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

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Date:   Sat, 2 Feb 2019 18:16:36 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     Florian Fainelli <f.fainelli@...il.com>
Cc:     Rundong Ge <rdong.ge@...il.com>, 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

On Sat, Feb 02, 2019 at 09:05:11AM -0800, Florian Fainelli wrote:
> 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:

Hi Rundong, Florian

I've seen issues with tcpdump causing the promiscuous count to go
negative. I wounder if this will fix that at well?

	  Andrew