[net-next,2/2] net: dsa: lan9303: Clear offload_fwd_mark for IGMP

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(+)

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

> 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);

Hi Egil

That is much nicer. But please add a couple of #defines for the 0x18
bits.

	Andrew

On 13. nov. 2017 14:02, Andrew Lunn wrote:
>> 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);
> 
> Hi Egil
> 
> That is much nicer. But please add a couple of #defines for the 0x18
> bits.
> 
Of course!

> 	Andrew
> 

Egil