[dpdk-stable] [PATCH 3/3] net/virtio: add missing read barrier for packed dequeue

[Ilya Maximets]

Read barrier is required between reading the flags (desc_is_used)
and the content of descriptor to ensure the ordering.
Otherwise, speculative read of desc.id could be reordered with
reading of the desc.flags.

Fixes: a76290c8f1cf ("net/virtio: implement Rx path for packed queues")
Cc: stable at dpdk.org

Signed-off-by: Ilya Maximets <i.maximets at samsung.com>
---
 drivers/net/virtio/virtio_rxtx.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/virtio/virtio_rxtx.c b/drivers/net/virtio/virtio_rxtx.c
index 5ffed6a51..4c701c514 100644
--- a/drivers/net/virtio/virtio_rxtx.c
+++ b/drivers/net/virtio/virtio_rxtx.c
@@ -124,6 +124,7 @@ virtqueue_dequeue_burst_rx_packed(struct virtqueue *vq,
 		used_idx = vq->vq_used_cons_idx;
 		if (!desc_is_used(&desc[used_idx], vq))
 			return i;
+		virtio_rmb(vq->hw->weak_barriers);
 		len[i] = desc[used_idx].len;
 		id = desc[used_idx].id;
 		cookie = (struct rte_mbuf *)vq->vq_descx[id].cookie;
-- 
2.17.1