Cc: Johannes Berg <johannes@...>, Greg KH <gregkh@...>, Andrew Morton <akpm@...>, Len Brown <lenb@...>, Ingo Molnar <mingo@...>, ACPI Devel Maling List <linux-acpi@...>, LKML <linux-kernel@...>, pm list <linux-pm@...>
It has some problems.
First, note that the list manipulations in dpm_suspend(),
device_power_down(), and so on aren't protected by dpm_list_mtx. So
your patch could corrupt the list pointers. Are you assuming that no
other threads can be running at this time?
Note also that device_pm_destroy_suspended() does up(&dev->sem), but it
doesn't know whether or not dev->sem was locked to begin with.
Do you want to rule out the possibility of a driver's suspend or remove
methods calling destroy_suspended_device() on its own device? With
your synchronous approach, this would mean that the suspend/resume
method would indirectly end up calling the remove method. This is
dangerous at best; with USB it would be a lockdep violation. With an
asynchronous approach, on the other hand, this wouldn't be a problem.
Alan Stern
--
