From 466bd3030973910118ca601da8072be97a1e2209 Mon Sep 17 00:00:00 2001
From: Yong Zhang <yong.zhang@windriver.com>
Date: Wed, 20 Oct 2010 15:57:33 -0700
Subject: [PATCH] timer: Warn when del_timer_sync() is called in hardirq
 context

Add explict warning when del_timer_sync() is called in hardirq
context.

Signed-off-by: Yong Zhang <yong.zhang0@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 kernel/timer.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/kernel/timer.c b/kernel/timer.c
index 612de03..483e54b 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -974,7 +974,11 @@ int del_timer_sync(struct timer_list *timer)
 	lock_map_release(&timer->lockdep_map);
 	local_bh_enable();
 #endif
-
+	/*
+	 * don't use it in hardirq context, because it
+	 * could lead to deadlock.
+	 */
+	WARN_ON(in_irq());
 	for (;;) {
 		int ret = try_to_del_timer_sync(timer);
 		if (ret >= 0)
-- 
2.7.4