From mboxrd@z Thu Jan  1 00:00:00 1970
From: Hangbin Liu <liuhangbin@gmail.com>
Subject: Re: [PATCH net] ipvlan: call dev_change_flags when reset ipvlan mode
Date: Wed, 20 Jun 2018 11:22:54 +0800
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Cc: Linux Kernel Network Developers <netdev@vger.kernel.org>,
        Stefano Brivio <sbrivio@redhat.com>,
        Paolo Abeni <pabeni@redhat.com>,
        David Miller <davem@davemloft.net>,
        Mahesh Bandewar <maheshb@google.com>
To: Cong Wang <xiyou.wangcong@gmail.com>
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On Tue, Jun 19, 2018 at 02:10:18PM -0700, Cong Wang wrote:
> On Mon, Jun 18, 2018 at 7:04 AM, Hangbin Liu <liuhangbin@gmail.com> wrote:
> > @@ -94,10 +95,13 @@ static int ipvlan_set_port_mode(struct ipvl_port *port, u16 nval)
> >                         mdev->l3mdev_ops = NULL;
> >                 }
> >                 list_for_each_entry(ipvlan, &port->ipvlans, pnode) {
> > +                       flags = ipvlan->dev->flags;
> >                         if (nval == IPVLAN_MODE_L3 || nval == IPVLAN_MODE_L3S)
> > -                               ipvlan->dev->flags |= IFF_NOARP;
> > +                               dev_change_flags(ipvlan->dev,
> > +                                                flags | IFF_NOARP);
> >                         else
> > -                               ipvlan->dev->flags &= ~IFF_NOARP;
> > +                               dev_change_flags(ipvlan->dev,
> > +                                                flags & ~IFF_NOARP);
> 
> You need to check the return value of dev_change_flags().

Hi Wang Cong,

The only case dev_change_flags() return an err is when we change IFF_UP flag.
Since we only set/reset IFF_NOARP, do you think we still need to check the
return value?

Thanks
Hangbin