Re: [RFC][PATCH -mm 2/2] PM: Introduce suspend notifiers

["Rafael J. Wysocki" <rjw@sisk.pl>]

Hi,

On Sunday, 22 April 2007 15:00, Pavel Machek wrote:
> Hi!
> 
> 
> > Index: linux-2.6.21-rc6-mm1/Documentation/power/suspend-notifiers.txt
> > ===================================================================
> > --- /dev/null	1970-01-01 00:00:00.000000000 +0000
> > +++ linux-2.6.21-rc6-mm1/Documentation/power/suspend-notifiers.txt	2007-04-21 23:24:50.000000000 +0200
> > @@ -0,0 +1,41 @@
> > +Suspend notifiers
> > +	(C) 2007 Rafael J. Wysocki <rjw@sisk.pl>, GPL
> > +
> > +There are some operations that device drivers may want to carry out in their
> > +.suspend() routines, but shouldn't, because they can cause a suspend to fail.
> > +For example, a driver may want to allocate a substantial amount of memory
> > +(like 50 MB) in .suspend(), but that shouldn't be done after the swsusp's memory
> > +shrinker has run.  Also, there may be some operations, that subsystems may want
> > +to carry out before a suspend or after a resume, requiring the system to be
> > +fully functional, so the drivers' .suspend() and .resume() routines are not
> > +suitable for this purpose.
> > +
> > +The subsystems that have such needs can register suspend notifiers that will be
> > +notified of the following events by the suspend core:
> > +
> > +SUSPEND_PREPARE		the system is going to suspend, tasks will be frozen
> > +			immediately
> > +
> > +SUSPEND_ENTER_PREPARE	tasks have been frozen, memory is going to be freed
> > +			and devices are going to be suspended
> > +
> > +SUSPEND_THAW_PREPARE	devices have been resumed, tasks will be thawed
> > +			immediately
> > +
> > +SUSPEND_FINISHED	the resume is complete, the system is fully functional
> 
> + This hook is called even if suspend fails, so that we do not
> + leak memory.
> 
> 
> ?

Yes, I'll add something like this.