Added protection around usage of thd->mysys_var

(May be changed to 0 by scheduler)

sql/mysqld.cc

@@ -957,6 +957,7 @@ static void close_connections(void)
 
     tmp->killed= THD::KILL_CONNECTION;
     thread_scheduler.post_kill_notification(tmp);
+    pthread_mutex_lock(&tmp->LOCK_thd_data);
     if (tmp->mysys_var)
     {
       tmp->mysys_var->abort=1;
@@ -979,6 +980,7 @@ static void close_connections(void)
       }
       pthread_mutex_unlock(&tmp->mysys_var->mutex);
     }
+    pthread_mutex_unlock(&tmp->LOCK_thd_data);
   }
   (void) pthread_mutex_unlock(&LOCK_thread_count); // For unlink from list
 

sql/scheduler.cc

@@ -235,9 +235,7 @@ void thd_scheduler::thread_detach()
   if (thread_attached)
   {
     THD* thd = (THD*)list.data;
-    pthread_mutex_lock(&thd->LOCK_thd_data);
-    thd->mysys_var= NULL;
-    pthread_mutex_unlock(&thd->LOCK_thd_data);
+    thd->reset_globals();
     thread_attached= FALSE;
 #ifndef DBUG_OFF
     /*

sql/sql_class.cc

@@ -1166,6 +1166,19 @@ bool THD::store_globals()
 }
 
 
+/**
+   Untie THD from current thread
+
+   Used when using --thread-handling=pool-of-threads
+*/
+
+void THD::reset_globals()
+{
+  pthread_mutex_lock(&LOCK_thd_data);
+  mysys_var= 0;
+  pthread_mutex_unlock(&LOCK_thd_data);
+}
+
 /*
   Cleanup after query.
 

sql/sql_class.h

@@ -1906,6 +1906,7 @@ public:
   void cleanup(void);
   void cleanup_after_query();
   bool store_globals();
+  void reset_globals();
 #ifdef SIGNAL_WITH_VIO_CLOSE
   inline void set_active_vio(Vio* vio)
   {

sql/sql_insert.cc

@@ -2279,6 +2279,7 @@ void kill_delayed_threads(void)
   while ((di= it++))
   {
     di->thd.killed= THD::KILL_CONNECTION;
+    pthread_mutex_lock(&di->thd.LOCK_thd_data);
     if (di->thd.mysys_var)
     {
       pthread_mutex_lock(&di->thd.mysys_var->mutex);
@@ -2297,6 +2298,7 @@ void kill_delayed_threads(void)
       }
       pthread_mutex_unlock(&di->thd.mysys_var->mutex);
     }
+    pthread_mutex_unlock(&di->thd.LOCK_thd_data);
   }
   VOID(pthread_mutex_unlock(&LOCK_delayed_insert)); // For unlink from list
 }

sql/sql_show.cc

@@ -1747,6 +1747,7 @@ void mysqld_list_processes(THD *thd,const char *user, bool verbose)
         if ((thd_info->db=tmp->db))             // Safe test
           thd_info->db=thd->strdup(thd_info->db);
         thd_info->command=(int) tmp->command;
+        pthread_mutex_lock(&tmp->LOCK_thd_data);
         if ((mysys_var= tmp->mysys_var))
           pthread_mutex_lock(&mysys_var->mutex);
         thd_info->proc_info= (char*) (tmp->killed == THD::KILL_CONNECTION? "Killed" : 0);
@@ -1766,6 +1767,7 @@ void mysqld_list_processes(THD *thd,const char *user, bool verbose)
 #endif
         if (mysys_var)
           pthread_mutex_unlock(&mysys_var->mutex);
+        pthread_mutex_unlock(&tmp->LOCK_thd_data);
 
         thd_info->start_time= tmp->start_time;
         thd_info->query=0;