Re: [tip:core/debug] debug lockups: Improve lockup detection

Ingo Molnar
2009-08-03T08:00:07Z

* Andrew Morton <akpm@linux-foundation.org> wrote:

> On Sun, 2 Aug 2009 22:41:50 +0200 Ingo Molnar <mingo@elte.hu> wrote:
>
> >
> > * Andrew Morton <akpm@linux-foundation.org> wrote:
> >
> > > On Sun, 2 Aug 2009 21:26:57 +0200 Ingo Molnar <mingo@elte.hu> wrote:
> > >
> > > > > I think this just broke all non-x86 non-sparc SMP architectures.
> > > >
> > > > Yeah - it 'broke' them in the sense of them not having a working
> > > > trigger_all_cpu_backtrace() implementation to begin with.
> > >
> > > c'mon. It broke them in the sense that sysrq-l went from "works"
> > > to "doesn't work".
> >
> > You are right (i broke it with my patch) but the thing is,
> > sysrq-l almost useless currently: it uses schedule_work() which
> > assumes a mostly working system with full irqs and scheduling
> > working fine. Now, i dont need sysrq-l on mostly working
> > systems.
> >
> > So the 'breakage' is of something that was largely useless: and
> > now you put the onus of implementing it for _all_ architectures
> > (which i dont use) on me?
>
> I never said that.
>
> It's appropriate that those architectures be left with their
> existing level of functionality/usefulness, as you're already
> discussing.

Ok, agreed.

> > > It's better to break the build or to emit warnings than to
> > > silently and secretly break their stuff.
> >
> > But that warning will bounce the ball back to me, wont it? My
> > patch will be blamed for 'breaking' those architectures, right?
>
> It's a very crude and somewhat rude way of communicating
> information to other architecture maintainers.
>
> A better way would be to send them an email explaining the problem
> and outlining some solutions, no?

I've restored the generic fallback code so there should be no change
in functionality. I'll test it and push it out - you can check that
patch via the commit notification email.

Thanks,

Ingo