linux-kernel - [PATCH wq#fixes-2.6.38] workqueue: make sure MAYDAY_INITIAL

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Message-ID: <20110216171904.GK19830@htj.dyndns.org>
Date:	Wed, 16 Feb 2011 18:19:04 +0100
From:	Tejun Heo <tj@...nel.org>
To:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Cc:	Ray Jui <rjui@...adcom.com>
Subject: [PATCH wq#fixes-2.6.38] workqueue: make sure
 MAYDAY_INITIAL_TIMEOUT is at least 2 jiffies long

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>
Cc: stable@...nel.org
---
 kernel/workqueue.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 88a3e34..ee6578b 100644
--- 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 */
-- 
1.7.1

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