From patchwork Tue Jul 27 05:56:05 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bard Liao X-Patchwork-Id: 12401523 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=-16.7 required=3.0 tests=BAYES_00,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=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 13218C4338F for ; Tue, 27 Jul 2021 05:58:15 +0000 (UTC) Received: from alsa0.perex.cz (alsa0.perex.cz [77.48.224.243]) (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 09C38610E9 for ; Tue, 27 Jul 2021 05:58:14 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 09C38610E9 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=alsa-project.org Received: from alsa1.perex.cz (alsa1.perex.cz [207.180.221.201]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by alsa0.perex.cz (Postfix) with ESMTPS id 20CB01EE3; Tue, 27 Jul 2021 07:57:22 +0200 (CEST) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa0.perex.cz 20CB01EE3 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=alsa-project.org; s=default; t=1627365492; bh=TJnHzTlJ6/OtlNjZ3yTpJkn7BYsDgE1FPMZMiCDmf8g=; h=From:To:Subject:Date:In-Reply-To:References:Cc:List-Id: List-Unsubscribe:List-Archive:List-Post:List-Help:List-Subscribe: From; b=QLjfwnbgA/BR9AptWF81/JlBdK6gHjBmP8HI2oYH3YIUbTmOPNPKe3wM9ZAqn3gaU J2qUPnqnHJSaq+3Opd34EYO975ZnDb9utT5bKQ38byVRJP70H2bO/mqut0aY+qHNip /Yg/IIn6Kp+BW/dKUOpaUoRcdrPOfS7QGOe/5GwQ= Received: from alsa1.perex.cz (localhost.localdomain [127.0.0.1]) by alsa1.perex.cz (Postfix) with ESMTP id 00CB7F80258; Tue, 27 Jul 2021 07:56:35 +0200 (CEST) Received: by alsa1.perex.cz (Postfix, from userid 50401) id 36D7CF804BD; Tue, 27 Jul 2021 07:56:33 +0200 (CEST) Received: from mga07.intel.com (mga07.intel.com [134.134.136.100]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by alsa1.perex.cz (Postfix) with ESMTPS id 30125F80258 for ; Tue, 27 Jul 2021 07:56:24 +0200 (CEST) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa1.perex.cz 30125F80258 X-IronPort-AV: E=McAfee;i="6200,9189,10057"; a="276163939" X-IronPort-AV: E=Sophos;i="5.84,272,1620716400"; d="scan'208";a="276163939" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Jul 2021 22:56:19 -0700 X-IronPort-AV: E=Sophos;i="5.84,272,1620716400"; d="scan'208";a="474302610" Received: from bard-ubuntu.sh.intel.com ([10.239.185.57]) by fmsmga008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Jul 2021 22:56:17 -0700 From: Bard Liao To: broonie@kernel.org, tiwai@suse.de Subject: [PATCH 1/4] soundwire: intel: fix potential race condition during power down Date: Tue, 27 Jul 2021 13:56:05 +0800 Message-Id: <20210727055608.30247-2-yung-chuan.liao@linux.intel.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20210727055608.30247-1-yung-chuan.liao@linux.intel.com> References: <20210727055608.30247-1-yung-chuan.liao@linux.intel.com> Cc: vkoul@kernel.org, alsa-devel@alsa-project.org, pierre-louis.bossart@linux.intel.com, bard.liao@intel.com X-BeenThere: alsa-devel@alsa-project.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: "Alsa-devel mailing list for ALSA developers - http://www.alsa-project.org" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: alsa-devel-bounces@alsa-project.org Sender: "Alsa-devel" 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 a0178779a5ba..3af922e20e64 100644 --- a/drivers/soundwire/intel.c +++ b/drivers/soundwire/intel.c @@ -464,12 +464,14 @@ 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) { @@ -486,18 +488,19 @@ 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)