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>, Rander Wang <rander.wang@intel.com>, Sanyog Kale <sanyog.r.kale@intel.com> Subject: [PATCH 01/10] soundwire: bus: fix race condition with probe_complete signaling Date: Tue, 14 Jan 2020 18:08:35 -0600 [thread overview] Message-ID: <20200115000844.14695-2-pierre-louis.bossart@linux.intel.com> (raw) In-Reply-To: <20200115000844.14695-1-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: Rander Wang <rander.wang@intel.com> Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com> --- 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); -- 2.20.1
WARNING: multiple messages have this Message-ID (diff)
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>, Rander Wang <rander.wang@intel.com>, Bard liao <yung-chuan.liao@linux.intel.com>, Rander Wang <rander.wang@linux.intel.com> Subject: [alsa-devel] [PATCH 01/10] soundwire: bus: fix race condition with probe_complete signaling Date: Tue, 14 Jan 2020 18:08:35 -0600 [thread overview] Message-ID: <20200115000844.14695-2-pierre-louis.bossart@linux.intel.com> (raw) In-Reply-To: <20200115000844.14695-1-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: Rander Wang <rander.wang@intel.com> Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com> --- 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); -- 2.20.1 _______________________________________________ Alsa-devel mailing list Alsa-devel@alsa-project.org https://mailman.alsa-project.org/mailman/listinfo/alsa-devel
next prev parent reply other threads:[~2020-01-15 0:09 UTC|newest] Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-01-15 0:08 [PATCH 00/10] soundwire: bus: fix race conditions, add suspend-resume Pierre-Louis Bossart 2020-01-15 0:08 ` [alsa-devel] " Pierre-Louis Bossart 2020-01-15 0:08 ` Pierre-Louis Bossart [this message] 2020-01-15 0:08 ` [alsa-devel] [PATCH 01/10] soundwire: bus: fix race condition with probe_complete signaling Pierre-Louis Bossart 2020-01-15 0:08 ` [PATCH 02/10] soundwire: bus: fix race condition with enumeration_complete signaling Pierre-Louis Bossart 2020-01-15 0:08 ` [alsa-devel] " Pierre-Louis Bossart 2020-01-15 0:08 ` [PATCH 03/10] soundwire: bus: fix race condition with initialization_complete signaling Pierre-Louis Bossart 2020-01-15 0:08 ` [alsa-devel] " Pierre-Louis Bossart 2020-01-15 0:08 ` [PATCH 04/10] soundwire: bus: add PM/no-PM versions of read/write functions Pierre-Louis Bossart 2020-01-15 0:08 ` [alsa-devel] " Pierre-Louis Bossart 2020-01-15 0:08 ` [PATCH 05/10] soundwire: bus: write Slave Device Number without runtime_pm Pierre-Louis Bossart 2020-01-15 0:08 ` [alsa-devel] " Pierre-Louis Bossart 2020-01-15 0:08 ` [PATCH 06/10] soundwire: bus: add helper to clear Slave status to UNATTACHED Pierre-Louis Bossart 2020-01-15 0:08 ` [alsa-devel] " Pierre-Louis Bossart 2020-01-15 0:08 ` [PATCH 07/10] soundwire: bus: disable pm_runtime in sdw_slave_delete Pierre-Louis Bossart 2020-01-15 0:08 ` [alsa-devel] " Pierre-Louis Bossart 2020-01-15 0:08 ` [PATCH 08/10] soundwire: bus: fix io error when processing alert event Pierre-Louis Bossart 2020-01-15 0:08 ` [alsa-devel] " Pierre-Louis Bossart 2020-01-15 0:08 ` [PATCH 09/10] soundwire: bus: add clock stop helpers Pierre-Louis Bossart 2020-01-15 0:08 ` [alsa-devel] " Pierre-Louis Bossart 2020-01-15 0:08 ` [PATCH 10/10] soundwire: bus: don't treat CMD_IGNORED as error on ClockStop Pierre-Louis Bossart 2020-01-15 0:08 ` [alsa-devel] " Pierre-Louis Bossart 2020-02-10 14:30 ` [alsa-devel] [PATCH 00/10] soundwire: bus: fix race conditions, add suspend-resume Pierre-Louis Bossart 2020-02-10 14:30 ` Pierre-Louis Bossart 2020-02-25 10:27 ` Vinod Koul 2020-02-25 10:27 ` Vinod Koul 2020-02-25 15:23 ` Pierre-Louis Bossart
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=20200115000844.14695-2-pierre-louis.bossart@linux.intel.com \ --to=pierre-louis.bossart@linux.intel.com \ --cc=alsa-devel@alsa-project.org \ --cc=broonie@kernel.org \ --cc=gregkh@linuxfoundation.org \ --cc=jank@cadence.com \ --cc=linux-kernel@vger.kernel.org \ --cc=rander.wang@intel.com \ --cc=rander.wang@linux.intel.com \ --cc=ranjani.sridharan@linux.intel.com \ --cc=sanyog.r.kale@intel.com \ --cc=slawomir.blauciak@intel.com \ --cc=srinivas.kandagatla@linaro.org \ --cc=tiwai@suse.de \ --cc=vkoul@kernel.org \ --cc=yung-chuan.liao@linux.intel.com \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.