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;
285 if C.Common.Base_Priority < Get_Priority (Self_ID) then
286 Activate_Prio := Get_Priority (Self_ID);
288 Activate_Prio := C.Common.Base_Priority;
291 System.Task_Primitives.Operations.Create_Task
292 (C, Task_Wrapper'Address,
294 (C.Common.Compiler_Data.Pri_Stack_Info.Size),
295 Activate_Prio, Success);
297 -- There would be a race between the created task and the creator
298 -- to do the following initialization, if we did not have a
299 -- Lock/Unlock_RTS pair in the task wrapper to prevent it from
303 C.Common.State := Activating;
306 P.Awake_Count := P.Awake_Count + 1;
307 P.Alive_Count := P.Alive_Count + 1;
309 if P.Common.State = Master_Completion_Sleep and then
310 C.Master_of_Task = P.Master_Within
312 pragma Assert (Self_ID /= P);
313 P.Common.Wait_Count := P.Common.Wait_Count + 1;
316 for J in System.Tasking.Debug.Known_Tasks'Range loop
317 if System.Tasking.Debug.Known_Tasks (J) = null then
318 System.Tasking.Debug.Known_Tasks (J) := C;
319 C.Known_Tasks_Index := J;
324 if Global_Task_Debug_Event_Set then
325 Debug.Signal_Debug_Event
326 (Debug.Debug_Event_Activating, C);
329 C.Common.State := Runnable;
335 -- No need to set Awake_Count, State, etc. here since the loop
336 -- below will do that for any Unactivated tasks.
340 Self_ID.Common.Activation_Failed := True;
344 C := C.Common.Activation_Link;
347 if not Single_Lock then
351 -- Close the entries of any tasks that failed thread creation, and count
352 -- those that have not finished activation.
354 Write_Lock (Self_ID);
355 Self_ID.Common.State := Activator_Sleep;
357 C := Chain_Access.T_ID;
361 if C.Common.State = Unactivated then
362 C.Common.Activator := null;
363 C.Common.State := Terminated;
365 Utilities.Cancel_Queued_Entry_Calls (C);
367 elsif C.Common.Activator /= null then
368 Self_ID.Common.Wait_Count := Self_ID.Common.Wait_Count + 1;
372 P := C.Common.Activation_Link;
373 C.Common.Activation_Link := null;
377 -- Wait for the activated tasks to complete activation. It is
378 -- unsafe to abort any of these tasks until the count goes to zero.
381 exit when Self_ID.Common.Wait_Count = 0;
382 Sleep (Self_ID, Activator_Sleep);
385 Self_ID.Common.State := Runnable;
392 -- Remove the tasks from the chain
394 Chain_Access.T_ID := null;
395 Initialization.Undefer_Abort_Nestable (Self_ID);
397 if Self_ID.Common.Activation_Failed then
398 Self_ID.Common.Activation_Failed := False;
399 raise Tasking_Error with "Failure during activation";
403 -------------------------
404 -- Complete_Activation --
405 -------------------------
407 procedure Complete_Activation is
408 Self_ID : constant Task_Id := STPO.Self;
411 Initialization.Defer_Abort_Nestable (Self_ID);
417 Vulnerable_Complete_Activation (Self_ID);
423 Initialization.Undefer_Abort_Nestable (Self_ID);
425 -- ??? Why do we need to allow for nested deferral here?
427 if Runtime_Traces then
428 Send_Trace_Info (T_Activate);
430 end Complete_Activation;
432 ---------------------
433 -- Complete_Master --
434 ---------------------
436 procedure Complete_Master is
437 Self_ID : constant Task_Id := STPO.Self;
440 (Self_ID.Deferral_Level > 0
441 or else not System.Restrictions.Abort_Allowed);
442 Vulnerable_Complete_Master (Self_ID);
449 -- See comments on Vulnerable_Complete_Task for details
451 procedure Complete_Task is
452 Self_ID : constant Task_Id := STPO.Self;
456 (Self_ID.Deferral_Level > 0
457 or else not System.Restrictions.Abort_Allowed);
459 Vulnerable_Complete_Task (Self_ID);
461 -- All of our dependents have terminated. Never undefer abort again!
469 -- Compiler interface only. Do not call from within the RTS. This must be
470 -- called to create a new task.
472 procedure Create_Task
474 Size : System.Parameters.Size_Type;
475 Task_Info : System.Task_Info.Task_Info_Type;
476 Relative_Deadline : Ada.Real_Time.Time_Span;
477 Num_Entries : Task_Entry_Index;
478 Master : Master_Level;
479 State : Task_Procedure_Access;
480 Discriminants : System.Address;
481 Elaborated : Access_Boolean;
482 Chain : in out Activation_Chain;
484 Created_Task : out Task_Id;
485 Build_Entry_Names : Boolean)
488 Self_ID : constant Task_Id := STPO.Self;
490 Base_Priority : System.Any_Priority;
493 pragma Unreferenced (Relative_Deadline);
494 -- EDF scheduling is not supported by any of the target platforms so
495 -- this parameter is not passed any further.
498 -- If Master is greater than the current master, it means that Master
499 -- has already awaited its dependent tasks. This raises Program_Error,
500 -- by 4.8(10.3/2). See AI-280. Ignore this check for foreign threads.
502 if Self_ID.Master_of_Task /= Foreign_Task_Level
503 and then Master > Self_ID.Master_Within
505 raise Program_Error with
506 "create task after awaiting termination";
509 -- If pragma Detect_Blocking is active must be checked whether this
510 -- potentially blocking operation is called from a protected action.
512 if System.Tasking.Detect_Blocking
513 and then Self_ID.Common.Protected_Action_Nesting > 0
515 raise Program_Error with "potentially blocking operation";
519 (Debug.Trace (Self_ID, "Create_Task", 'C'));
521 if Priority = Unspecified_Priority then
522 Base_Priority := Self_ID.Common.Base_Priority;
524 Base_Priority := System.Any_Priority (Priority);
527 -- Find parent P of new Task, via master level number
532 while P.Master_of_Task >= Master loop
533 P := P.Common.Parent;
538 Initialization.Defer_Abort_Nestable (Self_ID);
541 T := New_ATCB (Num_Entries);
544 Initialization.Undefer_Abort_Nestable (Self_ID);
545 raise Storage_Error with "Cannot allocate task";
548 -- RTS_Lock is used by Abort_Dependents and Abort_Tasks. Up to this
549 -- point, it is possible that we may be part of a family of tasks that
553 Write_Lock (Self_ID);
555 -- Now, we must check that we have not been aborted. If so, we should
556 -- give up on creating this task, and simply return.
