From: Sylwester Nawrocki <s.nawrocki@samsung.com>
Date: Fri, 23 Aug 2013 15:03:44 +0000 (+0200)
Subject: clkdev: Fix race condition in clock lookup from device tree
X-Git-Tag: v3.14-rc1~109^2~27^2^2~2
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3a3d2b0551d79ef476ef57424beeb8f68789fbcd;p=pandora-kernel.git

clkdev: Fix race condition in clock lookup from device tree

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. E.g. 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>
Reviewed-by: Mike Turquette <mturquette@linaro.org>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
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