From patchwork Wed Jan 15 00:08:35 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Pierre-Louis Bossart X-Patchwork-Id: 193842 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=-9.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,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 B643EC33C9E for ; Wed, 15 Jan 2020 00:11:30 +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 3E39424673 for ; Wed, 15 Jan 2020 00:11:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alsa-project.org header.i=@alsa-project.org header.b="JQwQiqd/" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3E39424673 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-devel-bounces@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 8C5DE17C1; Wed, 15 Jan 2020 01:10:37 +0100 (CET) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa0.perex.cz 8C5DE17C1 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=alsa-project.org; s=default; t=1579047087; bh=bbc1T15SwJJ5bGiGP+LpOlmDP4EZ3GgZFn0HKJGpa0I=; h=From:To:Date:In-Reply-To:References:Cc:Subject:List-Id: List-Unsubscribe:List-Archive:List-Post:List-Help:List-Subscribe: From; b=JQwQiqd/U1380XKkz+xa54tw0xcu2VV7FxLSfBpSgoNm/OYUvrijexdkuys3BZahz ViwWeyB34HXz/1ytV2QLo4en8nY1/oz8fudsYJq+TRrW6OuB+fBwpWzeF0j4HNypiD aL1Lq+DRqPGDEIj1uYnpOPmV7tFa20fTybV5h2Mg= Received: from alsa1.perex.cz (localhost.localdomain [127.0.0.1]) by alsa1.perex.cz (Postfix) with ESMTP id 44DA5F8026F; Wed, 15 Jan 2020 01:09:47 +0100 (CET) Received: by alsa1.perex.cz (Postfix, from userid 50401) id 4D46EF80121; Wed, 15 Jan 2020 01:09:45 +0100 (CET) Received: from mga18.intel.com (mga18.intel.com [134.134.136.126]) (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 4B381F80121 for ; Wed, 15 Jan 2020 01:09:39 +0100 (CET) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa1.perex.cz 4B381F80121 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by orsmga106.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 14 Jan 2020 16:09:38 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,320,1574150400"; d="scan'208";a="273468540" Received: from emkilgox-mobl2.amr.corp.intel.com (HELO pbossart-mobl3.amr.corp.intel.com) ([10.251.0.151]) by FMSMGA003.fm.intel.com with ESMTP; 14 Jan 2020 16:09:35 -0800 From: Pierre-Louis Bossart To: alsa-devel@alsa-project.org Date: Tue, 14 Jan 2020 18:08:35 -0600 Message-Id: <20200115000844.14695-2-pierre-louis.bossart@linux.intel.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200115000844.14695-1-pierre-louis.bossart@linux.intel.com> References: <20200115000844.14695-1-pierre-louis.bossart@linux.intel.com> MIME-Version: 1.0 Cc: Pierre-Louis Bossart , tiwai@suse.de, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, Ranjani Sridharan , vkoul@kernel.org, broonie@kernel.org, srinivas.kandagatla@linaro.org, jank@cadence.com, slawomir.blauciak@intel.com, Sanyog Kale , Rander Wang , Bard liao , Rander Wang Subject: [alsa-devel] [PATCH 01/10] soundwire: bus: fix race condition with probe_complete signaling 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" The driver probe takes care of basic initialization and is invoked when a Slave becomes attached, after a match between the Slave DevID registers and ACPI/DT entries. The update_status callback is invoked when a Slave state changes, e.g. when it is assigned a non-zero Device Number and it reports with an ATTACHED/ALERT state. The state change detection is usually hardware-based and based on the SoundWire frame rate (e.g. double-digit microseconds) while the probe is a pure software operation, which may involve a kernel module load. In corner cases, it's possible that the state changes before the probe completes. This patch suggests the use of wait_for_completion to avoid races on startup, so that the update_status callback does not rely on invalid pointers/data structures. Signed-off-by: Rander Wang Signed-off-by: Pierre-Louis Bossart --- drivers/soundwire/bus.c | 25 ++++++++++++++++++++++--- drivers/soundwire/bus.h | 1 + drivers/soundwire/bus_type.c | 5 +++++ drivers/soundwire/slave.c | 2 ++ 4 files changed, 30 insertions(+), 3 deletions(-) diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c index 6106577fb3ed..4980dfd6f3a3 100644 --- a/drivers/soundwire/bus.c +++ b/drivers/soundwire/bus.c @@ -970,10 +970,29 @@ static int sdw_handle_slave_alerts(struct sdw_slave *slave) static int sdw_update_slave_status(struct sdw_slave *slave, enum sdw_slave_status status) { - if (slave->ops && slave->ops->update_status) - return slave->ops->update_status(slave, status); + unsigned long time; - return 0; + if (!slave->probed) { + /* + * the slave status update is typically handled in an + * interrupt thread, which can race with the driver + * probe, e.g. when a module needs to be loaded. + * + * make sure the probe is complete before updating + * status. + */ + time = wait_for_completion_timeout(&slave->probe_complete, + msecs_to_jiffies(DEFAULT_PROBE_TIMEOUT)); + if (!time) { + dev_err(&slave->dev, "Probe not complete, timed out\n"); + return -ETIMEDOUT; + } + } + + if (!slave->ops || !slave->ops->update_status) + return 0; + + return slave->ops->update_status(slave, status); } /** diff --git a/drivers/soundwire/bus.h b/drivers/soundwire/bus.h index cb482da914da..acb8d11a4c84 100644 --- a/drivers/soundwire/bus.h +++ b/drivers/soundwire/bus.h @@ -5,6 +5,7 @@ #define __SDW_BUS_H #define DEFAULT_BANK_SWITCH_TIMEOUT 3000 +#define DEFAULT_PROBE_TIMEOUT 2000 #if IS_ENABLED(CONFIG_ACPI) int sdw_acpi_find_slaves(struct sdw_bus *bus); diff --git a/drivers/soundwire/bus_type.c b/drivers/soundwire/bus_type.c index 4a465f55039f..17f096dd6806 100644 --- a/drivers/soundwire/bus_type.c +++ b/drivers/soundwire/bus_type.c @@ -110,6 +110,11 @@ static int sdw_drv_probe(struct device *dev) slave->bus->clk_stop_timeout = max_t(u32, slave->bus->clk_stop_timeout, slave->prop.clk_stop_timeout); + slave->probed = true; + complete(&slave->probe_complete); + + dev_dbg(dev, "probe complete\n"); + return 0; } diff --git a/drivers/soundwire/slave.c b/drivers/soundwire/slave.c index 19919975bb6d..08db0488e02d 100644 --- a/drivers/soundwire/slave.c +++ b/drivers/soundwire/slave.c @@ -47,6 +47,8 @@ static int sdw_slave_add(struct sdw_bus *bus, slave->bus = bus; slave->status = SDW_SLAVE_UNATTACHED; slave->dev_num = 0; + init_completion(&slave->probe_complete); + slave->probed = false; mutex_lock(&bus->bus_lock); list_add_tail(&slave->node, &bus->slaves);