From 9abdf580d910e13ade68cbb23da9b5d83b839f8d Mon Sep 17 00:00:00 2001
From: Felix Fietkau <nbd@openwrt.org>
Date: Thu, 26 Oct 2006 01:33:36 +0000
Subject: [PATCH] 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/lib/network/config.sh |  7 ++++++-
 package/base-files/default/sbin/ifdown           | 14 ++++++++++++--
 package/ppp/files/ppp.sh                         | 10 ++++++++--
 3 files changed, 26 insertions(+), 5 deletions(-)

diff --git a/package/base-files/default/lib/network/config.sh b/package/base-files/default/lib/network/config.sh
index 25c7278e99..9c91a7cabf 100755
--- a/package/base-files/default/lib/network/config.sh
+++ b/package/base-files/default/lib/network/config.sh
@@ -121,8 +121,12 @@ setup_interface() {
 		;;
 		dhcp)
 			# prevent udhcpc from starting more than once
+			lock "/var/lock/dhcp-$iface"
 			pid="$(cat "$pidfile" 2>/dev/null)"
-			[ -d "/proc/$pid" ] && grep udhcpc "/proc/${pid}/cmdline" >/dev/null 2>/dev/null && return 0
+			[ -d "/proc/$pid" ] && grep udhcpc "/proc/${pid}/cmdline" >/dev/null 2>/dev/null && {
+				lock -u "/var/lock/dhcp-$iface"
+				return 0
+			}
 
 			config_get ipaddr "$config" ipaddr
 			config_get netmask "$config" netmask
@@ -135,6 +139,7 @@ setup_interface() {
 			# don't stay running in background if dhcp is not the main proto on the interface (e.g. when using pptp)
 			[ "$proto1" != "$proto" ] && dhcpopts="-n -q"
 			$DEBUG udhcpc -i "$iface" ${ipaddr:+-r $ipaddr} ${hostname:+-H $hostname} -b -p "$pidfile" ${dhcpopts:- -R &}
+			lock -u "/var/lock/dhcp-$iface"
 		;;
 		*)
 			if ( eval "type setup_interface_$proto" ) >/dev/null 2>/dev/null; then
diff --git a/package/base-files/default/sbin/ifdown b/package/base-files/default/sbin/ifdown
index 37d0918e85..50d59d1df8 100755
--- a/package/base-files/default/sbin/ifdown
+++ b/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
diff --git a/package/ppp/files/ppp.sh b/package/ppp/files/ppp.sh
index 133400509c..35572a0a0d 100644
--- a/package/ppp/files/ppp.sh
+++ b/package/ppp/files/ppp.sh
@@ -7,10 +7,14 @@ scan_ppp() {
 
 start_pppd() {
 	local cfg="$1"; shift
-	
+
 	# make sure only one pppd process is started
+	lock "/var/lock/ppp-${cfg}"
 	local pid="$(cat /var/run/ppp-${cfg}.pid 2>/dev/null)"
-	[ -d "/proc/$pid" ] && grep pppd "/proc/$pid/cmdline" 2>/dev/null >/dev/null && return 0
+	[ -d "/proc/$pid" ] && grep pppd "/proc/$pid/cmdline" 2>/dev/null >/dev/null && {
+		lock -u "/var/lock/ppp-${cfg}"
+		return 0
+	}
 
 	config_get device "$cfg" device
 	config_get unit "$cfg" unit
@@ -31,4 +35,6 @@ start_pppd() {
 		${username:+user "$username" password "$password"} \
 		linkname "$cfg" \
 		ipparam "$cfg"
+
+	lock -u "/var/lock/ppp-${cfg}"
 }