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From: Peter Zijlstra <peterz@infradead.org>
To: Johannes Berg <johannes@sipsolutions.net>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Linux Kernel list <linux-kernel@vger.kernel.org>,
	Ingo Molnar <mingo@elte.hu>
Subject: Re: [PATCH 1/2] lockdep: implement full check without irq checking
Date: Thu, 30 Oct 2008 12:15:16 +0100	[thread overview]
Message-ID: <1225365316.7803.69.camel@twins> (raw)
In-Reply-To: <1225362995.3690.10.camel@johannes.berg>

On Thu, 2008-10-30 at 11:36 +0100, Johannes Berg wrote:

> > del_timer_sync():
> > 
> >   local_irq_save(flags);
> >   lock_aquire(my fake timer lock);
> >   lock_release(...);
> >   local_irq_restore(flags);
> > 
> > and make that conditional CONFIG_PROVE_LOCKING and or wrap it up
> > somewhere..
> 
> Yeah, that is possible, but it seemed to me that would affect the
> performance of del_timer_sync() quite a bit. Not sure it matters. And on
> powerpc (which I care about) it won't actually affect performance much
> because we lazily disable IRQs, but still. The >= 2 change also seemed
> to generate smaller code?

Its debug code, and I the >= 2 change makes the code much less obvious.

So I prefer the slightly less performant but conceptually cleaner IRQ
disable variant.



  reply	other threads:[~2008-10-30 11:15 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-10-23 19:35 [PATCH 0/2] Timer sync lock checking Johannes Berg
2008-10-23 19:44 ` [PATCH 1/2] lockdep: implement full check without irq checking Johannes Berg
2008-10-29 15:23   ` Peter Zijlstra
2008-10-30 10:36     ` Johannes Berg
2008-10-30 11:15       ` Peter Zijlstra [this message]
2008-10-30 11:25         ` Johannes Berg
2008-10-23 19:46 ` [PATCH 2/2] timer: implement lockdep deadlock detection Johannes Berg
2008-10-23 20:37 ` [PATCH 3/2] tasklet: " Johannes Berg

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