PM: sleep: Fix handling devices with direct_complete set on errors

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.com/
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

diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
index 1b0eb83f70615788d83c009391d511fe202371d3..ad50018b80479df8e3a6df9c8bafab880e1385c3 100644 (file)
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -938,6 +938,9 @@ static void 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) {
                /*
                 * Allow new children to be added under the device after this
@@ -963,9 +966,6 @@ static void 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);
@@ -1005,7 +1005,6 @@ static void 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);
 
@@ -1669,6 +1668,7 @@ 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;
                        }