virtio/ringtest: fix up need_event math

last kicked event index must be updated unconditionally:
even if we don't need to kick, we do not want to re-check
the same entry for events.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Cornelia Huck <cohuck@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>

diff --git a/tools/virtio/ringtest/ring.c b/tools/virtio/ringtest/ring.c
index 747c5dd..2b9859b 100644 (file)
--- a/tools/virtio/ringtest/ring.c
+++ b/tools/virtio/ringtest/ring.c
@@ -188,16 +188,18 @@ bool enable_call()
 
 void kick_available(void)
 {
+       bool need;
+
        /* Flush in previous flags write */
        /* Barrier C (for pairing) */
        smp_mb();
-       if (!need_event(event->kick_index,
-                       guest.avail_idx,
-                       guest.kicked_avail_idx))
-               return;
+       need = need_event(event->kick_index,
+                          guest.avail_idx,
+                          guest.kicked_avail_idx);
 
        guest.kicked_avail_idx = guest.avail_idx;
-       kick();
+       if (need)
+               kick();
 }
 
 /* host side */
@@ -253,14 +255,18 @@ bool use_buf(unsigned *lenp, void **bufp)
 
 void call_used(void)
 {
+       bool need;
+
        /* Flush in previous flags write */
        /* Barrier D (for pairing) */
        smp_mb();
-       if (!need_event(event->call_index,
+
+       need = need_event(event->call_index,
                        host.used_idx,
-                       host.called_used_idx))
-               return;
+                       host.called_used_idx);
 
        host.called_used_idx = host.used_idx;
-       call();
+
+       if (need)
+               call();
 }