linux-kernel - Re: [PATCH net-next] rxrpc: Fix missing IPV6 #ifdef

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Date:   Thu, 10 Nov 2022 16:37:41 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     David Howells <dhowells@...hat.com>
Cc:     netdev@...r.kernel.org, kernel test robot <lkp@...el.com>,
        Marc Dionne <marc.dionne@...istor.com>,
        linux-afs@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next] rxrpc: Fix missing IPV6 #ifdef

On Thu, Nov 10, 2022 at 02:09:45PM +0000, David Howells wrote:
> Andrew Lunn <andrew@...n.ch> wrote:
> 
> > > +#ifdef CONFIG_AF_RXRPC_IPV6
> > >  	return ipv6_icmp_error(sk, skb, err, port, info, payload);
> > > +#endif
> > 
> > Can this be if (IS_ENABLED(CONFIG_AF_RXRPC_IPV6) {} rather than
> > #ifdef? It gives better build testing.
> 
> Sure.  Does it actually make that much of a difference?  I guess the
> declaration is there even if IPV6 is disabled.

And that is the point. Even if this feature is disabled, the type
checking will be performed, the number of parameters etc. Somebody who
modifies ipv6_icmp_error() is going to find problems with a single
compilation, rather than having to use a big collection of random
configs.

So this is a review comment i often make. Avoid #ifdef if you can, use
IS_ENABLED() inside an if statement.

	Andrew