From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 92298C4361B for ; Sat, 19 Dec 2020 20:46:16 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 54A8422D72 for ; Sat, 19 Dec 2020 20:46:16 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 54A8422D72 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=simonsouth.net Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To:Message-Id:Date: Subject:To:From:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=V/4O/cZ27TuDoSzmCTnw9cGfDFE/yxWzW5Uf6m/qPq4=; b=BbnSVYfUsCO1cSdM4SjRxFi7x vjUVSbeJoXE/SxXfltxiApgV5o0EGZqy1RDFDR2MWDdHm+yUMLixU9To/PIfpKC5vWSaeALvl5QyU yOQnpOSz7kW3csdaQHwlfNO+C3yrQWTDuiSxAnQsfLJqgMx0s0zXbRrM7zsPQFXNR+UX1mrnsVY7i zcPoHzhttWzBtfVM0FdFSg1oEWwjjYGLzLy/1FvrkXlEN3yu8qZcz+5O/dgc67AL9aua48foS4MY/ C/zumh42hPlgr+9AKtrO8rw4BTgnhTc+9SIjprTfWdHYOyxq+w4s9HIAEV8pzfxTfjh9Yz7n96mfD A/qqR+hag==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kqj67-0001Ix-PJ; Sat, 19 Dec 2020 20:45:03 +0000 Received: from mailout.easymail.ca ([64.68.200.34]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kqj64-0001Ho-Bn; Sat, 19 Dec 2020 20:45:01 +0000 Received: from localhost (localhost [127.0.0.1]) by mailout.easymail.ca (Postfix) with ESMTP id 26F2DC2537; Sat, 19 Dec 2020 20:45:00 +0000 (UTC) X-Virus-Scanned: Debian amavisd-new at emo04-pco.easydns.vpn Received: from mailout.easymail.ca ([127.0.0.1]) by localhost (emo04-pco.easydns.vpn [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id Hmgycagr5TIp; Sat, 19 Dec 2020 20:44:59 +0000 (UTC) Received: from localhost.localdomain (unknown [108.162.141.195]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mailout.easymail.ca (Postfix) with ESMTPSA id E5D59BFBC9; Sat, 19 Dec 2020 20:44:45 +0000 (UTC) From: Simon South To: tpiepho@gmail.com, thierry.reding@gmail.com, u.kleine-koenig@pengutronix.de, lee.jones@linaro.org, heiko@sntech.de, bbrezillon@kernel.org, linux-pwm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org Subject: [PATCH v2 2/3] pwm: rockchip: Eliminate potential race condition when probing Date: Sat, 19 Dec 2020 15:44:09 -0500 Message-Id: X-Mailer: git-send-email 2.29.2 In-Reply-To: References: MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201219_154500_431903_6B8DF2E2 X-CRM114-Status: GOOD ( 18.27 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: simon@simonsouth.net Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Commit 48cf973cae33 ("pwm: rockchip: Avoid glitches on already running PWMs") introduced a potential race condition in rockchip_pwm_probe() as the function could disable the clock of a PWM device after having registered it through a call to pwmchip_add(). Eliminate this possibility by moving the code that disables the clock of a non-enabled PWM ahead of the code that registers the device. Also refactor the code slightly to eliminate goto targets as the error handlers no longer share any recovery steps. Fixes: 48cf973cae33 ("pwm: rockchip: Avoid glitches on already running PWMs") Fixes: 457f74abbed0 ("pwm: rockchip: Keep enabled PWMs running while probing") Reported-by: Trent Piepho Signed-off-by: Simon South --- drivers/pwm/pwm-rockchip.c | 31 +++++++++++++++---------------- 1 file changed, 15 insertions(+), 16 deletions(-) diff --git a/drivers/pwm/pwm-rockchip.c b/drivers/pwm/pwm-rockchip.c index d2058138ce1e..f286a498b82c 100644 --- a/drivers/pwm/pwm-rockchip.c +++ b/drivers/pwm/pwm-rockchip.c @@ -289,6 +289,7 @@ static int rockchip_pwm_probe(struct platform_device *pdev) struct rockchip_pwm_chip *pc; struct resource *r; u32 enable_conf, ctrl; + bool enabled; int ret, count; id = of_match_device(rockchip_pwm_dt_ids, &pdev->dev); @@ -335,7 +336,8 @@ static int rockchip_pwm_probe(struct platform_device *pdev) ret = clk_prepare_enable(pc->pclk); if (ret) { dev_err(&pdev->dev, "Can't enable APB clk: %d\n", ret); - goto err_clk; + clk_disable_unprepare(pc->clk); + return ret; } platform_set_drvdata(pdev, pc); @@ -351,29 +353,26 @@ static int rockchip_pwm_probe(struct platform_device *pdev) pc->chip.of_pwm_n_cells = 3; } - ret = pwmchip_add(&pc->chip); - if (ret < 0) { - clk_unprepare(pc->clk); - dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret); - goto err_pclk; - } - /* Keep the PWM clk enabled if the PWM appears to be up and running. */ enable_conf = pc->data->enable_conf; ctrl = readl_relaxed(pc->base + pc->data->regs.ctrl); - if ((ctrl & enable_conf) != enable_conf) + enabled = ((ctrl & enable_conf) == enable_conf); + if (!enabled) clk_disable(pc->clk); clk_disable(pc->pclk); - return 0; - -err_pclk: - clk_disable_unprepare(pc->pclk); -err_clk: - clk_disable_unprepare(pc->clk); + ret = pwmchip_add(&pc->chip); + if (ret < 0) { + dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret); + if (enabled) + clk_disable(pc->clk); + clk_unprepare(pc->clk); + clk_unprepare(pc->pclk); + return ret; + } - return ret; + return 0; } static int rockchip_pwm_remove(struct platform_device *pdev) -- 2.29.2 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel