diff options
| author | Vladislav Vaintroub <wlad@mariadb.com> | 2018-01-27 17:46:31 +0000 |
|---|---|---|
| committer | Vladislav Vaintroub <wlad@mariadb.com> | 2018-01-29 07:33:52 +0000 |
| commit | 7cdf759c86a3b80bf215fcc6baab87b930425170 (patch) | |
| tree | fa541cde13156bd523bb9884ed5f163905aa519d /sql/sql_show.cc | |
| parent | 1da063a45bc43ac2c5761d8e091e55b8cac123cf (diff) | |
| download | mariadb-git-7cdf759c86a3b80bf215fcc6baab87b930425170.tar.gz | |
MDEV-14485 Server hangs on startup in THD::init
Solve 3 way deadlock between plugin_initialiaze(), THD::init() and
mysql_sys_var_char().
The deadlock exists because of the lock order inversion between
LOCK_global_system_variables mutex and LOCK_system_variables_hash
read-write lock-
In this case, it is enough to change LOCK_system_variables_hash to prefer
reads to fix the deadlock, i.e change it to mysql_prlock_t
Diffstat (limited to 'sql/sql_show.cc')
| -rw-r--r-- | sql/sql_show.cc | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/sql/sql_show.cc b/sql/sql_show.cc index 03107aa4574..60796df35d4 100644 --- a/sql/sql_show.cc +++ b/sql/sql_show.cc @@ -7399,7 +7399,7 @@ int fill_variables(THD *thd, TABLE_LIST *tables, COND *cond) COND *partial_cond= make_cond_for_info_schema(thd, cond, tables); - mysql_rwlock_rdlock(&LOCK_system_variables_hash); + mysql_prlock_rdlock(&LOCK_system_variables_hash); /* Avoid recursive LOCK_system_variables_hash acquisition in @@ -7414,7 +7414,7 @@ int fill_variables(THD *thd, TABLE_LIST *tables, COND *cond) res= show_status_array(thd, wild, enumerate_sys_vars(thd, sorted_vars, scope), scope, NULL, "", tables->table, upper_case_names, partial_cond); - mysql_rwlock_unlock(&LOCK_system_variables_hash); + mysql_prlock_unlock(&LOCK_system_variables_hash); DBUG_RETURN(res); } |