From: Michael S. Tsirkin Date: Sun, 6 Mar 2011 11:03:26 +0000 (+0200) Subject: KVM: improve comment on rcu use in irqfd_deassign X-Git-Tag: v3.12-rc1~6893^2~9 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=c8ce057eafd49da6a7afe7791bd84163f65f6132;p=kernel%2Fkernel-generic.git KVM: improve comment on rcu use in irqfd_deassign The RCU use in kvm_irqfd_deassign is tricky: we have rcu_assign_pointer but no synchronize_rcu: synchronize_rcu is done by kvm_irq_routing_update which we share a spinlock with. Fix up a comment in an attempt to make this clearer. Signed-off-by: Michael S. Tsirkin Signed-off-by: Avi Kivity --- diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c index 2ca4535..3656849 100644 --- a/virt/kvm/eventfd.c +++ b/virt/kvm/eventfd.c @@ -313,8 +313,9 @@ kvm_irqfd_deassign(struct kvm *kvm, int fd, int gsi) if (irqfd->eventfd == eventfd && irqfd->gsi == gsi) { /* * This rcu_assign_pointer is needed for when - * another thread calls kvm_irqfd_update before - * we flush workqueue below. + * another thread calls kvm_irq_routing_update before + * we flush workqueue below (we synchronize with + * kvm_irq_routing_update using irqfds.lock). * It is paired with synchronize_rcu done by caller * of that function. */