Re: [lm-sensors] broken suspend [Was: 2.6.24-rc2-mm1]

Rafael J. Wysocki
2007-11-21T19:02:35Z

On Wednesday, 21 of November 2007, Alan Stern wrote:
> On Wed, 21 Nov 2007, Rafael J. Wysocki wrote:
>
> > > Is it possible to unregister a driver on CPU_DOWN_PREPARE_FROZEN?
> >
> > No. In that case the suspend core is holding the device's mutex and your
> > attempt to unregister it will deadlock with it.
> >
> > Do you _have_ _to_ unregister the device at all? Why don't you just leave
> > it registered on CPU_DOWN_PREPARE_FROZEN? The CPU is not going away
> > physically in this case and it's _guaranteed_ that _cpu_up() will be called on
> > it as soon as the hibernation image is ready or we are back from suspend.
>
> This leaves the device registered if for some reason the number of CPUs
> after resuming from hibernation is smaller than the number of CPUs
> before hibernation. Of course, in theory that's never supposed to
> happen...

Yes, that clearly would be a bug.

Rafael