Bug #38816: kill + flush tables with read lock + stored

            procedures causes crashes!

The problem of that bugreport was mostly fixed by the
patch for bug 38691.
However, attached test case focused on another crash or
valgrind warning problem: SHOW PROCESSLIST query accesses
freed memory of SP instruction that run in a parallel
connection.

Changes of thd->query/thd->query_length in dangerous
places have been guarded with the per-thread
LOCK_thd_data mutex (the THD::LOCK_delete mutex has been
renamed to THD::LOCK_thd_data).


sql/ha_myisam.cc:
  Bug #38816: kill + flush tables with read lock + stored
              procedures causes crashes!
  
  Modification of THD::query/query_length has been guarded
  with the a THD::set_query() method call/LOCK_thd_data
  mutex.
  Unnecessary locking with the global LOCK_thread_count
  mutex has been removed.
sql/log_event.cc:
  Bug #38816: kill + flush tables with read lock + stored
              procedures causes crashes!
  
  Modification of THD::query/query_length has been guarded
  with the THD::set_query()) method call/LOCK_thd_data
  mutex.
sql/slave.cc:
  Bug #38816: kill + flush tables with read lock + stored
              procedures causes crashes!
  
  Modification of THD::query/query_length has been guarded
  with the THD::set_query() method call/LOCK_thd_data mutex.
  
  The THD::LOCK_delete mutex has been renamed to
  THD::LOCK_thd_data.
sql/sp_head.cc:
  Bug #38816: kill + flush tables with read lock + stored
              procedures causes crashes!
  
  Modification of THD::query/query_length has been guarded
  with the a THD::set_query() method call/LOCK_thd_data
  mutex.
sql/sql_class.cc:
  Bug #38816: kill + flush tables with read lock + stored
              procedures causes crashes!
  
  The new THD::LOCK_thd_data mutex and THD::set_query()
  method has been added to guard modifications of THD::query/
  THD::query_length fields, also the Statement::set_statement()
  method has been overloaded in the THD class.
  
  The THD::LOCK_delete mutex has been renamed to
  THD::LOCK_thd_data.
sql/sql_class.h:
  Bug #38816: kill + flush tables with read lock + stored
              procedures causes crashes!
  
  The new THD::LOCK_thd_data mutex and THD::set_query()
  method has been added to guard modifications of THD::query/
  THD::query_length fields, also the Statement::set_statement()
  method has been overloaded in the THD class.
  
  The THD::LOCK_delete mutex has been renamed to
  THD::LOCK_thd_data.
sql/sql_insert.cc:
  Bug #38816: kill + flush tables with read lock + stored
              procedures causes crashes!
  
  Modification of THD::query/query_length has been guarded
  with the a THD::set_query() method call/LOCK_thd_data
  mutex.
sql/sql_parse.cc:
  Bug #38816: kill + flush tables with read lock + stored
              procedures causes crashes!
  
  Modification of THD::query/query_length has been guarded
  with the a THD::set_query() method call/LOCK_thd_data mutex.
sql/sql_repl.cc:
  Bug #38816: kill + flush tables with read lock + stored
              procedures causes crashes!
  
  The THD::LOCK_delete mutex has been renamed to
  THD::LOCK_thd_data.
sql/sql_show.cc:
  Bug #38816: kill + flush tables with read lock + stored
              procedures causes crashes!
  
  Inter-thread read of THD::query/query_length field has
  been protected with a new per-thread LOCK_thd_data
  mutex in the mysqld_list_processes function.

1 files changed, 3 insertions, 8 deletions

diff --git a/sql/ha_myisam.cc b/sql/ha_myisam.cc
index dadd39bb6e8..dfd739f6db8 100644
--- a/sql/ha_myisam.cc
+++ b/sql/ha_myisam.cc
@@ -1487,10 +1487,8 @@ bool ha_myisam::check_and_repair(THD *thd)
 
   old_query= thd->query;
   old_query_length= thd->query_length;
-  pthread_mutex_lock(&LOCK_thread_count);
-  thd->query= (char*) table->s->table_name;
-  thd->query_length= (uint32) strlen(table->s->table_name);
-  pthread_mutex_unlock(&LOCK_thread_count);
+  thd->set_query((char*) table->s->table_name,
+                 (uint32) strlen(table->s->table_name));
 
   if ((marked_crashed= mi_is_crashed(file)) || check(thd, &check_opt))
   {
@@ -1503,10 +1501,7 @@ bool ha_myisam::check_and_repair(THD *thd)
     if (repair(thd, &check_opt))
       error=1;
   }
-  pthread_mutex_lock(&LOCK_thread_count);
-  thd->query= old_query;
-  thd->query_length= old_query_length;
-  pthread_mutex_unlock(&LOCK_thread_count);
+  thd->set_query(old_query, old_query_length);
   DBUG_RETURN(error);
 }