From 07056eb984573b483576d45d7b8c259ad66dcd66 Mon Sep 17 00:00:00 2001 From: Dmitry Shulga Date: Thu, 23 Jun 2011 20:41:04 +0700 Subject: [PATCH] Fixed Bug#11756013 (formerly known as bug#47870): BOGUS "THE TABLE MYSQL.PROC IS MISSING,..." There was a race condition between loading a stored routine (function/procedure/trigger) specified by fully qualified name SCHEMA_NAME.PROC_NAME and dropping the stored routine database. The problem was that there is a window for race condition when one server thread tries to load a stored routine being executed and the other thread tries to drop the stored routine schema. This condition race window exists in implementation of function mysql_change_db() called by db_load_routine() during loading of stored routine to cache. Function mysql_change_db() calls check_db_dir_existence() that might failed because specified database was dropped during concurrent execution of DROP SCHEMA statement. db_load_routine() calls mysql_change_db() with flag 'force_switch' set to 'true' value so when referenced db is not found then my_error() is not called and function mysql_change_db() returns ok. This shadows information about schema opening error in db_load_routine(). Then db_load_routine() makes attempt to parse stored routine that is failed. This makes to return error to sp_cache_routines_and_add_tables_aux() but since during error generation a call to my_error wasn't made and hence THD::main_da wasn't set we set the generic "mysql.proc table corrupt" error when running sp_cache_routines_and_add_tables_aux(). The fix is to install an error handler inside db_load_routine() for the mysql_op_change_db() call, and check later if the ER_BAD_DB_ERROR was caught. --- mysql-test/r/sp_sync.result | 14 ++++++++++++- mysql-test/t/sp_sync.test | 31 ++++++++++++++++++++++++++- sql/sp.cc | 42 ++++++++++++++++++++++++++++++++++++- sql/sql_db.cc | 3 +++ 4 files changed, 87 insertions(+), 3 deletions(-) diff --git a/mysql-test/r/sp_sync.result b/mysql-test/r/sp_sync.result index afa37e70531..17292f4c1a8 100644 --- a/mysql-test/r/sp_sync.result +++ b/mysql-test/r/sp_sync.result @@ -1,4 +1,4 @@ -Tests of syncronization of stored procedure execution. +Tests of synchronization of stored procedure execution. # # Bug#48157: crash in Item_field::used_tables # @@ -20,4 +20,16 @@ SET DEBUG_SYNC = 'now SIGNAL go'; # code, this test statement will hang. DROP TABLE t1, t2; DROP PROCEDURE p1; +# +# test for bug#11756013 +# +DROP SCHEMA IF EXISTS s1; +CREATE SCHEMA s1; +CREATE PROCEDURE s1.p1() BEGIN END; +SET DEBUG_SYNC='before_db_dir_check SIGNAL check_db WAIT_FOR dropped_schema'; +CALL s1.p1; +SET DEBUG_SYNC='now WAIT_FOR check_db'; +DROP SCHEMA s1; +SET DEBUG_SYNC='now SIGNAL dropped_schema'; +ERROR 42000: Unknown database 's1' SET DEBUG_SYNC = 'RESET'; diff --git a/mysql-test/t/sp_sync.test b/mysql-test/t/sp_sync.test index f9dae17b039..d8458f69eef 100644 --- a/mysql-test/t/sp_sync.test +++ b/mysql-test/t/sp_sync.test @@ -1,7 +1,10 @@ # This test should work in embedded server after mysqltest is fixed -- source include/not_embedded.inc ---echo Tests of syncronization of stored procedure execution. +# Save the initial number of concurrent sessions +--source include/count_sessions.inc + +--echo Tests of synchronization of stored procedure execution. --source include/have_debug_sync.inc @@ -54,5 +57,31 @@ connection default; DROP TABLE t1, t2; DROP PROCEDURE p1; +--echo # +--echo # test for bug#11756013 +--echo # +--disable_warnings +DROP SCHEMA IF EXISTS s1; +--enable_warnings +CREATE SCHEMA s1; +CREATE PROCEDURE s1.p1() BEGIN END; + +connect (con3, localhost, root); +SET DEBUG_SYNC='before_db_dir_check SIGNAL check_db WAIT_FOR dropped_schema'; +--send CALL s1.p1 + +connection default; +SET DEBUG_SYNC='now WAIT_FOR check_db'; +DROP SCHEMA s1; +SET DEBUG_SYNC='now SIGNAL dropped_schema'; + +connection con3; +--error ER_BAD_DB_ERROR +--reap +connection default; +disconnect con3; + SET DEBUG_SYNC = 'RESET'; +# Wait till we reached the initial number of concurrent sessions +--source include/wait_until_count_sessions.inc diff --git a/sql/sp.cc b/sql/sp.cc index ddddaee2e10..78d1dc7e22c 100644 --- a/sql/sp.cc +++ b/sql/sp.cc @@ -708,6 +708,37 @@ Silence_deprecated_warning::handle_error(uint sql_errno, const char *message, } +class Bad_db_error_handler : public Internal_error_handler +{ +public: + Bad_db_error_handler() + :m_error_caught(false) + {} + + virtual bool handle_error(uint sql_errno, const char *message, + MYSQL_ERROR::enum_warning_level level, + THD *thd); + + bool error_caught() const { return m_error_caught; } + +private: + bool m_error_caught; +}; + +bool +Bad_db_error_handler::handle_error(uint sql_errno, const char *message, + MYSQL_ERROR::enum_warning_level level, + THD *thd) +{ + if (sql_errno == ER_BAD_DB_ERROR) + { + m_error_caught= true; + return true; + } + return false; +} + + static int db_load_routine(THD *thd, int type, sp_name *name, sp_head **sphp, ulong sql_mode, const char *params, const char *returns, @@ -725,7 +756,7 @@ db_load_routine(THD *thd, int type, sp_name *name, sp_head **sphp, ha_rows old_select_limit= thd->variables.select_limit; sp_rcontext *old_spcont= thd->spcont; Silence_deprecated_warning warning_handler; - + Bad_db_error_handler db_not_exists_handler; char definer_user_name_holder[USERNAME_LENGTH + 1]; LEX_STRING definer_user_name= { definer_user_name_holder, USERNAME_LENGTH }; @@ -766,6 +797,7 @@ db_load_routine(THD *thd, int type, sp_name *name, sp_head **sphp, goto end; } + thd->push_internal_handler(&db_not_exists_handler); /* Change the current database (if needed). @@ -776,9 +808,17 @@ db_load_routine(THD *thd, int type, sp_name *name, sp_head **sphp, &cur_db_changed)) { ret= SP_INTERNAL_ERROR; + thd->pop_internal_handler(); goto end; } + thd->pop_internal_handler(); + if (db_not_exists_handler.error_caught()) + { + ret= SP_INTERNAL_ERROR; + my_error(ER_BAD_DB_ERROR, MYF(0), name->m_db.str); + goto end; + } thd->spcont= NULL; { diff --git a/sql/sql_db.cc b/sql/sql_db.cc index d7d7f43a7aa..e0d848321a7 100644 --- a/sql/sql_db.cc +++ b/sql/sql_db.cc @@ -26,6 +26,7 @@ #ifdef __WIN__ #include #endif +#include "debug_sync.h" #define MAX_DROP_TABLE_Q_LEN 1024 @@ -1702,6 +1703,8 @@ bool mysql_change_db(THD *thd, const LEX_STRING *new_db_name, bool force_switch) } #endif + DEBUG_SYNC(thd, "before_db_dir_check"); + if (check_db_dir_existence(new_db_file_name.str)) { if (force_switch)