1 ------------------------------------------------------------------------------
3 -- GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS --
5 -- S Y S T E M . T A S K I N G . S T A G E S --
9 -- Copyright (C) 1992-2009, Free Software Foundation, Inc. --
11 -- GNARL is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 3, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. --
18 -- As a special exception under Section 7 of GPL version 3, you are granted --
19 -- additional permissions described in the GCC Runtime Library Exception, --
20 -- version 3.1, as published by the Free Software Foundation. --
22 -- You should have received a copy of the GNU General Public License and --
23 -- a copy of the GCC Runtime Library Exception along with this program; --
24 -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
25 -- <http://www.gnu.org/licenses/>. --
27 -- GNARL was developed by the GNARL team at Florida State University. --
28 -- Extensive contributions were provided by Ada Core Technologies, Inc. --
30 ------------------------------------------------------------------------------
33 -- Turn off polling, we do not want ATC polling to take place during tasking
34 -- operations. It causes infinite loops and other problems.
37 with Ada.Unchecked_Deallocation;
39 with System.Tasking.Debug;
40 with System.Address_Image;
41 with System.Task_Primitives;
42 with System.Task_Primitives.Operations;
43 with System.Tasking.Utilities;
44 with System.Tasking.Queuing;
45 with System.Tasking.Rendezvous;
46 with System.OS_Primitives;
47 with System.Secondary_Stack;
48 with System.Storage_Elements;
49 with System.Restrictions;
50 with System.Standard_Library;
51 with System.Traces.Tasking;
52 with System.Stack_Usage;
54 with System.Soft_Links;
55 -- These are procedure pointers to non-tasking routines that use task
56 -- specific data. In the absence of tasking, these routines refer to global
57 -- data. In the presence of tasking, they must be replaced with pointers to
58 -- task-specific versions. Also used for Create_TSD, Destroy_TSD,
59 -- Get_Current_Excep, Finalize_Global_List, Task_Termination, Handler.
61 with System.Tasking.Initialization;
62 pragma Elaborate_All (System.Tasking.Initialization);
63 -- This insures that tasking is initialized if any tasks are created
65 package body System.Tasking.Stages is
67 package STPO renames System.Task_Primitives.Operations;
68 package SSL renames System.Soft_Links;
69 package SSE renames System.Storage_Elements;
70 package SST renames System.Secondary_Stack;
76 use Task_Primitives.Operations;
80 use System.Traces.Tasking;
82 -----------------------
83 -- Local Subprograms --
84 -----------------------
87 Ada.Unchecked_Deallocation (Ada_Task_Control_Block, Task_Id);
89 procedure Free_Entry_Names (T : Task_Id);
90 -- Deallocate all string names associated with task entries
92 procedure Trace_Unhandled_Exception_In_Task (Self_Id : Task_Id);
93 -- This procedure outputs the task specific message for exception
96 procedure Task_Wrapper (Self_ID : Task_Id);
97 pragma Convention (C, Task_Wrapper);
98 -- This is the procedure that is called by the GNULL from the new context
99 -- when a task is created. It waits for activation and then calls the task
100 -- body procedure. When the task body procedure completes, it terminates
103 -- The Task_Wrapper's address will be provided to the underlying threads
104 -- library as the task entry point. Convention C is what makes most sense
105 -- for that purpose (Export C would make the function globally visible,
106 -- and affect the link name on which GDB depends). This will in addition
107 -- trigger an automatic stack alignment suitable for GCC's assumptions if
110 -- "Vulnerable_..." in the procedure names below means they must be called
111 -- with abort deferred.
113 procedure Vulnerable_Complete_Task (Self_ID : Task_Id);
114 -- Complete the calling task. This procedure must be called with
115 -- abort deferred. It should only be called by Complete_Task and
116 -- Finalize_Global_Tasks (for the environment task).
118 procedure Vulnerable_Complete_Master (Self_ID : Task_Id);
119 -- Complete the current master of the calling task. This procedure
120 -- must be called with abort deferred. It should only be called by
121 -- Vulnerable_Complete_Task and Complete_Master.
123 procedure Vulnerable_Complete_Activation (Self_ID : Task_Id);
124 -- Signal to Self_ID's activator that Self_ID has completed activation.
125 -- This procedure must be called with abort deferred.
127 procedure Abort_Dependents (Self_ID : Task_Id);
128 -- Abort all the direct dependents of Self at its current master nesting
129 -- level, plus all of their dependents, transitively. RTS_Lock should be
130 -- locked by the caller.
132 procedure Vulnerable_Free_Task (T : Task_Id);
133 -- Recover all runtime system storage associated with the task T. This
134 -- should only be called after T has terminated and will no longer be
137 -- For tasks created by an allocator that fails, due to an exception, it is
138 -- called from Expunge_Unactivated_Tasks.
140 -- Different code is used at master completion, in Terminate_Dependents,
141 -- due to a need for tighter synchronization with the master.
143 ----------------------
144 -- Abort_Dependents --
145 ----------------------
147 procedure Abort_Dependents (Self_ID : Task_Id) is
154 P := C.Common.Parent;
158 -- ??? C is supposed to take care of its own dependents, so
159 -- there should be no need to worry about them. Need to double
162 if C.Master_of_Task = Self_ID.Master_Within then
163 Utilities.Abort_One_Task (Self_ID, C);
164 C.Dependents_Aborted := True;
170 P := P.Common.Parent;
173 C := C.Common.All_Tasks_Link;
176 Self_ID.Dependents_Aborted := True;
177 end Abort_Dependents;
183 procedure Abort_Tasks (Tasks : Task_List) is
185 Utilities.Abort_Tasks (Tasks);
192 -- Note that locks of activator and activated task are both locked here.
193 -- This is necessary because C.Common.State and Self.Common.Wait_Count have
194 -- to be synchronized. This is safe from deadlock because the activator is
195 -- always created before the activated task. That satisfies our
196 -- in-order-of-creation ATCB locking policy.
198 -- At one point, we may also lock the parent, if the parent is different
199 -- from the activator. That is also consistent with the lock ordering
200 -- policy, since the activator cannot be created before the parent.
202 -- Since we are holding both the activator's lock, and Task_Wrapper locks
203 -- that before it does anything more than initialize the low-level ATCB
204 -- components, it should be safe to wait to update the counts until we see
205 -- that the thread creation is successful.
207 -- If the thread creation fails, we do need to close the entries of the
208 -- task. The first phase, of dequeuing calls, only requires locking the
209 -- acceptor's ATCB, but the waking up of the callers requires locking the
210 -- caller's ATCB. We cannot safely do this while we are holding other
211 -- locks. Therefore, the queue-clearing operation is done in a separate
212 -- pass over the activation chain.
214 procedure Activate_Tasks (Chain_Access : Activation_Chain_Access) is
215 Self_ID : constant Task_Id := STPO.Self;
218 Next_C, Last_C : Task_Id;
219 Activate_Prio : System.Any_Priority;
221 All_Elaborated : Boolean := True;
224 -- If pragma Detect_Blocking is active, then we must check whether this
225 -- potentially blocking operation is called from a protected action.
