afexists()

[Doug Barton]

I don't have any specific objections to this change, although adding 
more calls to afexists() highlights an issue I addressed previously in 
looking at network.subr. On my system (with IPv6) it's called over 25 
times at each boot, which given that it's a moderately expensive test 
indicates an opportunity for optimization.

Attached is a patch which caches a positive result for support for a 
given address family. I don't think caching negative results is a good 
idea since that could change as the boot progresses.

I plan to commit this on Friday if there are no objections.


Doug


-------- Original Message --------
Subject: svn commit: r222515 - in head/etc: . defaults
Date: Tue, 31 May 2011 00:25:52 +0000 (UTC)
From: Bjoern A. Zeeb <bz at FreeBSD.org>
To: src-committers at freebsd.org, svn-src-all at freebsd.org, 
svn-src-head at freebsd.org

Author: bz
Date: Tue May 31 00:25:52 2011
New Revision: 222515
URL: http://svn.freebsd.org/changeset/base/222515

Log:
   No logner set an IPv4 loopback address by default in defaults/rc.conf.
   If not specified, network.subr will add it automatically if we have
   INET support (1).

   In network.subr only call the address family up/down functions
   if the respective AF is available.

   Switch to new kern.features variables for inet and inet6 as the
   inet sysctl tree is also available for IPv6-only kernels leading
   to unexpected results.

   Suggested by:	hrs (1)
   Reviewed by:	hrs
   Sponsored by:	The FreeBSD Foundation
   Sponsored by:	iXsystems
   MFC after:	20 days

Modified:
   head/etc/defaults/rc.conf
   head/etc/network.subr
	
-------------- next part --------------
Index: network.subr
===================================================================
--- network.subr	(revision 222515)
+++ network.subr	(working copy)
@@ -351,22 +351,35 @@
 #	1 otherwise.
 afexists()
 {
-	local _af
-	_af=$1
-
-	case ${_af} in
+	case "$1" in
 	inet)
-		${SYSCTL_N} kern.features.inet > /dev/null 2>&1
+		[ -n "$afexists_inet" ] && return 0
+		if ${SYSCTL_N} kern.features.inet > /dev/null 2>&1; then
+			afexists_inet=afexists_inet
+			return 0
+		fi
 		;;
 	inet6)
-		${SYSCTL_N} kern.features.inet6 > /dev/null 2>&1
+		[ -n "$afexists_inet6" ] && return 0
+		if ${SYSCTL_N} kern.features.inet6 > /dev/null 2>&1; then
+			afexists_inet6=afexists_inet6
+			return 0
+		fi
 		;;
 	ipx)
-		${SYSCTL_N} net.ipx > /dev/null 2>&1
+		[ -n "$afexists_ipx" ] && return 0
+		if ${SYSCTL_N} net.ipx > /dev/null 2>&1; then
+			afexists_ipx=afexists_ipx
+			return 0
+		fi
 		;;
 	atm)
+		[ -n "$afexists_atm" ] && return 0
 		if [ -x /sbin/atmconfig ]; then
-			/sbin/atmconfig diag list > /dev/null 2>&1
+			if /sbin/atmconfig diag list > /dev/null 2>&1; then
+				afexists_atm=afexists_atm
+				return 0
+			fi
 		else
 			return 1
 		fi