On Tuesday, 3 July 2007 15:19, Rafael J. Wysocki wrote:
> On Tuesday, 3 July 2007 07:30, Benjamin Herrenschmidt wrote:
> > 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.
>
> Around wait_for_completion()? I don't think that's a good idea. :-)
Sorry, I mistunderstood you (I think).
Yes, I could use a spinlock for protecting usermodehelper_disabled, but
why would that be better than the current code?
Greetings,
Rafael
--
"Premature optimization is the root of all evil." - Donald Knuth
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