[IPV4] ipconfig: Fix regression in ip command line processing

The recent changes for ip command line processing fixed some problems
but unfortunately broke some common usage scenarios.  In current
2.6.24-rc6 the following command line results in no IP address
assignment, which is surely a regression:

 ip=10.0.2.15::10.0.2.2:255.255.255.0::eth0:off

Please find below a patch that works for all cases I can find.

Signed-off-by: Amos Waterland <apw@us.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/nfsroot.txt

@@ -145,6 +145,7 @@ ip=<client-ip>:<server-ip>:<gw-ip>:<netmask>:<hostname>:<device>:<autoconf>
 		this option.
 
                   off or none: don't use autoconfiguration
+				(do static IP assignment instead)
 		  on or any:   use any protocol available in the kernel
 			       (default)
 		  dhcp:        use DHCP

net/ipv4/ipconfig.c

@@ -1404,8 +1404,7 @@ static int __init ic_proto_name(char *name)
 		return 1;
 	}
 	if (!strcmp(name, "off") || !strcmp(name, "none")) {
-		ic_enable = 0;
-		return 1;
+		return 0;
 	}
 #ifdef CONFIG_IP_PNP_DHCP
 	else if (!strcmp(name, "dhcp")) {
@@ -1442,10 +1441,22 @@ static int __init ip_auto_config_setup(char *addrs)
 	ic_set_manually = 1;
 	ic_enable = 1;
 
+	/*
+	 * If any dhcp, bootp etc options are set, leave autoconfig on
+	 * and skip the below static IP processing.
+	 */
 	if (ic_proto_name(addrs))
 		return 1;
 
-	/* Parse the whole string */
+	/* If no static IP is given, turn off autoconfig and bail.  */
+	if (*addrs == 0 ||
+	    strcmp(addrs, "off") == 0 ||
+	    strcmp(addrs, "none") == 0) {
+		ic_enable = 0;
+		return 1;
+	}
+
+	/* Parse string for static IP assignment.  */
 	ip = addrs;
 	while (ip && *ip) {
 		if ((cp = strchr(ip, ':')))
@@ -1483,7 +1494,10 @@ static int __init ip_auto_config_setup(char *addrs)
 				strlcpy(user_dev_name, ip, sizeof(user_dev_name));
 				break;
 			case 6:
-				ic_proto_name(ip);
+				if (ic_proto_name(ip) == 0 &&
+				    ic_myaddr == NONE) {
+					ic_enable = 0;
+				}
 				break;
 			}
 		}