558 if not Self_ID.Callable then
559 pragma Assert (Self_ID.Pending_ATC_Level = 0);
560 pragma Assert (Self_ID.Pending_Action);
562 (Chain.T_ID = null or else Chain.T_ID.Common.State = Unactivated);
566 Initialization.Undefer_Abort_Nestable (Self_ID);
568 -- ??? Should never get here
570 pragma Assert (False);
571 raise Standard'Abort_Signal;
574 Initialize_ATCB (Self_ID, State, Discriminants, P, Elaborated,
575 Base_Priority, Task_Info, Size, T, Success);
581 Initialization.Undefer_Abort_Nestable (Self_ID);
582 raise Storage_Error with "Failed to initialize task";
585 if Master = Foreign_Task_Level + 2 then
587 -- This should not happen, except when a foreign task creates non
588 -- library-level Ada tasks. In this case, we pretend the master is
589 -- a regular library level task, otherwise the run-time will get
590 -- confused when waiting for these tasks to terminate.
592 T.Master_of_Task := Library_Task_Level;
594 T.Master_of_Task := Master;
597 T.Master_Within := T.Master_of_Task + 1;
599 for L in T.Entry_Calls'Range loop
600 T.Entry_Calls (L).Self := T;
601 T.Entry_Calls (L).Level := L;
604 if Task_Image'Length = 0 then
605 T.Common.Task_Image_Len := 0;
608 T.Common.Task_Image (1) := Task_Image (Task_Image'First);
610 -- Remove unwanted blank space generated by 'Image
612 for J in Task_Image'First + 1 .. Task_Image'Last loop
613 if Task_Image (J) /= ' '
614 or else Task_Image (J - 1) /= '('
617 T.Common.Task_Image (Len) := Task_Image (J);
618 exit when Len = T.Common.Task_Image'Last;
622 T.Common.Task_Image_Len := Len;
625 if Build_Entry_Names then
627 new Entry_Names_Array (1 .. Entry_Index (Num_Entries));
633 -- Create TSD as early as possible in the creation of a task, since it
634 -- may be used by the operation of Ada code within the task.
636 SSL.Create_TSD (T.Common.Compiler_Data);
637 T.Common.Activation_Link := Chain.T_ID;
639 Initialization.Initialize_Attributes_Link.all (T);
641 Initialization.Undefer_Abort_Nestable (Self_ID);
643 if Runtime_Traces then
644 Send_Trace_Info (T_Create, T);
652 function Current_Master return Master_Level is
654 return STPO.Self.Master_Within;
661 procedure Enter_Master is
662 Self_ID : constant Task_Id := STPO.Self;
664 Self_ID.Master_Within := Self_ID.Master_Within + 1;
667 -------------------------------
668 -- Expunge_Unactivated_Tasks --
669 -------------------------------
671 -- See procedure Close_Entries for the general case
673 procedure Expunge_Unactivated_Tasks (Chain : in out Activation_Chain) is
674 Self_ID : constant Task_Id := STPO.Self;
676 Call : Entry_Call_Link;
681 (Debug.Trace (Self_ID, "Expunge_Unactivated_Tasks", 'C'));
683 Initialization.Defer_Abort_Nestable (Self_ID);
686 -- Experimentation has shown that abort is sometimes (but not always)
687 -- already deferred when this is called.
689 -- That may indicate an error. Find out what is going on
693 pragma Assert (C.Common.State = Unactivated);
695 Temp := C.Common.Activation_Link;
697 if C.Common.State = Unactivated then
701 for J in 1 .. C.Entry_Num loop
702 Queuing.Dequeue_Head (C.Entry_Queues (J), Call);
703 pragma Assert (Call = null);
708 Initialization.Remove_From_All_Tasks_List (C);
711 Vulnerable_Free_Task (C);
717 Initialization.Undefer_Abort_Nestable (Self_ID);
718 end Expunge_Unactivated_Tasks;
720 ---------------------------
721 -- Finalize_Global_Tasks --
722 ---------------------------
725 -- We have a potential problem here if finalization of global objects does
726 -- anything with signals or the timer server, since by that time those
727 -- servers have terminated.
729 -- It is hard to see how that would occur
731 -- However, a better solution might be to do all this finalization
732 -- using the global finalization chain.
734 procedure Finalize_Global_Tasks is
735 Self_ID : constant Task_Id := STPO.Self;
738 pragma Unreferenced (Ignore);
741 if Self_ID.Deferral_Level = 0 then
743 -- In principle, we should be able to predict whether abort is
744 -- already deferred here (and it should not be deferred yet but in
745 -- practice it seems Finalize_Global_Tasks is being called sometimes,
746 -- from RTS code for exceptions, with abort already deferred.
748 Initialization.Defer_Abort_Nestable (Self_ID);
750 -- Never undefer again!!!
753 -- This code is only executed by the environment task
755 pragma Assert (Self_ID = Environment_Task);
757 -- Set Environment_Task'Callable to false to notify library-level tasks
758 -- that it is waiting for them.
760 Self_ID.Callable := False;
762 -- Exit level 2 master, for normal tasks in library-level packages
766 -- Force termination of "independent" library-level server tasks
770 Abort_Dependents (Self_ID);
772 if not Single_Lock then
776 -- We need to explicitly wait for the task to be terminated here
777 -- because on true concurrent system, we may end this procedure before
778 -- the tasks are really terminated.
780 Write_Lock (Self_ID);
783 exit when Utilities.Independent_Task_Count = 0;
785 -- We used to yield here, but this did not take into account low
786 -- priority tasks that would cause dead lock in some cases (true
790 (Self_ID, 0.01, System.OS_Primitives.Relative,
791 Self_ID.Common.State, Ignore, Ignore);
794 -- ??? On multi-processor environments, it seems that the above loop
795 -- isn't sufficient, so we need to add an additional delay.
