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Date: Thu, 3 Feb 2011 16:35:00 +0100 (CET)
From: Thomas Gleixner <tglx@linutronix.de>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
cc: Tejun Heo <tj@kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
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        Johannes Berg <johannes@sipsolutions.net>,
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Subject: Re: [PATCH 1/4] lockdep, timer: Fix del_timer_sync() annotation
In-Reply-To: <20110203141548.039540914@chello.nl>
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References: <20110203140940.072679794@chello.nl> <20110203141548.039540914@chello.nl>
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On Thu, 3 Feb 2011, Peter Zijlstra wrote:

> 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
> happending without letting lockdep think IRQs are in fact disabled.
> 
> Reported-by: Nick Bowler <nbowler@elliptictech.com>

Nick, can you please test ?

Thanks,

	tglx

> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
> LKML-Reference: <new-submission>
> ---
>  kernel/timer.c |    6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> Index: linux-2.6/kernel/timer.c
> ===================================================================
> --- linux-2.6.orig/kernel/timer.c
> +++ linux-2.6/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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