Re: [PATCH 1/2] migration: Add a file_error argument to close_return_path_on_source()

[Cédric Le Goater]

On 2/2/24 15:30, Fabiano Rosas wrote:

Cédric Le Goater <c...@redhat.com> writes:

close_return_path_on_source() retrieves the migration error from the
the QEMUFile '->to_dst_file' to know if a shutdown is required to exit
the return-path thread. However, in migrate_fd_cleanup(), '->to_dst_file'
is cleaned up before calling close_return_path_on_source() and the
shutdown is never performed, leaving the source and destination
waiting for an event to occur.

Isn't this just missing qemu_file_shutdown() at migrate_fd_cleanup?

     if (s->to_dst_file) {
         ...
         migration_ioc_unregister_yank_from_file(tmp);
+       qemu_file_shutdown(tmp);
         qemu_fclose(tmp);
     }

That would make the return-path thread exit indeed. It should not
be necessary when there are no errors though and this is done
outside of the close_return_path_on_source() helper. There could
be side effects.


I took into account Peter's comment and replaced the changes of
PATCH 1 with :

@@ -2372,8 +2372,7 @@ static bool close_return_path_on_source(
      * cause it to unblock if it's stuck waiting for the destination.
      */
     WITH_QEMU_LOCK_GUARD(&ms->qemu_file_lock) {
-        if (ms->to_dst_file && ms->rp_state.from_dst_file &&
-            qemu_file_get_error(ms->to_dst_file)) {
+        if (migrate_has_error(ms) && ms->rp_state.from_dst_file) {
             qemu_file_shutdown(ms->rp_state.from_dst_file);
         }
     }

Nevertheless, we need to qemu_file_shutdown() correctly the socket
for this to work and the problem seems more complex than just moving
code as I did in PATCH 2.

Thanks,

C.