Messages in this thread Patch in this message | | | Date | Fri, 24 Sep 2010 09:24:55 -0700 | From | Greg KH <> | Subject | [67/80] PM: Prevent waiting forever on asynchronous resume after failing suspend |
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2.6.35-stable review patch. If anyone has any objections, please let us know.
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From: Colin Cross <ccross@android.com>
commit 152e1d592071c8b312bb898bc1118b64e4aea535 upstream.
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> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- drivers/base/power/main.c | 1 + 1 file changed, 1 insertion(+)
--- a/drivers/base/power/main.c +++ b/drivers/base/power/main.c @@ -59,6 +59,7 @@ void device_pm_init(struct device *dev) { dev->power.status = DPM_ON; init_completion(&dev->power.completion); + complete_all(&dev->power.completion); pm_runtime_init(dev); }
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