From http://article.gmane.org/gmane.linux.kernel/1945822 :

>>   The last thing the power manager does, right before
>> writing "mem" to /sys/power/state, is write the wakeup_count that it
>> read earlier to /sys/power/wakeup_count.  If the write fails, the
>> power manager considers the suspend attempt failed, reads the new
>> wakeup_count, and starts a timer (usually 10 seconds) to retry the
>> suspend.  The same thing happens if the write to /sys/power/state
>> fails.
>
> Is this something that logind should do as well?
>

We do it to avoid a race condition where a wakeup event occurs after
userspace has started the suspend process but before anything writes
"mem" to /sys/power/state.  I'm guessing that this is something logind
should be doing as well since the chances of missing a wakeup event
increase the longer any given delay inhibitor takes to delay a
suspend.