On Mon, Jul 13, 2009 at 11:03:56AM -0400, Gregory Haskins wrote:
> Gleb Natapov wrote:
> > On Mon, Jul 13, 2009 at 10:29:02AM -0400, Gregory Haskins wrote:
> >
> >> Gleb Natapov wrote:
> >>
> >>> diff --git a/virt/kvm/irq_comm.c b/virt/kvm/irq_comm.c
> >>> index 6c57e46..ce8fcd3 100644
> >>> --- a/virt/kvm/irq_comm.c
> >>> +++ b/virt/kvm/irq_comm.c
> >>> @@ -210,7 +210,8 @@ int kvm_request_irq_source_id(struct kvm *kvm)
> >>> unsigned long *bitmap = &kvm->arch.irq_sources_bitmap;
> >>> int irq_source_id;
> >>>
> >>> - mutex_lock(&kvm->irq_lock);
> >>> + WARN_ON(!mutex_is_locked(&kvm->lock));
> >>>
> >>>
> >> Shouldn't this be fatal? (e.g. BUG_ON). I know the usage between
> >> BUG/WARN is controversial, but it seems to me that something is
> >> completely broken if you expect it to be locked and its not. Might as
> >> well fail the system, IMO.
> >>
> >>
> > Well I don't really care but we have WARN_ON() in the code currently.
> >
>
> Well, that is perhaps unfortunate, but not relevant. I am not reviewing
> those patches ;)
>
> > Besides the chances are good that even without locking around this
> > function nothing will break, so why kill host kernel?
> >
>
> The question to ask is: Is it legal to continue to run if the mutex is
> found unlocked? If not, the offending caller should be found/fixed as
> early as possible IMO, and an oops should be sufficient to do so. I
> think WARN_ON tends to gets overused/abused, so lets not perpetuate it
> simply because of precedence.
>
I will have to end this particular thread about WARN_ON by stating
that Avi told me to put it there. I'll let him decide.
--
Gleb.
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