Re: [PATCH net-next v2 3/6] net/x25: replace x25_kill_by_device with x25_kill_by_neigh

[Martin Schiller]

On 2020-11-17 20:50, Xie He wrote:
> On Mon, Nov 16, 2020 at 6:00 AM Martin Schiller <ms@xxxxxxxxxx> wrote:
> > Remove unnecessary function x25_kill_by_device.
>
> > -/*
> > - *     Kill all bound sockets on a dropped device.
> > - */
> > -static void x25_kill_by_device(struct net_device *dev)
> > -{
> > -       struct sock *s;
> > -
> > -       write_lock_bh(&x25_list_lock);
> > -
> > -       sk_for_each(s, &x25_list)
> > -               if (x25_sk(s)->neighbour && x25_sk(s)->neighbour->dev 
> > == dev)
> > -                       x25_disconnect(s, ENETUNREACH, 0, 0);
> > -
> > -       write_unlock_bh(&x25_list_lock);
> > -}
> > -
> >  /*
> >   *     Handle device status changes.
> >   */
> > @@ -273,7 +257,11 @@ static int x25_device_event(struct notifier_block 
> > *this, unsigned long event,
> >                 case NETDEV_DOWN:
> >                         pr_debug("X.25: got event NETDEV_DOWN for 
> > device: %s\n",
> >                                  dev->name);
> > -                       x25_kill_by_device(dev);
> > +                       nb = x25_get_neigh(dev);
> > +                       if (nb) {
> > +                               x25_kill_by_neigh(nb);
> > +                               x25_neigh_put(nb);
> > +                       }
> >                         x25_route_device_down(dev);
> >                         x25_link_device_down(dev);
> >                         break;
>
> This patch might not be entirely necessary. x25_kill_by_neigh and
> x25_kill_by_device are just two helper functions. One function takes
> nb as the argument and the other one takes dev as the argument. But
> they do almost the same things. It doesn't harm to keep both. In C++
> we often have different functions with the same name doing almost the
> same things.

Well I don't like to have 2 functions doing the same thing.
But after another look at this code, I've found that I also need to
remove the call to x25_clear_forward_by_dev() in the function
x25_route_device_down(). Otherwise, it will be called twice.

> The original code also seems to be a little more efficient than the new 
> code.

The only difference would be the x25_get_neigh() and x25_neigh_put()
calls. That shouldn't cost to much.