From 3ed4ede17d8ab1da9b74e623523fbe3e7b2f38e8 Mon Sep 17 00:00:00 2001
From: Jan Orel <jorel@opennebula.systems>
Date: Fri, 18 Jan 2019 15:44:44 +0100
Subject: [PATCH] B #2629 Prevent race-condition when spawning multiple VMs

---
 src/mad/ruby/scripts_common.rb              | 4 ++--
 src/vnm_mad/remotes/ovswitch/OpenvSwitch.rb | 2 +-
 src/vnm_mad/remotes/vxlan/vxlan.rb          | 4 +++-
 3 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/src/mad/ruby/scripts_common.rb b/src/mad/ruby/scripts_common.rb
index 29642ffd25..4381299a9b 100644
--- a/src/mad/ruby/scripts_common.rb
+++ b/src/mad/ruby/scripts_common.rb
@@ -75,11 +75,11 @@ module OpenNebula
     # Executes a command, if it fails returns error message and exits
     # If a second parameter is present it is used as the error message when
     # the command fails
-    def self.exec_and_log(command, message=nil)
+    def self.exec_and_log(command, message=nil, allowed_return_code=0)
         output=`#{command} 2>&1 1>/dev/null`
         code=$?.exitstatus
 
-        if code!=0
+        if code!=0 && code!=allowed_return_code
             log_error "Command \"#{command}\" failed."
             log_error output
             if !message
diff --git a/src/vnm_mad/remotes/ovswitch/OpenvSwitch.rb b/src/vnm_mad/remotes/ovswitch/OpenvSwitch.rb
index 33ed662ff3..1bd32f253e 100644
--- a/src/vnm_mad/remotes/ovswitch/OpenvSwitch.rb
+++ b/src/vnm_mad/remotes/ovswitch/OpenvSwitch.rb
@@ -391,7 +391,7 @@ private
     def create_bridge
         return if @bridges.keys.include? @nic[:bridge]
 
-        OpenNebula.exec_and_log("#{command(:ovs_vsctl)} add-br #{@nic[:bridge]}")
+        OpenNebula.exec_and_log("#{command(:ovs_vsctl)} --may-exist add-br #{@nic[:bridge]}")
 
         set_bridge_options
 
diff --git a/src/vnm_mad/remotes/vxlan/vxlan.rb b/src/vnm_mad/remotes/vxlan/vxlan.rb
index a74f026d6c..1c67d467e4 100644
--- a/src/vnm_mad/remotes/vxlan/vxlan.rb
+++ b/src/vnm_mad/remotes/vxlan/vxlan.rb
@@ -65,9 +65,11 @@ module VXLAN
             ip_link_conf << "#{option} #{value} "
         end
 
+        # `ip link add ...` returns 2 when vxlan device already exists
+        # allow it to prevent race conditions
         OpenNebula.exec_and_log("#{command(:ip)} link add #{@nic[@attr_vlan_dev]}"\
             " #{mtu} type vxlan id #{@nic[@attr_vlan_id]} #{group} #{ttl}"\
-            " #{tep} #{ip_link_conf}")
+            " #{tep} #{ip_link_conf}", nil, 2)
 
         OpenNebula.exec_and_log("#{command(:ip)} link set #{@nic[@attr_vlan_dev]} up")
     end