qemu-kvm/kvm-migration-Consolidate-return-path-closing-code.patch

From 33f0f63da753fff2a3d2bf14542abe0665878e3d Mon Sep 17 00:00:00 2001
From: Fabiano Rosas <farosas@suse.de>
Date: Mon, 18 Sep 2023 14:28:20 -0300
Subject: [PATCH 06/13] migration: Consolidate return path closing code
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RH-Author: Peter Xu <peterx@redhat.com>
RH-MergeRequest: 203: migration: Fix race that dest preempt thread close too early
RH-Jira: RHEL-11219
RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>
RH-Acked-by: Leonardo Brás <leobras@redhat.com>
RH-Commit: [6/8] d3a4e08e1f1afe92afac12a3404a84d1c23e0f02 (peterx/qemu-kvm)

We'll start calling the await_return_path_close_on_source() function
from other parts of the code, so move all of the related checks and
tracepoints into it.

Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20230918172822.19052-7-farosas@suse.de>
(cherry picked from commit d50f5dc075cbb891bfe4a9378600a4871264468a)
Signed-off-by: Peter Xu <peterx@redhat.com>
---
 migration/migration.c | 29 ++++++++++++++---------------
 1 file changed, 14 insertions(+), 15 deletions(-)

diff --git a/migration/migration.c b/migration/migration.c
index e2e4a7d8ae..ac4541b971 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -2050,6 +2050,14 @@ static int open_return_path_on_source(MigrationState *ms,
 /* Returns 0 if the RP was ok, otherwise there was an error on the RP */
 static int await_return_path_close_on_source(MigrationState *ms)
 {
+    int ret;
+
+    if (!ms->rp_state.rp_thread_created) {
+        return 0;
+    }
+
+    trace_migration_return_path_end_before();
+
     /*
      * If this is a normal exit then the destination will send a SHUT
      * and the rp_thread will exit, however if there's an error we
@@ -2067,7 +2075,10 @@ static int await_return_path_close_on_source(MigrationState *ms)
     qemu_thread_join(&ms->rp_state.rp_thread);
     ms->rp_state.rp_thread_created = false;
     trace_await_return_path_close_on_source_close();
-    return ms->rp_state.error;
+
+    ret = ms->rp_state.error;
+    trace_migration_return_path_end_after(ret);
+    return ret;
 }
 
 static inline void
@@ -2363,20 +2374,8 @@ static void migration_completion(MigrationState *s)
         goto fail;
     }
 
-    /*
-     * If rp was opened we must clean up the thread before
-     * cleaning everything else up (since if there are no failures
-     * it will wait for the destination to send it's status in
-     * a SHUT command).
-     */
-    if (s->rp_state.rp_thread_created) {
-        int rp_error;
-        trace_migration_return_path_end_before();
-        rp_error = await_return_path_close_on_source(s);
-        trace_migration_return_path_end_after(rp_error);
-        if (rp_error) {
-            goto fail;
-        }
+    if (await_return_path_close_on_source(s)) {
+        goto fail;
     }
 
     if (qemu_file_get_error(s->to_dst_file)) {
-- 
2.39.3