ovs-lib: Keep internal interface ip during upgrade.

Commit 9b5422a("ovs-lib: Try to call exit before killing.")
introduced a problem where internal interfaces are destroyed and
recreated, losing their IP address.

Commit 9aad5a5("ovs-vswitchd: Preserve datapath ports across
graceful shutdown.") fixed the problem by changing ovs-vswitchd
to preserve the ports on `ovs-appctl exit`.  Unfortunately, this fix is
not enough during upgrade from <= 2.5.0, where an old ovs-vswitchd is
running (without the fix) and a new ovs-lib script is performing the
restart.

The problem seem to affect both RHEL and ubuntu.

This commit fixes the upgrade by looking at the running daemon
version and avoid using `ovs-appctl exit` if it's < 2.5.90.

Suggested-by: Gurucharan Shetty <[email protected]>
Signed-off-by: Daniele Di Proietto <[email protected]>
Acked-by: Gurucharan Shetty <[email protected]>
Acked-by: Ben Pfaff <[email protected]>

utilities/ovs-lib.in

@@ -132,6 +132,22 @@ pid_comm_check () {
     [ "$1" = "`cat /proc/$2/comm`" ]
 }
 
+# version_geq version_a version_b
+#
+# Compare (dot separated) version numbers.  Returns true (exit code 0) if
+# version_a is greater or equal than version_b, otherwise false (exit code 1).
+version_geq() {
+    echo $1 $2 | awk '{
+        n1 = split($1, a, ".");
+        n2 = split($2, b, ".");
+        n = (n1 > n2) ? n1 : n2;
+        for (i = 1; i <= n; i++) {
+            if (a[i]+0 < b[i]+0) exit 1
+            if (a[i]+0 > b[i]+0) exit 0
+        }
+    }'
+}
+
 start_daemon () {
     priority=$1
     wrapper=$2
@@ -202,10 +218,23 @@ start_daemon () {
 stop_daemon () {
     if test -e "$rundir/$1.pid"; then
         if pid=`cat "$rundir/$1.pid"`; then
-            for action in EXIT .1 .25 .65 1 \
-                          TERM .1 .25 .65 1 1 1 1 \
-                          KILL 1 1 1 2 10 15 30 \
-                          FAIL; do
+
+            graceful="EXIT .1 .25 .65 1"
+            actions="TERM .1 .25 .65 1 1 1 1 \
+                     KILL 1 1 1 2 10 15 30 \
+                     FAIL"
+            version=`ovs-appctl -T 1 -t $rundir/$1.$pid.ctl version \
+                     | awk 'NR==1{print $NF}'`
+
+            # Use `ovs-appctl exit` only if the running daemon version
+            # is >= 2.5.90.  This script might be used during upgrade to
+            # stop older versions of daemons which do not behave correctly
+            # with `ovs-appctl exit` (e.g. ovs-vswitchd <= 2.5.0 deletes
+            # internal ports).
+            if version_geq "$version" "2.5.90"; then
+                actions="$graceful $actions"
+            fi
+            for action in $actions; do
                 if pid_exists "$pid" >/dev/null 2>&1; then :; else
                     return 0
                 fi