Subject: Re: [PATCH] ipv6: xfrm6: fix dubious code

From: Steffen Klassert <[email-masked]>
Date: Tue, 24 May 2011 07:02:42 +0200

On Mon, May 23, 2011 at 04:33:02PM -0400, David Miller wrote:
> From: Ben Hutchings <[email-masked]>
> Date: Mon, 23 May 2011 08:36:00 -0700
> 
> > On Mon, 2011-05-23 at 10:42 +0200, Eric Dumazet wrote:
> >> net/ipv6/xfrm6_tunnel.c: In function ‘xfrm6_tunnel_rcv’:
> >> net/ipv6/xfrm6_tunnel.c:244:53: warning: the omitted middle operand
> >> in ?: will always be ‘true’, suggest explicit middle operand
> >> 
> >> Signed-off-by: Eric Dumazet <[email-masked]>
> >> ---
> >>  net/ipv6/xfrm6_tunnel.c |    2 +-
> >>  1 file changed, 1 insertion(+), 1 deletion(-)
> >> 
> >> diff --git a/net/ipv6/xfrm6_tunnel.c b/net/ipv6/xfrm6_tunnel.c
> >> index a6770a0..fb9b0c3 100644
> >> --- a/net/ipv6/xfrm6_tunnel.c
> >> +++ b/net/ipv6/xfrm6_tunnel.c
> >> @@ -241,7 +241,7 @@ static int xfrm6_tunnel_rcv(struct sk_buff *skb)
> >>  	__be32 spi;
> >>  
> >>  	spi = xfrm6_tunnel_spi_lookup(net, (const xfrm_address_t *)&iph->saddr);
> >> -	return xfrm6_rcv_spi(skb, IPPROTO_IPV6, spi) > 0 ? : 0;
> >> +	return xfrm6_rcv_spi(skb, IPPROTO_IPV6, spi) > 0 ? 1 : 0;
> >>  }
> >>  
> >>  static int xfrm6_tunnel_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
> > 
> > I suspect that this was intended to return the result of xfrm6_rcv_spi()
> > if > 0.
> 
> I also suspect this was the intent, but I'm not sure why it matters
> at all.
> 
> The equivalent code implementing the same operations on the ipv4
> side return xfrm4_rcv_spi()'s return value directly.
> 
> So we need to either decide that we can do the same thing here on the
> ipv6 side, or document exactly why we can't.

I think we can return the value directly like ipv4 does it. xfrm6_rcv_spi()
returns the return value of xfrm_input() which returns 0 in any case.