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Wed, 21 Aug 2013 02:36:08 +0900 (KST) From: Sylwester Nawrocki To: linux-arm-kernel@lists.infradead.org Subject: [PATCH v2 4/4] clkdev: Fix race condition in clock lookup from device tree Date: Tue, 20 Aug 2013 19:34:23 +0200 Message-id: <1377020063-30213-5-git-send-email-s.nawrocki@samsung.com> X-Mailer: git-send-email 1.7.9.5 In-reply-to: <1377020063-30213-1-git-send-email-s.nawrocki@samsung.com> References: <1377020063-30213-1-git-send-email-s.nawrocki@samsung.com> X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFvrHLMWRmVeSWpSXmKPExsVy+t9jQV3OlcJBBrMPsFlMffiEzeL9xnlM Fgf+7GC06PlTaXG26Q27RefEJewWmx5fY7W4vGsOm8WEqZPYLeb8mcJscfsyr8WBJ8vZLJ5O uMhmcWmPisX3b9/YLA6/aWe1eP/T0eLpuiXMFutnvGaxWNjwhd3i5oQfzA6iHi3NPWweK6d7 e1z+/obZY+esu+weHz7GeczumMnqMX/6I2aPTas62TzuXNvD5nF05Vomj81L6j12f21i9Ojb sorR4/MmuQC+KC6blNSczLLUIn27BK6MnTflCv7wVfy4cpqpgXE9TxcjJ4eEgInErmuXWSBs MYkL99azdTFycQgJTGeUuLm5gRHC6WCSaOpYywhSxSZgKNF7tA/MFhHQkJjS9ZgdpIhZYDGL xLbNi5i7GDk4hAVCJY60SYPUsAioShw72ssKYvMKuEl07vnOClIiIaAgMWeSDUiYU8BdYsLJ HWAlQkAljybMY53AyLuAkWEVo2hqQXJBcVJ6rpFecWJucWleul5yfu4mRnCsPJPewbiqweIQ owAHoxIP74ZC4SAh1sSy4srcQ4wSHMxKIrzbMoBCvCmJlVWpRfnxRaU5qcWHGKU5WJTEeQ+2 WgcKCaQnlqRmp6YWpBbBZJk4OKUaGB1nlBsovNWWU3VpFSqpTU47aHz+iEbGG8/rdmccnp3O 5Z7xyeChe1/EpYS3dnMD89rL9bwKFS41Wj4zETzOsfhb23fG7UuurcrpXxDTUtYpwL5zVuHn 7yKJsvbdR8/82qZ55NnE5sYf1tqcvGWnYux8D+1jWG06zcY1meuJx49S0yIBdwEnJZbijERD Leai4kQAgiMggZECAAA= X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20130820_133640_430504_A0DC113E X-CRM114-Status: GOOD ( 12.71 ) X-Spam-Score: -9.7 (---------) Cc: vapier@gentoo.org, linux-mips@linux-mips.org, mturquette@linaro.org, linux-sh@vger.kernel.org, jiada_wang@mentor.com, t.figa@samsung.com, linux-kernel@vger.kernel.org, ralf@linux-mips.org, kyungmin.park@samsung.com, broonie@kernel.org, laurent.pinchart@ideasonboard.com, Sylwester Nawrocki , uclinux-dist-devel@blackfin.uclinux.org, grant.likely@linaro.org, linux@arm.linux.org.uk, shawn.guo@linaro.org, LW@KARO-electronics.de, g.liakhovetski@gmx.de, sebastian.hesselbarth@gmail.com X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-7.0 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP 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 Signed-off-by: Kyungmin Park Reviewed-by: Mike Turquette Acked-by: Russell King --- Changes since v1: - include "clk.h". --- drivers/clk/clkdev.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) -- 1.7.9.5 diff --git a/drivers/clk/clkdev.c b/drivers/clk/clkdev.c index 442a313..48f6721 100644 --- a/drivers/clk/clkdev.c +++ b/drivers/clk/clkdev.c @@ -21,6 +21,8 @@ #include #include +#include "clk.h" + static LIST_HEAD(clocks); static DEFINE_MUTEX(clocks_mutex); @@ -39,7 +41,13 @@ struct clk *of_clk_get(struct device_node *np, int index) if (rc) return ERR_PTR(rc); - clk = of_clk_get_from_provider(&clkspec); + of_clk_lock(); + clk = __of_clk_get_from_provider(&clkspec); + + if (!IS_ERR(clk) && !__clk_get(clk)) + clk = ERR_PTR(-ENOENT); + + of_clk_unlock(); of_node_put(clkspec.np); return clk; } @@ -157,7 +165,7 @@ struct clk *clk_get(struct device *dev, const char *con_id) if (dev) { clk = of_clk_get_by_name(dev->of_node, con_id); - if (!IS_ERR(clk) && __clk_get(clk)) + if (!IS_ERR(clk)) return clk; }