To: Thomas Gleixner <tglx@linutronix.de>
From: Milton Miller <miltonm@bga.com>
cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/4] irq: radix_tree_insert can fail
In-Reply-To: <alpine.LFD.2.02.1105251017460.3078@ionos>
Message-ID: <radix-insert-can-fail-reply1@mdm.bga.com>
References: <generic-irq-changes@mdm.bga.com>
	<radix-insert-can-fail@mdm.bga.com>
	 <alpine.LFD.2.02.1105251017460.3078@ionos>
Date: Wed, 25 May 2011 05:48:11 -0500
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1429
Lines: 31

On Wed, 25 May 2011 about 10:18:40 +0200 (CEST), Thomas Gleixner wrote:
> On Wed, 25 May 2011, Milton Miller wrote:
> 
> > Check the insert, and if it fails cleanup and free all partial work.
> > 
> > Sparse irq was not checking the return code from radix_tree_insert,
> > but it may need to allocate memory and can fail.  If it failed,
> > it still claimed success to the caller but the affected irq(s) are
> > unavailable and the reference to the affected descriptors is leaked.
> > 
> > Signed-off-by: Milton Miller <miltonm@bga.com>
> > ---
> > I started by tring to change free_desc to take the descriptor pointer
> > and pushing that down, but that soon ran into conflicts between the
> > array and sparse implementations, and/or the old dynamic irq cleanup
> > function that is still used by some architectures.  This version is
> > targeted, and also protects against scribbles to irq_data.irq.
> 
> The simpler solution is to move irq_insert_desc() into alloc_desc()
> and deal with the error case there.

And I see that this one too as written does not compile, due to
my faulty config testing.  I'll explore your idea tomorrow after
some sleep, but it makes sense.

milton
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