MDEV-10824 - Crash in CREATE OR REPLACE TABLE t1 AS SELECT spfunc()

Code flow hit incorrect branch while closing table instances before removal.
This branch expects thread to hold open table instance, whereas CREATE OR
REPLACE doesn't actually hold open table instance.

Before CREATE OR REPLACE TABLE it was impossible to hit this condition in
LTM_PRELOCKED mode, thus the problem didn't expose itself during DROP TABLE
or DROP DATABASE.

Fixed by adjusting condition to take into account LTM_PRELOCKED mode, which can
be set during CREATE OR REPLACE TABLE.

Author: svoj

mysql-test/r/create_or_replace.result

@@ -442,3 +442,14 @@ KILL QUERY con_id;
 ERROR 70100: Query execution was interrupted
 drop table t1;
 DROP TABLE t2;
+#
+# MDEV-10824 - Crash in CREATE OR REPLACE TABLE t1 AS SELECT spfunc()
+#
+CREATE TABLE t1(a INT);
+CREATE FUNCTION f1() RETURNS VARCHAR(16383) RETURN 'test';
+CREATE OR REPLACE TABLE t1 AS SELECT f1();
+LOCK TABLE t1 WRITE;
+CREATE OR REPLACE TABLE t1 AS SELECT f1();
+UNLOCK TABLES;
+DROP FUNCTION f1;
+DROP TABLE t1;

mysql-test/t/create_or_replace.test

@@ -386,3 +386,15 @@ drop table t1;
 # Cleanup
 #
 DROP TABLE t2;
+
+--echo #
+--echo # MDEV-10824 - Crash in CREATE OR REPLACE TABLE t1 AS SELECT spfunc()
+--echo #
+CREATE TABLE t1(a INT);
+CREATE FUNCTION f1() RETURNS VARCHAR(16383) RETURN 'test';
+CREATE OR REPLACE TABLE t1 AS SELECT f1();
+LOCK TABLE t1 WRITE;
+CREATE OR REPLACE TABLE t1 AS SELECT f1();
+UNLOCK TABLES;
+DROP FUNCTION f1;
+DROP TABLE t1;

sql/sql_table.cc

@@ -2464,7 +2464,8 @@ int mysql_rm_table_no_locks(THD *thd, TABLE_LIST *tables, bool if_exists,
       if (table_type && table_type != view_pseudo_hton)
         ha_lock_engine(thd, table_type);
 
-      if (thd->locked_tables_mode)
+      if (thd->locked_tables_mode == LTM_LOCK_TABLES ||
+          thd->locked_tables_mode == LTM_PRELOCKED_UNDER_LOCK_TABLES)
       {
         if (wait_while_table_is_used(thd, table->table, HA_EXTRA_NOT_USED))
         {