Re: [PATCH net-next v2] net: bridge: locally receive all multicast packets if IFF_ALLMULTI is set

[Shengyu Qu]

在 2025/4/14 16:42, Ido Schimmel 写道:
> On Sat, Apr 12, 2025 at 09:16:13PM +0800, Shengyu Qu wrote:
> > If multicast snooping is enabled, multicast packets may not always end up
> > on the local bridge interface, if the host is not a member of the multicast
> > group. Similar to how IFF_PROMISC allows all packets to be received
> > locally, let IFF_ALLMULTI allow all multicast packets to be received.
>
> Would be good to explain in the commit message why this is needed when
> you can instead configure the bridge as a router port. Felix provided
> useful information on v1:
>
> https://lore.kernel.org/netdev/7932cd23-571e-4646-b5dd-467ec8106695@xxxxxxxx/
Hi,

Thanks for reply. I'll add that in next version.

> > Signed-off-by: Felix Fietkau <nbd@xxxxxxxx>
> > Signed-off-by: Shengyu Qu <wiagn233@xxxxxxxxxxx>
> > ---
> > Since Felix didn't send v2 for this patch, I decided to do it by myself.
>
> Felix provided his SoB on v2? If not, "Reported-by" might be more
> appropriate.
Will change.
> > Changes since v1:
> >   - Move to net-next
> >   - Changed code according to Nikolay's advice
> > ---
> >   net/bridge/br_input.c | 3 ++-
> >   1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
> > index 232133a0fd21..aefcc3614373 100644
> > --- a/net/bridge/br_input.c
> > +++ b/net/bridge/br_input.c
> > @@ -189,7 +189,8 @@ int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb
> >   		if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) &&
> >   		    br_multicast_querier_exists(brmctx, eth_hdr(skb), mdst)) {
> >   			if ((mdst && mdst->host_joined) ||
> > -			    br_multicast_is_router(brmctx, skb)) {
> > +			    br_multicast_is_router(brmctx, skb) ||
> > +				(br->dev->flags & IFF_ALLMULTI)) {
>
> The alignment here is off. Also, you can drop the parenthesis.
Will fix.

> >   				local_rcv = true;
> >   				DEV_STATS_INC(br->dev, multicast);
> >   			}
> > --
> > 2.43.0

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