227 if System.Tasking.Detect_Blocking
228 and then Self_ID.Common.Protected_Action_Nesting > 0
230 raise Program_Error with "potentially blocking operation";
234 (Debug.Trace (Self_ID, "Activate_Tasks", 'C'));
236 Initialization.Defer_Abort_Nestable (Self_ID);
238 pragma Assert (Self_ID.Common.Wait_Count = 0);
240 -- Lock RTS_Lock, to prevent activated tasks from racing ahead before
241 -- we finish activating the chain.
245 -- Check that all task bodies have been elaborated
247 C := Chain_Access.T_ID;
250 if C.Common.Elaborated /= null
251 and then not C.Common.Elaborated.all
253 All_Elaborated := False;
256 -- Reverse the activation chain so that tasks are activated in the
257 -- same order they're declared.
259 Next_C := C.Common.Activation_Link;
260 C.Common.Activation_Link := Last_C;
265 Chain_Access.T_ID := Last_C;
267 if not All_Elaborated then
269 Initialization.Undefer_Abort_Nestable (Self_ID);
270 raise Program_Error with "Some tasks have not been elaborated";
273 -- Activate all the tasks in the chain. Creation of the thread of
274 -- control was deferred until activation. So create it now.
276 C := Chain_Access.T_ID;
278 if C.Common.State /= Terminated then
279 pragma Assert (C.Common.State = Unactivated);
281 P := C.Common.Parent;
286 (if C.Common.Base_Priority < Get_Priority (Self_ID)
287 then Get_Priority (Self_ID)
288 else C.Common.Base_Priority);
290 System.Task_Primitives.Operations.Create_Task
291 (C, Task_Wrapper'Address,
293 (C.Common.Compiler_Data.Pri_Stack_Info.Size),
294 Activate_Prio, Success);
296 -- There would be a race between the created task and the creator
297 -- to do the following initialization, if we did not have a
298 -- Lock/Unlock_RTS pair in the task wrapper to prevent it from
302 C.Common.State := Activating;
305 P.Awake_Count := P.Awake_Count + 1;
306 P.Alive_Count := P.Alive_Count + 1;
308 if P.Common.State = Master_Completion_Sleep and then
309 C.Master_of_Task = P.Master_Within
311 pragma Assert (Self_ID /= P);
312 P.Common.Wait_Count := P.Common.Wait_Count + 1;
315 for J in System.Tasking.Debug.Known_Tasks'Range loop
316 if System.Tasking.Debug.Known_Tasks (J) = null then
317 System.Tasking.Debug.Known_Tasks (J) := C;
318 C.Known_Tasks_Index := J;
323 if Global_Task_Debug_Event_Set then
324 Debug.Signal_Debug_Event
325 (Debug.Debug_Event_Activating, C);
328 C.Common.State := Runnable;
334 -- No need to set Awake_Count, State, etc. here since the loop
335 -- below will do that for any Unactivated tasks.
339 Self_ID.Common.Activation_Failed := True;
343 C := C.Common.Activation_Link;
346 if not Single_Lock then
350 -- Close the entries of any tasks that failed thread creation, and count
351 -- those that have not finished activation.
353 Write_Lock (Self_ID);
354 Self_ID.Common.State := Activator_Sleep;
356 C := Chain_Access.T_ID;
360 if C.Common.State = Unactivated then
361 C.Common.Activator := null;
362 C.Common.State := Terminated;
364 Utilities.Cancel_Queued_Entry_Calls (C);
366 elsif C.Common.Activator /= null then
367 Self_ID.Common.Wait_Count := Self_ID.Common.Wait_Count + 1;
371 P := C.Common.Activation_Link;
372 C.Common.Activation_Link := null;
376 -- Wait for the activated tasks to complete activation. It is
377 -- unsafe to abort any of these tasks until the count goes to zero.
380 exit when Self_ID.Common.Wait_Count = 0;
381 Sleep (Self_ID, Activator_Sleep);
384 Self_ID.Common.State := Runnable;
391 -- Remove the tasks from the chain
393 Chain_Access.T_ID := null;
394 Initialization.Undefer_Abort_Nestable (Self_ID);
396 if Self_ID.Common.Activation_Failed then
397 Self_ID.Common.Activation_Failed := False;
398 raise Tasking_Error with "Failure during activation";
402 -------------------------
403 -- Complete_Activation --
404 -------------------------
406 procedure Complete_Activation is
407 Self_ID : constant Task_Id := STPO.Self;
410 Initialization.Defer_Abort_Nestable (Self_ID);
416 Vulnerable_Complete_Activation (Self_ID);
422 Initialization.Undefer_Abort_Nestable (Self_ID);
424 -- ??? Why do we need to allow for nested deferral here?
426 if Runtime_Traces then
427 Send_Trace_Info (T_Activate);
429 end Complete_Activation;
431 ---------------------
432 -- Complete_Master --
433 ---------------------
435 procedure Complete_Master is
436 Self_ID : constant Task_Id := STPO.Self;
439 (Self_ID.Deferral_Level > 0
440 or else not System.Restrictions.Abort_Allowed);
441 Vulnerable_Complete_Master (Self_ID);
448 -- See comments on Vulnerable_Complete_Task for details
450 procedure Complete_Task is
451 Self_ID : constant Task_Id := STPO.Self;
455 (Self_ID.Deferral_Level > 0
456 or else not System.Restrictions.Abort_Allowed);
458 Vulnerable_Complete_Task (Self_ID);
460 -- All of our dependents have terminated. Never undefer abort again!
468 -- Compiler interface only. Do not call from within the RTS. This must be
469 -- called to create a new task.
471 procedure Create_Task
473 Size : System.Parameters.Size_Type;
474 Task_Info : System.Task_Info.Task_Info_Type;
475 Relative_Deadline : Ada.Real_Time.Time_Span;
476 Num_Entries : Task_Entry_Index;
477 Master : Master_Level;
478 State : Task_Procedure_Access;
479 Discriminants : System.Address;
480 Elaborated : Access_Boolean;
481 Chain : in out Activation_Chain;
483 Created_Task : out Task_Id;
484 Build_Entry_Names : Boolean)
487 Self_ID : constant Task_Id := STPO.Self;
489 Base_Priority : System.Any_Priority;
492 pragma Unreferenced (Relative_Deadline);
493 -- EDF scheduling is not supported by any of the target platforms so
494 -- this parameter is not passed any further.
497 -- If Master is greater than the current master, it means that Master
498 -- has already awaited its dependent tasks. This raises Program_Error,
499 -- by 4.8(10.3/2). See AI-280. Ignore this check for foreign threads.
501 if Self_ID.Master_of_Task /= Foreign_Task_Level
502 and then Master > Self_ID.Master_Within
504 raise Program_Error with
505 "create task after awaiting termination";
508 -- If pragma Detect_Blocking is active must be checked whether this
509 -- potentially blocking operation is called from a protected action.
511 if System.Tasking.Detect_Blocking
512 and then Self_ID.Common.Protected_Action_Nesting > 0
514 raise Program_Error with "potentially blocking operation";
517 pragma Debug (Debug.Trace (Self_ID, "Create_Task", 'C'));
520 (if Priority = Unspecified_Priority
521 then Self_ID.Common.Base_Priority
522 else System.Any_Priority (Priority));
524 -- Find parent P of new Task, via master level number
529 while P.Master_of_Task >= Master loop
530 P := P.Common.Parent;
535 Initialization.Defer_Abort_Nestable (Self_ID);
538 T := New_ATCB (Num_Entries);
541 Initialization.Undefer_Abort_Nestable (Self_ID);
542 raise Storage_Error with "Cannot allocate task";
545 -- RTS_Lock is used by Abort_Dependents and Abort_Tasks. Up to this
546 -- point, it is possible that we may be part of a family of tasks that
550 Write_Lock (Self_ID);
552 -- Now, we must check that we have not been aborted. If so, we should
553 -- give up on creating this task, and simply return.
