Subject: Re: [PATCH net-next 1/1] net: neighbour: Simplify ifdefs around neigh_app_ns()

From: [email-masked] (Eric W. Biederman)
Date: Wed, 28 Aug 2013 18:32:19 -0700

Joe Perches <[email-masked]> writes:

> On Wed, 2013-08-28 at 13:09 -0600, Tim Gardner wrote:
>> On 08/28/2013 12:51 PM, Joe Perches wrote:
>> > On Wed, 2013-08-28 at 12:24 -0600, Tim Gardner wrote:
>> >> Drop a couple of ifdef/endif pairs by moving the ifdef
>> >> surrounding neigh_app_ns() to the interior of neigh_app_ns().
>> > []
>> >> This is an admittedly trivial change. I stumbled on it while trying to figure
>> >> out why Ubuntu doesn't have CONFIG_ARPD enabled.
>
>> > I'd be more inclined to make neigh_app_ns static inline
>> > in the .h file and remove the EXPORT_SYMBOL
>
>> I thought about that as well, but then you'd have to extern
>> __neigh_notify(), which is currently a static function and large enough
>> to not really be suitable for inlining. Seems like unnecessary churn to me.
>
> Hi Tim.
>
> As is, this makes the call to neight_app_ns
> impossible to optimize away.
>
> Perhaps this:
>
> (this does add a possibly unused neigh_notify as a global symbol)
>
> Rename __neigh_notify to neigh_notify and make public
> Add static inline neigh_app_ns
> Remove #ifdefs around use of neigh_app_ns

Again.  Why not just remove CONFIG_ARPD entirely?  A config option to
compile out a single line of code seems like a real waste.

Eric

> ---
>
> Compile tested only
>
>  include/net/neighbour.h | 10 +++++++++-
>  net/core/neighbour.c    | 15 +++------------
>  net/ipv4/arp.c          |  2 --
>  net/ipv6/ndisc.c        |  2 --
>  4 files changed, 12 insertions(+), 17 deletions(-)
>
> diff --git a/include/net/neighbour.h b/include/net/neighbour.h
> index 536501a..a08b0a7 100644
> --- a/include/net/neighbour.h
> +++ b/include/net/neighbour.h
> @@ -249,7 +249,15 @@ static inline struct net *pneigh_net(const struct pneigh_entry *pneigh)
>  	return read_pnet(&pneigh->net);
>  }
>  
> -void neigh_app_ns(struct neighbour *n);
> +void neigh_notify(struct neighbour *n, int type, int flags);
> +
> +static inline void neigh_app_ns(struct neighbour *n)
> +{
> +#ifdef CONFIG_ARPD
> +	neigh_notify(n, RTM_GETNEIGH, NLM_F_REQUEST);
> +#endif
> +}
> +
>  void neigh_for_each(struct neigh_table *tbl,
>  		    void (*cb)(struct neighbour *, void *), void *cookie);
>  void __neigh_for_each_release(struct neigh_table *tbl,
> diff --git a/net/core/neighbour.c b/net/core/neighbour.c
> index 60533db..6ec5f86 100644
> --- a/net/core/neighbour.c
> +++ b/net/core/neighbour.c
> @@ -50,7 +50,6 @@ do {						\
>  #define PNEIGH_HASHMASK		0xF
>  
>  static void neigh_timer_handler(unsigned long arg);
> -static void __neigh_notify(struct neighbour *n, int type, int flags);
>  static void neigh_update_notify(struct neighbour *neigh);
>  static int pneigh_ifdown(struct neigh_table *tbl, struct net_device *dev);
>  
> @@ -103,7 +102,7 @@ static void neigh_cleanup_and_release(struct neighbour *neigh)
>  	if (neigh->parms->neigh_cleanup)
>  		neigh->parms->neigh_cleanup(neigh);
>  
> -	__neigh_notify(neigh, RTM_DELNEIGH, 0);
> +	neigh_notify(neigh, RTM_DELNEIGH, 0);
>  	neigh_release(neigh);
>  }
>  
> @@ -2215,7 +2214,7 @@ nla_put_failure:
>  static void neigh_update_notify(struct neighbour *neigh)
>  {
>  	call_netevent_notifiers(NETEVENT_NEIGH_UPDATE, neigh);
> -	__neigh_notify(neigh, RTM_NEWNEIGH, 0);
> +	neigh_notify(neigh, RTM_NEWNEIGH, 0);
>  }
>  
>  static int neigh_dump_table(struct neigh_table *tbl, struct sk_buff *skb,
> @@ -2735,7 +2734,7 @@ static inline size_t neigh_nlmsg_size(void)
>  	       + nla_total_size(4); /* NDA_PROBES */
>  }
>  
> -static void __neigh_notify(struct neighbour *n, int type, int flags)
> +void neigh_notify(struct neighbour *n, int type, int flags)
>  {
>  	struct net *net = dev_net(n->dev);
>  	struct sk_buff *skb;
> @@ -2759,14 +2758,6 @@ errout:
>  		rtnl_set_sk_err(net, RTNLGRP_NEIGH, err);
>  }
>  
> -#ifdef CONFIG_ARPD
> -void neigh_app_ns(struct neighbour *n)
> -{
> -	__neigh_notify(n, RTM_GETNEIGH, NLM_F_REQUEST);
> -}
> -EXPORT_SYMBOL(neigh_app_ns);
> -#endif /* CONFIG_ARPD */
> -
>  #ifdef CONFIG_SYSCTL
>  static int zero;
>  static int int_max = INT_MAX;
> diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c
> index 4429b01..7808093 100644
> --- a/net/ipv4/arp.c
> +++ b/net/ipv4/arp.c
> @@ -368,9 +368,7 @@ static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb)
>  	} else {
>  		probes -= neigh->parms->app_probes;
>  		if (probes < 0) {
> -#ifdef CONFIG_ARPD
>  			neigh_app_ns(neigh);
> -#endif
>  			return;
>  		}
>  	}
> diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
> index 04d31c2..d5693ad 100644
> --- a/net/ipv6/ndisc.c
> +++ b/net/ipv6/ndisc.c
> @@ -663,9 +663,7 @@ static void ndisc_solicit(struct neighbour *neigh, struct sk_buff *skb)
>  		}
>  		ndisc_send_ns(dev, neigh, target, target, saddr);
>  	} else if ((probes -= neigh->parms->app_probes) < 0) {
> -#ifdef CONFIG_ARPD
>  		neigh_app_ns(neigh);
> -#endif
>  	} else {
>  		addrconf_addr_solict_mult(target, &mcaddr);
>  		ndisc_send_ns(dev, NULL, target, &mcaddr, saddr);