MDEV-22915: Assertion 'binlog_table_maps == 0 || locked_tables_mode == LTM_LOCK_TABLES' failed in THD::reset_for_next_command

close_thread_tables() would not flush pending row events to the binlog cache
in certain conditions if LOCK TABLES was active. This could result in the
row events being binlogged without STMT_END_F flag, and eventually leave the
THD in an invalid state that triggered assertions later.

Reviewed-by: Monty <monty@mariadb.org>
Signed-off-by: Kristian Nielsen <knielsen@knielsen-hq.org>

Author: knielsen

mysql-test/suite/binlog/r/binlog_mdev22915.result

@@ -0,0 +1,31 @@
+RESET MASTER;
+connect  con1,localhost,root,,;
+CREATE TABLE t1 (a INT) ENGINE=InnoDB;
+CREATE  TRIGGER tr BEFORE UPDATE ON t1 FOR EACH ROW BEGIN END;
+LOCK TABLES t1 WRITE;
+LOAD DATA INFILE 'x' INTO TABLE x;
+ERROR HY000: Table 'x' was not locked with LOCK TABLES
+SET AUTOCOMMIT= OFF;
+INSERT INTO t1 VALUES (1);
+SAVEPOINT A;
+COMMIT;
+disconnect con1;
+connect  con2,localhost,root,,;
+SELECT 1;
+1
+1
+disconnect con2;
+connection default;
+include/show_binlog_events.inc
+Log_name	Pos	Event_type	Server_id	End_log_pos	Info
+master-bin.000001	#	Gtid	#	#	GTID #-#-#
+master-bin.000001	#	Query	#	#	use `test`; CREATE TABLE t1 (a INT) ENGINE=InnoDB
+master-bin.000001	#	Gtid	#	#	GTID #-#-#
+master-bin.000001	#	Query	#	#	use `test`; CREATE DEFINER=`root`@`localhost` TRIGGER tr BEFORE UPDATE ON t1 FOR EACH ROW BEGIN END
+master-bin.000001	#	Gtid	#	#	BEGIN GTID #-#-#
+master-bin.000001	#	Annotate_rows	#	#	INSERT INTO t1 VALUES (1)
+master-bin.000001	#	Table_map	#	#	table_id: # (test.t1)
+master-bin.000001	#	Write_rows_v1	#	#	table_id: # flags: STMT_END_F
+master-bin.000001	#	Query	#	#	SAVEPOINT `A`
+master-bin.000001	#	Xid	#	#	COMMIT /* XID */
+DROP TABLE t1;

mysql-test/suite/binlog/t/binlog_mdev22915.test

@@ -0,0 +1,33 @@
+--source include/have_innodb.inc
+--source include/have_binlog_format_row.inc
+
+RESET MASTER;
+
+# This sequence of statements triggered a bug, where the pending LOCK TABLES
+# would skip flusing the pending row event for INSERT to the trx cache. And
+# Then the pending event would be overwritten by the SAVEPOINT, leaving an
+# invalid state in the THD. And then a later connection would pick the THD
+# with invalid state and trigger an assertion.
+--connect (con1,localhost,root,,)
+CREATE TABLE t1 (a INT) ENGINE=InnoDB;
+CREATE  TRIGGER tr BEFORE UPDATE ON t1 FOR EACH ROW BEGIN END;
+LOCK TABLES t1 WRITE;
+--error ER_TABLE_NOT_LOCKED
+LOAD DATA INFILE 'x' INTO TABLE x;
+SET AUTOCOMMIT= OFF;
+INSERT INTO t1 VALUES (1);
+SAVEPOINT A;
+COMMIT;
+--disconnect con1
+
+--connect (con2,localhost,root,,)
+SELECT 1;
+ 
+# Cleanup
+--disconnect con2
+--connection default
+# Show the binlog events.
+# When the bug occurs, the Write_rows event is missing STMT_END_F.
+--source include/show_binlog_events.inc
+
+DROP TABLE t1;

sql/sql_base.cc

@@ -957,6 +957,8 @@ int close_thread_tables(THD *thd)
 
     if (thd->locked_tables_mode == LTM_LOCK_TABLES)
     {
+      if (thd->lock)
+        (void)thd->binlog_flush_pending_rows_event(TRUE);
       error= 0;
       goto end;
     }