[dpdk-dev] [PATCH] vhost: fix assuming packed ring size is a power of 2

[Maxime Coquelin <maxime.coquelin@redhat.com>]

Unlike split ring, packed ring does not mandate the ring size
to be a power of 2. So we have to use a modulo operation when
wrapping ring index.

Fixes: 873e8dad6f49 ("vhost: support packed ring in async datapath")
Cc: stable@dpdk.org

Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
---
 lib/vhost/virtio_net.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/vhost/virtio_net.c b/lib/vhost/virtio_net.c
index b93482587c..43011b5a2a 100644
--- a/lib/vhost/virtio_net.c
+++ b/lib/vhost/virtio_net.c
@@ -2131,7 +2131,7 @@ uint16_t rte_vhost_poll_enqueue_completed(int vid, uint16_t queue_id,
 
 	if (vq_is_packed(dev)) {
 		for (i = 0; i < n_pkts_put; i++) {
-			from = (start_idx + i) & (vq_size - 1);
+			from = (start_idx + i) % vq_size;
 			n_buffers += pkts_info[from].nr_buffers;
 			pkts[i] = pkts_info[from].mbuf;
 		}
-- 
2.31.1