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References: <20210220043203.11754-1-yejune.deng@gmail.com> <3b69191b-9bd5-9050-9126-17b4905a67e9@gmail.com>
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From:   Yejune Deng <yejune.deng@gmail.com>
Date:   Sun, 21 Feb 2021 10:20:44 +0800
Message-ID: <CABWKuGW5bvPDvNv5=Fj_=f9=gk--=_w28jsCJ8MK5t7ysK+s8g@mail.gmail.com>
Subject: Re: [PATCH] arp: Remove the arp_hh_ops structure
To:     David Ahern <dsahern@gmail.com>
Cc:     David Miller <davem@davemloft.net>, yoshfuji@linux-ipv6.org,
        dsahern@kernel.org, Jakub Kicinski <kuba@kernel.org>,
        netdev <netdev@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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Sorry,it was my fault, I will resubmit.

On Sun, Feb 21, 2021 at 9:54 AM David Ahern <dsahern@gmail.com> wrote:
>
> On 2/19/21 9:32 PM, Yejune Deng wrote:
> >  static const struct neigh_ops arp_direct_ops = {
> >       .family =               AF_INET,
> >       .output =               neigh_direct_output,
> > @@ -277,15 +269,10 @@ static int arp_constructor(struct neighbour *neigh)
> >                       memcpy(neigh->ha, dev->broadcast, dev->addr_len);
> >               }
> >
> > -             if (dev->header_ops->cache)
> > -                     neigh->ops = &arp_hh_ops;
> > -             else
> > -                     neigh->ops = &arp_generic_ops;
>
> How did you test this?
>
> you took out the neigh->ops assignment, so all of the neigh->ops in
> net/core/neighbour.c are going to cause a NULL dereference.
>
>
> > -
> > -             if (neigh->nud_state & NUD_VALID)
> > -                     neigh->output = neigh->ops->connected_output;
> > +             if (!dev->header_ops->cache && (neigh->nud_state & NUD_VALID))
> > +                     neigh->output = arp_generic_ops.connected_output;
> >               else
> > -                     neigh->output = neigh->ops->output;
> > +                     neigh->output = arp_generic_ops.output;
> >       }
> >       return 0;
> >  }
> >
>