Re: [PATCH] PM: Acquire device locks on suspend

Rafael J. Wysocki
2008-01-05T21:11:40Z

On Saturday, 5 of January 2008, Alan Stern wrote:
> On Sat, 5 Jan 2008, Rafael J. Wysocki wrote:
>
> > > Another thing to watch out for: Just in case somebody ends up calling
> > > destroy_suspended_device(dev) from within dev's own resume method, you
> > > should interchange the resume_device() and the list_move_tail()
> > > calls in dpm_resume().
> >
> > However, if we unregister them all at once after releasing pm_sleep_rwsem,
> > that shouldn't be necessary, right?
>
> It's still necessary, because destroy_suspended_device() still has to
> move the device from one list to another. You don't want it to end up
> on the dpm_locked list.

Hmm. That means we'd have to do the same thing in dpm_power_up() in case
someone calls destroy_suspended_device() from resume_device_early(dev).

Still, even doing that is not enough, since someone can call
destroy_suspended_device() from a .suspend() routine and then the device
will end up on a wrong list just as well.

Greetings,
Rafael