Re: [Linux 2.6.29-rc2] BUG: using smp_processor_id() in preemptible

From: Ingo Molnar
Date: Tue Jan 27 2009 - 10:50:34 EST



* Rafael J. Wysocki <rjw@xxxxxxx> wrote:

> > In fact whatever check you put in it's _always_ going to be
> > fundamentally more fragile than direct instrumentation: you cannot
> > possibly check all possible places that enable interrupts. (they could
> > be disabling interrupts as a _restore_irqs() sequence for example)
>
> In this particular case, I'm not really interested in that. What I'm
> interested in is which driver's ->suspend_late() or ->resume_early() (or
> the equivalents for sysdevs) has enabled interrupts, which is quite easy
> to check directly.

But this is exactly what it does - without any need for debug checks
spread around!

You'll get a _full stack dump_ from the very driver that is enabling
interrupts! You dont get a trace - you get a stack dump of the very place
that is buggy. It does not get any better than that.

Ingo
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