From patchwork Fri Apr 3 18:13:07 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Doug Anderson X-Patchwork-Id: 6159491 Return-Path: X-Original-To: patchwork-linux-mmc@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 20C969F350 for ; Fri, 3 Apr 2015 18:14:08 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 36E38203B0 for ; Fri, 3 Apr 2015 18:14:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 341B3203C3 for ; Fri, 3 Apr 2015 18:14:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753219AbbDCSNt (ORCPT ); Fri, 3 Apr 2015 14:13:49 -0400 Received: from mail-ig0-f179.google.com ([209.85.213.179]:34577 "EHLO mail-ig0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753223AbbDCSNo (ORCPT ); Fri, 3 Apr 2015 14:13:44 -0400 Received: by igcau2 with SMTP id au2so68757703igc.1 for ; Fri, 03 Apr 2015 11:13:43 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=crtqmLuj1prcygpKbkSbB+OCsUTppDsRBqNKMMMS0xQ=; b=mWLMORVLkjZNyX+vIhDti/rIQ5zKeotGOg2dBvrKcNI7I8Hy4BdhOzoj5aUeN3kjH1 QAHtvbJt6APMY+FlxpDsv6ggJLOCBIKkChhjsAZDSwatoxGoNlgN06EF8tQydYFHbahH RAaCOmyTwTRWzMjWmosYneLtdmyoFAHovPPvg= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=crtqmLuj1prcygpKbkSbB+OCsUTppDsRBqNKMMMS0xQ=; b=NzeNMaEVjwoVttMqmqmxSej68HJFNm/aLKsS3aFJ4Ze14Z4mEsggwnpsbFW3t7wU/h ZBxBri3qCJyN6iKFjRTymDS6Qbbm/ki1DZDtKKXkAjd8gXfsL47VKdnOwSsHW6y+Hx1h 6QdMYXqqSofJmxNguXP+Fut38cza+LaF761+8jkuiNRFhhcP5BkP9YEeqta6NlKavJAl 6jZp0Q5a6pMENYnUdRvnvLsbq74JZs08GxH05eRiSnmB8x9zL6Dz0+waM46icWX6f5KX aeMs3iXPVvtukx2VEvJ440LzmZjrq/k6DH/mIzi8JVop6+bs6TNor0vvFH7xp0hovtHa kVXQ== X-Gm-Message-State: ALoCoQnw7oZovmWlmhTd57r0RTb5kQwqPerLd4ojM+Ng5x/Fii9KFhOSCAWRoLRreWfYPwIb8pew X-Received: by 10.42.198.143 with SMTP id eo15mr5568033icb.8.1428084823101; Fri, 03 Apr 2015 11:13:43 -0700 (PDT) Received: from tictac.mtv.corp.google.com ([172.22.65.76]) by mx.google.com with ESMTPSA id 37sm2321629ioj.0.2015.04.03.11.13.42 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Fri, 03 Apr 2015 11:13:42 -0700 (PDT) From: Doug Anderson To: Jaehoon Chung , Seungwon Jeon , Ulf Hansson Cc: Alim Akhtar , Sonny Rao , Andrew Bresticker , Heiko Stuebner , Addy Ke , Alexandru Stan , javier.martinez@collabora.co.uk, linux-rockchip@lists.infradead.org, Doug Anderson , linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 3/3] mmc: dw_mmc: Add locking around cmd11 timer Date: Fri, 3 Apr 2015 11:13:07 -0700 Message-Id: <1428084787-8710-3-git-send-email-dianders@chromium.org> X-Mailer: git-send-email 2.2.0.rc0.207.ga3a616c In-Reply-To: <1428084787-8710-1-git-send-email-dianders@chromium.org> References: <1428084787-8710-1-git-send-email-dianders@chromium.org> Sender: linux-mmc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-mmc@vger.kernel.org X-Spam-Status: No, score=-6.8 required=5.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_HI,T_DKIM_INVALID,T_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 It is possible for the cmd11 interrupt to fire and delete the cmd11_timer before the cmd11_timer was actually setup. Let's fix this race by adding a few spinlocks. Note that the race wasn't seen in practice without adding some printk statements, but it still seems wise to fix. Fixes: 5c935165da79 ("mmc: dw_mmc: Add a timeout for sending CMD11") Signed-off-by: Doug Anderson --- drivers/mmc/host/dw_mmc.c | 24 +++++++++++++++++++++--- 1 file changed, 21 insertions(+), 3 deletions(-) diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c index 357ef04..105a602 100644 --- a/drivers/mmc/host/dw_mmc.c +++ b/drivers/mmc/host/dw_mmc.c @@ -1022,14 +1022,23 @@ static void __dw_mci_start_request(struct dw_mci *host, dw_mci_start_command(host, cmd, cmdflags); if (cmd->opcode == SD_SWITCH_VOLTAGE) { + unsigned long irqflags; + /* * Databook says to fail after 2ms w/ no response, but evidence * shows that sometimes the cmd11 interrupt takes over 130ms. * We'll set to 500ms, plus an extra jiffy just in case jiffies * is just about to roll over. + * + * We do this whole thing under spinlock and only if the + * command hasn't already completed (indicating the the irq + * already ran so we don't want the timeout). */ - mod_timer(&host->cmd11_timer, - jiffies + msecs_to_jiffies(500) + 1); + spin_lock_irqsave(&host->irq_lock, irqflags); + if (!test_bit(EVENT_CMD_COMPLETE, &host->pending_events)) + mod_timer(&host->cmd11_timer, + jiffies + msecs_to_jiffies(500) + 1); + spin_unlock_irqrestore(&host->irq_lock, irqflags); } if (mrq->stop) @@ -2170,11 +2179,20 @@ static irqreturn_t dw_mci_interrupt(int irq, void *dev_id) /* Check volt switch first, since it can look like an error */ if ((host->state == STATE_SENDING_CMD11) && (pending & SDMMC_INT_VOLT_SWITCH)) { - del_timer(&host->cmd11_timer); + unsigned long irqflags; mci_writel(host, RINTSTS, SDMMC_INT_VOLT_SWITCH); pending &= ~SDMMC_INT_VOLT_SWITCH; + + /* + * Hold the lock; we know cmd11_timer can't be kicked + * off after the lock is released, so safe to delete. + */ + spin_lock_irqsave(&host->irq_lock, irqflags); dw_mci_cmd_interrupt(host, pending); + spin_unlock_irqrestore(&host->irq_lock, irqflags); + + del_timer(&host->cmd11_timer); } if (pending & DW_MCI_CMD_ERROR_FLAGS) {