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Re: [PATCH v3 2/5] clkdev: Fix race condition in clock lookup from devic

To: linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v3 2/5] clkdev: Fix race condition in clock lookup from device tree
From: Sylwester Nawrocki <s.nawrocki@samsung.com>
Date: Fri, 23 Aug 2013 17:22:01 +0200
Cc: Sylwester Nawrocki <s.nawrocki@samsung.com>, linux@arm.linux.org.uk, mturquette@linaro.org, jiada_wang@mentor.com, broonie@kernel.org, vapier@gentoo.org, ralf@linux-mips.org, kyungmin.park@samsung.com, myungjoo.ham@samsung.com, shawn.guo@linaro.org, sebastian.hesselbarth@gmail.com, LW@KARO-electronics.de, t.figa@samsung.com, g.liakhovetski@gmx.de, laurent.pinchart@ideasonboard.com, linux-kernel@vger.kernel.org, uclinux-dist-devel@blackfin.uclinux.org, linux-mips@linux-mips.org, linux-sh@vger.kernel.org
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On 08/23/2013 05:03 PM, 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@samsung.com>
> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>

Oops, I missed to add:

Reviewed-by: Mike Turquette <mturquette@linaro.org>

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

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