diff options
| author | Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com> | 2020-01-15 03:08:35 +0300 |
|---|---|---|
| committer | Vinod Koul <vkoul@kernel.org> | 2020-02-25 13:27:01 +0300 |
| commit | 2140b66b5d3ecf6c7c0fa9dc5eebb41855765ace (patch) | |
| tree | 81685de05051ea3febde16436dfbace43dfec4de /drivers/soundwire/bus.c | |
| parent | eff346f24ba97c3a7c16261d3157adf61ac8960c (diff) | |
| download | linux-2140b66b5d3ecf6c7c0fa9dc5eebb41855765ace.tar.xz | |
soundwire: bus: fix race condition with probe_complete signaling
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>
Link: https://lore.kernel.org/r/20200115000844.14695-2-pierre-louis.bossart@linux.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Diffstat (limited to 'drivers/soundwire/bus.c')
| -rw-r--r-- | drivers/soundwire/bus.c | 25 |
1 files changed, 22 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); } /** |