798 (Self_ID, 0.01, System.OS_Primitives.Relative,
799 Self_ID.Common.State, Ignore, Ignore);
807 -- Complete the environment task
809 Vulnerable_Complete_Task (Self_ID);
811 -- Handle normal task termination by the environment task, but only
812 -- for the normal task termination. In the case of Abnormal and
813 -- Unhandled_Exception they must have been handled before, and the
814 -- task termination soft link must have been changed so the task
815 -- termination routine is not executed twice.
817 SSL.Task_Termination_Handler.all (Ada.Exceptions.Null_Occurrence);
819 -- Finalize the global list for controlled objects if needed
821 SSL.Finalize_Global_List.all;
823 -- Reset the soft links to non-tasking
825 SSL.Abort_Defer := SSL.Abort_Defer_NT'Access;
826 SSL.Abort_Undefer := SSL.Abort_Undefer_NT'Access;
827 SSL.Lock_Task := SSL.Task_Lock_NT'Access;
828 SSL.Unlock_Task := SSL.Task_Unlock_NT'Access;
829 SSL.Get_Jmpbuf_Address := SSL.Get_Jmpbuf_Address_NT'Access;
830 SSL.Set_Jmpbuf_Address := SSL.Set_Jmpbuf_Address_NT'Access;
831 SSL.Get_Sec_Stack_Addr := SSL.Get_Sec_Stack_Addr_NT'Access;
832 SSL.Set_Sec_Stack_Addr := SSL.Set_Sec_Stack_Addr_NT'Access;
833 SSL.Check_Abort_Status := SSL.Check_Abort_Status_NT'Access;
834 SSL.Get_Stack_Info := SSL.Get_Stack_Info_NT'Access;
836 -- Don't bother trying to finalize Initialization.Global_Task_Lock
837 -- and System.Task_Primitives.RTS_Lock.
839 end Finalize_Global_Tasks;
841 ----------------------
842 -- Free_Entry_Names --
843 ----------------------
845 procedure Free_Entry_Names (T : Task_Id) is
846 Names : Entry_Names_Array_Access := T.Entry_Names;
848 procedure Free_Entry_Names_Array_Access is new
849 Ada.Unchecked_Deallocation
850 (Entry_Names_Array, Entry_Names_Array_Access);
857 Free_Entry_Names_Array (Names.all);
858 Free_Entry_Names_Array_Access (Names);
859 end Free_Entry_Names;
865 procedure Free_Task (T : Task_Id) is
866 Self_Id : constant Task_Id := Self;
869 if T.Common.State = Terminated then
871 -- It is not safe to call Abort_Defer or Write_Lock at this stage
873 Initialization.Task_Lock (Self_Id);
876 Initialization.Finalize_Attributes_Link.all (T);
877 Initialization.Remove_From_All_Tasks_List (T);
880 Initialization.Task_Unlock (Self_Id);
882 Free_Entry_Names (T);
883 System.Task_Primitives.Operations.Finalize_TCB (T);
885 -- If the task is not terminated, then we simply ignore the call. This
886 -- happens when a user program attempts an unchecked deallocation on
887 -- a non-terminated task.
894 ---------------------------
895 -- Move_Activation_Chain --
896 ---------------------------
898 procedure Move_Activation_Chain
899 (From, To : Activation_Chain_Access;
900 New_Master : Master_ID)
902 Self_ID : constant Task_Id := STPO.Self;
907 (Debug.Trace (Self_ID, "Move_Activation_Chain", 'C'));
909 -- Nothing to do if From is empty, and we can check that without
918 Initialization.Defer_Abort (Self_ID);
920 -- Loop through the From chain, changing their Master_of_Task
921 -- fields, and to find the end of the chain.
924 C.Master_of_Task := New_Master;
925 exit when C.Common.Activation_Link = null;
926 C := C.Common.Activation_Link;
929 -- Hook From in at the start of To
931 C.Common.Activation_Link := To.all.T_ID;
932 To.all.T_ID := From.all.T_ID;
936 From.all.T_ID := null;
938 Initialization.Undefer_Abort (Self_ID);
939 end Move_Activation_Chain;
941 -- Compiler interface only. Do not call from within the RTS
947 procedure Set_Entry_Name
949 Pos : Task_Entry_Index;
953 pragma Assert (T.Entry_Names /= null);
955 T.Entry_Names (Entry_Index (Pos)) := Val;
962 -- The task wrapper is a procedure that is called first for each task body
963 -- and which in turn calls the compiler-generated task body procedure.
964 -- The wrapper's main job is to do initialization for the task. It also
965 -- has some locally declared objects that serve as per-task local data.
966 -- Task finalization is done by Complete_Task, which is called from an
967 -- at-end handler that the compiler generates.
969 procedure Task_Wrapper (Self_ID : Task_Id) is
970 use type SSE.Storage_Offset;
971 use System.Standard_Library;
972 use System.Stack_Usage;
974 Bottom_Of_Stack : aliased Integer;
976 Task_Alternate_Stack :
977 aliased SSE.Storage_Array (1 .. Alternate_Stack_Size);
978 -- The alternate signal stack for this task, if any
980 Use_Alternate_Stack : constant Boolean := Alternate_Stack_Size /= 0;
981 -- Whether to use above alternate signal stack for stack overflows
983 Secondary_Stack_Size :
984 constant SSE.Storage_Offset :=
985 Self_ID.Common.Compiler_Data.Pri_Stack_Info.Size *
986 SSE.Storage_Offset (Parameters.Sec_Stack_Ratio) / 100;
988 Secondary_Stack : aliased SSE.Storage_Array (1 .. Secondary_Stack_Size);
990 pragma Warnings (Off);
991 -- Why are warnings being turned off here???
993 Secondary_Stack_Address : System.Address := Secondary_Stack'Address;
994 -- Address of secondary stack. In the fixed secondary stack case, this
995 -- value is not modified, causing a warning, hence the bracketing with
996 -- Warnings (Off/On). But why is so much *more* bracketed???
