Hi, Sergey! Looks ok, see a couple of question (and minor style-related comments) below.
On Dec 27, Sergey Vojtovich wrote: > At lp:maria/5.5 > > ------------------------------------------------------------ > revno: 4009 > revision-id: [email protected] > parent: [email protected] > committer: Sergey Vojtovich <[email protected]> > branch nick: 5.5-mdev5345 > timestamp: Fri 2013-12-27 14:14:19 +0400 > message: > MDEV-5345 - Deadlock between mysql_change_user(), SHOW VARIABLES and > INSTALL PLUGIN > > There was mixed lock order between LOCK_plugin, LOCK_global_system_variables > and LOCK_system_variables_hash. This patch ensures that write-lock on > LOCK_system_variables_hash doesn't intersect with LOCK_plugin. > > Fixed by moving initialization/deinitialization of plugin options from > plugin_add()/plugin_del() to plugin_initialize()/plugin_deinitalize(). > So that plugin options are handled without protection of LOCK_plugin. > === added file 'mysql-test/r/plugin_vars.result' > --- a/mysql-test/r/plugin_vars.result 1970-01-01 00:00:00 +0000 > +++ b/mysql-test/r/plugin_vars.result 2013-12-27 10:14:19 +0000 > @@ -0,0 +1,22 @@ > +# > +# MDEV-5345 - Deadlock between mysql_change_user(), SHOW VARIABLES and > +# INSTALL PLUGIN > +# > +CREATE PROCEDURE p_install(x INT) > +BEGIN > +DECLARE CONTINUE HANDLER FOR 1126 BEGIN END; > +WHILE x DO > +SET x= x - 1; > +INSTALL PLUGIN no_such_plugin SONAME 'no_such_object'; > +END WHILE; > +END| > +CREATE PROCEDURE p_show_vars(x INT) > +WHILE x DO > +SET x= x - 1; > +SHOW VARIABLES; > +END WHILE| > +CALL p_install(100);; > +CALL p_show_vars(100);; Note two semicolons at the end. The mysqltest syntax is either builtin_command arguments; or --builtin_command arguments I mean, it either ends with a semicolon or starts with dash-dash. Not a big deal, of course :) > +USE test; > +DROP PROCEDURE p_install; > +DROP PROCEDURE p_show_vars; > > === added file 'mysql-test/t/plugin_vars.test' > --- a/mysql-test/t/plugin_vars.test 1970-01-01 00:00:00 +0000 > +++ b/mysql-test/t/plugin_vars.test 2013-12-27 10:14:19 +0000 > @@ -0,0 +1,56 @@ > +--echo # > +--echo # MDEV-5345 - Deadlock between mysql_change_user(), SHOW VARIABLES and > +--echo # INSTALL PLUGIN > +--echo # > + > +# Prepare test > +delimiter |; > +CREATE PROCEDURE p_install(x INT) > +BEGIN > + DECLARE CONTINUE HANDLER FOR 1126 BEGIN END; > + WHILE x DO > + SET x= x - 1; > + INSTALL PLUGIN no_such_plugin SONAME 'no_such_object'; > + END WHILE; > +END| > + > +CREATE PROCEDURE p_show_vars(x INT) > +WHILE x DO > + SET x= x - 1; > + SHOW VARIABLES; > +END WHILE| > +delimiter ;| > + > +connect(con1, localhost, root,,); > +connect(con2, localhost, root,,); > + > +# Start test > +connection con1; > +--send CALL p_install(100); > + > +connection con2; > +--send CALL p_show_vars(100); Why did you prefer this test over a deterministic one with debug sync points? > +connection default; > + > +disable_result_log; > +let $i= 100; > +while ($i) > +{ > + change_user; > + dec $i; > +} > + > +# Cleanup > +connection con1; > +reap; > +connection con2; > +reap; > +connection default; > +enable_result_log; > + > +disconnect con1; > +disconnect con2; > +USE test; > +DROP PROCEDURE p_install; > +DROP PROCEDURE p_show_vars; > > === modified file 'sql/sql_plugin.cc' > --- a/sql/sql_plugin.cc 2013-12-12 17:14:08 +0000 > +++ b/sql/sql_plugin.cc 2013-12-27 10:14:19 +0000 > @@ -201,7 +202,7 @@ static bool initialized= 0; > write-lock on LOCK_system_variables_hash is required before modifying > the following variables/structures > */ > -static MEM_ROOT plugin_mem_root; > +static MEM_ROOT plugin_vars_mem_root; ok, so you couldn't consistently use one lock for plugin_mem_root, and had to create a second memroot. I see. another option would be to use one memroot and a dedicated lock for it. but I don't think it matters much what solution we use here :) > static uint global_variables_dynamic_size= 0; > static HASH bookmark_hash; > > @@ -1342,7 +1337,8 @@ void plugin_unlock_list(THD *thd, plugin > } > > > -static int plugin_initialize(struct st_plugin_int *plugin) > +static int plugin_initialize(MEM_ROOT *tmp_root, struct st_plugin_int > *plugin, > + int *argc, char **argv, bool initialize) this looks pretty weird. plugin_initialize() function that doesn't initialize if its initialize argument is false? perhaps it's better to rename the function then? Or create another one that tests plugin options and invokes plugin_initialize() if necessary? > { > int ret= 1; > DBUG_ENTER("plugin_initialize"); > @@ -1413,6 +1421,14 @@ static int plugin_initialize(struct st_p > ret= 0; > > err: > + if (ret) > + { > + mysql_rwlock_wrlock(&LOCK_system_variables_hash); > + mysql_del_sys_var_chain(plugin->system_vars); > + mysql_rwlock_unlock(&LOCK_system_variables_hash); > + restore_pluginvar_names(plugin->system_vars); may be, you'd move these four lines in a separate function? like, cleanup_plugin_sysvars() ? > + } > + > mysql_mutex_lock(&LOCK_plugin); > plugin->state= state; > > @@ -1646,9 +1654,10 @@ int plugin_init(int *argc, char **argv, > for (i= 0; i < plugin_array.elements; i++) > { > plugin_ptr= *dynamic_element(&plugin_array, i, struct st_plugin_int **); > - if (plugin_ptr->state == PLUGIN_IS_UNINITIALIZED) > + if (plugin_ptr->plugin_dl && plugin_ptr->state == > PLUGIN_IS_UNINITIALIZED) Why? > { > - if (plugin_initialize(plugin_ptr)) > + if (plugin_initialize(&tmp_root, plugin_ptr, argc, argv, > + !(flags & PLUGIN_INIT_SKIP_INITIALIZATION))) > { > plugin_ptr->state= PLUGIN_IS_DYING; > *(reap++)= plugin_ptr; Regards, Sergei _______________________________________________ Mailing list: https://launchpad.net/~maria-developers Post to : [email protected] Unsubscribe : https://launchpad.net/~maria-developers More help : https://help.launchpad.net/ListHelp
