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From: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
To: alsa-devel@alsa-project.org
Cc: linux-kernel@vger.kernel.org, tiwai@suse.de, broonie@kernel.org,
	vkoul@kernel.org, gregkh@linuxfoundation.org, jank@cadence.com,
	srinivas.kandagatla@linaro.org, slawomir.blauciak@intel.com,
	Bard liao <yung-chuan.liao@linux.intel.com>,
	Rander Wang <rander.wang@linux.intel.com>,
	Ranjani Sridharan <ranjani.sridharan@linux.intel.com>,
	Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>,
	Sanyog Kale <sanyog.r.kale@intel.com>
Subject: [PATCH v2 02/19] soundwire: fix race between driver probe and update_status callback
Date: Wed,  6 Nov 2019 13:22:06 -0600	[thread overview]
Message-ID: <20191106192223.6003-3-pierre-louis.bossart@linux.intel.com> (raw)
In-Reply-To: <20191106192223.6003-1-pierre-louis.bossart@linux.intel.com>

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: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
---
 drivers/soundwire/bus.c      | 24 +++++++++++++++++++++---
 drivers/soundwire/bus.h      |  1 +
 drivers/soundwire/bus_type.c |  5 +++++
 drivers/soundwire/slave.c    |  2 ++
 4 files changed, 29 insertions(+), 3 deletions(-)

diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c
index 4b22ee996a65..903aee258800 100644
--- a/drivers/soundwire/bus.c
+++ b/drivers/soundwire/bus.c
@@ -961,10 +961,28 @@ 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->ops || !slave->ops->update_status)
+		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;
+		}
+	}
+	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 fd234f63bf2f..ac484384bd6e 100644
--- a/drivers/soundwire/bus_type.c
+++ b/drivers/soundwire/bus_type.c
@@ -118,6 +118,11 @@ static int sdw_slave_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 c87267f12a3b..81b94cd3985e 100644
--- a/drivers/soundwire/slave.c
+++ b/drivers/soundwire/slave.c
@@ -52,6 +52,8 @@ 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);
-- 
2.20.1


WARNING: multiple messages have this Message-ID
From: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
To: alsa-devel@alsa-project.org
Cc: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>,
	tiwai@suse.de, gregkh@linuxfoundation.org,
	linux-kernel@vger.kernel.org,
	Ranjani Sridharan <ranjani.sridharan@linux.intel.com>,
	vkoul@kernel.org, broonie@kernel.org,
	srinivas.kandagatla@linaro.org, jank@cadence.com,
	slawomir.blauciak@intel.com,
	Sanyog Kale <sanyog.r.kale@intel.com>,
	Bard liao <yung-chuan.liao@linux.intel.com>,
	Rander Wang <rander.wang@linux.intel.com>
Subject: [alsa-devel] [PATCH v2 02/19] soundwire: fix race between driver probe and update_status callback
Date: Wed,  6 Nov 2019 13:22:06 -0600	[thread overview]
Message-ID: <20191106192223.6003-3-pierre-louis.bossart@linux.intel.com> (raw)
In-Reply-To: <20191106192223.6003-1-pierre-louis.bossart@linux.intel.com>

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: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
---
 drivers/soundwire/bus.c      | 24 +++++++++++++++++++++---
 drivers/soundwire/bus.h      |  1 +
 drivers/soundwire/bus_type.c |  5 +++++
 drivers/soundwire/slave.c    |  2 ++
 4 files changed, 29 insertions(+), 3 deletions(-)

diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c
index 4b22ee996a65..903aee258800 100644
--- a/drivers/soundwire/bus.c
+++ b/drivers/soundwire/bus.c
@@ -961,10 +961,28 @@ 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->ops || !slave->ops->update_status)
+		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;
+		}
+	}
+	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 fd234f63bf2f..ac484384bd6e 100644
--- a/drivers/soundwire/bus_type.c
+++ b/drivers/soundwire/bus_type.c
@@ -118,6 +118,11 @@ static int sdw_slave_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 c87267f12a3b..81b94cd3985e 100644
--- a/drivers/soundwire/slave.c
+++ b/drivers/soundwire/slave.c
@@ -52,6 +52,8 @@ 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);
-- 
2.20.1

