linux-kernel - Re: [regression] Latest git has WARN

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Date:	Fri, 3 Oct 2008 17:20:53 +0200
From:	Christian Borntraeger <borntraeger@...ibm.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Thomas Gleixner <tglx@...utronix.de>, linux-kernel@...r.kernel.org,
	Jesse Brandeburg <jesse.brandeburg@...el.com>
Subject: Re: [regression] Latest git has WARN_ON storm with e1000e driver

Am Freitag, 3. Oktober 2008 schrieben Sie:
> Which spinlock is it? It sure shouldn't be anything in the generic drievr 
> layer: __driver_attach takes a lock, but it's a semaphore (dev->sem), not 
> a spinlock. In fact, al lot of drivers will sleep or do allocations, so if 
> the driver layer were to call the probe function with a spinlock held, 
> things would be really broken.
> 
> The callchain has "spin_lock_irqsave" in it, but that's stale stack data. 

Very good point indeed. Seems my analysis was wrong. I made a short test and 
preempt_count() returns 1 when the WARN_ON triggers. So its either a spinlock 
or something else that increased my preempt_count.
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