5 files changed, 72 insertions, 4 deletions
diff --git a/mysql-test/r/drop.result b/mysql-test/r/drop.result
index 54bd05e526f..8c6bd582232 100644
--- a/mysql-test/r/drop.result
+++ b/mysql-test/r/drop.result
@@ -77,8 +77,8 @@ drop table t1;
 drop database if exists mysqltest;
 drop table if exists t1;
 create table t1 (i int);
-lock tables t1 read;
 create database mysqltest;
+lock tables t1 read;
 drop table t1;
 show open tables;
 drop database mysqltest;
diff --git a/mysql-test/r/schema.result b/mysql-test/r/schema.result
index 33a2d4d9448..b43f601caef 100644
--- a/mysql-test/r/schema.result
+++ b/mysql-test/r/schema.result
@@ -24,7 +24,26 @@ INSERT INTO schema1.t1 VALUES (1);
 DROP SCHEMA schema1;
 # Connection default
 ALTER SCHEMA schema1 DEFAULT CHARACTER SET utf8;
-ERROR HY000: Can't create/write to file './schema1/db.opt' (Errcode: 2)
+Got one of the listed errors
 SET autocommit= TRUE;
 # Connection 2
 # Connection default
+#
+# Bug #49988 MDL deadlocks with mysql_create_db, reload_acl_and_cache
+#
+DROP SCHEMA IF EXISTS schema1;
+# Connection default
+CREATE SCHEMA schema1;
+CREATE TABLE schema1.t1 (id INT);
+LOCK TABLE schema1.t1 WRITE;
+# Connection con2
+DROP SCHEMA schema1;
+# Connection default
+# CREATE SCHEMA used to give a deadlock.
+# Now we prohibit CREATE SCHEMA in LOCK TABLES mode.
+CREATE SCHEMA IF NOT EXISTS schema1;
+ERROR HY000: Can't execute the given command because you have active locked tables or an active transaction
+# UNLOCK TABLES so DROP SCHEMA can continue.
+UNLOCK TABLES;
+# Connection con2
+# Connection default
diff --git a/mysql-test/t/drop.test b/mysql-test/t/drop.test
index 4aeb7165bcb..5ef4a28b202 100644
--- a/mysql-test/t/drop.test
+++ b/mysql-test/t/drop.test
@@ -100,8 +100,8 @@ drop database if exists mysqltest;
 drop table if exists t1;
 --enable_warnings
 create table t1 (i int);
-lock tables t1 read;
 create database mysqltest;
+lock tables t1 read;
 connect (addconroot1, localhost, root,,);
 --send drop table t1
 connect (addconroot2, localhost, root,,);
diff --git a/mysql-test/t/schema.test b/mysql-test/t/schema.test
index a380a6241dd..f106b9e4865 100644
--- a/mysql-test/t/schema.test
+++ b/mysql-test/t/schema.test
@@ -46,7 +46,8 @@ let $wait_condition= SELECT COUNT(*)= 1 FROM information_schema.processlist
                      WHERE state= 'Waiting for table' 
                      AND info='DROP SCHEMA schema1';
 --source include/wait_condition.inc
---error 1
+# Listing the error twice to prevent result diffences based on filename
+--error 1,1
 ALTER SCHEMA schema1 DEFAULT CHARACTER SET utf8;
 SET autocommit= TRUE;
 
@@ -59,6 +60,48 @@ connection default;
 disconnect con2;
 
 
+--echo #
+--echo # Bug #49988 MDL deadlocks with mysql_create_db, reload_acl_and_cache
+--echo #
+
+--disable_warnings
+DROP SCHEMA IF EXISTS schema1;
+--enable_warnings
+
+connect (con2, localhost, root);
+
+--echo # Connection default
+connection default;
+CREATE SCHEMA schema1;
+CREATE TABLE schema1.t1 (id INT);
+LOCK TABLE schema1.t1 WRITE;
+
+--echo # Connection con2
+connection con2;
+--send DROP SCHEMA schema1
+
+--echo # Connection default
+connection default;
+let $wait_condition=SELECT COUNT(*)=1 FROM information_schema.processlist 
+  WHERE state='Waiting for table' and info='DROP SCHEMA schema1';
+--source include/wait_condition.inc
+
+--echo # CREATE SCHEMA used to give a deadlock.
+--echo # Now we prohibit CREATE SCHEMA in LOCK TABLES mode.
+--error ER_LOCK_OR_ACTIVE_TRANSACTION
+CREATE SCHEMA IF NOT EXISTS schema1;
+
+--echo # UNLOCK TABLES so DROP SCHEMA can continue.
+UNLOCK TABLES;
+
+--echo # Connection con2
+connection con2;
+--reap
+
+--echo # Connection default
+connection default;
+disconnect con2;
+
 # Check that all connections opened by test cases in this file are really
 # gone so execution of other tests won't be affected by their presence.
 --source include/wait_until_count_sessions.inc
diff --git a/sql/sql_parse.cc b/sql/sql_parse.cc
index 689b2cec270..486cb9af288 100644
--- a/sql/sql_parse.cc
+++ b/sql/sql_parse.cc
@@ -3402,6 +3402,12 @@ end_with_restore_list:
     if (check_access(thd,CREATE_ACL,lex->name.str, 0, 1, 0,
                      is_schema_db(lex->name.str)))
       break;
+    if (thd->locked_tables_mode)
+    {
+      my_message(ER_LOCK_OR_ACTIVE_TRANSACTION,
+                 ER(ER_LOCK_OR_ACTIVE_TRANSACTION), MYF(0));
+      goto error;
+    }
     res= mysql_create_db(thd,(lower_case_table_names == 2 ? alias :
                               lex->name.str), &create_info, 0);
     break;