998 Small_Overflow_Guard : constant := 12 * 1024;
999 -- Note: this used to be 4K, but was changed to 12K, since smaller
1000 -- values resulted in segmentation faults from dynamic stack analysis.
1002 Big_Overflow_Guard : constant := 16 * 1024;
1003 Small_Stack_Limit : constant := 64 * 1024;
1004 -- ??? These three values are experimental, and seems to work on most
1005 -- platforms. They still need to be analyzed further. They also need
1006 -- documentation, what are they???
1009 Natural (Self_ID.Common.Compiler_Data.Pri_Stack_Info.Size);
1011 Overflow_Guard : Natural;
1012 -- Size of the overflow guard, used by dynamic stack usage analysis
1014 pragma Warnings (On);
1016 SEH_Table : aliased SSE.Storage_Array (1 .. 8);
1017 -- Structured Exception Registration table (2 words)
1019 procedure Install_SEH_Handler (Addr : System.Address);
1020 pragma Import (C, Install_SEH_Handler, "__gnat_install_SEH_handler");
1021 -- Install the SEH (Structured Exception Handling) handler
1023 Cause : Cause_Of_Termination := Normal;
1024 -- Indicates the reason why this task terminates. Normal corresponds to
1025 -- a task terminating due to completing the last statement of its body,
1026 -- or as a result of waiting on a terminate alternative. If the task
1027 -- terminates because it is being aborted then Cause will be set to
1028 -- Abnormal. If the task terminates because of an exception raised by
1029 -- the execution of its task body, then Cause is set to
1030 -- Unhandled_Exception.
1032 EO : Exception_Occurrence;
1033 -- If the task terminates because of an exception raised by the
1034 -- execution of its task body, then EO will contain the associated
1035 -- exception occurrence. Otherwise, it will contain Null_Occurrence.
1037 TH : Termination_Handler := null;
1038 -- Pointer to the protected procedure to be executed upon task
1041 procedure Search_Fall_Back_Handler (ID : Task_Id);
1042 -- Procedure that searches recursively a fall-back handler through the
1043 -- master relationship. If the handler is found, its pointer is stored
1046 ------------------------------
1047 -- Search_Fall_Back_Handler --
1048 ------------------------------
1050 procedure Search_Fall_Back_Handler (ID : Task_Id) is
1052 -- If there is a fall back handler, store its pointer for later
1055 if ID.Common.Fall_Back_Handler /= null then
1056 TH := ID.Common.Fall_Back_Handler;
1058 -- Otherwise look for a fall back handler in the parent
1060 elsif ID.Common.Parent /= null then
1061 Search_Fall_Back_Handler (ID.Common.Parent);
1063 -- Otherwise, do nothing
1068 end Search_Fall_Back_Handler;
1071 pragma Assert (Self_ID.Deferral_Level = 1);
1073 -- Assume a size of the stack taken at this stage
1075 if Size < Small_Stack_Limit then
1076 Overflow_Guard := Small_Overflow_Guard;
1078 Overflow_Guard := Big_Overflow_Guard;
1081 if not Parameters.Sec_Stack_Dynamic then
1082 Self_ID.Common.Compiler_Data.Sec_Stack_Addr :=
1083 Secondary_Stack'Address;
1084 SST.SS_Init (Secondary_Stack_Address, Integer (Secondary_Stack'Last));
1085 Size := Size - Natural (Secondary_Stack_Size);
1088 if Use_Alternate_Stack then
1089 Self_ID.Common.Task_Alternate_Stack := Task_Alternate_Stack'Address;
1092 Size := Size - Overflow_Guard;
1094 if System.Stack_Usage.Is_Enabled then
1097 (Self_ID.Common.Analyzer,
1098 Self_ID.Common.Task_Image
1099 (1 .. Self_ID.Common.Task_Image_Len),
1101 (Self_ID.Common.Compiler_Data.Pri_Stack_Info.Size),
1103 SSE.To_Integer (Bottom_Of_Stack'Address));
1105 Fill_Stack (Self_ID.Common.Analyzer);
1108 -- Set the guard page at the bottom of the stack. The call to unprotect
1109 -- the page is done in Terminate_Task
1111 Stack_Guard (Self_ID, True);
1113 -- Initialize low-level TCB components, that cannot be initialized by
1114 -- the creator. Enter_Task sets Self_ID.LL.Thread
1116 Enter_Task (Self_ID);
1118 -- We setup the SEH (Structured Exception Handling) handler if supported
1121 Install_SEH_Handler (SEH_Table'Address);
1123 -- Initialize exception occurrence
1125 Save_Occurrence (EO, Ada.Exceptions.Null_Occurrence);
1127 -- We lock RTS_Lock to wait for activator to finish activating the rest
1128 -- of the chain, so that everyone in the chain comes out in priority
1131 -- This also protects the value of
1132 -- Self_ID.Common.Activator.Common.Wait_Count.
1137 if not System.Restrictions.Abort_Allowed then
1139 -- If Abort is not allowed, reset the deferral level since it will
1140 -- not get changed by the generated code. Keeping a default value
1141 -- of one would prevent some operations (e.g. select or delay) to
1142 -- proceed successfully.
1144 Self_ID.Deferral_Level := 0;
1147 if Global_Task_Debug_Event_Set then
1148 Debug.Signal_Debug_Event
1149 (Debug.Debug_Event_Run, Self_ID);
1153 -- We are separating the following portion of the code in order to
1154 -- place the exception handlers in a different block. In this way,
1155 -- we do not call Set_Jmpbuf_Address (which needs Self) before we
1156 -- set Self in Enter_Task
1158 -- Call the task body procedure
1160 -- The task body is called with abort still deferred. That
1161 -- eliminates a dangerous window, for which we had to patch-up in
1164 -- During the expansion of the task body, we insert an RTS-call
1165 -- to Abort_Undefer, at the first point where abort should be
1168 Self_ID.Common.Task_Entry_Point (Self_ID.Common.Task_Arg);
1169 Initialization.Defer_Abort_Nestable (Self_ID);
1172 -- We can't call Terminate_Task in the exception handlers below,
1173 -- since there may be (e.g. in the case of GCC exception handling)
1174 -- clean ups associated with the exception handler that need to
1175 -- access task specific data.
