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PM: Prevent waiting forever on asynchronous resume after abort

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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>
This commit is contained in:
Colin Cross
2010-09-01 18:35:55 -07:00
parent 43e1b91e2f
commit 3d46a3cb10
1 changed files with 2 additions and 1 deletions
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3
drivers/base/power/main.c
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@@ -528,7 +528,8 @@ static int device_resume(struct device *dev, pm_message_t state, bool async)
TRACE_DEVICE(dev); TRACE_DEVICE(dev);
TRACE_RESUME(0); 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); device_lock(dev);
dev->power.status = DPM_RESUMING; dev->power.status = DPM_RESUMING;