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, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 8D138C4338F for ; Wed, 18 Aug 2021 02:50:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6FE5261051 for ; Wed, 18 Aug 2021 02:50:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235909AbhHRCuy (ORCPT ); Tue, 17 Aug 2021 22:50:54 -0400 Received: from mga14.intel.com ([192.55.52.115]:5298 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235554AbhHRCux (ORCPT ); Tue, 17 Aug 2021 22:50:53 -0400 X-IronPort-AV: E=McAfee;i="6200,9189,10079"; a="215969433" X-IronPort-AV: E=Sophos;i="5.84,330,1620716400"; d="scan'208";a="215969433" Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Aug 2021 19:50:19 -0700 X-IronPort-AV: E=Sophos;i="5.84,330,1620716400"; d="scan'208";a="520723293" Received: from bard-ubuntu.sh.intel.com ([10.239.185.57]) by fmsmga003-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Aug 2021 19:50:15 -0700 From: Bard Liao To: alsa-devel@alsa-project.org, vkoul@kernel.org Cc: vinod.koul@linaro.org, linux-kernel@vger.kernel.org, gregkh@linuxfoundation.org, srinivas.kandagatla@linaro.org, rander.wang@linux.intel.com, pierre-louis.bossart@linux.intel.com, sanyog.r.kale@intel.com, bard.liao@intel.com Subject: [PATCH v2 1/3] soundwire: intel: fix potential race condition during power down Date: Wed, 18 Aug 2021 10:49:52 +0800 Message-Id: <20210818024954.16873-2-yung-chuan.liao@linux.intel.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20210818024954.16873-1-yung-chuan.liao@linux.intel.com> References: <20210818024954.16873-1-yung-chuan.liao@linux.intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Pierre-Louis Bossart The power down sequence sets the link_up flag as false outside of the mutex_lock. This is potentially unsafe. In additional the flow in that sequence can be improved by first testing if the link was powered, setting the link_up flag as false and proceeding with the power down. In case the CPA bits cannot be cleared, we only flag an error since we cannot deal with interrupts any longer. Signed-off-by: Pierre-Louis Bossart Reviewed-by: Ranjani Sridharan Signed-off-by: Bard Liao --- drivers/soundwire/intel.c | 23 +++++++++++++---------- 1 file changed, 13 insertions(+), 10 deletions(-) diff --git a/drivers/soundwire/intel.c b/drivers/soundwire/intel.c index 9794bc222fb5..808dda1380c2 100644 --- a/drivers/soundwire/intel.c +++ b/drivers/soundwire/intel.c @@ -538,12 +538,14 @@ static int intel_link_power_down(struct sdw_intel *sdw) mutex_lock(sdw->link_res->shim_lock); - intel_shim_master_ip_to_glue(sdw); - if (!(*shim_mask & BIT(link_id))) dev_err(sdw->cdns.dev, "%s: Unbalanced power-up/down calls\n", __func__); + sdw->cdns.link_up = false; + + intel_shim_master_ip_to_glue(sdw); + *shim_mask &= ~BIT(link_id); if (!*shim_mask) { @@ -560,18 +562,19 @@ static int intel_link_power_down(struct sdw_intel *sdw) link_control &= spa_mask; ret = intel_clear_bit(shim, SDW_SHIM_LCTL, link_control, cpa_mask); + if (ret < 0) { + dev_err(sdw->cdns.dev, "%s: could not power down link\n", __func__); + + /* + * we leave the sdw->cdns.link_up flag as false since we've disabled + * the link at this point and cannot handle interrupts any longer. + */ + } } mutex_unlock(sdw->link_res->shim_lock); - if (ret < 0) { - dev_err(sdw->cdns.dev, "%s: could not power down link\n", __func__); - - return ret; - } - - sdw->cdns.link_up = false; - return 0; + return ret; } static void intel_shim_sync_arm(struct sdw_intel *sdw) -- 2.17.1