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 X-Patchwork-Id: 20919 X-Patchwork-Delegate: sylvester.nawrocki@gmail.com Received: from mail.tu-berlin.de ([130.149.7.33]) by www.linuxtv.org with esmtp (Exim 4.72) (envelope-from ) id 1VoG1y-0001ZA-68; Wed, 04 Dec 2013 18:14:34 +0100 X-tubIT-Incoming-IP: 209.132.180.67 Received: from vger.kernel.org ([209.132.180.67]) by mail.tu-berlin.de (exim-4.72/mailfrontend-8) with esmtp id 1VoG1w-0005mW-jy; Wed, 04 Dec 2013 18:14:34 +0100 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933088Ab3LDRNl (ORCPT + 1 other); Wed, 4 Dec 2013 12:13:41 -0500 Received: from mailout4.samsung.com ([203.254.224.34]:13518 "EHLO mailout4.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933022Ab3LDRNi (ORCPT ); Wed, 4 Dec 2013 12:13:38 -0500 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>; 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 Cc: linux@arm.linux.org.uk, linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, jiada_wang@mentor.com, laurent.pinchart@ideasonboard.com, kyungmin.park@samsung.com, Sylwester Nawrocki 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== Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org X-PMX-Version: 6.0.0.2142326, Antispam-Engine: 2.7.2.2107409, Antispam-Data: 2013.12.4.170614 X-PMX-Spam: Gauge=IIIIIIII, Probability=8%, Report=' MULTIPLE_RCPTS 0.1, HTML_00_01 0.05, HTML_00_10 0.05, BODYTEXTP_SIZE_3000_LESS 0, BODY_SIZE_2000_2999 0, BODY_SIZE_5000_LESS 0, BODY_SIZE_7000_LESS 0, URI_ENDS_IN_HTML 0, __ANY_URI 0, __CP_URI_IN_BODY 0, __HAS_FROM 0, __HAS_MSGID 0, __HAS_X_MAILER 0, __HAS_X_MAILING_LIST 0, __IN_REP_TO 0, __MIME_TEXT_ONLY 0, __MULTIPLE_RCPTS_CC_X2 0, __SANE_MSGID 0, __SUBJ_ALPHA_END 0, __TO_MALFORMED_2 0, __TO_NO_NAME 0, __URI_NO_WWW 0, __URI_NS ' 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; }