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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 <mst@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
master
Michael S. Tsirkin 11 years ago
committed by Marcelo Tosatti
parent
commit
c8ce057eaf
  1. 5
      virt/kvm/eventfd.c

5
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.
*/

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