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

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Date:	Fri, 3 Oct 2008 21:41:06 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
cc:	Christian Borntraeger <borntraeger@...ibm.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Jesse Brandeburg <jesse.brandeburg@...el.com>,
	Arjan van de Ven <arjan@...radead.org>
Subject: Re: [regression] Latest git has WARN_ON storm with e1000e driver

On Fri, 3 Oct 2008, Linus Torvalds wrote:
> On Fri, 3 Oct 2008, Christian Borntraeger wrote:
> > 
> > kernel_init does lock_kernel (which does preempt_disable).
> > The kernel_unlock is done in init_post. As far as I can see, this happens 
> > after the driver init calls.
> 
> Yes. I just came to the same conclusion: preempt_count is 1 already in 
> do_one_initcall().
> 
> So this whole bug is actually because that debug test is just _broken_. It 
> shouldn't be WARN_ON(preempt_count()), it should be 'might_sleep()', which 
> does it right.
> 
> The right thing to check is "in_atomic() || irqs_disabled()".
> 
> Duh. That was wasted effort for a buggy test.

Stupid me. Yes I should have used might_sleep. It just did not trigger
here as I did not have the driver compiled into the kernel.

Sorry,

	tglx
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