Deadlock between SELECT, DROP TABLE, SHOW STATUS and SET @@global.log_output

rdlock(LOCK_logger)                -> lock(LOCK_open)                    SELECT 1

lock(LOCK_open)                    -> lock(LOCK_status)                  DROP TABLE t1

lock(LOCK_status)                  -> lock(LOCK_global_system_variables) SHOW STATUS

lock(LOCK_global_system_variables) -> wrlock(LOCK_logger)                SET @@global.log_output=DEFAULT

--source include/have_example_plugin.inc

SET @@global.log_output='TABLE';

INSTALL SONAME 'ha_example';

CREATE TABLE t1(a int) ENGINE=EXAMPLE;

SELECT * FROM t1;

UNINSTALL SONAME 'ha_example';

connect(con1, localhost, root,,);

connect(con2, localhost, root,,);

connect(con3, localhost, root,,);

connection con1;

SET debug_sync='fix_log_output SIGNAL ready WAIT_FOR go';

send SET @@global.log_output=DEFAULT;

connection con2;

SET debug_sync='now WAIT_FOR ready';

SET debug_sync='fill_status SIGNAL ready';

send SHOW STATUS LIKE 'slave_open_temp_tables';

connection con3;

SET debug_sync='now WAIT_FOR ready';

SET debug_sync='remove_status_vars SIGNAL ready';

send DROP TABLE t1;

connection default;

SELECT 1;

connection con1;

reap;

disconnect con1;

connection con2;

reap;

disconnect con2;

connection con3;

reap;

disconnect con3;

connection default;

SET debug_sync='RESET';

=== modified file 'sql/log.cc'

--- sql/log.cc	2014-08-02 19:26:16 +0000

+++ sql/log.cc	2014-09-24 11:02:19 +0000

@@ -600,6 +600,11 @@ void Log_to_csv_event_handler::cleanup()

   ulonglong save_thd_options;

   bool save_time_zone_used;

   DBUG_ENTER("log_general");

+  if (!strncmp(sql_text, "SELECT 1", sql_text_len))

+  {

+    debug_sync_set_action(thd, STRING_WITH_LEN("now WAIT_FOR ready"));

+    debug_sync_set_action(thd, STRING_WITH_LEN("now SIGNAL go"));

+  }

   /*

     CSV uses TIME_to_timestamp() internally if table needs to be repaired

=== modified file 'sql/sql_show.cc'

--- sql/sql_show.cc	2014-09-12 06:41:35 +0000

+++ sql/sql_show.cc	2014-09-24 09:58:42 +0000

@@ -2543,6 +2543,7 @@ void remove_status_vars(SHOW_VAR *list)

 {

   if (status_vars_inited)

   {

+    DEBUG_SYNC(current_thd, "remove_status_vars");

     mysql_mutex_lock(&LOCK_status);

     SHOW_VAR *all= dynamic_element(&all_status_vars, 0, SHOW_VAR *);

@@ -6986,6 +6987,7 @@ int fill_status(THD *thd, TABLE_LIST *ta

     partial_cond->val_int();

   mysql_mutex_lock(&LOCK_status);

+  DEBUG_SYNC(thd, "fill_status");

   if (option_type == OPT_GLOBAL)

     calc_sum_of_all_status(&tmp);

   res= show_status_array(thd, wild,

=== modified file 'sql/sys_vars.cc'

--- sql/sys_vars.cc	2014-08-02 19:26:16 +0000

+++ sql/sys_vars.cc	2014-09-24 10:48:38 +0000

@@ -3246,6 +3246,7 @@ static bool check_not_empty_set(sys_var

 }

 static bool fix_log_output(sys_var *self, THD *thd, enum_var_type type)

 {

+  DEBUG_SYNC(thd, "fix_log_output");

   logger.lock_exclusive();

   logger.init_slow_log(log_output_options);

   logger.init_general_log(log_output_options);