From patchwork Fri Aug 30 14:53:19 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Sylwester Nawrocki/Kernel \\(PLT\\) /SRPOL/Staff Engineer/Samsung Electronics" X-Patchwork-Id: 2852092 Return-Path: X-Original-To: patchwork-linux-sh@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 5CE67C0AB5 for ; Fri, 30 Aug 2013 14:54:43 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 19A6C205DC for ; Fri, 30 Aug 2013 14:54:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D7706205BB for ; Fri, 30 Aug 2013 14:54:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755636Ab3H3OyU (ORCPT ); Fri, 30 Aug 2013 10:54:20 -0400 Received: from mailout3.samsung.com ([203.254.224.33]:44976 "EHLO mailout3.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755703Ab3H3OyS (ORCPT ); Fri, 30 Aug 2013 10:54:18 -0400 Received: from epcpsbgm1.samsung.com (epcpsbgm1 [203.254.230.26]) by mailout3.samsung.com (Oracle Communications Messaging Server 7u4-24.01(7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTP id <0MSC002TJMQ4N5M0@mailout3.samsung.com>; Fri, 30 Aug 2013 23:54:17 +0900 (KST) X-AuditID: cbfee61a-b7f7a6d00000235f-06-5220b218c2e9 Received: from epmmp1.local.host ( [203.254.227.16]) by epcpsbgm1.samsung.com (EPCPMTA) with SMTP id 48.1F.09055.812B0225; Fri, 30 Aug 2013 23:54:16 +0900 (KST) Received: from amdc1344.digital.local ([106.116.147.32]) by mmp1.samsung.com (Oracle Communications Messaging Server 7u4-24.01 (7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTPA id <0MSC00KB2MP05U90@mmp1.samsung.com>; Fri, 30 Aug 2013 23:54:16 +0900 (KST) From: Sylwester Nawrocki To: linux-arm-kernel@lists.infradead.org Cc: linux@arm.linux.org.uk, mturquette@linaro.org, jiada_wang@mentor.com, kyungmin.park@samsung.com, myungjoo.ham@samsung.com, t.figa@samsung.com, g.liakhovetski@gmx.de, laurent.pinchart@ideasonboard.com, linux-kernel@vger.kernel.org, linux-mips@linux-mips.org, linux-sh@vger.kernel.org, Sylwester Nawrocki Subject: [PATCH v6 2/5] clkdev: Fix race condition in clock lookup from device tree Date: Fri, 30 Aug 2013 16:53:19 +0200 Message-id: <1377874402-2944-3-git-send-email-s.nawrocki@samsung.com> X-Mailer: git-send-email 1.7.9.5 In-reply-to: <1377874402-2944-1-git-send-email-s.nawrocki@samsung.com> References: <1377874402-2944-1-git-send-email-s.nawrocki@samsung.com> X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFjrILMWRmVeSWpSXmKPExsVy+t9jAV2JTQpBBtcnmlq83ziPyaLnT6XF 2aY37BadE5ewW2x6fI3V4vKuOWwWE6ZOYreY82cKs8Xty7wWTydcZLO43biCzeLwm3ZWi/Uz XrM48Hq0NPeweXz4GOcxu2Mmq8eda3vYPI6uXMvksXlJvcfur02MHn1bVjF6fN4kF8AZxWWT kpqTWZZapG+XwJUx651DwSL+ik+db5kaGI/ydDFyckgImEgcb7vJBGGLSVy4t56ti5GLQ0hg EaPEtWWtzBBOB5PElzPzGUGq2AQMJXqP9oHZIgIaElO6HrODFDELXGaS2PSlix0kISwQKnHl 314wm0VAVeLu4/vMIDavgKvEnNuvWbsYOYDWKUjMmWQDEuYUcJO4MA1kMyfQMqCSE6sYJzDy LmBkWMUomlqQXFCclJ5rqFecmFtcmpeul5yfu4kRHLDPpHYwrmywOMQowMGoxMObsFQhSIg1 say4MvcQowQHs5II78fFQCHelMTKqtSi/Pii0pzU4kOM0hwsSuK8B1qtA4UE0hNLUrNTUwtS i2CyTBycUg2MknMY6idxyhl+ed1ctXaVzjI3a8ZNS/f98XRhKU+Pt5rHOLn0l+q727UpVzy6 H5fKRPH3SfDcD/DsYuNnfNiUGWaf9eOn6Ertb0e78v40iZsLn9kwz9/W29FNdUGkjaHuZ+cn Oz5obLJrsLhjkrFnCrtwb8eqXayrNv1zaarhkFuvEbB50kIlluKMREMt5qLiRACJFLouVAIA AA== Sender: linux-sh-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-sh@vger.kernel.org X-Spam-Status: No, score=-9.0 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, 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. 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 Acked-by: Russell King --- Changes since v2: - none. Changes since v1: - include "clk.h". --- drivers/clk/clkdev.c | 12 ++++++++++-- 1 file 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; }