Re: [dpdk-stable] [PATCH v2 2/4] net/virtio: fix segmented packet issue in mergeable Rx path

[David Marchand <david.marchand@redhat.com>]

On Wed, Jun 5, 2019 at 10:11 AM Maxime Coquelin <maxime.coquelin@redhat.com>
wrote:

> After having dequeued a burst of descriptors, there may be a
> need to dequeue a few more if the last packet was segmented
> and not complete. When it happens, the extra segments were
> not properly attached to the mbuf chain, and so were lost.
>
> Also, head segment data_len field is wrongly summed with
> the length of all the segments of the chain.
>
> This patch fixes both the mbuf chaining and head segment's
> data_len field
>
> Fixes: bcac5aa207f8 ("net/virtio: improve batching in mergeable path")
> Cc: stable@dpdk.org
>
> Reported-by: Yaroslav Brustinov <ybrustin@cisco.com>
> Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
> ---
>  drivers/net/virtio/virtio_rxtx.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/drivers/net/virtio/virtio_rxtx.c
> b/drivers/net/virtio/virtio_rxtx.c
> index 6b3baf0423..9469ecb743 100644
> --- a/drivers/net/virtio/virtio_rxtx.c
> +++ b/drivers/net/virtio/virtio_rxtx.c
> @@ -1614,7 +1614,7 @@ virtio_recv_mergeable_pkts(void *rx_queue,
>         struct virtqueue *vq = rxvq->vq;
>         struct virtio_hw *hw = vq->hw;
>         struct rte_mbuf *rxm;
> -       struct rte_mbuf *prev;
> +       struct rte_mbuf *prev = NULL;
>         uint16_t nb_used, num, nb_rx = 0;
>         uint32_t len[VIRTIO_MBUF_BURST_SZ];
>         struct rte_mbuf *rcv_pkts[VIRTIO_MBUF_BURST_SZ];
> @@ -1721,7 +1721,6 @@ virtio_recv_mergeable_pkts(void *rx_queue,
>                 uint16_t rcv_cnt = RTE_MIN((uint16_t)seg_res,
>                                         VIRTIO_MBUF_BURST_SZ);
>
> -               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,
> @@ -1738,7 +1737,6 @@ virtio_recv_mergeable_pkts(void *rx_queue,
>                                 prev->next = rxm;
>                                 prev = rxm;
>                                 rx_pkts[nb_rx]->pkt_len += len[extra_idx];
> -                               rx_pkts[nb_rx]->data_len += len[extra_idx];
>                                 extra_idx += 1;
>                         };
>                         seg_res -= rcv_cnt;
> --
> 2.21.0
>
>
Idem previous patch, you have missed a data_len line 1704.
Reviewed-by: David Marchand <david.marchand@redhat.com>


-- 
David Marchand