555 if not Self_ID.Callable then
556 pragma Assert (Self_ID.Pending_ATC_Level = 0);
557 pragma Assert (Self_ID.Pending_Action);
559 (Chain.T_ID = null or else Chain.T_ID.Common.State = Unactivated);
563 Initialization.Undefer_Abort_Nestable (Self_ID);
565 -- ??? Should never get here
567 pragma Assert (False);
568 raise Standard'Abort_Signal;
571 Initialize_ATCB (Self_ID, State, Discriminants, P, Elaborated,
572 Base_Priority, Task_Info, Size, T, Success);
578 Initialization.Undefer_Abort_Nestable (Self_ID);
579 raise Storage_Error with "Failed to initialize task";
582 if Master = Foreign_Task_Level + 2 then
584 -- This should not happen, except when a foreign task creates non
585 -- library-level Ada tasks. In this case, we pretend the master is
586 -- a regular library level task, otherwise the run-time will get
587 -- confused when waiting for these tasks to terminate.
589 T.Master_of_Task := Library_Task_Level;
592 T.Master_of_Task := Master;
595 T.Master_Within := T.Master_of_Task + 1;
597 for L in T.Entry_Calls'Range loop
598 T.Entry_Calls (L).Self := T;
599 T.Entry_Calls (L).Level := L;
602 if Task_Image'Length = 0 then
603 T.Common.Task_Image_Len := 0;
606 T.Common.Task_Image (1) := Task_Image (Task_Image'First);
608 -- Remove unwanted blank space generated by 'Image
610 for J in Task_Image'First + 1 .. Task_Image'Last loop
611 if Task_Image (J) /= ' '
612 or else Task_Image (J - 1) /= '('
615 T.Common.Task_Image (Len) := Task_Image (J);
616 exit when Len = T.Common.Task_Image'Last;
620 T.Common.Task_Image_Len := Len;
626 -- Note: we should not call 'new' while holding locks since new
627 -- may use locks (e.g. RTS_Lock under Windows) itself and cause a
630 if Build_Entry_Names then
632 new Entry_Names_Array (1 .. Entry_Index (Num_Entries));
635 -- Create TSD as early as possible in the creation of a task, since it
636 -- may be used by the operation of Ada code within the task.
638 SSL.Create_TSD (T.Common.Compiler_Data);
639 T.Common.Activation_Link := Chain.T_ID;
641 Initialization.Initialize_Attributes_Link.all (T);
643 Initialization.Undefer_Abort_Nestable (Self_ID);
645 if Runtime_Traces then
646 Send_Trace_Info (T_Create, T);
654 function Current_Master return Master_Level is
656 return STPO.Self.Master_Within;
663 procedure Enter_Master is
664 Self_ID : constant Task_Id := STPO.Self;
666 Self_ID.Master_Within := Self_ID.Master_Within + 1;
669 -------------------------------
670 -- Expunge_Unactivated_Tasks --
671 -------------------------------
673 -- See procedure Close_Entries for the general case
675 procedure Expunge_Unactivated_Tasks (Chain : in out Activation_Chain) is
676 Self_ID : constant Task_Id := STPO.Self;
678 Call : Entry_Call_Link;
683 (Debug.Trace (Self_ID, "Expunge_Unactivated_Tasks", 'C'));
685 Initialization.Defer_Abort_Nestable (Self_ID);
688 -- Experimentation has shown that abort is sometimes (but not always)
689 -- already deferred when this is called.
691 -- That may indicate an error. Find out what is going on
695 pragma Assert (C.Common.State = Unactivated);
697 Temp := C.Common.Activation_Link;
699 if C.Common.State = Unactivated then
703 for J in 1 .. C.Entry_Num loop
704 Queuing.Dequeue_Head (C.Entry_Queues (J), Call);
705 pragma Assert (Call = null);
710 Initialization.Remove_From_All_Tasks_List (C);
713 Vulnerable_Free_Task (C);
719 Initialization.Undefer_Abort_Nestable (Self_ID);
720 end Expunge_Unactivated_Tasks;
722 ---------------------------
723 -- Finalize_Global_Tasks --
724 ---------------------------
727 -- We have a potential problem here if finalization of global objects does
728 -- anything with signals or the timer server, since by that time those
729 -- servers have terminated.
731 -- It is hard to see how that would occur
733 -- However, a better solution might be to do all this finalization
734 -- using the global finalization chain.
736 procedure Finalize_Global_Tasks is
737 Self_ID : constant Task_Id := STPO.Self;
740 pragma Unreferenced (Ignore);
743 if Self_ID.Deferral_Level = 0 then
745 -- In principle, we should be able to predict whether abort is
746 -- already deferred here (and it should not be deferred yet but in
747 -- practice it seems Finalize_Global_Tasks is being called sometimes,
748 -- from RTS code for exceptions, with abort already deferred.
750 Initialization.Defer_Abort_Nestable (Self_ID);
752 -- Never undefer again!!!
755 -- This code is only executed by the environment task
757 pragma Assert (Self_ID = Environment_Task);
759 -- Set Environment_Task'Callable to false to notify library-level tasks
760 -- that it is waiting for them.
762 Self_ID.Callable := False;
764 -- Exit level 2 master, for normal tasks in library-level packages
768 -- Force termination of "independent" library-level server tasks
772 Abort_Dependents (Self_ID);
774 if not Single_Lock then
778 -- We need to explicitly wait for the task to be terminated here
779 -- because on true concurrent system, we may end this procedure before
780 -- the tasks are really terminated.
782 Write_Lock (Self_ID);
785 exit when Utilities.Independent_Task_Count = 0;
787 -- We used to yield here, but this did not take into account low
788 -- priority tasks that would cause dead lock in some cases (true
792 (Self_ID, 0.01, System.OS_Primitives.Relative,
793 Self_ID.Common.State, Ignore, Ignore);
796 -- ??? On multi-processor environments, it seems that the above loop
797 -- isn't sufficient, so we need to add an additional delay.
800 (Self_ID, 0.01, System.OS_Primitives.Relative,
801 Self_ID.Common.State, Ignore, Ignore);
809 -- Complete the environment task
811 Vulnerable_Complete_Task (Self_ID);
813 -- Handle normal task termination by the environment task, but only
814 -- for the normal task termination. In the case of Abnormal and
815 -- Unhandled_Exception they must have been handled before, and the
816 -- task termination soft link must have been changed so the task
817 -- termination routine is not executed twice.
