Re: [PATCH] powerpc: warn on spurious irq events (but ratelimited)

[Michael Ellerman <michael@ellerman.id.au>]

On Mon, 2015-12-21 at 18:18 -0500, Paul Gortmaker wrote:
> On Mon, Dec 7, 2015 at 8:38 PM, Paul Gortmaker
> <paul.gortmaker@windriver.com> wrote:
> > It might be worth warning on spurious IRQ events; they might
> > point someone at a bogus DTS value or similar.
> > 
> > But ratelimit them to ensure we aren't too spammy about it.
> > 
> > Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> > Cc: Paul Mackerras <paulus@samba.org>
> > Cc: Michael Ellerman <mpe@ellerman.id.au>
> > Cc: linuxppc-dev@lists.ozlabs.org
> > Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
> > ---
> >  arch/powerpc/kernel/irq.c | 6 ++++--
> >  1 file changed, 4 insertions(+), 2 deletions(-)
> > 
> > diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
> > index 290559df1e8b..5c777e3a4c04 100644
> > --- a/arch/powerpc/kernel/irq.c
> > +++ b/arch/powerpc/kernel/irq.c
> > @@ -497,10 +497,12 @@ void __do_irq(struct pt_regs *regs)
> >         may_hard_irq_enable();
> > 
> >         /* And finally process it */
> > -       if (unlikely(irq == NO_IRQ))
> > +       if (unlikely(irq == NO_IRQ)) {
> > +               printk_ratelimited(KERN_WARNING "spurious irq on %d\n", irq);
> 
> If we did decide we cared about this patch, then no need for "irq" above, as
> we already know it is equal to NO_IRQ.

I'm not convinced it's worth printing, we already have a counter in proc.

I think it's more likely to just lead to console spam.

But maybe I'm wrong and you can convince me otherwise :)

cheers