From patchwork Wed Dec 4 17:12:05 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: 3283941 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 75F5A9F37A for ; Wed, 4 Dec 2013 17:15:53 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 489E6204A7 for ; Wed, 4 Dec 2013 17:15:52 +0000 (UTC) Received: from casper.infradead.org (casper.infradead.org [85.118.1.10]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 6F14E201E4 for ; Wed, 4 Dec 2013 17:15:47 +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 1VoG1v-0006JF-Dm; Wed, 04 Dec 2013 17:14:32 +0000 Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1VoG1g-0002sd-Nb; Wed, 04 Dec 2013 17:14:16 +0000 Received: from mailout4.samsung.com ([203.254.224.34]) by merlin.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1VoG1Q-0002o1-MI for linux-arm-kernel@lists.infradead.org; Wed, 04 Dec 2013 17:14:02 +0000 Received: from epcpsbgm1.samsung.com (epcpsbgm1 [203.254.230.26]) by mailout4.samsung.com (Oracle Communications Messaging Server 7u4-24.01(7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTP id <0MXA005PLL6P2RA0@mailout4.samsung.com> for linux-arm-kernel@lists.infradead.org; Thu, 05 Dec 2013 02:13:37 +0900 (KST) X-AuditID: cbfee61a-b7f796d000004313-a1-529f62c1b109 Received: from epmmp1.local.host ( [203.254.227.16]) by epcpsbgm1.samsung.com (EPCPMTA) with SMTP id 68.89.17171.1C26F925; Thu, 05 Dec 2013 02:13:37 +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 <0MXA00HNVL4BBJ20@mmp1.samsung.com>; Thu, 05 Dec 2013 02:13:37 +0900 (KST) From: Sylwester Nawrocki To: mturquette@linaro.org, linux-arm-kernel@lists.infradead.org Subject: [RESEND PATCH v7 3/5] clkdev: Fix race condition in clock lookup from device tree Date: Wed, 04 Dec 2013 18:12:05 +0100 Message-id: <1386177127-2894-4-git-send-email-s.nawrocki@samsung.com> X-Mailer: git-send-email 1.7.9.5 In-reply-to: <1386177127-2894-1-git-send-email-s.nawrocki@samsung.com> References: <1386177127-2894-1-git-send-email-s.nawrocki@samsung.com> X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFlrKLMWRmVeSWpSXmKPExsVy+t9jAd2DSfODDHbMFrTo+VNpcbbpDbtF 58Ql7BabHl9jtbi8aw6bRc+GrawWty/zWjydcJHN4vCbdlYHTo+W5h42j9kdM1k97lzbw+ax eUm9x+6vTYwefVtWMXp83iQXwB7FZZOSmpNZllqkb5fAldHY+4Cp4Dp/xabNd9gaGL/ydDFy ckgImEj87rnBCGGLSVy4t56ti5GLQ0hgEaPElwmnmSCcDiaJpe9OsINUsQkYSvQe7QPrEBGw l2hveQHWwSxwl1Hi+bmHYAlhgRiJtlnrwWwWAVWJU1O62UBsXgFXidf3/wPZHEDrFCTmTLIB CXMKuEnsm7GFBcQWAio5v/Mx+wRG3gWMDKsYRVMLkguKk9JzDfWKE3OLS/PS9ZLzczcxggPv mdQOxpUNFocYBTgYlXh4XyTODxJiTSwrrsw9xCjBwawkwjs5ECjEm5JYWZValB9fVJqTWnyI UZqDRUmc90CrdaCQQHpiSWp2ampBahFMlomDU6qBUefucVEpD+kHS32fr1Pr2B1jyhLF82bb pO67txYGKro8t4/9fPH83twJK869PXFqvbn53aZf7JwPdWqLn768U7b545QV/ApzTOoCHKak t+8w3nJ1reP8R8l7JG/XGFf0Pe51FpSRi3tTsORu8vf7iyO1KxekCfaeMkk7/GGBwaQOWaPr x35JxiixFGckGmoxFxUnAgCH09ggOAIAAA== X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20131204_121401_010364_E368A354 X-CRM114-Status: GOOD ( 13.14 ) X-Spam-Score: -6.9 (------) Cc: linux@arm.linux.org.uk, jiada_wang@mentor.com, linux-kernel@vger.kernel.org, kyungmin.park@samsung.com, laurent.pinchart@ideasonboard.com, Sylwester Nawrocki , linux-media@vger.kernel.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=-4.2 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 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; }