MDE-21369 rpl.rpl_timezone fails with valgrind: Use of uninitialised value.

It's not safe to chenge the THD::thread_id.
So send the thread_id as an argument to the mysql_audit_external_lock.

sql/sql_audit.h

@@ -291,7 +291,9 @@ void mysql_audit_notify_connection_change_user(THD *thd)
 }
 
 static inline
-void mysql_audit_external_lock(THD *thd, TABLE_SHARE *share, int lock)
+void mysql_audit_external_lock_ex(THD *thd, my_thread_id thread_id,
+    const char *user, const char *host, const char *ip, query_id_t query_id,
+    TABLE_SHARE *share, int lock)
 {
   if (lock != F_UNLCK && mysql_audit_table_enabled())
   {
@@ -300,14 +302,14 @@ void mysql_audit_external_lock(THD *thd, TABLE_SHARE *share, int lock)
 
     event.event_subclass= MYSQL_AUDIT_TABLE_LOCK;
     event.read_only= lock == F_RDLCK;
-    event.thread_id= (unsigned long)thd->thread_id;
+    event.thread_id= (unsigned long)thread_id;
-    event.user= sctx->user;
+    event.user= user;
     event.priv_user= sctx->priv_user;
     event.priv_host= sctx->priv_host;
     event.external_user= sctx->external_user;
     event.proxy_user= sctx->proxy_user;
-    event.host= sctx->host;
+    event.host= host;
-    event.ip= sctx->ip;
+    event.ip= ip;
     event.database= share->db.str;
     event.database_length= (unsigned int)share->db.length;
     event.table= share->table_name.str;
@@ -316,12 +318,20 @@ void mysql_audit_external_lock(THD *thd, TABLE_SHARE *share, int lock)
     event.new_database_length= 0;
     event.new_table= 0;
     event.new_table_length= 0;
-    event.query_id= thd->query_id;
+    event.query_id= query_id;
 
     mysql_audit_notify(thd, MYSQL_AUDIT_TABLE_CLASS, &event);
   }
 }
 
+static inline
+void mysql_audit_external_lock(THD *thd, TABLE_SHARE *share, int lock)
+{
+  mysql_audit_external_lock_ex(thd, thd->thread_id, thd->security_ctx->user,
+      thd->security_ctx->host, thd->security_ctx->ip, thd->query_id,
+      share, lock);
+}
+
 static inline
 void mysql_audit_create_table(TABLE *table)
 {

sql/sql_insert.cc

@@ -2076,36 +2076,16 @@ public:
     passed from connection thread to the handler thread.
   */
   MDL_request grl_protection;
-  my_thread_id orig_thread_id;
-  void set_default_user()
-  {
-    thd.security_ctx->user=(char*) delayed_user;
-    thd.security_ctx->host=(char*) my_localhost;
-    thd.security_ctx->ip= NULL;
-    thd.query_id= 0;
-    thd.thread_id= orig_thread_id;
-  }
-
-  void set_user_from_row(const delayed_row *r)
-  {
-    if (r)
-    {
-      thd.security_ctx->user= r->user;
-      thd.security_ctx->host= r->host;
-      thd.security_ctx->ip= r->ip;
-      thd.query_id= r->query_id;
-      thd.thread_id= r->thread_id;
-    }
-  }
-
   Delayed_insert(SELECT_LEX *current_select)
     :locks_in_memory(0), thd(next_thread_id()),
      table(0),tables_in_use(0), stacked_inserts(0),
      status(0), retry(0), handler_thread_initialized(FALSE), group_count(0)
   {
     DBUG_ENTER("Delayed_insert constructor");
-    orig_thread_id= thd.thread_id;
+    thd.security_ctx->user=(char*) delayed_user;
-    set_default_user();
+    thd.security_ctx->host=(char*) my_localhost;
+    thd.security_ctx->ip= NULL;
+    thd.query_id= 0;
     strmake_buf(thd.security_ctx->priv_user, thd.security_ctx->user);
     thd.current_tablenr=0;
     thd.set_command(COM_DELAYED_INSERT);
@@ -3081,7 +3061,6 @@ pthread_handler_t handle_delayed_insert(void *arg)
 
       if (di->tables_in_use && ! thd->lock && !thd->killed)
       {
-        di->set_user_from_row(di->rows.head());
         /*
           Request for new delayed insert.
           Lock the table, but avoid to be blocked by a global read lock.
@@ -3103,16 +3082,18 @@ pthread_handler_t handle_delayed_insert(void *arg)
       {
         delayed_row *row;
         I_List_iterator<delayed_row> it(di->rows);
+        my_thread_id cur_thd= di->thd.thread_id;
+
         while ((row= it++))
         {
-          if (di->thd.thread_id != row->thread_id)
+          if (cur_thd != row->thread_id)
           {
-            di->set_user_from_row(row);
+            mysql_audit_external_lock_ex(&di->thd, row->thread_id,
-            mysql_audit_external_lock(&di->thd, di->table->s, F_WRLCK);
+                row->user, row->host, row->ip, row->query_id,
+                di->table->s, F_WRLCK);
+            cur_thd= row->thread_id;
           }
         }
-        di->set_default_user();
-
         if (di->handle_inserts())
         {
           /* Some fatal error */