819 SSL.Task_Termination_Handler.all (Ada.Exceptions.Null_Occurrence);
821 -- Finalize the global list for controlled objects if needed
823 SSL.Finalize_Global_List.all;
825 -- Reset the soft links to non-tasking
827 SSL.Abort_Defer := SSL.Abort_Defer_NT'Access;
828 SSL.Abort_Undefer := SSL.Abort_Undefer_NT'Access;
829 SSL.Lock_Task := SSL.Task_Lock_NT'Access;
830 SSL.Unlock_Task := SSL.Task_Unlock_NT'Access;
831 SSL.Get_Jmpbuf_Address := SSL.Get_Jmpbuf_Address_NT'Access;
832 SSL.Set_Jmpbuf_Address := SSL.Set_Jmpbuf_Address_NT'Access;
833 SSL.Get_Sec_Stack_Addr := SSL.Get_Sec_Stack_Addr_NT'Access;
834 SSL.Set_Sec_Stack_Addr := SSL.Set_Sec_Stack_Addr_NT'Access;
835 SSL.Check_Abort_Status := SSL.Check_Abort_Status_NT'Access;
836 SSL.Get_Stack_Info := SSL.Get_Stack_Info_NT'Access;
838 -- Don't bother trying to finalize Initialization.Global_Task_Lock
839 -- and System.Task_Primitives.RTS_Lock.
841 end Finalize_Global_Tasks;
843 ----------------------
844 -- Free_Entry_Names --
845 ----------------------
847 procedure Free_Entry_Names (T : Task_Id) is
848 Names : Entry_Names_Array_Access := T.Entry_Names;
850 procedure Free_Entry_Names_Array_Access is new
851 Ada.Unchecked_Deallocation
852 (Entry_Names_Array, Entry_Names_Array_Access);
859 Free_Entry_Names_Array (Names.all);
860 Free_Entry_Names_Array_Access (Names);
861 end Free_Entry_Names;
867 procedure Free_Task (T : Task_Id) is
868 Self_Id : constant Task_Id := Self;
871 if T.Common.State = Terminated then
873 -- It is not safe to call Abort_Defer or Write_Lock at this stage
875 Initialization.Task_Lock (Self_Id);
878 Initialization.Finalize_Attributes_Link.all (T);
879 Initialization.Remove_From_All_Tasks_List (T);
882 Initialization.Task_Unlock (Self_Id);
884 Free_Entry_Names (T);
885 System.Task_Primitives.Operations.Finalize_TCB (T);
887 -- If the task is not terminated, then we simply ignore the call. This
888 -- happens when a user program attempts an unchecked deallocation on
889 -- a non-terminated task.
896 ---------------------------
897 -- Move_Activation_Chain --
898 ---------------------------
900 procedure Move_Activation_Chain
901 (From, To : Activation_Chain_Access;
902 New_Master : Master_ID)
904 Self_ID : constant Task_Id := STPO.Self;
909 (Debug.Trace (Self_ID, "Move_Activation_Chain", 'C'));
911 -- Nothing to do if From is empty, and we can check that without
920 Initialization.Defer_Abort (Self_ID);
922 -- Loop through the From chain, changing their Master_of_Task
923 -- fields, and to find the end of the chain.
926 C.Master_of_Task := New_Master;
927 exit when C.Common.Activation_Link = null;
928 C := C.Common.Activation_Link;
931 -- Hook From in at the start of To
933 C.Common.Activation_Link := To.all.T_ID;
934 To.all.T_ID := From.all.T_ID;
938 From.all.T_ID := null;
940 Initialization.Undefer_Abort (Self_ID);
941 end Move_Activation_Chain;
943 -- Compiler interface only. Do not call from within the RTS
949 procedure Set_Entry_Name
951 Pos : Task_Entry_Index;
955 pragma Assert (T.Entry_Names /= null);
957 T.Entry_Names (Entry_Index (Pos)) := Val;
964 -- The task wrapper is a procedure that is called first for each task body
965 -- and which in turn calls the compiler-generated task body procedure.
966 -- The wrapper's main job is to do initialization for the task. It also
967 -- has some locally declared objects that serve as per-task local data.
968 -- Task finalization is done by Complete_Task, which is called from an
969 -- at-end handler that the compiler generates.
971 procedure Task_Wrapper (Self_ID : Task_Id) is
972 use type SSE.Storage_Offset;
973 use System.Standard_Library;
974 use System.Stack_Usage;
976 Bottom_Of_Stack : aliased Integer;
978 Task_Alternate_Stack :
979 aliased SSE.Storage_Array (1 .. Alternate_Stack_Size);
980 -- The alternate signal stack for this task, if any
982 Use_Alternate_Stack : constant Boolean := Alternate_Stack_Size /= 0;
983 -- Whether to use above alternate signal stack for stack overflows
985 Secondary_Stack_Size :
986 constant SSE.Storage_Offset :=
987 Self_ID.Common.Compiler_Data.Pri_Stack_Info.Size *
988 SSE.Storage_Offset (Parameters.Sec_Stack_Ratio) / 100;
990 Secondary_Stack : aliased SSE.Storage_Array (1 .. Secondary_Stack_Size);
992 pragma Warnings (Off);
993 -- Why are warnings being turned off here???
995 Secondary_Stack_Address : System.Address := Secondary_Stack'Address;
996 -- Address of secondary stack. In the fixed secondary stack case, this
997 -- value is not modified, causing a warning, hence the bracketing with
998 -- Warnings (Off/On). But why is so much *more* bracketed???
1000 Small_Overflow_Guard : constant := 12 * 1024;
1001 -- Note: this used to be 4K, but was changed to 12K, since smaller
1002 -- values resulted in segmentation faults from dynamic stack analysis.
1004 Big_Overflow_Guard : constant := 16 * 1024;
1005 Small_Stack_Limit : constant := 64 * 1024;
1006 -- ??? These three values are experimental, and seems to work on most
1007 -- platforms. They still need to be analyzed further. They also need
1008 -- documentation, what are they???
1011 Natural (Self_ID.Common.Compiler_Data.Pri_Stack_Info.Size);
1013 Overflow_Guard : Natural;
1014 -- Size of the overflow guard, used by dynamic stack usage analysis
1016 pragma Warnings (On);
1018 SEH_Table : aliased SSE.Storage_Array (1 .. 8);
1019 -- Structured Exception Registration table (2 words)
1021 procedure Install_SEH_Handler (Addr : System.Address);
1022 pragma Import (C, Install_SEH_Handler, "__gnat_install_SEH_handler");
1023 -- Install the SEH (Structured Exception Handling) handler
1025 Cause : Cause_Of_Termination := Normal;
1026 -- Indicates the reason why this task terminates. Normal corresponds to
1027 -- a task terminating due to completing the last statement of its body,
1028 -- or as a result of waiting on a terminate alternative. If the task
1029 -- terminates because it is being aborted then Cause will be set to
1030 -- Abnormal. If the task terminates because of an exception raised by
1031 -- the execution of its task body, then Cause is set to
1032 -- Unhandled_Exception.
1034 EO : Exception_Occurrence;
1035 -- If the task terminates because of an exception raised by the
1036 -- execution of its task body, then EO will contain the associated
1037 -- exception occurrence. Otherwise, it will contain Null_Occurrence.
