From ba679ae52f0e9d698c1b36d28a5bc8c233e57a2e Mon Sep 17 00:00:00 2001
From: Sergey Vojtovich <svoj@mariadb.org>
Date: Thu, 26 Mar 2020 19:19:41 +0400
Subject: [PATCH] Fix for rpl_start_stop_slave failure

One may access freed THD members after LOCK_thd_kill is released.

With original code it can happen when killing wsrep-disabled thread on a
wsrep-enabled server. With 91ab42a8 it is happening on a wsrep-disabled
server.
---
 sql/sql_parse.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sql/sql_parse.cc b/sql/sql_parse.cc
index 9af4afd4b03..ffba46b4573 100644
--- a/sql/sql_parse.cc
+++ b/sql/sql_parse.cc
@@ -9086,8 +9086,8 @@ kill_one_thread(THD *thd, longlong id, killed_state kill_signal, killed_type typ
     else
       error= (type == KILL_TYPE_QUERY ? ER_KILL_QUERY_DENIED_ERROR :
                                         ER_KILL_DENIED_ERROR);
-    mysql_mutex_unlock(&tmp->LOCK_thd_kill);
     if (WSREP(tmp)) mysql_mutex_unlock(&tmp->LOCK_thd_data);
+    mysql_mutex_unlock(&tmp->LOCK_thd_kill);
   }
   DBUG_PRINT("exit", ("%d", error));
   DBUG_RETURN(error);