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PM: Prevent waiting forever on asynchronous resume after failing suspend
During suspend, the power.completion is expected to be set when a device has not yet started suspending. Set it on init to fix a corner case where a device is resumed when its parent has never 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> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
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@ -59,6 +59,7 @@ void device_pm_init(struct device *dev)
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{
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dev->power.status = DPM_ON;
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init_completion(&dev->power.completion);
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complete_all(&dev->power.completion);
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dev->power.wakeup_count = 0;
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pm_runtime_init(dev);
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}
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