virtio: inline virtio_queue_set_host_notifier_fd_handler

Of the three possible parameter combinations for
virtio_queue_set_host_notifier_fd_handler:

- assign=true/set_handler=true is only called from
  virtio_device_start_ioeventfd

- assign=false/set_handler=false is called from
  set_host_notifier_internal but it only does something when
  reached from virtio_device_stop_ioeventfd_impl; otherwise
  there is no EventNotifier set on qemu_get_aio_context().

- assign=true/set_handler=false is called from
  set_host_notifier_internal, but it is not doing anything:
  with the new start_ioeventfd and stop_ioeventfd methods,
  there is never an EventNotifier set on qemu_get_aio_context()
  at this point.  This is enforced by the assertion in
  virtio_bus_set_host_notifier.

Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 11 insertions, 8 deletions

diff --git a/hw/virtio/virtio-bus.c b/hw/virtio/virtio-bus.c
index fd105b80a7..670746c18c 100644
--- a/hw/virtio/virtio-bus.c
+++ b/hw/virtio/virtio-bus.c
@@ -163,19 +163,22 @@ static int set_host_notifier_internal(DeviceState *proxy, VirtioBusState *bus,
                          __func__, strerror(-r), r);
             return r;
         }
-        virtio_queue_set_host_notifier_fd_handler(vq, true, false);
-        r = k->ioeventfd_assign(proxy, notifier, n, assign);
+        r = k->ioeventfd_assign(proxy, notifier, n, true);
         if (r < 0) {
             error_report("%s: unable to assign ioeventfd: %d", __func__, r);
-            virtio_queue_set_host_notifier_fd_handler(vq, false, false);
-            event_notifier_cleanup(notifier);
-            return r;
+            goto cleanup_event_notifier;
         }
+        return 0;
     } else {
-        k->ioeventfd_assign(proxy, notifier, n, assign);
-        virtio_queue_set_host_notifier_fd_handler(vq, false, false);
-        event_notifier_cleanup(notifier);
+        k->ioeventfd_assign(proxy, notifier, n, false);
     }
+
+cleanup_event_notifier:
+    /* Test and clear notifier after disabling event,
+     * in case poll callback didn't have time to run.
+     */
+    virtio_queue_host_notifier_read(notifier);
+    event_notifier_cleanup(notifier);
     return r;
 }