netdev - Re: [PATCH] net: dsa: slave: Don't propagate flag changes on down slave interfaces

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Date:   Sat, 2 Feb 2019 09:05:11 -0800
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Rundong Ge <rdong.ge@...il.com>, andrew@...n.ch
Cc:     vivien.didelot@...il.com, davem@...emloft.net,
        netdev@...r.kernel.org
Subject: Re: [PATCH] net: dsa: slave: Don't propagate flag changes on down
 slave interfaces

Le 2/2/19 à 6:29 AM, Rundong Ge a écrit :
> The unbalance of master's promiscuity or allmulti will happen after ifdown
> and ifup a slave interface which is in a bridge.
> 
> When we ifdown a slave interface , both the 'dsa_slave_close' and
> 'dsa_slave_change_rx_flags' will clear the master's flags. The flags
> of master will be decrease twice.
> In the other hand, if we ifup the slave interface again, since the
> slave's flags were cleared the 'dsa_slave_open' won't set the master's
> flag, only 'dsa_slave_change_rx_flags' that triggered by 'br_add_if'
> will set the master's flags. The flags of master is increase once.
> 
> Only propagating flag changes when a slave interface is up makes
> sure this does not happen. The 'vlan_dev_change_rx_flags' had the
> same problem and was fixed, and changes here follows that fix.

VLAN code under net/8021q/vlan_dev.c::vlan_dev_change_rx_flags() appears
to do the same thing that you are proposing, so this looks fine to me.
Since that is a bugfix, we should probably add:

Fixes: 91da11f870f0 ("net: Distributed Switch Architecture protocol
support")

?

> 
> Signed-off-by: Rundong Ge <rdong.ge@...il.com>
> ---
>  net/dsa/slave.c | 13 ++++++++-----
>  1 file changed, 8 insertions(+), 5 deletions(-)
> 
> diff --git a/net/dsa/slave.c b/net/dsa/slave.c
> index a3fcc1d..b5e4482 100644
> --- a/net/dsa/slave.c
> +++ b/net/dsa/slave.c
> @@ -140,11 +140,14 @@ static int dsa_slave_close(struct net_device *dev)
>  static void dsa_slave_change_rx_flags(struct net_device *dev, int change)
>  {
>  	struct net_device *master = dsa_slave_to_master(dev);
> -
> -	if (change & IFF_ALLMULTI)
> -		dev_set_allmulti(master, dev->flags & IFF_ALLMULTI ? 1 : -1);
> -	if (change & IFF_PROMISC)
> -		dev_set_promiscuity(master, dev->flags & IFF_PROMISC ? 1 : -1);
> +	if (dev->flags & IFF_UP) {
> +		if (change & IFF_ALLMULTI)
> +			dev_set_allmulti(master,
> +					 dev->flags & IFF_ALLMULTI ? 1 : -1);
> +		if (change & IFF_PROMISC)
> +			dev_set_promiscuity(master,
> +					    dev->flags & IFF_PROMISC ? 1 : -1);
> +	}
>  }
>  
>  static void dsa_slave_set_rx_mode(struct net_device *dev)
> 


-- 
Florian