
-__attribute__((alias("urcu_qsbr_unregister_thread")))
+URCU_ATTR_ALIAS("urcu_qsbr_unregister_thread")
 void rcu_unregister_thread_qsbr();
 
 void urcu_qsbr_exit(void)
@@ -516,7 +525,7 @@ void urcu_qsbr_exit(void)
 	 * assert(cds_list_empty(&registry));
 	 */
 }
-__attribute__((alias("urcu_qsbr_exit"))) void rcu_exit_qsbr();
+URCU_ATTR_ALIAS("urcu_qsbr_exit") void rcu_exit_qsbr();
 
 DEFINE_RCU_FLAVOR(rcu_flavor);
 DEFINE_RCU_FLAVOR_ALIAS(rcu_flavor, alias_rcu_flavor);