1039 TH : Termination_Handler := null;
1040 -- Pointer to the protected procedure to be executed upon task
1043 procedure Search_Fall_Back_Handler (ID : Task_Id);
1044 -- Procedure that searches recursively a fall-back handler through the
1045 -- master relationship. If the handler is found, its pointer is stored
1048 ------------------------------
1049 -- Search_Fall_Back_Handler --
1050 ------------------------------
1052 procedure Search_Fall_Back_Handler (ID : Task_Id) is
1054 -- If there is a fall back handler, store its pointer for later
1057 if ID.Common.Fall_Back_Handler /= null then
1058 TH := ID.Common.Fall_Back_Handler;
1060 -- Otherwise look for a fall back handler in the parent
1062 elsif ID.Common.Parent /= null then
1063 Search_Fall_Back_Handler (ID.Common.Parent);
1065 -- Otherwise, do nothing
1070 end Search_Fall_Back_Handler;
1073 pragma Assert (Self_ID.Deferral_Level = 1);
1075 -- Assume a size of the stack taken at this stage
1078 (if Size < Small_Stack_Limit
1079 then Small_Overflow_Guard
1080 else Big_Overflow_Guard);
1082 if not Parameters.Sec_Stack_Dynamic then
1083 Self_ID.Common.Compiler_Data.Sec_Stack_Addr :=
1084 Secondary_Stack'Address;
1085 SST.SS_Init (Secondary_Stack_Address, Integer (Secondary_Stack'Last));
1086 Size := Size - Natural (Secondary_Stack_Size);
1089 if Use_Alternate_Stack then
1090 Self_ID.Common.Task_Alternate_Stack := Task_Alternate_Stack'Address;
1093 Size := Size - Overflow_Guard;
1095 if System.Stack_Usage.Is_Enabled then
1098 (Self_ID.Common.Analyzer,
1099 Self_ID.Common.Task_Image
1100 (1 .. Self_ID.Common.Task_Image_Len),
1102 (Self_ID.Common.Compiler_Data.Pri_Stack_Info.Size),
1104 SSE.To_Integer (Bottom_Of_Stack'Address));
1106 Fill_Stack (Self_ID.Common.Analyzer);
1109 -- Set the guard page at the bottom of the stack. The call to unprotect
1110 -- the page is done in Terminate_Task
1112 Stack_Guard (Self_ID, True);
1114 -- Initialize low-level TCB components, that cannot be initialized by
1115 -- the creator. Enter_Task sets Self_ID.LL.Thread
1117 Enter_Task (Self_ID);
1119 -- We setup the SEH (Structured Exception Handling) handler if supported
1122 Install_SEH_Handler (SEH_Table'Address);
1124 -- Initialize exception occurrence
1126 Save_Occurrence (EO, Ada.Exceptions.Null_Occurrence);
1128 -- We lock RTS_Lock to wait for activator to finish activating the rest
1129 -- of the chain, so that everyone in the chain comes out in priority
1132 -- This also protects the value of
1133 -- Self_ID.Common.Activator.Common.Wait_Count.
1138 if not System.Restrictions.Abort_Allowed then
1140 -- If Abort is not allowed, reset the deferral level since it will
1141 -- not get changed by the generated code. Keeping a default value
1142 -- of one would prevent some operations (e.g. select or delay) to
1143 -- proceed successfully.
1145 Self_ID.Deferral_Level := 0;
1148 if Global_Task_Debug_Event_Set then
1149 Debug.Signal_Debug_Event
1150 (Debug.Debug_Event_Run, Self_ID);
1154 -- We are separating the following portion of the code in order to
1155 -- place the exception handlers in a different block. In this way,
1156 -- we do not call Set_Jmpbuf_Address (which needs Self) before we
1157 -- set Self in Enter_Task
1159 -- Call the task body procedure
1161 -- The task body is called with abort still deferred. That
1162 -- eliminates a dangerous window, for which we had to patch-up in
1165 -- During the expansion of the task body, we insert an RTS-call
1166 -- to Abort_Undefer, at the first point where abort should be
1169 Self_ID.Common.Task_Entry_Point (Self_ID.Common.Task_Arg);
1170 Initialization.Defer_Abort_Nestable (Self_ID);
1173 -- We can't call Terminate_Task in the exception handlers below,
1174 -- since there may be (e.g. in the case of GCC exception handling)
1175 -- clean ups associated with the exception handler that need to
1176 -- access task specific data.
1178 -- Defer abort so that this task can't be aborted while exiting
1180 when Standard'Abort_Signal =>
1181 Initialization.Defer_Abort_Nestable (Self_ID);
1183 -- Update the cause that motivated the task termination so that
1184 -- the appropriate information is passed to the task termination
1185 -- procedure. Task termination as a result of waiting on a
1186 -- terminate alternative is a normal termination, although it is
1187 -- implemented using the abort mechanisms.
1189 if Self_ID.Terminate_Alternative then
1192 if Global_Task_Debug_Event_Set then
1193 Debug.Signal_Debug_Event
1194 (Debug.Debug_Event_Terminated, Self_ID);
1199 if Global_Task_Debug_Event_Set then
1200 Debug.Signal_Debug_Event
1201 (Debug.Debug_Event_Abort_Terminated, Self_ID);
1205 -- ??? Using an E : others here causes CD2C11A to fail on Tru64
1207 Initialization.Defer_Abort_Nestable (Self_ID);
1209 -- Perform the task specific exception tracing duty. We handle
1210 -- these outputs here and not in the common notification routine
1211 -- because we need access to tasking related data and we don't
1212 -- want to drag dependencies against tasking related units in the
1213 -- the common notification units. Additionally, no trace is ever
1214 -- triggered from the common routine for the Unhandled_Raise case
1215 -- in tasks, since an exception never appears unhandled in this
1216 -- context because of this handler.
1218 if Exception_Trace = Unhandled_Raise then
1219 Trace_Unhandled_Exception_In_Task (Self_ID);
1222 -- Update the cause that motivated the task termination so that
1223 -- the appropriate information is passed to the task termination
1224 -- procedure, as well as the associated Exception_Occurrence.
1226 Cause := Unhandled_Exception;
1228 Save_Occurrence (EO, SSL.Get_Current_Excep.all.all);
1230 if Global_Task_Debug_Event_Set then
1231 Debug.Signal_Debug_Event
1232 (Debug.Debug_Event_Exception_Terminated, Self_ID);
1236 -- Look for a task termination handler. This code is for all tasks but
1237 -- the environment task. The task termination code for the environment
1238 -- task is executed by SSL.Task_Termination_Handler.
1244 Write_Lock (Self_ID);
1246 if Self_ID.Common.Specific_Handler /= null then
1247 TH := Self_ID.Common.Specific_Handler;
1249 -- Look for a fall-back handler following the master relationship
1252 Search_Fall_Back_Handler (Self_ID);
1261 -- Execute the task termination handler if we found it
1264 TH.all (Cause, Self_ID, EO);
1267 if System.Stack_Usage.Is_Enabled then
1268 Compute_Result (Self_ID.Common.Analyzer);
1269 Report_Result (Self_ID.Common.Analyzer);
1272 Terminate_Task (Self_ID);
1275 --------------------
1276 -- Terminate_Task --
1277 --------------------
1279 -- Before we allow the thread to exit, we must clean up. This is a
1280 -- delicate job. We must wake up the task's master, who may immediately try
1281 -- to deallocate the ATCB out from under the current task WHILE IT IS STILL
1284 -- To avoid this, the parent task must be blocked up to the latest
1285 -- statement executed. The trouble is that we have another step that we
1286 -- also want to postpone to the very end, i.e., calling SSL.Destroy_TSD.
