linux-kernel - Re: [PATCH net] net: bridge: mst: Check vlan state for egress decision

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Message-ID: <8f3fe53c-0bee-44d9-9c23-6fdd3362ebe4@blackwall.org>
Date: Fri, 5 Jul 2024 09:19:20 +0300
From: Nikolay Aleksandrov <razor@...ckwall.org>
To: Elliot Ayrey <elliot.ayrey@...iedtelesis.co.nz>, davem@...emloft.net
Cc: Roopa Prabhu <roopa@...dia.com>, Eric Dumazet <edumazet@...gle.com>,
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
 Tobias Waldekranz <tobias@...dekranz.com>, bridge@...ts.linux.dev,
 netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net] net: bridge: mst: Check vlan state for egress
 decision

On 05/07/2024 06:00, Elliot Ayrey wrote:
> If a port is blocking in the common instance but forwarding in an MST
> instance, traffic egressing the bridge will be dropped because the
> state of the common instance is overriding that of the MST instance.
> 
> Fix this by temporarily forcing the port state to forwarding when in
> MST mode to allow checking the vlan state via br_allowed_egress().
> This is similar to what happens in br_handle_frame_finish() when
> checking ingress traffic, which was introduced in the change below.
> 
> Fixes: ec7328b59176 ("net: bridge: mst: Multiple Spanning Tree (MST) mode")
> Signed-off-by: Elliot Ayrey <elliot.ayrey@...iedtelesis.co.nz>
> ---
>  net/bridge/br_forward.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/net/bridge/br_forward.c b/net/bridge/br_forward.c
> index d97064d460dc..911b37a38a32 100644
> --- a/net/bridge/br_forward.c
> +++ b/net/bridge/br_forward.c
> @@ -22,10 +22,16 @@ static inline int should_deliver(const struct net_bridge_port *p,
>  				 const struct sk_buff *skb)
>  {
>  	struct net_bridge_vlan_group *vg;
> +	u8 state;

state = p->state
...

> +
> +	if (br_mst_is_enabled(p->br))
> +		state = BR_STATE_FORWARDING;

...
and you can drop the else clause

> +	else
> +		state = p->state;
>  
>  	vg = nbp_vlan_group_rcu(p);
>  	return ((p->flags & BR_HAIRPIN_MODE) || skb->dev != p->dev) &&
> -		p->state == BR_STATE_FORWARDING && br_allowed_egress(vg, skb) &&
> +		state == BR_STATE_FORWARDING && br_allowed_egress(vg, skb) &&
>  		nbp_switchdev_allowed_egress(p, skb) &&
>  		!br_skb_isolated(p, skb);
>  }