PM: Prevent waiting forever on asynchronous resume after abort
Only wait on a parent device during resume if the parent device is
suspended.
Consider three drivers, A, B, and C. The parent of A is C, and C
has async_suspend set. On boot, C->power.completion is initialized
to 0.
During the first suspend:
suspend_devices_and_enter(...)
dpm_resume(...)
device_suspend(A)
device_suspend(B) returns error, aborts suspend
dpm_resume_end(...)
dpm_resume(...)
device_resume(A)
dpm_wait(A->parent == C)
wait_for_completion(C->power.completion)
The wait_for_completion will never complete, because
complete_all(C->power.completion) will only be called from
device_suspend(C) or device_resume(C), neither of which is called
if suspend is aborted before C.
After a successful suspend->resume cycle, where B doesn't abort
suspend, C->power.completion is left in the completed state by the
call to device_resume(C), and the same call path will work if B
aborts suspend.
Signed-off-by: Colin Cross <ccross@android.com>
diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
index c31045e..111a77d 100644
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -512,7 +512,8 @@
TRACE_DEVICE(dev);
TRACE_RESUME(0);
- dpm_wait(dev->parent, async);
+ if (dev->parent && dev->parent->power.status >= DPM_OFF)
+ dpm_wait(dev->parent, async);
device_lock(dev);
dev->power.in_suspend = false;