From 969d2f855d7312c3b1745566f4635331cb0bfa60 Mon Sep 17 00:00:00 2001
From: Sebastian Eydam <sebastian.eydam@cyberus-technology.de>
Date: Wed, 25 Mar 2026 15:12:33 +0100
Subject: [PATCH] vm-migration: stop sending abandon after error response

When the receiver of a live migration encounters an error, it sends an
error response. The sender of the migration would then send an abandon
request and wait for a response. This abandon request is not necessary,
because the receiver already abandoned the migration due to the error it
encountered.

From now on this function will not send an abandon request to the
receiver anymore, thus it was renamed to "ok_or_error".

Also, this case was always broken, because after sending the error
response, the receiver just exits without waiting for the additional
abandon request.

On-behalf-of: SAP sebastian.eydam@sap.com
Signed-off-by: Sebastian Eydam <sebastian.eydam@cyberus-technology.de>
---
 vm-migration/src/protocol.rs   | 12 ++----------
 vmm/src/migration/transport.rs |  4 +---
 vmm/src/vm.rs                  |  7 +++----
 3 files changed, 6 insertions(+), 17 deletions(-)

diff --git a/vm-migration/src/protocol.rs b/vm-migration/src/protocol.rs
index ae6836d98..fac7c5cc5 100644
--- a/vm-migration/src/protocol.rs
+++ b/vm-migration/src/protocol.rs
@@ -362,17 +362,9 @@ impl Response {
         })
     }
 
-    pub fn ok_or_abandon<T>(
-        self,
-        fd: &mut T,
-        error: MigratableError,
-    ) -> Result<Response, MigratableError>
-    where
-        T: Read + Write,
-    {
+    /// Return the response if its status is `Ok`; return the caller-provided error for any other status.
+    pub fn ok_or_error(self, error: MigratableError) -> Result<Response, MigratableError> {
         if self.status != Status::Ok {
-            Request::abandon().write_to(fd)?;
-            Response::read_from(fd)?;
             return Err(error);
         }
         Ok(self)
diff --git a/vmm/src/migration/transport.rs b/vmm/src/migration/transport.rs
index f5f490b29..cadec0a46 100644
--- a/vmm/src/migration/transport.rs
+++ b/vmm/src/migration/transport.rs
@@ -1115,9 +1115,7 @@ pub(crate) fn expect_ok_response(
     socket: &mut SocketStream,
     error: MigratableError,
 ) -> Result<(), MigratableError> {
-    Response::read_from(socket)?
-        .ok_or_abandon(socket, error)
-        .map(|_| ())
+    Response::read_from(socket)?.ok_or_error(error).map(|_| ())
 }
 
 /// Send a request and validate that the peer responds with OK.
diff --git a/vmm/src/vm.rs b/vmm/src/vm.rs
index 71b9363cf..ba60357fe 100644
--- a/vmm/src/vm.rs
+++ b/vmm/src/vm.rs
@@ -3026,10 +3026,9 @@ impl Vm {
                 .context("Error sending memory fd")
                 .map_err(MigratableError::MigrateSend)?;
 
-            Response::read_from(socket)?.ok_or_abandon(
-                socket,
-                MigratableError::MigrateSend(anyhow!("Error during memory fd migration")),
-            )?;
+            Response::read_from(socket)?.ok_or_error(MigratableError::MigrateSend(anyhow!(
+                "Error during memory fd migration"
+            )))?;
         }
 
         Ok(())