linux-kernel - Re: PROBLEM: in_atomic() misuse all over the place

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Message-ID: <20090131055508.GD18453@one.firstfloor.org>
Date:	Sat, 31 Jan 2009 06:55:08 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Andi Kleen <andi@...stfloor.org>, roger.larsson@...atan.se,
	linux-kernel@...r.kernel.org, mingo@...e.hu, rml@...h9.net,
	pavel@....cz, netdev@...r.kernel.org
Subject: Re: PROBLEM: in_atomic() misuse all over the place

> There's a bit of a problem here.  If someone accidentally uses
> gfp_any() inside a spinlock, it will do a sleeping allocation on
> non-preempt kernels and will do an atomic allocation on preemptible
> kernels, so we won't get to see the warning which would allow us to fix
> the bug.

Yes exporting the function to drivers is dangerous I agree because
it's easy to abuse.

> Would using irq_count() work?  If so, that would fix this up.

There's nothing that works reliably to detect spinlocks on non
preempt kernels.

-Andi

-- 
ak@...ux.intel.com -- Speaking for myself only.
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