On 17/03/14 19:11, Cornelia Huck wrote: > When registering a new irqfd, we call its ->poll method to collect any > event that might have previously been pending so that we can trigger it. > This is done under the kvm->irqfds.lock, which means the eventfd's ctx > lock is taken under it. > > However, if we get a POLLHUP in irqfd_wakeup, we will be called with the > ctx lock held before getting the irqfds.lock to deactivate the irqfd, > causing lockdep to complain. > > Calling the ->poll method does not really need the irqfds.lock, so let's > just move it after we've given up the irqfds.lock in kvm_irqfd_assign(). > > Signed-off-by: Cornelia Huck <cornelia.h...@de.ibm.com> Do you still have the lockdep message somewhere? Looking at the patch and the description this makes sense. Even without irqfd for s390: Reviewed-by: Christian Borntraeger <borntrae...@de.ibm.com>
Paolo, maybe this patch can go in independently from s390? Christian > --- > virt/kvm/eventfd.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c > index abe4d60..29c2a04 100644 > --- a/virt/kvm/eventfd.c > +++ b/virt/kvm/eventfd.c > @@ -391,19 +391,19 @@ kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd > *args) > lockdep_is_held(&kvm->irqfds.lock)); > irqfd_update(kvm, irqfd, irq_rt); > > - events = f.file->f_op->poll(f.file, &irqfd->pt); > - > list_add_tail(&irqfd->list, &kvm->irqfds.items); > > + spin_unlock_irq(&kvm->irqfds.lock); > + > /* > * Check if there was an event already pending on the eventfd > * before we registered, and trigger it as if we didn't miss it. > */ > + events = f.file->f_op->poll(f.file, &irqfd->pt); > + > if (events & POLLIN) > schedule_work(&irqfd->inject); > > - spin_unlock_irq(&kvm->irqfds.lock); > - > /* > * do not drop the file until the irqfd is fully initialized, otherwise > * we might race against the POLLHUP >
