Merge "workqueue: fix possible livelock with concurrent mod_delayed_work()"

1 files changed, 7 insertions, 0 deletions

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 316b316c7528..c0ab232e3abd 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -49,6 +49,7 @@
 #include <linux/moduleparam.h>
 #include <linux/uaccess.h>
 #include <linux/bug.h>
+#include <linux/delay.h>
 
 #include "workqueue_internal.h"
 
@@ -1285,6 +1286,12 @@ fail:
 	if (work_is_canceling(work))
 		return -ENOENT;
 	cpu_relax();
+	/*
+	 * The queueing is in progress in another context. If we keep
+	 * taking the pool->lock in a busy loop, the other context may
+	 * never get the lock. Give 1 usec delay to avoid this contention.
+	 */
+	udelay(1);
 	return -EAGAIN;
 }