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

[Benjamin Herrenschmidt]

On Tue, 2007-06-26 at 00:27 +0200, Rafael J. Wysocki wrote:
> > >     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.

That seems dodgy either way to me :-)

Just use a spinlock.

Ben.

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/