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[Ada] Independent tasks and the Fall_Back_Handler

Message ID 20160622103536.GA7030@adacore.com
State New
Headers show

Commit Message

Arnaud Charlet June 22, 2016, 10:35 a.m. UTC 
This patch fixes a bug in which if a Fall_Back_Handler is installed for the
environment task, independent tasks will call it. The following test should
run quietly:

with Ada.Text_IO;
package body Debug is

   protected body Dbg is
      procedure Termination
        (Cause   : in Task_Termination.Cause_Of_Termination;
         Task_Id : in Task_Identification.Task_Id;
         Except  : in Exceptions.Exception_Occurrence) is
      begin
         Text_IO.Put_Line
           (Task_Identification.Image (Task_Id) & " " & Cause'Img);
      end Termination;
   end Dbg;

end Debug;

with Ada.Exceptions,
  Ada.Task_Termination,
  Ada.Task_Identification;

use Ada;

package Debug is

   protected Dbg is
      procedure Termination
        (Cause   : in Task_Termination.Cause_Of_Termination;
         Task_Id : in Task_Identification.Task_Id;
         Except  : in Exceptions.Exception_Occurrence);
   end Dbg;

end Debug;

with Ada.Real_Time.Timing_Events,
  Ada.Task_Termination,
  Debug;
use Ada;

procedure Pb_Terminate is
begin
   Task_Termination.Set_Dependents_Fallback_Handler
     (Debug.Dbg.Termination'Access);
end Pb_Terminate;

Tested on x86_64-pc-linux-gnu, committed on trunk

2016-06-22  Bob Duff  <duff@adacore.com>

	* s-tassta.adb (Task_Wrapper): Fix handling of Fall_Back_Handler
	wrt independent tasks.
diff mbox

Patch

Index: s-tassta.adb
===================================================================
--- s-tassta.adb	(revision 237680)
+++ s-tassta.adb	(working copy)
@@ -6,7 +6,7 @@ 
 --                                                                          --
 --                                  B o d y                                 --
 --                                                                          --
---         Copyright (C) 1992-2014, Free Software Foundation, Inc.          --
+--         Copyright (C) 1992-2016, Free Software Foundation, Inc.          --
 --                                                                          --
 -- GNARL is free software; you can  redistribute it  and/or modify it under --
 -- terms of the  GNU General Public License as published  by the Free Soft- --
@@ -1339,7 +1339,13 @@ 
 
       if Self_ID.Common.Specific_Handler /= null then
          TH := Self_ID.Common.Specific_Handler;
-      else
+
+      --  Independent tasks should not call the Fall_Back_Handler (of the
+      --  environment task), because they are implementation artifacts that
+      --  should be invisible to Ada programs.
+
+      elsif Self_ID.Master_of_Task /= Independent_Task_Level then
+
          --  Look for a fall-back handler following the master relationship
          --  for the task. As specified in ARM C.7.3 par. 9/2, "the fall-back
          --  handler applies only to the dependent tasks of the task". Hence,