[PATCH v3 03/13] KVM: Initialize irqfd waitqueue callback when adding to the queue

[Sean Christopherson <seanjc@xxxxxxxxxx>]

Initialize the irqfd waitqueue callback immediately prior to inserting the
irqfd into the eventfd's waitqueue.  Pre-initializing the state in a
completely different context is all kinds of confusing, and incorrectly
suggests that the waitqueue function needs to be initialize prior to
vfs_poll().

Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
 virt/kvm/eventfd.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
index 42c02c35e542..8b9a87daa2bb 100644
--- a/virt/kvm/eventfd.c
+++ b/virt/kvm/eventfd.c
@@ -256,6 +256,13 @@ static void kvm_irqfd_register(struct file *file, 
wait_queue_head_t *wqh,
        struct kvm_irqfd_pt *p = container_of(pt, struct kvm_irqfd_pt, pt);
        struct kvm_kernel_irqfd *irqfd = p->irqfd;
 
+       /*
+        * Add the irqfd as a priority waiter on the eventfd, with a custom
+        * wake-up handler, so that KVM *and only KVM* is notified whenever the
+        * underlying eventfd is signaled.
+        */
+       init_waitqueue_func_entry(&irqfd->wait, irqfd_wakeup);
+
        add_wait_queue_priority(wqh, &irqfd->wait);
 }
 
@@ -395,12 +402,6 @@ kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args)
                mutex_unlock(&kvm->irqfds.resampler_lock);
        }
 
-       /*
-        * Install our own custom wake-up handling so we are notified via
-        * a callback whenever someone signals the underlying eventfd
-        */
-       init_waitqueue_func_entry(&irqfd->wait, irqfd_wakeup);
-
        /*
         * Set the irqfd routing and add it to KVM's list before registering
         * the irqfd with the eventfd, so that the routing information is valid
-- 
2.49.0.1151.ga128411c76-goog