row0mysql.c, sql_db.cc:

  Try to make sure DROP DATABASE does not cause a deadlock because we now let InnoDB wait MySQL does not have open handles to tables we drop

innobase/row/row0mysql.c

@@ -1802,6 +1802,7 @@ row_drop_database_for_mysql(
 	char*	name,	/* in: database name which ends to '/' */
 	trx_t*	trx)	/* in: transaction handle */
 {
+        dict_table_t* table;
 	char*	table_name;
 	int	err	= DB_SUCCESS;
 	
@@ -1812,12 +1813,27 @@ row_drop_database_for_mysql(
 	trx->op_info = "dropping database";
 	
 	trx_start_if_not_started(trx);
-
+loop:
 	mutex_enter(&(dict_sys->mutex));
 
 	while (table_name = dict_get_first_table_name_in_db(name)) {
 		ut_a(memcmp(table_name, name, strlen(name)) == 0);
 
+		table = dict_table_get_low(table_name);
+
+		ut_a(table);
+
+		/* Wait until MySQL does not have any queries running on
+		the table */
+
+		if (table->n_mysql_handles_opened > 0) {
+		        mutex_exit(&(dict_sys->mutex));
+
+		        os_thread_sleep(100000);
+
+		        goto loop;
+		}
+
 		err = row_drop_table_for_mysql(table_name, trx, TRUE);
 
 		mem_free(table_name);

sql/sql_db.cc

@@ -164,8 +164,6 @@ void mysql_rm_db(THD *thd,char *db,bool if_exists)
   }
   remove_db_from_cache(db);
 
-  ha_drop_database(path);
-
   if ((deleted=mysql_rm_known_files(thd, dirp, path,0)) >= 0)
   {
     if (!thd->query)
@@ -191,6 +189,14 @@ void mysql_rm_db(THD *thd,char *db,bool if_exists)
 exit:
   VOID(pthread_mutex_unlock(&LOCK_open));
   VOID(pthread_mutex_unlock(&LOCK_mysql_create_db));
+
+  /* It seems MySQL may call this function when there still are queries
+     running on tables of the database. Since InnoDB waits until the
+     queries have ended, we have to call ha_drop_database outside
+     the above two mutexes to avoid deadlocks. */
+
+  ha_drop_database(path);
+
   DBUG_VOID_RETURN;
 }