X-Git-Url: https://git.liburcu.org/?a=blobdiff_plain;f=src%2Fworkqueue.c;h=b6361adafb5b97f2116ac9b864111c8cc2a55d92;hb=7c40d7f5b2139ec9151daf8410b6b934234220d5;hp=cadcf874be6c76726dc1a3dd3e082c545b266e8b;hpb=a142df4e35dcf835439bf6714e49e95a2a68f7a6;p=userspace-rcu.git

diff --git a/src/workqueue.c b/src/workqueue.c
index cadcf87..b6361ad 100644
--- a/src/workqueue.c
+++ b/src/workqueue.c
@@ -25,7 +25,6 @@
 #include <stdio.h>
 #include <pthread.h>
 #include <signal.h>
-#include <assert.h>
 #include <stdlib.h>
 #include <stdint.h>
 #include <string.h>
@@ -36,6 +35,7 @@
 #include <sched.h>
 
 #include "compat-getcpu.h"
+#include <urcu/assert.h>
 #include <urcu/wfcqueue.h>
 #include <urcu/pointer.h>
 #include <urcu/list.h>
@@ -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);
@@ -210,8 +219,8 @@ static void *workqueue_thread(void *arg)
 		cds_wfcq_init(&cbs_tmp_head, &cbs_tmp_tail);
 		splice_ret = __cds_wfcq_splice_blocking(&cbs_tmp_head,
 			&cbs_tmp_tail, &workqueue->cbs_head, &workqueue->cbs_tail);
-		assert(splice_ret != CDS_WFCQ_RET_WOULDBLOCK);
-		assert(splice_ret != CDS_WFCQ_RET_DEST_NON_EMPTY);
+		urcu_posix_assert(splice_ret != CDS_WFCQ_RET_WOULDBLOCK);
+		urcu_posix_assert(splice_ret != CDS_WFCQ_RET_DEST_NON_EMPTY);
 		if (splice_ret != CDS_WFCQ_RET_SRC_EMPTY) {
 			if (workqueue->grace_period_fct)
 				workqueue->grace_period_fct(workqueue, workqueue->priv);
@@ -336,7 +345,7 @@ void urcu_workqueue_destroy(struct urcu_workqueue *workqueue)
 	if (urcu_workqueue_destroy_worker(workqueue)) {
 		urcu_die(errno);
 	}
-	assert(cds_wfcq_empty(&workqueue->cbs_head, &workqueue->cbs_tail));
+	urcu_posix_assert(cds_wfcq_empty(&workqueue->cbs_head, &workqueue->cbs_tail));
 	free(workqueue);
 }