5.4-stable review patch. If anyone has any objections, please let me know.
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From: Rafael J. Wysocki rafael.j.wysocki@intel.com
[ Upstream commit 03f1444016b71feffa1dfb8a51f15ba592f94b13 ]
When dpm_suspend() fails, some devices with power.direct_complete set may not have been handled by device_suspend() yet, so runtime PM has not been disabled for them yet even though power.direct_complete is set.
Since device_resume() expects that runtime PM has been disabled for all devices with power.direct_complete set, it will attempt to reenable runtime PM for the devices that have not been processed by device_suspend() which does not make sense. Had those devices had runtime PM disabled before device_suspend() had run, device_resume() would have inadvertently enable runtime PM for them, but this is not expected to happen because it would require ->prepare() callbacks to return positive values for devices with runtime PM disabled, which would be invalid.
In practice, this issue is most likely benign because pm_runtime_enable() will not allow the "disable depth" counter to underflow, but it causes a warning message to be printed for each affected device.
To allow device_resume() to distinguish the "direct complete" devices that have been processed by device_suspend() from those which have not been handled by it, make device_suspend() set power.is_suspended for "direct complete" devices.
Next, move the power.is_suspended check in device_resume() before the power.direct_complete check in it to make it skip the "direct complete" devices that have not been handled by device_suspend().
This change is based on a preliminary patch from Saravana Kannan.
Fixes: aae4518b3124 ("PM / sleep: Mechanism to avoid resuming runtime-suspended devices unnecessarily") Link: https://lore.kernel.org/linux-pm/20241114220921.2529905-2-saravanak@google.c... Reported-by: Saravana Kannan saravanak@google.com Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Reviewed-by: Saravana Kannan saravanak@google.com Link: https://patch.msgid.link/12627587.O9o76ZdvQC@rjwysocki.net Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/base/power/main.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c index ae382c4018fd8..7375624de5646 100644 --- a/drivers/base/power/main.c +++ b/drivers/base/power/main.c @@ -968,6 +968,9 @@ static int device_resume(struct device *dev, pm_message_t state, bool async) if (dev->power.syscore) goto Complete;
+ if (!dev->power.is_suspended) + goto Complete; + if (dev->power.direct_complete) { /* Match the pm_runtime_disable() in __device_suspend(). */ pm_runtime_enable(dev); @@ -986,9 +989,6 @@ static int device_resume(struct device *dev, pm_message_t state, bool async) */ dev->power.is_prepared = false;
- if (!dev->power.is_suspended) - goto Unlock; - if (dev->pm_domain) { info = "power domain "; callback = pm_op(&dev->pm_domain->ops, state); @@ -1028,7 +1028,6 @@ static int device_resume(struct device *dev, pm_message_t state, bool async) error = dpm_run_callback(callback, dev, state, info); dev->power.is_suspended = false;
- Unlock: device_unlock(dev); dpm_watchdog_clear(&wd);
@@ -1758,6 +1757,7 @@ static int __device_suspend(struct device *dev, pm_message_t state, bool async) pm_runtime_disable(dev); if (pm_runtime_status_suspended(dev)) { pm_dev_dbg(dev, state, "direct-complete "); + dev->power.is_suspended = true; goto Complete; }