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Alsa-devel@alsa-project.org
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  parent reply	other threads:[~2019-11-06 19:22 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-06 19:22 [PATCH v2 00/19] soundwire: code hardening and suspend-resume support Pierre-Louis Bossart
2019-11-06 19:22 ` [alsa-devel] " Pierre-Louis Bossart
2019-11-06 19:22 ` [PATCH v2 01/19] soundwire: intel/cadence: fix timeouts in MSI mode Pierre-Louis Bossart
2019-11-06 19:22   ` [alsa-devel] " Pierre-Louis Bossart
2019-11-06 19:22 ` Pierre-Louis Bossart [this message]
2019-11-06 19:22   ` [alsa-devel] [PATCH v2 02/19] soundwire: fix race between driver probe and update_status callback Pierre-Louis Bossart
2019-11-06 19:22 ` [PATCH v2 03/19] soundwire: bus: add PM/no-PM versions of read/write functions Pierre-Louis Bossart
2019-11-06 19:22   ` [alsa-devel] " Pierre-Louis Bossart
2019-11-06 19:22 ` [PATCH v2 04/19] soundwire: bus: write Slave Device Number without runtime_pm Pierre-Louis Bossart
2019-11-06 19:22   ` [alsa-devel] " Pierre-Louis Bossart
2019-11-06 19:22 ` [PATCH v2 05/19] soundwire: intel: add helpers for link power down and shim wake Pierre-Louis Bossart
2019-11-06 19:22   ` [alsa-devel] " Pierre-Louis Bossart
2019-11-06 19:22 ` [PATCH v2 06/19] soundwire: intel: Add basic power management support Pierre-Louis Bossart
2019-11-06 19:22   ` [alsa-devel] " Pierre-Louis Bossart
2019-11-06 19:22 ` [PATCH v2 07/19] soundwire: intel: add pm_runtime support Pierre-Louis Bossart
2019-11-06 19:22   ` [alsa-devel] " Pierre-Louis Bossart
2019-11-06 19:22 ` [PATCH v2 08/19] soundwire: intel: reset pm_runtime status during system resume Pierre-Louis Bossart
2019-11-06 19:22   ` [alsa-devel] " Pierre-Louis Bossart
2019-11-06 19:22 ` [PATCH v2 09/19] soundwire: bus: add helper to reset Slave status to UNATTACHED Pierre-Louis Bossart
2019-11-06 19:22   ` [alsa-devel] " Pierre-Louis Bossart
2019-11-06 19:22 ` [PATCH v2 10/19] soundwire: intel: call helper to reset Slave states on resume Pierre-Louis Bossart
2019-11-06 19:22   ` [alsa-devel] " Pierre-Louis Bossart
2019-11-06 19:22 ` [PATCH v2 11/19] soundwire: bus: check first if Slaves become UNATTACHED Pierre-Louis Bossart
2019-11-06 19:22   ` [alsa-devel] " Pierre-Louis Bossart
2019-11-06 19:22 ` [PATCH v2 12/19] soundwire: add enumeration_complete signaling Pierre-Louis Bossart
2019-11-06 19:22   ` [alsa-devel] " Pierre-Louis Bossart
2019-11-06 19:22 ` [PATCH v2 13/19] soundwire: bus: add initialization_complete signaling Pierre-Louis Bossart
2019-11-06 19:22   ` [alsa-devel] " Pierre-Louis Bossart
2019-11-06 19:22 ` [PATCH v2 14/19] soundwire: intel: disable pm_runtime when removing a master Pierre-Louis Bossart
2019-11-06 19:22   ` [alsa-devel] " Pierre-Louis Bossart
2019-11-06 19:22 ` [PATCH v2 15/19] soundwire: bus: disable pm_runtime in sdw_slave_delete Pierre-Louis Bossart
2019-11-06 19:22   ` [alsa-devel] " Pierre-Louis Bossart
2019-11-06 19:22 ` [PATCH v2 16/19] soundwire: stream: update state machine and add state checks Pierre-Louis Bossart
2019-11-06 19:22   ` [alsa-devel] " Pierre-Louis Bossart
2019-11-06 19:22 ` [PATCH v2 17/19] soundwire: stream: only prepare stream when it is configured Pierre-Louis Bossart
2019-11-06 19:22   ` [alsa-devel] " Pierre-Louis Bossart
2019-11-06 19:22 ` [PATCH v2 18/19] soundwire: stream: do not update parameters during DISABLED-PREPARED transition Pierre-Louis Bossart
2019-11-06 19:22   ` [alsa-devel] " Pierre-Louis Bossart
2019-11-06 19:22 ` [PATCH v2 19/19] soundwire: intel: reinitialize IP+DSP in .prepare() Pierre-Louis Bossart
2019-11-06 19:22   ` [alsa-devel] " Pierre-Louis Bossart

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