migration: Fix possible race when setting rp_state.error

We don't need to set the rp_state.error right after a shutdown because
qemu_file_shutdown() always sets the QEMUFile error, so the return
path thread would have seen it and set the rp error itself.

Setting the error outside of the thread is also racy because the
thread could clear it after we set 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: <20230918172822.19052-3-farosas@suse.de>
(cherry picked from commit 28a8347281e24c2e7bba6d3301472eda41d4c096)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

diff --git a/migration/migration.c b/migration/migration.c
index 6a7122694a88f07ee9890b8258a7d63a72246d58..b92c6ae436dad5192e8359f6c1275f69b329cdfb 100644 (file)
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -2063,7 +2063,6 @@ static int await_return_path_close_on_source(MigrationState *ms)
          * waiting for the destination.
          */
         qemu_file_shutdown(ms->rp_state.from_dst_file);
-        mark_source_rp_bad(ms);
     }
     trace_await_return_path_close_on_source_joining();
     qemu_thread_join(&ms->rp_state.rp_thread);