1287 -- We have to postpone that until the end because compiler-generated code
1288 -- is likely to try to access that data at just about any point.
1290 -- We can't call Destroy_TSD while we are holding any other locks, because
1291 -- it locks Global_Task_Lock, and our deadlock prevention rules require
1292 -- that to be the outermost lock. Our first "solution" was to just lock
1293 -- Global_Task_Lock in addition to the other locks, and force the parent to
1294 -- also lock this lock between its wakeup and its freeing of the ATCB. See
1295 -- Complete_Task for the parent-side of the code that has the matching
1296 -- calls to Task_Lock and Task_Unlock. That was not really a solution,
1297 -- since the operation Task_Unlock continued to access the ATCB after
1298 -- unlocking, after which the parent was observed to race ahead, deallocate
1299 -- the ATCB, and then reallocate it to another task. The call to
1300 -- Undefer_Abort in Task_Unlock by the "terminated" task was overwriting
1301 -- the data of the new task that reused the ATCB! To solve this problem, we
1302 -- introduced the new operation Final_Task_Unlock.
1304 procedure Terminate_Task (Self_ID : Task_Id) is
1305 Environment_Task : constant Task_Id := STPO.Environment_Task;
1306 Master_of_Task : Integer;
1309 Debug.Task_Termination_Hook;
1311 if Runtime_Traces then
1312 Send_Trace_Info (T_Terminate);
1315 -- Since GCC cannot allocate stack chunks efficiently without reordering
1316 -- some of the allocations, we have to handle this unexpected situation
1317 -- here. We should normally never have to call Vulnerable_Complete_Task
1320 if Self_ID.Common.Activator /= null then
1321 Vulnerable_Complete_Task (Self_ID);
1324 Initialization.Task_Lock (Self_ID);
1330 Master_of_Task := Self_ID.Master_of_Task;
1332 -- Check if the current task is an independent task If so, decrement
1333 -- the Independent_Task_Count value.
1335 if Master_of_Task = Independent_Task_Level then
1337 Utilities.Independent_Task_Count :=
1338 Utilities.Independent_Task_Count - 1;
1340 Write_Lock (Environment_Task);
1341 Utilities.Independent_Task_Count :=
1342 Utilities.Independent_Task_Count - 1;
1343 Unlock (Environment_Task);
1347 -- Unprotect the guard page if needed
1349 Stack_Guard (Self_ID, False);
1351 Utilities.Make_Passive (Self_ID, Task_Completed => True);
1357 pragma Assert (Check_Exit (Self_ID));
1359 SSL.Destroy_TSD (Self_ID.Common.Compiler_Data);
1360 Initialization.Final_Task_Unlock (Self_ID);
1362 -- WARNING: past this point, this thread must assume that the ATCB has
1363 -- been deallocated. It should not be accessed again.
1365 if Master_of_Task > 0 then
1374 function Terminated (T : Task_Id) return Boolean is
1375 Self_ID : constant Task_Id := STPO.Self;
1379 Initialization.Defer_Abort_Nestable (Self_ID);
1386 Result := T.Common.State = Terminated;
1393 Initialization.Undefer_Abort_Nestable (Self_ID);
1397 ----------------------------------------
1398 -- Trace_Unhandled_Exception_In_Task --
1399 ----------------------------------------
1401 procedure Trace_Unhandled_Exception_In_Task (Self_Id : Task_Id) is
1402 procedure To_Stderr (S : String);
1403 pragma Import (Ada, To_Stderr, "__gnat_to_stderr");
1405 use System.Soft_Links;
1406 use System.Standard_Library;
1408 function To_Address is new
1409 Ada.Unchecked_Conversion
1410 (Task_Id, System.Task_Primitives.Task_Address);
1412 function Tailored_Exception_Information
1413 (E : Exception_Occurrence) return String;
1415 (Ada, Tailored_Exception_Information,
1416 "__gnat_tailored_exception_information");
1418 Excep : constant Exception_Occurrence_Access :=
1419 SSL.Get_Current_Excep.all;
1422 -- This procedure is called by the task outermost handler in
1423 -- Task_Wrapper below, so only once the task stack has been fully
1424 -- unwound. The common notification routine has been called at the
1425 -- raise point already.
1427 -- Lock to prevent unsynchronized output
1429 Initialization.Task_Lock (Self_Id);
1430 To_Stderr ("task ");
1432 if Self_Id.Common.Task_Image_Len /= 0 then
1434 (Self_Id.Common.Task_Image (1 .. Self_Id.Common.Task_Image_Len));
1438 To_Stderr (System.Address_Image (To_Address (Self_Id)));
1439 To_Stderr (" terminated by unhandled exception");
1440 To_Stderr ((1 => ASCII.LF));
1441 To_Stderr (Tailored_Exception_Information (Excep.all));
1442 Initialization.Task_Unlock (Self_Id);
1443 end Trace_Unhandled_Exception_In_Task;
1445 ------------------------------------
1446 -- Vulnerable_Complete_Activation --
1447 ------------------------------------
1449 -- As in several other places, the locks of the activator and activated
1450 -- task are both locked here. This follows our deadlock prevention lock
1451 -- ordering policy, since the activated task must be created after the
1454 procedure Vulnerable_Complete_Activation (Self_ID : Task_Id) is
1455 Activator : constant Task_Id := Self_ID.Common.Activator;
1458 pragma Debug (Debug.Trace (Self_ID, "V_Complete_Activation", 'C'));
1460 Write_Lock (Activator);
1461 Write_Lock (Self_ID);
1463 pragma Assert (Self_ID.Common.Activator /= null);
1465 -- Remove dangling reference to Activator, since a task may
1466 -- outlive its activator.
1468 Self_ID.Common.Activator := null;
1470 -- Wake up the activator, if it is waiting for a chain of tasks to
1471 -- activate, and we are the last in the chain to complete activation.
1473 if Activator.Common.State = Activator_Sleep then
1474 Activator.Common.Wait_Count := Activator.Common.Wait_Count - 1;
1476 if Activator.Common.Wait_Count = 0 then
1477 Wakeup (Activator, Activator_Sleep);
1481 -- The activator raises a Tasking_Error if any task it is activating
1482 -- is completed before the activation is done. However, if the reason
1483 -- for the task completion is an abort, we do not raise an exception.
1486 if not Self_ID.Callable and then Self_ID.Pending_ATC_Level /= 0 then
1487 Activator.Common.Activation_Failed := True;
1493 -- After the activation, active priority should be the same as base
1494 -- priority. We must unlock the Activator first, though, since it
1495 -- should not wait if we have lower priority.
1497 if Get_Priority (Self_ID) /= Self_ID.Common.Base_Priority then
1498 Write_Lock (Self_ID);
1499 Set_Priority (Self_ID, Self_ID.Common.Base_Priority);
1502 end Vulnerable_Complete_Activation;
1504 --------------------------------
1505 -- Vulnerable_Complete_Master --
1506 --------------------------------
1508 procedure Vulnerable_Complete_Master (Self_ID : Task_Id) is
1511 CM : constant Master_Level := Self_ID.Master_Within;
1512 T : aliased Task_Id;
1514 To_Be_Freed : Task_Id;
1515 -- This is a list of ATCBs to be freed, after we have released all RTS
1516 -- locks. This is necessary because of the locking order rules, since
1517 -- the storage manager uses Global_Task_Lock.