1177 -- Defer abort so that this task can't be aborted while exiting
1179 when Standard'Abort_Signal =>
1180 Initialization.Defer_Abort_Nestable (Self_ID);
1182 -- Update the cause that motivated the task termination so that
1183 -- the appropriate information is passed to the task termination
1184 -- procedure. Task termination as a result of waiting on a
1185 -- terminate alternative is a normal termination, although it is
1186 -- implemented using the abort mechanisms.
1188 if Self_ID.Terminate_Alternative then
1191 if Global_Task_Debug_Event_Set then
1192 Debug.Signal_Debug_Event
1193 (Debug.Debug_Event_Terminated, Self_ID);
1198 if Global_Task_Debug_Event_Set then
1199 Debug.Signal_Debug_Event
1200 (Debug.Debug_Event_Abort_Terminated, Self_ID);
1204 -- ??? Using an E : others here causes CD2C11A to fail on Tru64
1206 Initialization.Defer_Abort_Nestable (Self_ID);
1208 -- Perform the task specific exception tracing duty. We handle
1209 -- these outputs here and not in the common notification routine
1210 -- because we need access to tasking related data and we don't
1211 -- want to drag dependencies against tasking related units in the
1212 -- the common notification units. Additionally, no trace is ever
1213 -- triggered from the common routine for the Unhandled_Raise case
1214 -- in tasks, since an exception never appears unhandled in this
1215 -- context because of this handler.
1217 if Exception_Trace = Unhandled_Raise then
1218 Trace_Unhandled_Exception_In_Task (Self_ID);
1221 -- Update the cause that motivated the task termination so that
1222 -- the appropriate information is passed to the task termination
1223 -- procedure, as well as the associated Exception_Occurrence.
1225 Cause := Unhandled_Exception;
1227 Save_Occurrence (EO, SSL.Get_Current_Excep.all.all);
1229 if Global_Task_Debug_Event_Set then
1230 Debug.Signal_Debug_Event
1231 (Debug.Debug_Event_Exception_Terminated, Self_ID);
1235 -- Look for a task termination handler. This code is for all tasks but
1236 -- the environment task. The task termination code for the environment
1237 -- task is executed by SSL.Task_Termination_Handler.
1243 Write_Lock (Self_ID);
1245 if Self_ID.Common.Specific_Handler /= null then
1246 TH := Self_ID.Common.Specific_Handler;
1248 -- Look for a fall-back handler following the master relationship
1251 Search_Fall_Back_Handler (Self_ID);
1260 -- Execute the task termination handler if we found it
1263 TH.all (Cause, Self_ID, EO);
1266 if System.Stack_Usage.Is_Enabled then
1267 Compute_Result (Self_ID.Common.Analyzer);
1268 Report_Result (Self_ID.Common.Analyzer);
1271 Terminate_Task (Self_ID);
1274 --------------------
1275 -- Terminate_Task --
1276 --------------------
1278 -- Before we allow the thread to exit, we must clean up. This is a
1279 -- delicate job. We must wake up the task's master, who may immediately try
1280 -- to deallocate the ATCB out from under the current task WHILE IT IS STILL
1283 -- To avoid this, the parent task must be blocked up to the latest
1284 -- statement executed. The trouble is that we have another step that we
1285 -- also want to postpone to the very end, i.e., calling SSL.Destroy_TSD.
1286 -- We have to postpone that until the end because compiler-generated code
1287 -- is likely to try to access that data at just about any point.
1289 -- We can't call Destroy_TSD while we are holding any other locks, because
1290 -- it locks Global_Task_Lock, and our deadlock prevention rules require
1291 -- that to be the outermost lock. Our first "solution" was to just lock
1292 -- Global_Task_Lock in addition to the other locks, and force the parent to
1293 -- also lock this lock between its wakeup and its freeing of the ATCB. See
1294 -- Complete_Task for the parent-side of the code that has the matching
1295 -- calls to Task_Lock and Task_Unlock. That was not really a solution,
1296 -- since the operation Task_Unlock continued to access the ATCB after
1297 -- unlocking, after which the parent was observed to race ahead, deallocate
1298 -- the ATCB, and then reallocate it to another task. The call to
1299 -- Undefer_Abort in Task_Unlock by the "terminated" task was overwriting
1300 -- the data of the new task that reused the ATCB! To solve this problem, we
1301 -- introduced the new operation Final_Task_Unlock.
1303 procedure Terminate_Task (Self_ID : Task_Id) is
1304 Environment_Task : constant Task_Id := STPO.Environment_Task;
1305 Master_of_Task : Integer;
1308 Debug.Task_Termination_Hook;
1310 if Runtime_Traces then
1311 Send_Trace_Info (T_Terminate);
1314 -- Since GCC cannot allocate stack chunks efficiently without reordering
1315 -- some of the allocations, we have to handle this unexpected situation
1316 -- here. We should normally never have to call Vulnerable_Complete_Task
1319 if Self_ID.Common.Activator /= null then
1320 Vulnerable_Complete_Task (Self_ID);
1323 Initialization.Task_Lock (Self_ID);
1329 Master_of_Task := Self_ID.Master_of_Task;
1331 -- Check if the current task is an independent task If so, decrement
1332 -- the Independent_Task_Count value.
1334 if Master_of_Task = Independent_Task_Level then
1336 Utilities.Independent_Task_Count :=
1337 Utilities.Independent_Task_Count - 1;
1339 Write_Lock (Environment_Task);
1340 Utilities.Independent_Task_Count :=
1341 Utilities.Independent_Task_Count - 1;
1342 Unlock (Environment_Task);
1346 -- Unprotect the guard page if needed
1348 Stack_Guard (Self_ID, False);
1350 Utilities.Make_Passive (Self_ID, Task_Completed => True);
1356 pragma Assert (Check_Exit (Self_ID));
1358 SSL.Destroy_TSD (Self_ID.Common.Compiler_Data);
1359 Initialization.Final_Task_Unlock (Self_ID);
1361 -- WARNING: past this point, this thread must assume that the ATCB has
1362 -- been deallocated. It should not be accessed again.
