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SubjectRe: [PATCH net-next 2/2] net: dsa: lan9303: Clear offload_fwd_mark for IGMP
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On 10. nov. 2017 12:54, Egil Hjelmeland wrote:
> Now that IGMP packets no longer is flooded in HW, we want the SW bridge to
> forward packets based on bridge configuration. To make that happen,
> IGMP packets must have skb->offload_fwd_mark = 0.
>
> Signed-off-by: Egil Hjelmeland <privat@egil-hjelmeland.no>
> ---
> net/dsa/tag_lan9303.c | 13 +++++++++++++
> 1 file changed, 13 insertions(+)
>
> diff --git a/net/dsa/tag_lan9303.c b/net/dsa/tag_lan9303.c
> index 5ba01fc3c6ba..b8c5e52b2eff 100644
> --- a/net/dsa/tag_lan9303.c
> +++ b/net/dsa/tag_lan9303.c
> @@ -92,6 +92,8 @@ static struct sk_buff *lan9303_rcv(struct sk_buff *skb, struct net_device *dev,
> {
> u16 *lan9303_tag;
> unsigned int source_port;
> + u16 ether_type_nw;
> + u8 ip_protocol;
>
> if (unlikely(!pskb_may_pull(skb, LAN9303_TAG_LEN))) {
> dev_warn_ratelimited(&dev->dev,
> @@ -129,6 +131,17 @@ static struct sk_buff *lan9303_rcv(struct sk_buff *skb, struct net_device *dev,
> skb->offload_fwd_mark = !ether_addr_equal(skb->data - ETH_HLEN,
> eth_stp_addr);
>
> + /* We also need IGMP packets to have skb->offload_fwd_mark = 0.
> + * Solving this for all conceivable situations would add more cost to
> + * every packet. Instead we handle just the common case:
> + * No VLAN tag + Ethernet II framing.
> + * Test least probable term first.
> + */
> + ether_type_nw = lan9303_tag[2];
> + ip_protocol = *(skb->data + 9);
> + if (ip_protocol == IPPROTO_IGMP && ether_type_nw == htons(ETH_P_IP))
> + skb->offload_fwd_mark = 0;
> +
> return skb;
> }
>
>

RTFM, my bad. The lan9303 has both STP and IGMP bits in the receive tag.
It is as simple as:

u16 lan9303_tag1 = ntohs(lan9303_tag[1]);
skb->offload_fwd_mark = !(lan9303_tag1 & 0x18);

Egil

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