linux-kernel - Re: [PATCH] of: fix recursive locking in of_get_next_available

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Message-Id: <20130211223907.271653E3530@localhost>
Date:	Mon, 11 Feb 2013 22:39:07 +0000
From:	Grant Likely <grant.likely@...retlab.ca>
To:	Stephen Warren <swarren@...dotorg.org>,
	Rob Herring <rob.herring@...xeda.com>
Cc:	Paul Gortmaker <paul.gortmaker@...driver.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-rt-users@...r.kernel.org,
	devicetree-discuss@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
	sparclinux@...r.kernel.org, Sam Ravnborg <sam@...nborg.org>,
	linux-next@...r.kernel.org, Stephen Warren <swarren@...dia.com>
Subject: Re: [PATCH] of: fix recursive locking in of_get_next_available_child()

On Mon, 11 Feb 2013 14:15:32 -0700, Stephen Warren <swarren@...dotorg.org> wrote:
> From: Stephen Warren <swarren@...dia.com>
> 
> of_get_next_available_child() acquires devtree_lock, then calls
> of_device_is_available() which calls of_get_property() which calls
> of_find_property() which tries to re-acquire devtree_lock, thus causing
> deadlock.
> 
> To avoid this, create a new __of_device_is_available() which calls
> __of_get_property() instead, which calls __of_find_property(), which
> does not take the lock,. Update of_get_next_available_child() to call
> the new __of_device_is_available() since it already owns the lock.
> 
> Signed-off-by: Stephen Warren <swarren@...dia.com>

Thanks for looking at this Stephen. I ended up applying my version of
this patch though just because it was more convenient to do so. It was
pretty much identical anyway.

g.
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