From e66d99f3486c0d6b9e5dd05baaa98a75145bd6eb Mon Sep 17 00:00:00 2001
From: Gregory Thiemonge <gthiemon@redhat.com>
Date: Thu, 5 Oct 2023 11:13:57 -0400
Subject: [PATCH] Fix race condition in cascade delete

update_vip was called multiple times concurrently when cascade deleting
a load balancer with many listeners, it may trigger a race condition
when fetching, computing and updating the SGs.
Calling update_vip for each listener is not necessary, it's now called
only once, that fixes the race condition and optimize the delete flow.

Closes-Bug: #2038529
Change-Id: I4a6e4830d0e916b1af1a11dd10097980a57d97ea
Signed-off-by: Gregory Thiemonge <gthiemon@redhat.com>
(cherry picked from commit 5c802aad949e4abd878f326c53123ddf8a299be0)
---
 .../controller/worker/v2/flows/listener_flows.py    |  3 ---
 .../worker/v2/flows/load_balancer_flows.py          | 13 ++++++++++---
 ...nditions-in-cascade-delete-1e100213445a17ec.yaml |  7 +++++++
 3 files changed, 17 insertions(+), 6 deletions(-)
 create mode 100644 releasenotes/notes/fix-potential-race-conditions-in-cascade-delete-1e100213445a17ec.yaml

diff --git a/octavia/controller/worker/v2/flows/listener_flows.py b/octavia/controller/worker/v2/flows/listener_flows.py
index a25904e090..08198bfd4e 100644
--- a/octavia/controller/worker/v2/flows/listener_flows.py
+++ b/octavia/controller/worker/v2/flows/listener_flows.py
@@ -113,9 +113,6 @@ class ListenerFlows(object):
         delete_listener_flow = linear_flow.Flow(
             constants.DELETE_LISTENER_FLOW + '-' + listener_id)
         # Should cascade delete all L7 policies
-        delete_listener_flow.add(network_tasks.UpdateVIPForDelete(
-            name='delete_update_vip_' + listener_id,
-            requires=constants.LOADBALANCER_ID))
         delete_listener_flow.add(database_tasks.DeleteListenerInDB(
             name='delete_listener_in_db_' + listener_id,
             requires=constants.LISTENER,
diff --git a/octavia/controller/worker/v2/flows/load_balancer_flows.py b/octavia/controller/worker/v2/flows/load_balancer_flows.py
index eecd5d31cb..5d604ac5ba 100644
--- a/octavia/controller/worker/v2/flows/load_balancer_flows.py
+++ b/octavia/controller/worker/v2/flows/load_balancer_flows.py
@@ -292,12 +292,19 @@ class LoadBalancerFlows(object):
         :param listeners: A list of listener dicts
         :return: The flow for the deletion
         """
-        listeners_delete_flow = unordered_flow.Flow('listeners_delete_flow')
+        delete_listeners_flow = linear_flow.Flow('delete_listeners_flow')
+        delete_listeners_flow.add(network_tasks.UpdateVIPForDelete(
+            name='delete_update_vip',
+            requires=constants.LOADBALANCER_ID))
+
+        delete_internal_flow = unordered_flow.Flow('delete_listeners_flows')
         for listener in listeners:
-            listeners_delete_flow.add(
+            delete_internal_flow.add(
                 self.listener_flows.get_delete_listener_internal_flow(
                     listener, flavor_dict=flavor_dict))
-        return listeners_delete_flow
+
+        delete_listeners_flow.add(delete_internal_flow)
+        return delete_listeners_flow
 
     def get_delete_load_balancer_flow(self, lb):
         """Creates a flow to delete a load balancer.
diff --git a/releasenotes/notes/fix-potential-race-conditions-in-cascade-delete-1e100213445a17ec.yaml b/releasenotes/notes/fix-potential-race-conditions-in-cascade-delete-1e100213445a17ec.yaml
new file mode 100644
index 0000000000..c331511da2
--- /dev/null
+++ b/releasenotes/notes/fix-potential-race-conditions-in-cascade-delete-1e100213445a17ec.yaml
@@ -0,0 +1,7 @@
+---
+fixes:
+  - |
+    Fix a potential race condition during the cascade deletion of load
+    balancers. When deleting a load balancer with multiple listeners, the
+    security groups of the VIP port may have been updated many times
+    concurrently, creating a race condition.