Re: [PATCH] can: Use common error handling code in vxcan_newlink()

[Oliver Hartkopp]

On 10/28/2017 10:23 AM, SF Markus Elfring wrote:
> > > @@ -227,10 +227,8 @@ static int vxcan_newlink(struct net *net, struct net_device *dev,
> > >  ÂÂÂÂÂ netif_carrier_off(peer);
> > >  Â ÂÂÂÂÂ err = rtnl_configure_link(peer, ifmp);
> > > -ÂÂÂ if (err < 0) {
> > > -ÂÂÂÂÂÂÂ unregister_netdevice(peer);
> > > -ÂÂÂÂÂÂÂ return err;
> > > -ÂÂÂ }
> > > +ÂÂÂ if (err)
> > > +ÂÂÂÂÂÂÂ goto unregister_network_device;
> >
> > You are changing semantic in the if-statement here.
>
> I got an other software development opinion for this implementation detail.
>
> http://elixir.free-electrons.com/linux/v4.14-rc6/source/net/core/rtnetlink.c#L2393
> https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/net/core/rtnetlink.c?id=36ef71cae353f88fd6e095e2aaa3e5953af1685d#n2513
>
> The success predicate for the function ârtnl_configure_linkâ is that
> the return value is zero. I would prefer to treat other values as
> an error code then.

Me not.

In rtnl_configure_link() the check is

	if (err < 0)
		return err;

And other calling sites as in linux/drivers/net/veth.c are checking for

	(err < 0)

too.

All checks done at the calling sites should be consistent.

So if you would like to change the if-statement:

1. Send a patch for vxcan.c to improve the error handling flow
2. Send a separate patch for all rtnl_configure_link() callers to unify 
the result check

Step 2 is optional ... and prepare yourself for more feedback ;-)

Regards,
Oliver