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. Kind Regards, -Greg
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