Messages in this thread |  | | | Date | Fri, 13 Mar 2009 11:38:28 +0100 | | From | Ingo Molnar <> | | Subject | Re: [tip:core/ipi] generic-ipi: eliminate spurious pointlessWARN_ON()s |
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* Peter Zijlstra <peterz@infradead.org> wrote:
> On Fri, 2009-03-13 at 09:21 +0000, Jan Beulich wrote: > > >>> Peter Zijlstra <peterz@infradead.org> 13.03.09 09:54 >>> > > >Wouldn't leaving them in place but changing them to: > > > > > >WARN_ON(irqs_disabled() && system_state == SYSTEM_RUNNING); > > > > > >be clearer? > > > > I don't think that would be precise: system_state gets set to > > SYSTEM_RUNNING much later than APs get brought up (i.e. there are > > cases where the WARN_ON()s could validly trigger with SYSTEM_BOOTING), > > and also doesn't cover states > SYSTEM_RUNNING (where, again, after > > perhaps having brought down all APs the warnings could become pointless, > > but the warnings could be meaningful as long as there are still some APs > > online). > > > > While from an abstract code reading perspective your suggestion might > > seem reasonable, the changed placement really reflects what the warning > > is trying to warn about - a potential deadlock which cannot occur under > > the conditions filtered out by conditionals the warnings were moved > > beyond. > > How about? > > WARN_ON_ONCE(irqs_disabled() && !oops_in_progress)
ok, that's indeed better - i've done that - see the upcoming commit messages in this thread.
I also changed all of panic() to be covered by oops_in_progress - see the other commit. Eric: that should make kexec [a tiny bit] more robust too, agreed?
Ingo
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