virtio/ringtest: fix up need_event math

Web:        https://git.kernel.org/torvalds/c/f229a55c31a7e12a15c7b4dcf9a97a9bf7a72ce8
Commit:     f229a55c31a7e12a15c7b4dcf9a97a9bf7a72ce8
Parent:     31919140ff8c88c236f697baa28a6305df45e4ea
Refname:    refs/heads/master
Author:     Michael S. Tsirkin <[email protected]>
AuthorDate: Thu Oct 26 04:48:01 2017 +0300
Committer:  Michael S. Tsirkin <[email protected]>
CommitDate: Wed Jan 31 01:47:35 2018 +0200

    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 <[email protected]>
    Acked-by: Cornelia Huck <[email protected]>
    Acked-by: Jason Wang <[email protected]>
---
 tools/virtio/ringtest/ring.c | 24 +++++++++++++++---------
 1 file changed, 15 insertions(+), 9 deletions(-)

diff --git a/tools/virtio/ringtest/ring.c b/tools/virtio/ringtest/ring.c
index 747c5dd47be8..2b9859beea65 100644
--- 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();
 }
--
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