netdev - Re: [Patch net-next 1/2] ping: some cleanup for net/ipv4/ping.c

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Message-ID: <1370243586.32297.5.camel@cr0>
Date:	Mon, 03 Jun 2013 15:13:06 +0800
From:	Cong Wang <amwang@...hat.com>
To:	Lorenzo Colitti <lorenzo@...gle.com>
Cc:	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"David S. Miller" <davem@...emloft.net>
Subject: Re: [Patch net-next 1/2] ping: some cleanup for net/ipv4/ping.c

On Mon, 2013-06-03 at 16:02 +0900, Lorenzo Colitti wrote:
> On Mon, Jun 3, 2013 at 2:55 PM, Cong Wang <amwang@...hat.com> wrote:
> > -static inline int ping_supported(int family, int type, int code)
> > +static inline bool ping_supported(int family, int type, int code)
> >  {
> > -       return (family == AF_INET && type == ICMP_ECHO && code == 0) ||
> > -              (family == AF_INET6 && type == ICMPV6_ECHO_REQUEST && code == 0);
> > +       if (family == AF_INET) {
> > +               if (type == ICMP_ECHO && code == 0)
> > +                       return true;
> > +#if IS_ENABLED(CONFIG_IPV6)
> > +       } else if (family == AF_INET6) {
> > +               if (type == ICMPV6_ECHO_REQUEST && code == 0)
> > +                       return true;
> > +#endif
> > +       }
> > +       return false;
> >  }
> 
> I don't think it's necessary to #ifdef out code here. It's not needed
> to get the code to compile, because AF_INET6 and ICMPV6_ECHO_REQUEST
> are defined even if CONFIG_IPV6=n. It's also not necessary at runtime,
> because if we get here with family = AF_INET6 even though IPv6 is
> disabled, then then there's already a problem. Adding the ifdef also
> makes the function much hard to read.

Remember it is a cleanup, not a bug fix, right? :) I don't think there
is any way to make this 10- line of code hard to read.

> 
> >
> >  /*
> > @@ -472,11 +480,13 @@ void ping_err(struct sk_buff *skb, int offset, u32 info)
> >                 type = icmp_hdr(skb)->type;
> >                 code = icmp_hdr(skb)->code;
> >                 icmph = (struct icmphdr *)(skb->data + offset);
> > +#if IS_ENABLED(CONFIG_IPV6)
> >         } else if (skb->protocol == htons(ETH_P_IPV6)) {
> >                 family = AF_INET6;
> >                 type = icmp6_hdr(skb)->icmp6_type;
> >                 code = icmp6_hdr(skb)->icmp6_code;
> >                 icmph = (struct icmphdr *) (skb->data + offset);
> > +#endif
> >         } else {
> >                 BUG();
> >         }
> 
> I think this is unnecessary too. ping_err is only called by icmp_err
> and by icmpv6_err, and if icmp_err is calling us on an IPv4 packet, or
> if icmpv6_err is calling us when IPv6 is unloaded, then there are
> bigger problems.

Again, it is just a clean up.


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