Re: [linux-pm] Re: [PATCH] Remove process freezer from suspend to RAM pathway

Oliver Neukum
2007-07-03T11:47:22Z

Am Dienstag, 3. Juli 2007 schrieb Benjamin Herrenschmidt:
> On Tue, 2007-07-03 at 09:44 +0200, Oliver Neukum wrote:
> > Am Dienstag, 3. Juli 2007 schrieb Benjamin Herrenschmidt:
> > > So to summarize, the plan that makes things work with fuse is:
> > >
> > > - For STR, don't do the freezer thing.
> > >
> > > - For STD, don't sys_sync() after you froze
> > >
> > > There might be -other- issues, but that should get you through some of
> >
> > At the risk of repeating myself. Character device drivers are written
> > with the assumption that normal io and suspend/resume do not race
> > with each other due to the freezer.
> > What do you intend to do about that?
>
> Ugh ... "character devices" ... that's a pretty wide statement...
> there's lots of those and very different one from the other...

That is a good summary of the problem ;-(

> Any sane device-driver will have to cope with being suspended in a
> "live" system. I've demonstrated multiple times in the past why this is
> necessary anyway, for things like dynamic power management, among
> others.

That is an interesting notion. I'd rather see device drivers reporting
their devices idle and requsting to be suspended.
But in any case it doesn't solve the problem.

Regards
Oliver