1364 if Master_of_Task > 0 then
1373 function Terminated (T : Task_Id) return Boolean is
1374 Self_ID : constant Task_Id := STPO.Self;
1378 Initialization.Defer_Abort_Nestable (Self_ID);
1385 Result := T.Common.State = Terminated;
1392 Initialization.Undefer_Abort_Nestable (Self_ID);
1396 ----------------------------------------
1397 -- Trace_Unhandled_Exception_In_Task --
1398 ----------------------------------------
1400 procedure Trace_Unhandled_Exception_In_Task (Self_Id : Task_Id) is
1401 procedure To_Stderr (S : String);
1402 pragma Import (Ada, To_Stderr, "__gnat_to_stderr");
1404 use System.Soft_Links;
1405 use System.Standard_Library;
1407 function To_Address is new
1408 Ada.Unchecked_Conversion
1409 (Task_Id, System.Task_Primitives.Task_Address);
1411 function Tailored_Exception_Information
1412 (E : Exception_Occurrence) return String;
1414 (Ada, Tailored_Exception_Information,
1415 "__gnat_tailored_exception_information");
1417 Excep : constant Exception_Occurrence_Access :=
1418 SSL.Get_Current_Excep.all;
1421 -- This procedure is called by the task outermost handler in
1422 -- Task_Wrapper below, so only once the task stack has been fully
1423 -- unwound. The common notification routine has been called at the
1424 -- raise point already.
1426 -- Lock to prevent unsynchronized output
1428 Initialization.Task_Lock (Self_Id);
1429 To_Stderr ("task ");
1431 if Self_Id.Common.Task_Image_Len /= 0 then
1433 (Self_Id.Common.Task_Image (1 .. Self_Id.Common.Task_Image_Len));
1437 To_Stderr (System.Address_Image (To_Address (Self_Id)));
1438 To_Stderr (" terminated by unhandled exception");
1439 To_Stderr ((1 => ASCII.LF));
1440 To_Stderr (Tailored_Exception_Information (Excep.all));
1441 Initialization.Task_Unlock (Self_Id);
1442 end Trace_Unhandled_Exception_In_Task;
1444 ------------------------------------
1445 -- Vulnerable_Complete_Activation --
1446 ------------------------------------
1448 -- As in several other places, the locks of the activator and activated
1449 -- task are both locked here. This follows our deadlock prevention lock
1450 -- ordering policy, since the activated task must be created after the
1453 procedure Vulnerable_Complete_Activation (Self_ID : Task_Id) is
1454 Activator : constant Task_Id := Self_ID.Common.Activator;
1457 pragma Debug (Debug.Trace (Self_ID, "V_Complete_Activation", 'C'));
1459 Write_Lock (Activator);
1460 Write_Lock (Self_ID);
1462 pragma Assert (Self_ID.Common.Activator /= null);
1464 -- Remove dangling reference to Activator, since a task may
1465 -- outlive its activator.
1467 Self_ID.Common.Activator := null;
1469 -- Wake up the activator, if it is waiting for a chain of tasks to
1470 -- activate, and we are the last in the chain to complete activation.
1472 if Activator.Common.State = Activator_Sleep then
1473 Activator.Common.Wait_Count := Activator.Common.Wait_Count - 1;
1475 if Activator.Common.Wait_Count = 0 then
1476 Wakeup (Activator, Activator_Sleep);
1480 -- The activator raises a Tasking_Error if any task it is activating
1481 -- is completed before the activation is done. However, if the reason
1482 -- for the task completion is an abort, we do not raise an exception.
1485 if not Self_ID.Callable and then Self_ID.Pending_ATC_Level /= 0 then
1486 Activator.Common.Activation_Failed := True;
1492 -- After the activation, active priority should be the same as base
1493 -- priority. We must unlock the Activator first, though, since it
1494 -- should not wait if we have lower priority.
1496 if Get_Priority (Self_ID) /= Self_ID.Common.Base_Priority then
1497 Write_Lock (Self_ID);
1498 Set_Priority (Self_ID, Self_ID.Common.Base_Priority);
1501 end Vulnerable_Complete_Activation;
1503 --------------------------------
1504 -- Vulnerable_Complete_Master --
1505 --------------------------------
1507 procedure Vulnerable_Complete_Master (Self_ID : Task_Id) is
1510 CM : constant Master_Level := Self_ID.Master_Within;
1511 T : aliased Task_Id;
1513 To_Be_Freed : Task_Id;
1514 -- This is a list of ATCBs to be freed, after we have released all RTS
1515 -- locks. This is necessary because of the locking order rules, since
1516 -- the storage manager uses Global_Task_Lock.
1518 pragma Warnings (Off);
1519 function Check_Unactivated_Tasks return Boolean;
1520 pragma Warnings (On);
1521 -- Temporary error-checking code below. This is part of the checks
1522 -- added in the new run time. Call it only inside a pragma Assert.
1524 -----------------------------
1525 -- Check_Unactivated_Tasks --
1526 -----------------------------
1528 function Check_Unactivated_Tasks return Boolean is
1530 if not Single_Lock then
1534 Write_Lock (Self_ID);
1536 C := All_Tasks_List;
1537 while C /= null loop
1538 if C.Common.Activator = Self_ID and then C.Master_of_Task = CM then
1542 if C.Common.Parent = Self_ID and then C.Master_of_Task = CM then
1545 if C.Common.State = Unactivated then
1552 C := C.Common.All_Tasks_Link;
1557 if not Single_Lock then
1562 end Check_Unactivated_Tasks;
1564 -- Start of processing for Vulnerable_Complete_Master
1568 (Debug.Trace (Self_ID, "V_Complete_Master", 'C'));
1570 pragma Assert (Self_ID.Common.Wait_Count = 0);
1572 (Self_ID.Deferral_Level > 0
1573 or else not System.Restrictions.Abort_Allowed);
1575 -- Count how many active dependent tasks this master currently has, and
1576 -- record this in Wait_Count.
1578 -- This count should start at zero, since it is initialized to zero for
1579 -- new tasks, and the task should not exit the sleep-loops that use this
1580 -- count until the count reaches zero.
