Re: BUG: using smp_processor_id() during suspend with 2.6.25-rc8

Rafael J. Wysocki
2008-04-11T15:29:27Z

On Friday, 11 of April 2008, Pavel Machek wrote:
> On Fri 2008-04-11 12:51:09, Ingo Molnar wrote:
> >
> > * Pavel Machek <pavel@ucw.cz> wrote:
> >
> > > diff --git a/lib/smp_processor_id.c b/lib/smp_processor_id.c
> > > index 6c90fb9..8195c37 100644
> > > --- a/lib/smp_processor_id.c
> > > +++ b/lib/smp_processor_id.c
> > > @@ -35,6 +35,13 @@ unsigned int debug_smp_processor_id(void
> > > goto out;
> > >
> > > /*
> > > + * It is valid to assume CPU-locality if there's just one
> > > + * CPU active
> > > + */
> > > + if (num_online_cpus() == 1)
> > > + goto out;
> >
> > thanks Pavel, i picked this up into sched-devel.git - it makes sense
> > independently of whether it solves the warning.
>
> Thanks!
>
> (I just want to fix the underlying problem in suspend, too. I guess
> I'll just do something like
>
> diff --git a/drivers/base/sys.c b/drivers/base/sys.c
> index 8e13fd9..adb7850 100644
> --- a/drivers/base/sys.c
> +++ b/drivers/base/sys.c
> @@ -367,6 +367,7 @@ int sysdev_suspend(pm_message_t state)
> /* Call auxillary drivers first */
> list_for_each_entry(drv, &cls->drivers, entry) {
> if (drv->suspend) {
> + BUG_ON(!in_interrupt());
> ret = drv->suspend(sysdev, state);
> if (ret)
> goto aux_driver;
> @@ -442,6 +443,7 @@ int sysdev_resume(void)
> list_for_each_entry(sysdev, &cls->kset.list, kobj.entry) {
> pr_debug(" %s\n", kobject_name(&sysdev->kobj));
>
> + BUG_ON(!in_interrupt());
> __sysdev_resume(sysdev);
> }
> }
>
> ...to catch this kind of problems early).

Well, I'd say the BUG_ON()s are over the top in here (why to crash the system
even if it wouldn't have crashed otherwise?).

WARN_ON_ONCE() should be enough.

Thanks,
Rafael