migration: Add cleanup hook for inwards migration

Add a cleanup hook for incoming migration that gets called
at the end as a way for a transport to allow cleanup.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20210421112834.107651-4-dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

migration/migration.c

@@ -280,6 +280,9 @@ void migration_incoming_state_destroy(void)
         g_array_free(mis->postcopy_remote_fds, TRUE);
         mis->postcopy_remote_fds = NULL;
     }
+    if (mis->transport_cleanup) {
+        mis->transport_cleanup(mis->transport_data);
+    }
 
     qemu_event_reset(&mis->main_thread_load_event);
 

migration/migration.h

@@ -49,6 +49,10 @@ struct PostcopyBlocktimeContext;
 struct MigrationIncomingState {
     QEMUFile *from_src_file;
 
+    /* A hook to allow cleanup at the end of incoming migration */
+    void *transport_data;
+    void (*transport_cleanup)(void *data);
+
     /*
      * Free at the start of the main state load, set as the main thread finishes
      * loading state.