Re: [PATCH net-next v2] bonding: Remove unnecessary check

[Jonathan Toppins]

On 8/24/22 14:07, Jay Vosburgh wrote:
> On 8/24/22, Sun Shouxin <sunshouxin@xxxxxxxxxxxxxxx> wrote:
> > This code is intended to support bond alb interface added to
> > Linux bridge by modifying MAC, however, it doesn't work for
> > one bond alb interface with vlan added to bridge.
> > Since commit d5410ac7b0ba("net:bonding:support balance-alb
> > interface with vlan to bridge"), new logic is adapted to handle
> > bond alb with or without vlan id, and then the code is deprecated.
>
> I think this could still be clearer; the actual changes relate to the stack of
> interfaces (e.g., eth0 -> bond0 -> vlan123 -> bridge0), not what VLAN tags
> incoming traffic contains.
>
> The code being removed here is specifically for the case of
> eth0 -> bond0 -> bridge0, without an intermediate VLAN interface
> in the stack (because, if memory serves, netif_is_bridge_port doesn't
> transfer through to the bond if there's a VLAN interface in between).
>
> Also, this code is for incoming traffic, assigning the bond's MAC to
> traffic arriving on interfaces other than the active interface (which bears
> the bond's MAC in alb mode; the other interfaces have different MACs).
> Commit d5410ac7b0ba affects the balance assignments for outgoing ARP
> traffic.  I'm not sure that d5410 is an exact replacement for the code this
> patch removes.

I would be more comfortable with a change like this if it can be 
demonstrated that an example test case functions as expected before and 
after the change. Could a selftests test be written with veths to 
demonstrate this code is indeed redundant?

-Jon

> > Suggested-by: Hu Yadi <huyd12@xxxxxxxxxxxxxxx>
> > Signed-off-by: Sun Shouxin <sunshouxin@xxxxxxxxxxxxxxx>
> > ---
> >   drivers/net/bonding/bond_main.c | 13 -------------
> >   1 file changed, 13 deletions(-)
> >
> > diff --git a/drivers/net/bonding/bond_main.c
> > b/drivers/net/bonding/bond_main.c
> > index 50e60843020c..6b0f0ce9b9a1 100644
> > --- a/drivers/net/bonding/bond_main.c
> > +++ b/drivers/net/bonding/bond_main.c
> > @@ -1578,19 +1578,6 @@ static rx_handler_result_t bond_handle_frame(struct
> > sk_buff **pskb)
> >
> >   	skb->dev = bond->dev;
> >
> > -	if (BOND_MODE(bond) == BOND_MODE_ALB &&
> > -	    netif_is_bridge_port(bond->dev) &&
> > -	    skb->pkt_type == PACKET_HOST) {
> > -
> > -		if (unlikely(skb_cow_head(skb,
> > -					  skb->data - skb_mac_header(skb)))) {
> > -			kfree_skb(skb);
> > -			return RX_HANDLER_CONSUMED;
> > -		}
> > -		bond_hw_addr_copy(eth_hdr(skb)->h_dest, bond->dev->dev_addr,
> > -				  bond->dev->addr_len);
> > -	}
> > -
> >   	return ret;
> >   }
> >
> > --
> > 2.27.0