1519 pragma Warnings (Off);
1520 function Check_Unactivated_Tasks return Boolean;
1521 pragma Warnings (On);
1522 -- Temporary error-checking code below. This is part of the checks
1523 -- added in the new run time. Call it only inside a pragma Assert.
1525 -----------------------------
1526 -- Check_Unactivated_Tasks --
1527 -----------------------------
1529 function Check_Unactivated_Tasks return Boolean is
1531 if not Single_Lock then
1535 Write_Lock (Self_ID);
1537 C := All_Tasks_List;
1538 while C /= null loop
1539 if C.Common.Activator = Self_ID and then C.Master_of_Task = CM then
1543 if C.Common.Parent = Self_ID and then C.Master_of_Task = CM then
1546 if C.Common.State = Unactivated then
1553 C := C.Common.All_Tasks_Link;
1558 if not Single_Lock then
1563 end Check_Unactivated_Tasks;
1565 -- Start of processing for Vulnerable_Complete_Master
1569 (Debug.Trace (Self_ID, "V_Complete_Master", 'C'));
1571 pragma Assert (Self_ID.Common.Wait_Count = 0);
1573 (Self_ID.Deferral_Level > 0
1574 or else not System.Restrictions.Abort_Allowed);
1576 -- Count how many active dependent tasks this master currently has, and
1577 -- record this in Wait_Count.
1579 -- This count should start at zero, since it is initialized to zero for
1580 -- new tasks, and the task should not exit the sleep-loops that use this
1581 -- count until the count reaches zero.
1583 -- While we're counting, if we run across any unactivated tasks that
1584 -- belong to this master, we summarily terminate them as required by
1588 Write_Lock (Self_ID);
1590 C := All_Tasks_List;
1591 while C /= null loop
1593 -- Terminate unactivated (never-to-be activated) tasks
1595 if C.Common.Activator = Self_ID and then C.Master_of_Task = CM then
1597 pragma Assert (C.Common.State = Unactivated);
1598 -- Usually, C.Common.Activator = Self_ID implies C.Master_of_Task
1599 -- = CM. The only case where C is pending activation by this
1600 -- task, but the master of C is not CM is in Ada 2005, when C is
1601 -- part of a return object of a build-in-place function.
1604 C.Common.Activator := null;
1605 C.Common.State := Terminated;
1606 C.Callable := False;
1607 Utilities.Cancel_Queued_Entry_Calls (C);
1611 -- Count it if dependent on this master
1613 if C.Common.Parent = Self_ID and then C.Master_of_Task = CM then
1616 if C.Awake_Count /= 0 then
1617 Self_ID.Common.Wait_Count := Self_ID.Common.Wait_Count + 1;
1623 C := C.Common.All_Tasks_Link;
1626 Self_ID.Common.State := Master_Completion_Sleep;
1629 if not Single_Lock then
1633 -- Wait until dependent tasks are all terminated or ready to terminate.
1634 -- While waiting, the task may be awakened if the task's priority needs
1635 -- changing, or this master is aborted. In the latter case, we abort the
1636 -- dependents, and resume waiting until Wait_Count goes to zero.
1638 Write_Lock (Self_ID);
1641 exit when Self_ID.Common.Wait_Count = 0;
1643 -- Here is a difference as compared to Complete_Master
1645 if Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level
1646 and then not Self_ID.Dependents_Aborted
1649 Abort_Dependents (Self_ID);
1653 Abort_Dependents (Self_ID);
1655 Write_Lock (Self_ID);
1658 Sleep (Self_ID, Master_Completion_Sleep);
1662 Self_ID.Common.State := Runnable;
1665 -- Dependents are all terminated or on terminate alternatives. Now,
1666 -- force those on terminate alternatives to terminate, by aborting them.
1668 pragma Assert (Check_Unactivated_Tasks);
1670 if Self_ID.Alive_Count > 1 then
1672 -- Consider finding a way to skip the following extra steps if there
1673 -- are no dependents with terminate alternatives. This could be done
1674 -- by adding another count to the ATCB, similar to Awake_Count, but
1675 -- keeping track of tasks that are on terminate alternatives.
1677 pragma Assert (Self_ID.Common.Wait_Count = 0);
1679 -- Force any remaining dependents to terminate by aborting them
1681 if not Single_Lock then
1685 Abort_Dependents (Self_ID);
1687 -- Above, when we "abort" the dependents we are simply using this
1688 -- operation for convenience. We are not required to support the full
1689 -- abort-statement semantics; in particular, we are not required to
1690 -- immediately cancel any queued or in-service entry calls. That is
1691 -- good, because if we tried to cancel a call we would need to lock
1692 -- the caller, in order to wake the caller up. Our anti-deadlock
1693 -- rules prevent us from doing that without releasing the locks on C
1694 -- and Self_ID. Releasing and retaking those locks would be wasteful
1695 -- at best, and should not be considered further without more
1696 -- detailed analysis of potential concurrent accesses to the ATCBs
1697 -- of C and Self_ID.
1699 -- Count how many "alive" dependent tasks this master currently has,
1700 -- and record this in Wait_Count. This count should start at zero,
1701 -- since it is initialized to zero for new tasks, and the task should
1702 -- not exit the sleep-loops that use this count until the count
1705 pragma Assert (Self_ID.Common.Wait_Count = 0);
1707 Write_Lock (Self_ID);
1709 C := All_Tasks_List;
1710 while C /= null loop
1711 if C.Common.Parent = Self_ID and then C.Master_of_Task = CM then
1714 pragma Assert (C.Awake_Count = 0);
1716 if C.Alive_Count > 0 then
1717 pragma Assert (C.Terminate_Alternative);
1718 Self_ID.Common.Wait_Count := Self_ID.Common.Wait_Count + 1;
1724 C := C.Common.All_Tasks_Link;
1727 Self_ID.Common.State := Master_Phase_2_Sleep;
1730 if not Single_Lock then
1734 -- Wait for all counted tasks to finish terminating themselves
1736 Write_Lock (Self_ID);
1739 exit when Self_ID.Common.Wait_Count = 0;
1740 Sleep (Self_ID, Master_Phase_2_Sleep);
1743 Self_ID.Common.State := Runnable;
1747 -- We don't wake up for abort here. We are already terminating just as
1748 -- fast as we can, so there is no point.
1750 -- Remove terminated tasks from the list of Self_ID's dependents, but
1751 -- don't free their ATCBs yet, because of lock order restrictions, which
1752 -- don't allow us to call "free" or "malloc" while holding any other
1753 -- locks. Instead, we put those ATCBs to be freed onto a temporary list,
1754 -- called To_Be_Freed.
