netdev - Re: [PATCH net v2 2/4] bonding: restore IFF_MASTER/SLAVE flags on bond enslave ether type change

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Date:   Tue, 14 Mar 2023 16:09:51 +0100
From:   Michal Kubiak <michal.kubiak@...el.com>
To:     Nikolay Aleksandrov <razor@...ckwall.org>
CC:     <netdev@...r.kernel.org>, <monis@...taire.com>,
        <syoshida@...hat.com>, <j.vosburgh@...il.com>,
        <andy@...yhouse.net>, <kuba@...nel.org>, <davem@...emloft.net>,
        <pabeni@...hat.com>, <edumazet@...gle.com>,
        <syzbot+9dfc3f3348729cc82277@...kaller.appspotmail.com>
Subject: Re: [PATCH net v2 2/4] bonding: restore IFF_MASTER/SLAVE flags on
 bond enslave ether type change

On Tue, Mar 14, 2023 at 01:14:24PM +0200, Nikolay Aleksandrov wrote:
> If the bond enslaves non-ARPHRD_ETHER device (changes its type), then
> releases it and enslaves ARPHRD_ETHER device (changes back) then we
> use ether_setup() to restore the bond device type but it also resets its
> flags and removes IFF_MASTER and IFF_SLAVE[1]. Use the bond_ether_setup
> helper to restore both after such transition.
> 
> [1] reproduce (nlmon is non-ARPHRD_ETHER):
>  $ ip l add nlmon0 type nlmon
>  $ ip l add bond2 type bond mode active-backup
>  $ ip l set nlmon0 master bond2
>  $ ip l set nlmon0 nomaster
>  $ ip l add bond1 type bond
>  (we use bond1 as ARPHRD_ETHER device to restore bond2's mode)
>  $ ip l set bond1 master bond2
>  $ ip l sh dev bond2
>  37: bond2: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000
>     link/ether be:d7:c5:40:5b:cc brd ff:ff:ff:ff:ff:ff promiscuity 0 minmtu 68 maxmtu 1500
>  (notice bond2's IFF_MASTER is missing)
> 
> Fixes: e36b9d16c6a6 ("bonding: clean muticast addresses when device changes type")
> Signed-off-by: Nikolay Aleksandrov <razor@...ckwall.org>
> ---
>  drivers/net/bonding/bond_main.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
> index d41024ad2c18..cd94baccdac5 100644
> --- a/drivers/net/bonding/bond_main.c
> +++ b/drivers/net/bonding/bond_main.c
> @@ -1878,10 +1878,8 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev,
>  
>  			if (slave_dev->type != ARPHRD_ETHER)
>  				bond_setup_by_slave(bond_dev, slave_dev);
> -			else {
> -				ether_setup(bond_dev);
> -				bond_dev->priv_flags &= ~IFF_TX_SKB_SHARING;
> -			}
> +			else
> +				bond_ether_setup(bond_dev);

As I already commented on your previous patch: there is the first call
of "bond_ether_setup()".
Please think about merging this patch with the previous one to avoid the
compilation warning.

Thanks,
Michal


>  
>  			call_netdevice_notifiers(NETDEV_POST_TYPE_CHANGE,
>  						 bond_dev);
> -- 
> 2.39.2
>