[tip:timers/urgent] lockdep, timer: Fix del_timer_sync() annotation

[tip-bot for Peter Zijlstra]

Commit-ID:  f266a5110d453b7987194460ac7edd31f1a5426c
Gitweb:     http://git.kernel.org/tip/f266a5110d453b7987194460ac7edd31f1a5426c
Author:     Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
AuthorDate: Thu, 3 Feb 2011 15:09:41 +0100
Committer:  Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Fri, 4 Feb 2011 10:31:22 +0100

lockdep, timer: Fix del_timer_sync() annotation

Calling local_bh_enable() will want to actually start processing
softirqs, which isn't a good idea since this can get called with IRQs
disabled.

Cure this by using _local_bh_enable() which doesn't start processing
softirqs, and use raw_local_irq_save() to avoid any softirqs from
happening without letting lockdep think IRQs are in fact disabled.

Reported-by: Nick Bowler <nbowler@xxxxxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Reviewed-by: Yong Zhang <yong.zhang0@xxxxxxxxx>
LKML-Reference: <20110203141548.039540914@xxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
 kernel/timer.c |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)

diff --git a/kernel/timer.c b/kernel/timer.c
index 43ca993..d53ce66 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -969,10 +969,14 @@ EXPORT_SYMBOL(try_to_del_timer_sync);
 int del_timer_sync(struct timer_list *timer)
 {
 #ifdef CONFIG_LOCKDEP
+	unsigned long flags;
+
+	raw_local_irq_save(flags);
 	local_bh_disable();
 	lock_map_acquire(&timer->lockdep_map);
 	lock_map_release(&timer->lockdep_map);
-	local_bh_enable();
+	_local_bh_enable();
+	raw_local_irq_restore(flags);
 #endif
 	/*
 	 * don't use it in hardirq context, because it
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