Re: [RFC net-next] net: bridge: igmp: Extend IGMP query with vlan support

[Nikolay Aleksandrov]

On 11/12/2020 11:26, Horatiu Vultur wrote:
> This patch tries to add vlan support to IGMP queries.
> It extends the function 'br_ip4_multicast_alloc_query' to add
> also a vlan tag if vlan is enabled. Therefore the bridge will send
> queries for each vlan the ports are in.
> 
> There are few other places that needs to be updated to be fully
> functional. But I am curious if this is the way to go forward or is
> there a different way of implementing this?
> 
> Signed-off-by: Horatiu Vultur <horatiu.vultur@xxxxxxxxxxxxx>
> ---
>  net/bridge/br_multicast.c | 31 ++++++++++++++++++++++++++-----
>  1 file changed, 26 insertions(+), 5 deletions(-)
> 

Hi Horatiu,
We've discussed this with other people on netdev before, the way forward is to
implement it as a per-vlan option and then have a per-vlan querier. Which would also
make the change much bigger and more complex. In general some of the multicast options
need to be replicated for vlans to get proper per-vlan multicast control and operation, but
that would require to change a lot of logic around the whole bridge (fast-path included,
where it'd be most sensitive). The good news is that these days we have per-vlan options
support and so only the actual per-vlan multicast implementation is left to be done.
I have this on my TODO list, unfortunately that list gets longer and longer,
so I'd be happy to review patches if someone decides to do it sooner. :)

Sorry, I couldn't find the previous discussion, it was a few years back.

Cheers,
 Nik

> diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
> index 484820c223a3..4c2db8a9efe0 100644
> --- a/net/bridge/br_multicast.c
> +++ b/net/bridge/br_multicast.c
> @@ -688,7 +688,8 @@ static struct sk_buff *br_ip4_multicast_alloc_query(struct net_bridge *br,
>  						    __be32 ip_dst, __be32 group,
>  						    bool with_srcs, bool over_lmqt,
>  						    u8 sflag, u8 *igmp_type,
> -						    bool *need_rexmit)
> +						    bool *need_rexmit,
> +						    __u16 vid)
>  {
>  	struct net_bridge_port *p = pg ? pg->key.port : NULL;
>  	struct net_bridge_group_src *ent;
> @@ -724,6 +725,9 @@ static struct sk_buff *br_ip4_multicast_alloc_query(struct net_bridge *br,
>  	}
>  
>  	pkt_size = sizeof(*eth) + sizeof(*iph) + 4 + igmp_hdr_size;
> +	if (br_vlan_enabled(br->dev) && vid != 0)
> +		pkt_size += 4;
> +
>  	if ((p && pkt_size > p->dev->mtu) ||
>  	    pkt_size > br->dev->mtu)
>  		return NULL;
> @@ -732,6 +736,9 @@ static struct sk_buff *br_ip4_multicast_alloc_query(struct net_bridge *br,
>  	if (!skb)
>  		goto out;
>  
> +	if (br_vlan_enabled(br->dev) && vid != 0)
> +		__vlan_hwaccel_put_tag(skb, htons(ETH_P_8021Q), vid);
> +
>  	skb->protocol = htons(ETH_P_IP);
>  
>  	skb_reset_mac_header(skb);
> @@ -1008,7 +1015,8 @@ static struct sk_buff *br_multicast_alloc_query(struct net_bridge *br,
>  						    ip4_dst, group->dst.ip4,
>  						    with_srcs, over_lmqt,
>  						    sflag, igmp_type,
> -						    need_rexmit);
> +						    need_rexmit,
> +						    group->vid);
>  #if IS_ENABLED(CONFIG_IPV6)
>  	case htons(ETH_P_IPV6): {
>  		struct in6_addr ip6_dst;
> @@ -1477,6 +1485,8 @@ static void br_multicast_send_query(struct net_bridge *br,
>  				    struct bridge_mcast_own_query *own_query)
>  {
>  	struct bridge_mcast_other_query *other_query = NULL;
> +	struct net_bridge_vlan_group *vg;
> +	struct net_bridge_vlan *v;
>  	struct br_ip br_group;
>  	unsigned long time;
>  
> @@ -1485,7 +1495,7 @@ static void br_multicast_send_query(struct net_bridge *br,
>  	    !br_opt_get(br, BROPT_MULTICAST_QUERIER))
>  		return;
>  
> -	memset(&br_group.dst, 0, sizeof(br_group.dst));
> +	memset(&br_group, 0, sizeof(br_group));
>  
>  	if (port ? (own_query == &port->ip4_own_query) :
>  		   (own_query == &br->ip4_own_query)) {
> @@ -1501,8 +1511,19 @@ static void br_multicast_send_query(struct net_bridge *br,
>  	if (!other_query || timer_pending(&other_query->timer))
>  		return;
>  
> -	__br_multicast_send_query(br, port, NULL, NULL, &br_group, false, 0,
> -				  NULL);
> +	if (br_vlan_enabled(br->dev) && port) {
> +		vg = nbp_vlan_group(port);
> +
> +		list_for_each_entry(v, &vg->vlan_list, vlist) {
> +			br_group.vid = v->vid == vg->pvid ? 0 : v->vid;
> +
> +			__br_multicast_send_query(br, port, NULL, NULL,
> +						  &br_group, false, 0, NULL);
> +		}
> +	} else {
> +		__br_multicast_send_query(br, port, NULL, NULL, &br_group,
> +					  false, 0, NULL);
> +	}
>  
>  	time = jiffies;
>  	time += own_query->startup_sent < br->multicast_startup_query_count ?
>