Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755424Ab3HXPVQ (ORCPT ); Sat, 24 Aug 2013 11:21:16 -0400 Received: from mail-ea0-f175.google.com ([209.85.215.175]:33786 "EHLO mail-ea0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755230Ab3HXPVM (ORCPT ); Sat, 24 Aug 2013 11:21:12 -0400 From: Sylwester Nawrocki To: linux-arm-kernel@lists.infradead.org Cc: 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, s.nawrocki@samsung.com Subject: [PATCH v4 2/5] clkdev: Fix race condition in clock lookup from device tree Date: Sat, 24 Aug 2013 17:19:46 +0200 Message-Id: <1377357589-13242-3-git-send-email-s.nawrocki@samsung.com> X-Mailer: git-send-email 1.7.4.1 In-Reply-To: <1377357589-13242-1-git-send-email-s.nawrocki@samsung.com> References: <1377357589-13242-1-git-send-email-s.nawrocki@samsung.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2187 Lines: 73 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 Signed-off-by: Kyungmin Park Reviewed-by: Mike Turquette Acked-by: Russell King --- Changes since v2: - none. Changes since v1: - include "clk.h". --- drivers/clk/clkdev.c | 12 ++++++++++-- 1 files changed, 10 insertions(+), 2 deletions(-) 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; } -- 1.7.4.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/