netdev - Re: [PATCH net] net: bridge: keep ports without IFF_UNICAST_FLT in BR

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Date: Mon, 3 Jul 2023 11:00:14 +0300
From: Ido Schimmel <idosch@...dia.com>
To: Vladimir Oltean <vladimir.oltean@....com>
Cc: netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Roopa Prabhu <roopa@...dia.com>,
	Nikolay Aleksandrov <razor@...ckwall.org>,
	"Michael S. Tsirkin" <mst@...hat.com>,
	Vlad Yasevich <vyasevic@...hat.com>,
	bridge@...ts.linux-foundation.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net] net: bridge: keep ports without IFF_UNICAST_FLT in
 BR_PROMISC mode

On Fri, Jun 30, 2023 at 07:41:18PM +0300, Vladimir Oltean wrote:
> diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
> index 3f04b40f6056..2450690f98cf 100644
> --- a/net/bridge/br_if.c
> +++ b/net/bridge/br_if.c
> @@ -166,8 +166,9 @@ void br_manage_promisc(struct net_bridge *br)
>  			 * This lets us disable promiscuous mode and write
>  			 * this config to hw.
>  			 */
> -			if (br->auto_cnt == 0 ||
> -			    (br->auto_cnt == 1 && br_auto_port(p)))
> +			if ((p->dev->priv_flags & IFF_UNICAST_FLT) &&
> +			    (br->auto_cnt == 0 ||
> +			     (br->auto_cnt == 1 && br_auto_port(p))))
>  				br_port_clear_promisc(p);
>  			else
>  				br_port_set_promisc(p);

IIUC, you are basically saying "If the port does not support unicast
filtering, then set it to promiscuous mode right away instead of waiting
for the addition of the first FDB entry to trigger it."

If so, LGTM.

Reviewed-by: Ido Schimmel <idosch@...dia.com>

Tested using [1].

Before:

# ~/tmp/promisc_repo.sh 
0

After:

# ~/tmp/promisc_repo.sh 
1

[1]
#!/bin/bash

ip link add name swp1 type dummy
ip link add name br1 type bridge vlan_filtering 1
ip link set dev swp1 master br1
ip -d -j -p link show dev swp1 | jq '.[]["promiscuity"]'