1582 -- While we're counting, if we run across any unactivated tasks that
1583 -- belong to this master, we summarily terminate them as required by
1587 Write_Lock (Self_ID);
1589 C := All_Tasks_List;
1590 while C /= null loop
1592 -- Terminate unactivated (never-to-be activated) tasks
1594 if C.Common.Activator = Self_ID and then C.Master_of_Task = CM then
1596 pragma Assert (C.Common.State = Unactivated);
1597 -- Usually, C.Common.Activator = Self_ID implies C.Master_of_Task
1598 -- = CM. The only case where C is pending activation by this
1599 -- task, but the master of C is not CM is in Ada 2005, when C is
1600 -- part of a return object of a build-in-place function.
1603 C.Common.Activator := null;
1604 C.Common.State := Terminated;
1605 C.Callable := False;
1606 Utilities.Cancel_Queued_Entry_Calls (C);
1610 -- Count it if dependent on this master
1612 if C.Common.Parent = Self_ID and then C.Master_of_Task = CM then
1615 if C.Awake_Count /= 0 then
1616 Self_ID.Common.Wait_Count := Self_ID.Common.Wait_Count + 1;
1622 C := C.Common.All_Tasks_Link;
1625 Self_ID.Common.State := Master_Completion_Sleep;
1628 if not Single_Lock then
1632 -- Wait until dependent tasks are all terminated or ready to terminate.
1633 -- While waiting, the task may be awakened if the task's priority needs
1634 -- changing, or this master is aborted. In the latter case, we abort the
1635 -- dependents, and resume waiting until Wait_Count goes to zero.
1637 Write_Lock (Self_ID);
1640 exit when Self_ID.Common.Wait_Count = 0;
1642 -- Here is a difference as compared to Complete_Master
1644 if Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level
1645 and then not Self_ID.Dependents_Aborted
1648 Abort_Dependents (Self_ID);
1652 Abort_Dependents (Self_ID);
1654 Write_Lock (Self_ID);
1657 Sleep (Self_ID, Master_Completion_Sleep);
1661 Self_ID.Common.State := Runnable;
1664 -- Dependents are all terminated or on terminate alternatives. Now,
1665 -- force those on terminate alternatives to terminate, by aborting them.
1667 pragma Assert (Check_Unactivated_Tasks);
1669 if Self_ID.Alive_Count > 1 then
1671 -- Consider finding a way to skip the following extra steps if there
1672 -- are no dependents with terminate alternatives. This could be done
1673 -- by adding another count to the ATCB, similar to Awake_Count, but
1674 -- keeping track of tasks that are on terminate alternatives.
1676 pragma Assert (Self_ID.Common.Wait_Count = 0);
1678 -- Force any remaining dependents to terminate by aborting them
1680 if not Single_Lock then
1684 Abort_Dependents (Self_ID);
1686 -- Above, when we "abort" the dependents we are simply using this
1687 -- operation for convenience. We are not required to support the full
1688 -- abort-statement semantics; in particular, we are not required to
1689 -- immediately cancel any queued or in-service entry calls. That is
1690 -- good, because if we tried to cancel a call we would need to lock
1691 -- the caller, in order to wake the caller up. Our anti-deadlock
1692 -- rules prevent us from doing that without releasing the locks on C
1693 -- and Self_ID. Releasing and retaking those locks would be wasteful
1694 -- at best, and should not be considered further without more
1695 -- detailed analysis of potential concurrent accesses to the ATCBs
1696 -- of C and Self_ID.
1698 -- Count how many "alive" dependent tasks this master currently has,
1699 -- and record this in Wait_Count. This count should start at zero,
1700 -- since it is initialized to zero for new tasks, and the task should
1701 -- not exit the sleep-loops that use this count until the count
1704 pragma Assert (Self_ID.Common.Wait_Count = 0);
1706 Write_Lock (Self_ID);
1708 C := All_Tasks_List;
1709 while C /= null loop
1710 if C.Common.Parent = Self_ID and then C.Master_of_Task = CM then
1713 pragma Assert (C.Awake_Count = 0);
1715 if C.Alive_Count > 0 then
1716 pragma Assert (C.Terminate_Alternative);
1717 Self_ID.Common.Wait_Count := Self_ID.Common.Wait_Count + 1;
1723 C := C.Common.All_Tasks_Link;
1726 Self_ID.Common.State := Master_Phase_2_Sleep;
1729 if not Single_Lock then
1733 -- Wait for all counted tasks to finish terminating themselves
1735 Write_Lock (Self_ID);
1738 exit when Self_ID.Common.Wait_Count = 0;
1739 Sleep (Self_ID, Master_Phase_2_Sleep);
1742 Self_ID.Common.State := Runnable;
1746 -- We don't wake up for abort here. We are already terminating just as
1747 -- fast as we can, so there is no point.
1749 -- Remove terminated tasks from the list of Self_ID's dependents, but
1750 -- don't free their ATCBs yet, because of lock order restrictions, which
1751 -- don't allow us to call "free" or "malloc" while holding any other
1752 -- locks. Instead, we put those ATCBs to be freed onto a temporary list,
1753 -- called To_Be_Freed.
1755 if not Single_Lock then
1759 C := All_Tasks_List;
1761 while C /= null loop
1762 if C.Common.Parent = Self_ID and then C.Master_of_Task >= CM then
1764 P.Common.All_Tasks_Link := C.Common.All_Tasks_Link;
1766 All_Tasks_List := C.Common.All_Tasks_Link;
1769 T := C.Common.All_Tasks_Link;
1770 C.Common.All_Tasks_Link := To_Be_Freed;
1776 C := C.Common.All_Tasks_Link;
1782 -- Free all the ATCBs on the list To_Be_Freed
1784 -- The ATCBs in the list are no longer in All_Tasks_List, and after
1785 -- any interrupt entries are detached from them they should no longer
1788 -- Global_Task_Lock (Task_Lock/Unlock) is locked in the loop below to
1789 -- avoid a race between a terminating task and its parent. The parent
1790 -- might try to deallocate the ACTB out from underneath the exiting
1791 -- task. Note that Free will also lock Global_Task_Lock, but that is
1792 -- OK, since this is the *one* lock for which we have a mechanism to
1793 -- support nested locking. See Task_Wrapper and its finalizer for more
1797 -- The check "T.Common.Parent /= null ..." below is to prevent dangling
1798 -- references to terminated library-level tasks, which could otherwise
1799 -- occur during finalization of library-level objects. A better solution
1800 -- might be to hook task objects into the finalization chain and
1801 -- deallocate the ATCB when the task object is deallocated. However,
1802 -- this change is not likely to gain anything significant, since all
1803 -- this storage should be recovered en-masse when the process exits.
