From patchwork Tue Oct 29 19:51:06 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: 3111211 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork1.web.kernel.org (Postfix) with ESMTP id C851B9F431 for ; Tue, 29 Oct 2013 19:54:23 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id EF3F320233 for ; Tue, 29 Oct 2013 19:54:22 +0000 (UTC) Received: from casper.infradead.org (casper.infradead.org [85.118.1.10]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 6D89020171 for ; Tue, 29 Oct 2013 19:54:17 +0000 (UTC) Received: from merlin.infradead.org ([2001:4978:20e::2]) by casper.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1VbFMQ-0001ve-8k; Tue, 29 Oct 2013 19:53:54 +0000 Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1VbFMI-0003Ve-Fa; Tue, 29 Oct 2013 19:53:46 +0000 Received: from mailout1.samsung.com ([203.254.224.24]) by merlin.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1VbFLx-00030r-6F for linux-arm-kernel@lists.infradead.org; Tue, 29 Oct 2013 19:53:25 +0000 Received: from epcpsbgm1.samsung.com (epcpsbgm1 [203.254.230.26]) by mailout1.samsung.com (Oracle Communications Messaging Server 7u4-24.01(7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTP id <0MVG00KQK4KKSZN0@mailout1.samsung.com> for linux-arm-kernel@lists.infradead.org; Wed, 30 Oct 2013 04:53:08 +0900 (KST) X-AuditID: cbfee61a-b7f836d0000025d7-9f-5270122440c6 Received: from epmmp1.local.host ( [203.254.227.16]) by epcpsbgm1.samsung.com (EPCPMTA) with SMTP id FE.32.09687.42210725; Wed, 30 Oct 2013 04:53:08 +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 <0MVG00CM84HJ3H10@mmp1.samsung.com>; Wed, 30 Oct 2013 04:53:08 +0900 (KST) From: Sylwester Nawrocki To: linux-arm-kernel@lists.infradead.org, mturquette@linaro.org Subject: [PATCH v7 3/5] clkdev: Fix race condition in clock lookup from device tree Date: Tue, 29 Oct 2013 20:51:06 +0100 Message-id: <1383076268-8984-4-git-send-email-s.nawrocki@samsung.com> X-Mailer: git-send-email 1.7.9.5 In-reply-to: <1383076268-8984-1-git-send-email-s.nawrocki@samsung.com> References: <1383076268-8984-1-git-send-email-s.nawrocki@samsung.com> X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFtrGLMWRmVeSWpSXmKPExsVy+t9jAV0VoYIgg0urxS16/lRanG16w27R OXEJu8Wmx9dYLS7vmsNmMWHqJHaLOX+mMFvcvsxr8XTCRTaLw2/aWS0WNnxhd+D2aGnuYfNY Od3bY3bHTFaPO9f2sHkcXbmWyWPzknqP3V+bGD36tqxi9Pi8SS6AM4rLJiU1J7MstUjfLoEr 4/ub9UwF1/krbkz9w9TA+JWni5GTQ0LAROLigg/MELaYxIV769m6GLk4hAQWMUoc+L2MCSQh JNDBJHHrSCSIzSZgKNF7tI8RxBYRsJf4MeElC0gDs8A8Jok5Hw6wgSSEBUIl5r95C9bMIqAq sbBtNiuIzSvgKvHi9U+gGg6gbQoScybZgJicAm4S+xeLQqxylTh16zLzBEbeBYwMqxhFUwuS C4qT0nMN9YoTc4tL89L1kvNzNzGCQ/OZ1A7GlQ0WhxgFOBiVeHgNHuQHCbEmlhVX5h5ilOBg VhLhnX4cKMSbklhZlVqUH19UmpNafIhRmoNFSZz3QKt1oJBAemJJanZqakFqEUyWiYNTqoFx T+XLyoddbcbvHFvW7v/vf0Wnddb/vTvlPJtv9RcmP9pozxKxvHeXm+g2HtbsxSldEzPCNyv+ Dp3ysVDtg+Gu7f82hs0Jubh+5pl3b154HdNk2pwwxevtVfGzjzW3vpBbZsDTec/q+jRfTzf2 DNn5H1gudX2XCdqRnuc/LcJisdd/pqPb37ueUmIpzkg01GIuKk4EAB7inslJAgAA X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20131029_155325_437850_070047C6 X-CRM114-Status: GOOD ( 13.26 ) X-Spam-Score: -7.4 (-------) Cc: linux-mips@linux-mips.org, linux@arm.linux.org.uk, linux-sh@vger.kernel.org, jiada_wang@mentor.com, linux-kernel@vger.kernel.org, kyungmin.park@samsung.com, laurent.pinchart@ideasonboard.com, Sylwester Nawrocki , uclinux-dist-devel@blackfin.uclinux.org 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=-4.7 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. 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 v6: - 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; }