From 07056eb984573b483576d45d7b8c259ad66dcd66 Mon Sep 17 00:00:00 2001 From: Dmitry Shulga Date: Thu, 23 Jun 2011 20:41:04 +0700 Subject: 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. --- sql/sql_db.cc | 3 +++ 1 file changed, 3 insertions(+) (limited to 'sql/sql_db.cc') 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) -- cgit v1.2.1