Re: [PATCH -mm] PM: Prevent frozen user mode helpers from failing the freezing of tasks (rev. 2)

[Pavel Machek]

Hi!

> > > [I hope the ACKs still apply.]
> > 
> > Uhuh, not 100% sure.
> > 
> > > +static int usermodehelper_disabled;
> > > +
> > 
> > 
> > ...
> > 
> > >  	case PM_HIBERNATION_PREPARE:
> > >  	case PM_SUSPEND_PREPARE:
> > >  		usermodehelper_disabled = 1;
> > > -		return NOTIFY_OK;
> > > +		smp_mb();
> > 
> > usermodehelper_disabled should be atomic variable, too, so we don't
> > have to play these ugly tricks by hand? This should not be
> > performance-critical, right?
> 
> Well, I think we'd need to add the barriers anyway.
> 
> The problem, as far as I understand it, is that the instructions can get
> reordered if there are no barriers in there.

Are you sure?  I thought atomic variables have barrirers built-in.

								Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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