X-Git-Url: https://git.lttng.org/?a=blobdiff_plain;f=src%2Furcu-defer-impl.h;h=b5d79262c03bb88a28cd376d78c4189ca3c578cd;hb=71693131550753be0fcd2b2d4175b53c697be5a3;hp=f96553365ba4f51035f427798edd2ac4eb981f13;hpb=2f6618651c31c05ba1adbb5cdcf0d92980c38f38;p=urcu.git

diff --git a/src/urcu-defer-impl.h b/src/urcu-defer-impl.h
index f965533..b5d7926 100644
--- a/src/urcu-defer-impl.h
+++ b/src/urcu-defer-impl.h
@@ -33,7 +33,6 @@
 #include <pthread.h>
 #include <stdio.h>
 #include <signal.h>
-#include <assert.h>
 #include <string.h>
 #include <errno.h>
 #include <poll.h>
@@ -43,6 +42,7 @@
 
 #include "urcu/futex.h"
 
+#include <urcu/assert.h>
 #include <urcu/compiler.h>
 #include <urcu/arch.h>
 #include <urcu/uatomic.h>
@@ -50,6 +50,7 @@
 #include <urcu/system.h>
 #include <urcu/tls-compat.h>
 #include "urcu-die.h"
+#include "urcu-utils.h"
 
 /*
  * Number of entries in the per-thread defer queue. Must be power of 2.
@@ -107,7 +108,7 @@ struct defer_queue {
 };
 
 /* Do not #define _LGPL_SOURCE to ensure we can emit the wrapper symbols */
-#include "urcu-defer.h"
+#include <urcu/defer.h>
 
 void __attribute__((destructor)) rcu_defer_exit(void);
 
@@ -193,17 +194,25 @@ static void wait_defer(void)
 		uatomic_set(&defer_thread_futex, 0);
 	} else {
 		cmm_smp_rmb();	/* Read queue before read futex */
-		if (uatomic_read(&defer_thread_futex) != -1)
-			return;
-		while (futex_noasync(&defer_thread_futex, FUTEX_WAIT, -1,
-				NULL, NULL, 0)) {
+		while (uatomic_read(&defer_thread_futex) == -1) {
+			if (!futex_noasync(&defer_thread_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);
@@ -324,9 +333,9 @@ static void _defer_rcu(void (*fct)(void *p), void *p)
 	 * Worse-case: must allow 2 supplementary entries for fct pointer.
 	 */
 	if (caa_unlikely(head - tail >= DEFER_QUEUE_SIZE - 2)) {
-		assert(head - tail <= DEFER_QUEUE_SIZE);
+		urcu_posix_assert(head - tail <= DEFER_QUEUE_SIZE);
 		rcu_defer_barrier_thread();
-		assert(head - CMM_LOAD_SHARED(URCU_TLS(defer_queue).tail) == 0);
+		urcu_posix_assert(head - CMM_LOAD_SHARED(URCU_TLS(defer_queue).tail) == 0);
 	}
 
 	/*
@@ -371,7 +380,7 @@ static void _defer_rcu(void (*fct)(void *p), void *p)
 	wake_up_defer();
 }
 
-static void *thr_defer(void *args)
+static void *thr_defer(void *args __attribute__((unused)))
 {
 	for (;;) {
 		/*
@@ -402,7 +411,7 @@ static void start_defer_thread(void)
 	int ret;
 
 	ret = pthread_create(&tid_defer, NULL, thr_defer, NULL);
-	assert(!ret);
+	urcu_posix_assert(!ret);
 }
 
 static void stop_defer_thread(void)
@@ -416,19 +425,19 @@ static void stop_defer_thread(void)
 	wake_up_defer();
 
 	ret = pthread_join(tid_defer, &tret);
-	assert(!ret);
+	urcu_posix_assert(!ret);
 
 	CMM_STORE_SHARED(defer_thread_stop, 0);
 	/* defer thread should always exit when futex value is 0 */
-	assert(uatomic_read(&defer_thread_futex) == 0);
+	urcu_posix_assert(uatomic_read(&defer_thread_futex) == 0);
 }
 
 int rcu_defer_register_thread(void)
 {
 	int was_empty;
 
-	assert(URCU_TLS(defer_queue).last_head == 0);
-	assert(URCU_TLS(defer_queue).q == NULL);
+	urcu_posix_assert(URCU_TLS(defer_queue).last_head == 0);
+	urcu_posix_assert(URCU_TLS(defer_queue).q == NULL);
 	URCU_TLS(defer_queue).q = malloc(sizeof(void *) * DEFER_QUEUE_SIZE);
 	if (!URCU_TLS(defer_queue).q)
 		return -ENOMEM;
@@ -465,7 +474,7 @@ void rcu_defer_unregister_thread(void)
 
 void rcu_defer_exit(void)
 {
-	assert(cds_list_empty(&registry_defer));
+	urcu_posix_assert(cds_list_empty(&registry_defer));
 }
 
 #endif /* _URCU_DEFER_IMPL_H */