Re: [dpdk-dev] [PATCH] vhost: remove unnecessary memset for virtio net hdr

["Xie, Huawei" <huawei.xie@intel.com>]

On 3/16/2016 2:44 PM, Yuanhan Liu wrote:
> We have to reset the virtio net hdr at virtio_enqueue_offload()
> before, due to all mbufs share a single virtio_hdr structure:
>
> 	struct virtio_net_hdr_mrg_rxbuf virtio_hdr = {{0, }, 0};
>
> 	foreach (mbuf) {
> 		virtio_enqueue_offload(mbuf, &virtio_hdr.hdr);
>
> 		copy net hdr and mbuf to desc buf
> 	}
>
> However, after the vhost rxtx refactor, the code looks like:
>
> 	copy_mbuf_to_desc(mbuf)
> 	{
> 		struct virtio_net_hdr_mrg_rxbuf virtio_hdr = {{0, }, 0}
>
> 		virtio_enqueue_offload(mbuf, &virtio_hdr.hdr);
>
> 		copy net hdr and mbuf to desc buf
> 	}
>
> 	foreach (mbuf) {
> 		copy_mbuf_to_desc(mbuf);
> 	}
>
> Therefore, the memset at virtio_enqueue_offload() is not necessary
> any more; remove it.
>
> Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
> ---
>  lib/librte_vhost/vhost_rxtx.c | 2 --
>  1 file changed, 2 deletions(-)
>
> diff --git a/lib/librte_vhost/vhost_rxtx.c b/lib/librte_vhost/vhost_rxtx.c
> index a6330f8..b4da665 100644
> --- a/lib/librte_vhost/vhost_rxtx.c
> +++ b/lib/librte_vhost/vhost_rxtx.c
> @@ -94,8 +94,6 @@ is_valid_virt_queue_idx(uint32_t idx, int is_tx, uint32_t qp_nb)
>  static void
>  virtio_enqueue_offload(struct rte_mbuf *m_buf, struct virtio_net_hdr *net_hdr)
>  {
> -	memset(net_hdr, 0, sizeof(struct virtio_net_hdr));
> -
>  	if (m_buf->ol_flags & PKT_TX_L4_MASK) {
>  		net_hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
>  		net_hdr->csum_start = m_buf->l2_len + m_buf->l3_len;

Acked-by: Huawei Xie <huawei.xie@intel.com>