File xen-3.4.0-hotplug-locking-rhel.patch of Package xen

--- xen-3.4.0.orig/tools/hotplug/Linux/locking.sh	2009-05-18 13:05:38.000000000 +0200
+++ xen-3.4.0/tools/hotplug/Linux/locking.sh	2009-05-23 14:39:07.000000000 +0200
@@ -1,5 +1,6 @@
 #
 # Copyright (c) 2005 XenSource Ltd.
+# Copyright (c) 2007 Red Hat
 #
 # This library is free software; you can redistribute it and/or
 # modify it under the terms of version 2.1 of the GNU Lesser General Public
@@ -19,80 +20,30 @@
 # Serialisation
 #
 
-LOCK_SLEEPTIME=1
-LOCK_SPINNING_RETRIES=5
-LOCK_RETRIES=100
 LOCK_BASEDIR=/var/run/xen-hotplug
 
-
-claim_lock()
-{
-  local lockdir="$LOCK_BASEDIR/$1"
-  mkdir -p "$LOCK_BASEDIR"
-  _claim_lock "$lockdir"
-}
-
-
-release_lock()
-{
-  _release_lock "$LOCK_BASEDIR/$1"
-}
-
-
-_claim_lock()
+_setlockfd()
 {
-  local lockdir="$1"
-  local owner=$(_lock_owner "$lockdir")
-  local retries=0
-
-  while [ $retries -lt $LOCK_RETRIES ]
-  do
-    mkdir "$lockdir" 2>/dev/null && trap "release_lock $1; sigerr" ERR &&
-      _update_lock_info "$lockdir" && return
-
-    local new_owner=$(_lock_owner "$lockdir")
-    if [ "$new_owner" != "$owner" ]
-    then
-      owner="$new_owner"
-      retries=0
-    fi
-
-    if [ $retries -gt $LOCK_SPINNING_RETRIES ]
-    then
-      sleep $LOCK_SLEEPTIME
-    else
-      sleep 0
-    fi
-    retries=$(($retries + 1))
-  done
-  _steal_lock "$lockdir"
+    local i
+    for ((i = 0; i < ${#_lockdict}; i++))
+    do [ -z "${_lockdict[$i]}" -o "${_lockdict[$i]}" = "$1" ] && break
+    done
+    _lockdict[$i]="$1"
+    let _lockfd=200+i
 }
 
 
-_release_lock()
-{
-  trap sigerr ERR
-  rm -rf "$1" 2>/dev/null || true
-}
-
-
-_steal_lock()
-{
-  local lockdir="$1"
-  local owner=$(cat "$lockdir/owner" 2>/dev/null || echo "unknown")
-  log err "Forced to steal lock on $lockdir from $owner!"
-  _release_lock "$lockdir"
-  _claim_lock "$lockdir"
-}
-
-
-_lock_owner()
+claim_lock()
 {
-  cat "$1/owner" 2>/dev/null || echo "unknown"
+    mkdir -p "$LOCK_BASEDIR"
+    _setlockfd $1
+    eval "exec $_lockfd>>$LOCK_BASEDIR/$1"
+    flock -x $_lockfd
 }
 
 
-_update_lock_info()
+release_lock()
 {
-  echo "$$: $0" >"$1/owner"
+    _setlockfd $1
+    flock -u $_lockfd
 }