1 files changed, 16 insertions, 0 deletions
diff --git a/migration/migration.h b/migration/migration.h
index 972597f4de..cd5534337c 100644
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -316,6 +316,12 @@ struct MigrationState {
          * be cleared in the rp_thread!
          */
         bool          rp_thread_created;
+        /*
+         * Used to synchronize between migration main thread and return
+         * path thread.  The migration thread can wait() on this sem, while
+         * other threads (e.g., return path thread) can kick it using a
+         * post().
+         */
         QemuSemaphore rp_sem;
         /*
          * We post to this when we got one PONG from dest. So far it's an
@@ -476,6 +482,7 @@ bool  migration_has_all_channels(void);
 uint64_t migrate_max_downtime(void);
 
 void migrate_set_error(MigrationState *s, const Error *error);
+bool migrate_has_error(MigrationState *s);
 
 void migrate_fd_connect(MigrationState *s, Error *error_in);
 
@@ -526,4 +533,13 @@ void migration_populate_vfio_info(MigrationInfo *info);
 void migration_reset_vfio_bytes_transferred(void);
 void postcopy_temp_page_reset(PostcopyTmpPage *tmp_page);
 
+/* Migration thread waiting for return path thread. */
+void migration_rp_wait(MigrationState *s);
+/*
+ * Kick the migration thread waiting for return path messages.  NOTE: the
+ * name can be slightly confusing (when read as "kick the rp thread"), just
+ * to remember the target is always the migration thread.
+ */
+void migration_rp_kick(MigrationState *s);
+
 #endif