Re: [PATCH] net: fec: fix receive VLAN CTAG HW acceleration issue

[Michael Grzeschik <mgr@pengutronix.de>]

On Tue, Mar 10, 2015 at 06:30:42PM +0800, Fugang Duan wrote:
> The current driver support receive VLAN CTAG HW acceleration feature
> (NETIF_F_HW_VLAN_CTAG_RX) through software simulation. There calls the
> api .skb_copy_to_linear_data_offset() to skip the VLAN tag, but there
> have overlap between the two memory data point range. The patch just fix
> the issue.
> 
> Reported-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
> Signed-off-by: Fugang Duan <B38611@freescale.com>
> ---
>  drivers/net/ethernet/freescale/fec_main.c |    4 +++-
>  1 files changed, 3 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
> index 9bb6220..c9b1dbb 100644
> --- a/drivers/net/ethernet/freescale/fec_main.c
> +++ b/drivers/net/ethernet/freescale/fec_main.c
> @@ -1475,12 +1475,14 @@ fec_enet_rx_queue(struct net_device *ndev, int budget, u16 queue_id)
>  			/* Push and remove the vlan tag */
>  			struct vlan_hdr *vlan_header =
>  					(struct vlan_hdr *) (data + ETH_HLEN);
> +			unsigned char eth_hdr[12];
>  			vlan_tag = ntohs(vlan_header->h_vlan_TCI);
>  
>  			vlan_packet_rcvd = true;
>  
> +			memcpy(eth_hdr, data, 2 * ETH_ALEN);
>  			skb_copy_to_linear_data_offset(skb, VLAN_HLEN,
> -						       data, (2 * ETH_ALEN));
> +						       eth_hdr, (2 * ETH_ALEN));
>  			skb_pull(skb, VLAN_HLEN);
>  		}
>  
> -- 
> 1.7.8

why not just use memmove instead of the skb_copy_to_linear_data_offset?

memmove(skb->data + VLAN_HLEN, data, (2 * ETH_ALEN));

Michael

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