From 2aa1b789b437fd92b314c8a5adcef827d6499951 Mon Sep 17 00:00:00 2001
From: David Gibson <david@gibson.dropbear.id.au>
Date: Thu, 27 Feb 2025 16:55:13 +1100
Subject: [PATCH] migrate, flow: Trivially succeed if migrating with no flows
We could get a migration request when we have no active flows; or at least
none that we need or are able to migrate. In this case after sending or
receiving the number of flows we continue to step through various lists.
In the target case, this could include communication with passt-repair. If
passt-repair wasn't started that could cause further errors, but of course
they shouldn't matter if we have nothing to repair.
Make it more obvious that there's nothing to do and avoid such errors by
short-circuiting flow_migrate_{source,target}() if there are no migratable
flows.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
---
flow.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/flow.c b/flow.c
index cc881e8..b187dff 100644
--- a/flow.c
+++ b/flow.c
@@ -1019,6 +1019,9 @@ int flow_migrate_source(struct ctx *c, const struct migrate_stage *stage,
debug("Sending %u flows", ntohl(count));
+ if (!count)
+ return 0;
+
/* Dump and send information that can be stored in the flow table.
*
* Limited rollback options here: if we fail to transfer any data (that
@@ -1088,6 +1091,9 @@ int flow_migrate_target(struct ctx *c, const struct migrate_stage *stage,
count = ntohl(count);
debug("Receiving %u flows", count);
+ if (!count)
+ return 0;
+
if ((rc = flow_migrate_repair_all(c, true)))
return -rc;