net/virtio: add barriers for extra descriptors on Rx split

There should be read barrier between checking VIRTQUEUE_NUSED (reading
the used->idx) and reading these descriptors. It's done for the first
checks at the beginning of these functions but missed while checking
for extra required descriptors.

Fixes: e5f456a98d3c ("net/virtio: support in-order Rx and Tx")
Fixes: 13ce5e7eb94f ("virtio: mergeable buffers")
Cc: stable@dpdk.org
Signed-off-by: Ilya Maximets <i.maximets@samsung.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>

diff --git a/drivers/net/virtio/virtio_rxtx.c b/drivers/net/virtio/virtio_rxtx.c
index 63e4370..5ffed6a 100644 (file)
--- a/drivers/net/virtio/virtio_rxtx.c
+++ b/drivers/net/virtio/virtio_rxtx.c
@@ -1456,6 +1456,7 @@ virtio_recv_pkts_inorder(void *rx_queue,
 
                prev = rcv_pkts[nb_rx];
                if (likely(VIRTQUEUE_NUSED(vq) >= rcv_cnt)) {
+                       virtio_rmb(hw->weak_barriers);
                        num = virtqueue_dequeue_rx_inorder(vq, rcv_pkts, len,
                                                           rcv_cnt);
                        uint16_t extra_idx = 0;
@@ -1642,6 +1643,7 @@ virtio_recv_mergeable_pkts(void *rx_queue,
 
                prev = rcv_pkts[nb_rx];
                if (likely(VIRTQUEUE_NUSED(vq) >= rcv_cnt)) {
+                       virtio_rmb(hw->weak_barriers);
                        num = virtqueue_dequeue_burst_rx(vq, rcv_pkts, len,
                                                           rcv_cnt);
                        uint16_t extra_idx = 0;