linux-kernel - [40/70] workqueue: make sure MAYDAY_INITIAL

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Date:	Tue, 22 Feb 2011 14:17:19 -0800
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Tejun Heo <tj@...nel.org>
Subject: [40/70] workqueue: make sure MAYDAY_INITIAL_TIMEOUT is at least 2 jiffies long

2.6.37-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Tejun Heo <tj@...nel.org>

commit 3233cdbd9fa347a6d6897a94cc6ed0302ae83c4f upstream.

MAYDAY_INITIAL_TIMEOUT is defined as HZ / 100 and depending on
configuration may end up 0 or 1.  Even when it's 1, depending on when
the mayday timer is added in the current jiffy interval, it may expire
way before a jiffy has passed.

Make sure MAYDAY_INITIAL_TIMEOUT is at least two to guarantee that at
least a full jiffy has passed before calling rescuers.

Signed-off-by: Tejun Heo <tj@...nel.org>
Reported-by: Ray Jui <rjui@...adcom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 kernel/workqueue.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -79,7 +79,9 @@ enum {
 	MAX_IDLE_WORKERS_RATIO	= 4,		/* 1/4 of busy can be idle */
 	IDLE_WORKER_TIMEOUT	= 300 * HZ,	/* keep idle ones for 5 mins */
 
-	MAYDAY_INITIAL_TIMEOUT	= HZ / 100,	/* call for help after 10ms */
+	MAYDAY_INITIAL_TIMEOUT  = HZ / 100 >= 2 ? HZ / 100 : 2,
+						/* call for help after 10ms
+						   (min two ticks) */
 	MAYDAY_INTERVAL		= HZ / 10,	/* and then every 100ms */
 	CREATE_COOLDOWN		= HZ,		/* time to breath after fail */
 	TRUSTEE_COOLDOWN	= HZ / 10,	/* for trustee draining */


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