use lock to remove race conditions in bringing up ppp and dhcp that would lead to multiple active processes

SVN-Revision: 5298

package/base-files/default/sbin/ifdown

@@ -12,14 +12,24 @@ debug "### ifdown $cfg ###"
 config_get proto "$cfg" proto
 [ -z "$proto" ] && { echo "interface not found."; exit; }
 
+# make sure all locks are removed
+for lock in "/var/lock/dhcp-$iface" "/var/lock/ppp-$iface"; do
+	[ -f "$lock" ] && {
+		lock -u "$lock"
+		sleep 1
+	}
+done
+
 # kill active ppp daemon and other processes
 config_get ifname "$cfg" ifname
 pids="$(cat /var/run/${ifname}.pid /var/run/ppp-${cfg}.pid 2>/dev/null)"
 for pid in $pids; do 
 	[ -d "/proc/$pid" ] && {
 		kill $pid
-		sleep 1
-		[ -d "/proc/$pid" ] && kill -9 $pid
+		[ -d "/proc/$pid" ] && {
+			sleep 1
+			kill -9 $pid 2>/dev/null >/dev/null
+		}
 	}
 done
 rm -f /var/run/${ifname}.pid /var/run/ppp-${cfg}.pid