linux/drivers/base/power
Colin Cross 152e1d5920 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>
2010-09-09 00:49:43 +02:00
..
generic_ops.c PM: Provide generic subsystem-level callbacks 2010-03-06 21:28:37 +01:00
main.c PM: Prevent waiting forever on asynchronous resume after failing suspend 2010-09-09 00:49:43 +02:00
Makefile PM: Make it possible to avoid races between wakeup and system sleep 2010-07-19 01:58:48 +02:00
power.h PM: Add a switch for disabling/enabling asynchronous suspend/resume 2010-02-26 20:39:10 +01:00
runtime.c PM / Runtime: Add runtime PM statistics (v3) 2010-07-19 02:01:06 +02:00
sysfs.c PM / Runtime: Add runtime PM statistics (v3) 2010-07-19 02:01:06 +02:00
trace.c driver core: struct device - replace bus_id with dev_name(), dev_set_name() 2009-01-06 10:44:31 -08:00
wakeup.c PM: Do not use dynamically allocated objects in pm_wakeup_event() 2010-07-19 02:00:35 +02:00