Re: [dpdk-dev] [PATCH] net/virtio: fix invalid indirect desc length

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

On 10/15/20 7:46 AM, Marvin Liu wrote:
> When transmitting indirect descriptors, first desc will store net_hdr
> and following descs will be mapped to mbuf segments. Total desc number
> will be seg_num plus one. Meaning of variable needed is the number of
> used descs in packed ring. This value will always be two for indirect
> desc. Now use mbuf segments number for calculating correct desc length.
> 
> Fixes: de8b3d238074 ("net/virtio: fix indirect descs in packed datapaths")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Marvin Liu <yong.liu@intel.com>
> 
> diff --git a/drivers/net/virtio/virtqueue.h b/drivers/net/virtio/virtqueue.h
> index 8c8ab9889..42c4c9882 100644
> --- a/drivers/net/virtio/virtqueue.h
> +++ b/drivers/net/virtio/virtqueue.h
> @@ -698,6 +698,7 @@ virtqueue_enqueue_xmit_packed(struct virtnet_tx *txvq, struct rte_mbuf *cookie,
>  	struct virtio_net_hdr *hdr;
>  	uint16_t prev;
>  	bool prepend_header = false;
> +	uint16_t seg_num = cookie->nb_segs;
>  
>  	id = in_order ? vq->vq_avail_idx : vq->vq_desc_head_idx;
>  
> @@ -732,7 +733,7 @@ virtqueue_enqueue_xmit_packed(struct virtnet_tx *txvq, struct rte_mbuf *cookie,
>  		 */
>  		start_dp[idx].addr  = txvq->virtio_net_hdr_mem +
>  			RTE_PTR_DIFF(&txr[idx].tx_packed_indir, txr);
> -		start_dp[idx].len   = (needed + 1) *
> +		start_dp[idx].len   = (seg_num + 1) *
>  			sizeof(struct vring_packed_desc);
>  		/* reset flags for indirect desc */
>  		head_flags = VRING_DESC_F_INDIRECT;
> 

Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>

Thanks,
Maxime