1756 if not Single_Lock then
1760 C := All_Tasks_List;
1762 while C /= null loop
1763 if C.Common.Parent = Self_ID and then C.Master_of_Task >= CM then
1765 P.Common.All_Tasks_Link := C.Common.All_Tasks_Link;
1767 All_Tasks_List := C.Common.All_Tasks_Link;
1770 T := C.Common.All_Tasks_Link;
1771 C.Common.All_Tasks_Link := To_Be_Freed;
1777 C := C.Common.All_Tasks_Link;
1783 -- Free all the ATCBs on the list To_Be_Freed
1785 -- The ATCBs in the list are no longer in All_Tasks_List, and after
1786 -- any interrupt entries are detached from them they should no longer
1789 -- Global_Task_Lock (Task_Lock/Unlock) is locked in the loop below to
1790 -- avoid a race between a terminating task and its parent. The parent
1791 -- might try to deallocate the ACTB out from underneath the exiting
1792 -- task. Note that Free will also lock Global_Task_Lock, but that is
1793 -- OK, since this is the *one* lock for which we have a mechanism to
1794 -- support nested locking. See Task_Wrapper and its finalizer for more
1798 -- The check "T.Common.Parent /= null ..." below is to prevent dangling
1799 -- references to terminated library-level tasks, which could otherwise
1800 -- occur during finalization of library-level objects. A better solution
1801 -- might be to hook task objects into the finalization chain and
1802 -- deallocate the ATCB when the task object is deallocated. However,
1803 -- this change is not likely to gain anything significant, since all
1804 -- this storage should be recovered en-masse when the process exits.
1806 while To_Be_Freed /= null loop
1808 To_Be_Freed := T.Common.All_Tasks_Link;
1810 -- ??? On SGI there is currently no Interrupt_Manager, that's why we
1811 -- need to check if the Interrupt_Manager_ID is null.
1813 if T.Interrupt_Entry and then Interrupt_Manager_ID /= null then
1815 Detach_Interrupt_Entries_Index : constant Task_Entry_Index := 1;
1816 -- Corresponds to the entry index of System.Interrupts.
1817 -- Interrupt_Manager.Detach_Interrupt_Entries.
1818 -- Be sure to update this value when changing
1819 -- Interrupt_Manager specs.
1821 type Param_Type is access all Task_Id;
1823 Param : aliased Param_Type := T'Access;
1826 System.Tasking.Rendezvous.Call_Simple
1827 (Interrupt_Manager_ID, Detach_Interrupt_Entries_Index,
1832 if (T.Common.Parent /= null
1833 and then T.Common.Parent.Common.Parent /= null)
1834 or else T.Master_of_Task > Library_Task_Level
1836 Initialization.Task_Lock (Self_ID);
1838 -- If Sec_Stack_Addr is not null, it means that Destroy_TSD
1839 -- has not been called yet (case of an unactivated task).
1841 if T.Common.Compiler_Data.Sec_Stack_Addr /= Null_Address then
1842 SSL.Destroy_TSD (T.Common.Compiler_Data);
1845 Vulnerable_Free_Task (T);
1846 Initialization.Task_Unlock (Self_ID);
1850 -- It might seem nice to let the terminated task deallocate its own
1851 -- ATCB. That would not cover the case of unactivated tasks. It also
1852 -- would force us to keep the underlying thread around past termination,
1853 -- since references to the ATCB are possible past termination.
1855 -- Currently, we get rid of the thread as soon as the task terminates,
1856 -- and let the parent recover the ATCB later.
1858 -- Some day, if we want to recover the ATCB earlier, at task
1859 -- termination, we could consider using "fat task IDs", that include the
1860 -- serial number with the ATCB pointer, to catch references to tasks
1861 -- that no longer have ATCBs. It is not clear how much this would gain,
1862 -- since the user-level task object would still be occupying storage.
1864 -- Make next master level up active. We don't need to lock the ATCB,
1865 -- since the value is only updated by each task for itself.
1867 Self_ID.Master_Within := CM - 1;
1868 end Vulnerable_Complete_Master;
1870 ------------------------------
1871 -- Vulnerable_Complete_Task --
1872 ------------------------------
1874 -- Complete the calling task
1876 -- This procedure must be called with abort deferred. It should only be
1877 -- called by Complete_Task and Finalize_Global_Tasks (for the environment
1880 -- The effect is similar to that of Complete_Master. Differences include
1881 -- the closing of entries here, and computation of the number of active
1882 -- dependent tasks in Complete_Master.
1884 -- We don't lock Self_ID before the call to Vulnerable_Complete_Activation,
1885 -- because that does its own locking, and because we do not need the lock
1886 -- to test Self_ID.Common.Activator. That value should only be read and
1887 -- modified by Self.
1889 procedure Vulnerable_Complete_Task (Self_ID : Task_Id) is
1892 (Self_ID.Deferral_Level > 0
1893 or else not System.Restrictions.Abort_Allowed);
1894 pragma Assert (Self_ID = Self);
1895 pragma Assert (Self_ID.Master_Within = Self_ID.Master_of_Task + 1
1897 Self_ID.Master_Within = Self_ID.Master_of_Task + 2);
1898 pragma Assert (Self_ID.Common.Wait_Count = 0);
1899 pragma Assert (Self_ID.Open_Accepts = null);
1900 pragma Assert (Self_ID.ATC_Nesting_Level = 1);
1902 pragma Debug (Debug.Trace (Self_ID, "V_Complete_Task", 'C'));
1908 Write_Lock (Self_ID);
1909 Self_ID.Callable := False;
1911 -- In theory, Self should have no pending entry calls left on its
1912 -- call-stack. Each async. select statement should clean its own call,
1913 -- and blocking entry calls should defer abort until the calls are
1914 -- cancelled, then clean up.
1916 Utilities.Cancel_Queued_Entry_Calls (Self_ID);
1919 if Self_ID.Common.Activator /= null then
1920 Vulnerable_Complete_Activation (Self_ID);
1927 -- If Self_ID.Master_Within = Self_ID.Master_of_Task + 2 we may have
1928 -- dependent tasks for which we need to wait. Otherwise we just exit.
1930 if Self_ID.Master_Within = Self_ID.Master_of_Task + 2 then
1931 Vulnerable_Complete_Master (Self_ID);
1933 end Vulnerable_Complete_Task;
1935 --------------------------
1936 -- Vulnerable_Free_Task --
1937 --------------------------
1939 -- Recover all runtime system storage associated with the task T. This
1940 -- should only be called after T has terminated and will no longer be
1943 -- For tasks created by an allocator that fails, due to an exception, it
1944 -- is called from Expunge_Unactivated_Tasks.
1946 -- For tasks created by elaboration of task object declarations it is
1947 -- called from the finalization code of the Task_Wrapper procedure. It is
1948 -- also called from Ada.Unchecked_Deallocation, for objects that are or
1951 procedure Vulnerable_Free_Task (T : Task_Id) is
1953 pragma Debug (Debug.Trace (Self, "Vulnerable_Free_Task", 'C', T));
1960 Initialization.Finalize_Attributes_Link.all (T);
1967 Free_Entry_Names (T);
1968 System.Task_Primitives.Operations.Finalize_TCB (T);
1969 end Vulnerable_Free_Task;
1971 -- Package elaboration code
1974 -- Establish the Adafinal oftlink
1976 -- This is not done inside the central RTS initialization routine
1977 -- to avoid with-ing this package from System.Tasking.Initialization.
1979 SSL.Adafinal := Finalize_Global_Tasks'Access;
1981 -- Establish soft links for subprograms that manipulate master_id's.
1982 -- This cannot be done when the RTS is initialized, because of various
1983 -- elaboration constraints.
1985 SSL.Current_Master := Stages.Current_Master'Access;
1986 SSL.Enter_Master := Stages.Enter_Master'Access;
1987 SSL.Complete_Master := Stages.Complete_Master'Access;
1988 end System.Tasking.Stages;