netdev - Re: [patch 1/2] net: don't use in_atomic() in gfp

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Message-Id: <20090211134942.a800067e.akpm@linux-foundation.org>
Date:	Wed, 11 Feb 2009 13:49:42 -0800
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
Cc:	netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>,
	Andi Kleen <andi@...stfloor.org>
Subject: Re: [patch 1/2] net: don't use in_atomic() in gfp_any()

Resend with cc's restored.  Please DO NOT edit the Cc: line :(

On Thu, 12 Feb 2009 06:38:55 +0900
Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp> wrote:

> Andrew Morton wrote:
> > Solve both these problems by switching to in_interrupt().  Now, if someone
> > runs a gfp_any() allocation from inside spinlock we will get the warning
> > if CONFIG_PREEMPT=y.
> 
> >  static inline gfp_t gfp_any(void)
> >  {
> > -	return in_atomic() ? GFP_ATOMIC : GFP_KERNEL;
> > +	return in_softirq() ? GFP_ATOMIC : GFP_KERNEL;
> >  }
> sed -i -e 's/in_softirq/in_interrupt/' ?

heh, good question.

I did all my testing with in_softirq() - the changelog didn't catch up.



Is gfp_any() supposed to be usable from hardirq context?

If so, we should use in_interrupt().

If not, we should use in_softirq(), and we'll then get might_sleep()
warnings if anyone uses gfp_any() from hard irq context.




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