linux-kernel - Re: [PATCH v2 4/4] clkdev: Fix race condition in clock lookup from device tree

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Message-ID: <20130820215221.GH17845@n2100.arm.linux.org.uk>
Date:	Tue, 20 Aug 2013 22:52:21 +0100
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	Sylwester Nawrocki <s.nawrocki@...sung.com>
Cc:	linux-arm-kernel@...ts.infradead.org, mturquette@...aro.org,
	jiada_wang@...tor.com, robherring2@...il.com,
	grant.likely@...aro.org, broonie@...nel.org, vapier@...too.org,
	ralf@...ux-mips.org, kyungmin.park@...sung.com,
	shawn.guo@...aro.org, sebastian.hesselbarth@...il.com,
	LW@...O-electronics.de, t.figa@...sung.com, g.liakhovetski@....de,
	laurent.pinchart@...asonboard.com, linux-kernel@...r.kernel.org,
	uclinux-dist-devel@...ckfin.uclinux.org, linux-mips@...ux-mips.org,
	linux-sh@...r.kernel.org
Subject: Re: [PATCH v2 4/4] clkdev: Fix race condition in clock lookup from
	device tree

On Tue, Aug 20, 2013 at 07:34:23PM +0200, Sylwester Nawrocki wrote:
> There is currently a race condition in the device tree part of clk_get()
> function, since the pointer returned from of_clk_get_by_name() may become
> invalid before __clk_get() call. I.e. due to the clock provider driver
> remove() callback being called in between of_clk_get_by_name() and
> __clk_get().
> 
> Fix this by doing both the look up and __clk_get() operations with the
> clock providers list mutex held. This ensures that the clock pointer
> returned from __of_clk_get_from_provider() call and passed to __clk_get()
> is valid, as long as the clock supplier module first removes its clock
> provider instance and then does clk_unregister() on the corresponding
> clocks.
> 
> Signed-off-by: Sylwester Nawrocki <s.nawrocki@...sung.com>
> Signed-off-by: Kyungmin Park <kyungmin.park@...sung.com>
> Reviewed-by: Mike Turquette <mturquette@...aro.org>

Thanks.

Acked-by: Russell King <rmk+kernel@....linux.org.uk>
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