X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=src%2Fworkqueue.c;h=5f806c17f7ebc36228b0ceea4d213bf71233db1d;hb=refs%2Fheads%2Fstable-0.13;hp=72170012eafc2fb925f885b9a666be610901ec3f;hpb=2388c075d46055bd33ee824c399d72c219b98d90;p=userspace-rcu.git

diff --git a/src/workqueue.c b/src/workqueue.c
index 7217001..5f806c1 100644
--- a/src/workqueue.c
+++ b/src/workqueue.c
@@ -121,7 +121,7 @@ static int set_thread_cpu_affinity(struct urcu_workqueue *workqueue)
 	return ret;
 }
 #else
-static int set_thread_cpu_affinity(struct urcu_workqueue *workqueue)
+static int set_thread_cpu_affinity(struct urcu_workqueue *workqueue __attribute__((unused)))
 {
 	return 0;
 }
@@ -131,16 +131,25 @@ static void futex_wait(int32_t *futex)
 {
 	/* Read condition before read futex */
 	cmm_smp_mb();
-	if (uatomic_read(futex) != -1)
-		return;
-	while (futex_async(futex, FUTEX_WAIT, -1, NULL, NULL, 0)) {
+	while (uatomic_read(futex) == -1) {
+		if (!futex_async(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);
@@ -378,7 +387,7 @@ struct urcu_workqueue_completion *urcu_workqueue_create_completion(void)
 {
 	struct urcu_workqueue_completion *completion;
 
-	completion = calloc(sizeof(*completion), 1);
+	completion = calloc(1, sizeof(*completion));
 	if (!completion)
 		urcu_die(errno);
 	urcu_ref_set(&completion->ref, 1);
@@ -409,7 +418,7 @@ void urcu_workqueue_queue_completion(struct urcu_workqueue *workqueue,
 {
 	struct urcu_workqueue_completion_work *work;
 
-	work = calloc(sizeof(*work), 1);
+	work = calloc(1, sizeof(*work));
 	if (!work)
 		urcu_die(errno);
 	work->completion = completion;