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| author | Michael S. Tsirkin <mst@redhat.com> | 2017-10-27 16:11:13 +0300 |
|---|---|---|
| committer | Michael S. Tsirkin <mst@redhat.com> | 2018-01-31 01:47:36 +0200 |
| commit | a311650ae6ad0c169ade2583f78aa519878ea13f (patch) | |
| tree | 53c54f8ff46aad3afab5de6672178f5271b08b32 /tools/virtio | |
| parent | f229a55c31a7e12a15c7b4dcf9a97a9bf7a72ce8 (diff) | |
| download | lwn-a311650ae6ad0c169ade2583f78aa519878ea13f.tar.gz lwn-a311650ae6ad0c169ade2583f78aa519878ea13f.zip | |
virtio/ringtest: virtio_ring: 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.
Reported-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Jens Freimann <jfreimann@redhat.com>
Diffstat (limited to 'tools/virtio')
| -rw-r--r-- | tools/virtio/ringtest/virtio_ring_0_9.c | 24 |
1 files changed, 14 insertions, 10 deletions
diff --git a/tools/virtio/ringtest/virtio_ring_0_9.c b/tools/virtio/ringtest/virtio_ring_0_9.c index bbc3043b2fb1..5fd3fbcb9e57 100644 --- a/tools/virtio/ringtest/virtio_ring_0_9.c +++ b/tools/virtio/ringtest/virtio_ring_0_9.c @@ -225,16 +225,18 @@ bool enable_call() void kick_available(void) { + bool need; + /* Flush in previous flags write */ /* Barrier C (for pairing) */ smp_mb(); - if (!vring_need_event(vring_avail_event(&ring), - guest.avail_idx, - guest.kicked_avail_idx)) - return; + need = vring_need_event(vring_avail_event(&ring), + guest.avail_idx, + guest.kicked_avail_idx); guest.kicked_avail_idx = guest.avail_idx; - kick(); + if (need) + kick(); } /* host side */ @@ -316,14 +318,16 @@ 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 (!vring_need_event(vring_used_event(&ring), - host.used_idx, - host.called_used_idx)) - return; + need = vring_need_event(vring_used_event(&ring), + host.used_idx, + host.called_used_idx); host.called_used_idx = host.used_idx; - call(); + if (need) + call(); } |