On 05.12.2018 12:49, Maxime Coquelin wrote:
> A read barrier is required to ensure the ordering between
> available index and the descriptor reads is enforced.
>
> Fixes: 4796ad63ba1f ("examples/vhost: import userspace vhost application")
> Cc: sta...@dpdk.org
>
> Reported-by: Jason Wang <jasow...@redhat.com>
> Signed-off-by: Maxime Coquelin <maxime.coque...@redhat.com>
> ---
> lib/librte_vhost/virtio_net.c | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
I'd like to have a bit more details about a bad scenario in a commit
message because it's not an obvious change at a first glance.
Otherwise,
Acked-by: Ilya Maximets <i.maxim...@samsung.com>
> diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c
> index 5e1a1a727..f11ebb54f 100644
> --- a/lib/librte_vhost/virtio_net.c
> +++ b/lib/librte_vhost/virtio_net.c
> @@ -791,6 +791,12 @@ virtio_dev_rx_split(struct virtio_net *dev, struct
> vhost_virtqueue *vq,
> rte_prefetch0(&vq->avail->ring[vq->last_avail_idx & (vq->size - 1)]);
> avail_head = *((volatile uint16_t *)&vq->avail->idx);
>
> + /*
> + * The ordering between avail index and
> + * desc reads needs to be enforced.
> + */
> + rte_smp_rmb();
> +
> for (pkt_idx = 0; pkt_idx < count; pkt_idx++) {
> uint32_t pkt_len = pkts[pkt_idx]->pkt_len + dev->vhost_hlen;
> uint16_t nr_vec = 0;
> @@ -1373,6 +1379,12 @@ virtio_dev_tx_split(struct virtio_net *dev, struct
> vhost_virtqueue *vq,
> if (free_entries == 0)
> return 0;
>
> + /*
> + * The ordering between avail index and
> + * desc reads needs to be enforced.
> + */
> + rte_smp_rmb();
> +
> VHOST_LOG_DEBUG(VHOST_DATA, "(%d) %s\n", dev->vid, __func__);
>
> count = RTE_MIN(count, MAX_PKT_BURST);
>