1805 while To_Be_Freed /= null loop
1807 To_Be_Freed := T.Common.All_Tasks_Link;
1809 -- ??? On SGI there is currently no Interrupt_Manager, that's
1810 -- why we need to check if the Interrupt_Manager_ID is null
1812 if T.Interrupt_Entry and Interrupt_Manager_ID /= null then
1814 Detach_Interrupt_Entries_Index : constant Task_Entry_Index := 1;
1815 -- Corresponds to the entry index of System.Interrupts.
1816 -- Interrupt_Manager.Detach_Interrupt_Entries.
1817 -- Be sure to update this value when changing
1818 -- Interrupt_Manager specs.
1820 type Param_Type is access all Task_Id;
1822 Param : aliased Param_Type := T'Access;
1825 System.Tasking.Rendezvous.Call_Simple
1826 (Interrupt_Manager_ID, Detach_Interrupt_Entries_Index,
1831 if (T.Common.Parent /= null
1832 and then T.Common.Parent.Common.Parent /= null)
1833 or else T.Master_of_Task > Library_Task_Level
1835 Initialization.Task_Lock (Self_ID);
1837 -- If Sec_Stack_Addr is not null, it means that Destroy_TSD
1838 -- has not been called yet (case of an unactivated task).
1840 if T.Common.Compiler_Data.Sec_Stack_Addr /= Null_Address then
1841 SSL.Destroy_TSD (T.Common.Compiler_Data);
1844 Vulnerable_Free_Task (T);
1845 Initialization.Task_Unlock (Self_ID);
1849 -- It might seem nice to let the terminated task deallocate its own
1850 -- ATCB. That would not cover the case of unactivated tasks. It also
1851 -- would force us to keep the underlying thread around past termination,
1852 -- since references to the ATCB are possible past termination.
1854 -- Currently, we get rid of the thread as soon as the task terminates,
1855 -- and let the parent recover the ATCB later.
1857 -- Some day, if we want to recover the ATCB earlier, at task
1858 -- termination, we could consider using "fat task IDs", that include the
1859 -- serial number with the ATCB pointer, to catch references to tasks
1860 -- that no longer have ATCBs. It is not clear how much this would gain,
1861 -- since the user-level task object would still be occupying storage.
1863 -- Make next master level up active. We don't need to lock the ATCB,
1864 -- since the value is only updated by each task for itself.
1866 Self_ID.Master_Within := CM - 1;
1867 end Vulnerable_Complete_Master;
1869 ------------------------------
1870 -- Vulnerable_Complete_Task --
1871 ------------------------------
1873 -- Complete the calling task
1875 -- This procedure must be called with abort deferred. It should only be
1876 -- called by Complete_Task and Finalize_Global_Tasks (for the environment
1879 -- The effect is similar to that of Complete_Master. Differences include
1880 -- the closing of entries here, and computation of the number of active
1881 -- dependent tasks in Complete_Master.
1883 -- We don't lock Self_ID before the call to Vulnerable_Complete_Activation,
1884 -- because that does its own locking, and because we do not need the lock
1885 -- to test Self_ID.Common.Activator. That value should only be read and
1886 -- modified by Self.
1888 procedure Vulnerable_Complete_Task (Self_ID : Task_Id) is
1891 (Self_ID.Deferral_Level > 0
1892 or else not System.Restrictions.Abort_Allowed);
1893 pragma Assert (Self_ID = Self);
1894 pragma Assert (Self_ID.Master_Within = Self_ID.Master_of_Task + 1
1896 Self_ID.Master_Within = Self_ID.Master_of_Task + 2);
1897 pragma Assert (Self_ID.Common.Wait_Count = 0);
1898 pragma Assert (Self_ID.Open_Accepts = null);
1899 pragma Assert (Self_ID.ATC_Nesting_Level = 1);
1901 pragma Debug (Debug.Trace (Self_ID, "V_Complete_Task", 'C'));
1907 Write_Lock (Self_ID);
1908 Self_ID.Callable := False;
1910 -- In theory, Self should have no pending entry calls left on its
1911 -- call-stack. Each async. select statement should clean its own call,
1912 -- and blocking entry calls should defer abort until the calls are
1913 -- cancelled, then clean up.
1915 Utilities.Cancel_Queued_Entry_Calls (Self_ID);
1918 if Self_ID.Common.Activator /= null then
1919 Vulnerable_Complete_Activation (Self_ID);
1926 -- If Self_ID.Master_Within = Self_ID.Master_of_Task + 2 we may have
1927 -- dependent tasks for which we need to wait. Otherwise we just exit.
1929 if Self_ID.Master_Within = Self_ID.Master_of_Task + 2 then
1930 Vulnerable_Complete_Master (Self_ID);
1932 end Vulnerable_Complete_Task;
1934 --------------------------
1935 -- Vulnerable_Free_Task --
1936 --------------------------
1938 -- Recover all runtime system storage associated with the task T. This
1939 -- should only be called after T has terminated and will no longer be
1942 -- For tasks created by an allocator that fails, due to an exception, it
1943 -- is called from Expunge_Unactivated_Tasks.
1945 -- For tasks created by elaboration of task object declarations it is
1946 -- called from the finalization code of the Task_Wrapper procedure. It is
1947 -- also called from Ada.Unchecked_Deallocation, for objects that are or
1950 procedure Vulnerable_Free_Task (T : Task_Id) is
1952 pragma Debug (Debug.Trace (Self, "Vulnerable_Free_Task", 'C', T));
1959 Initialization.Finalize_Attributes_Link.all (T);
1966 Free_Entry_Names (T);
1967 System.Task_Primitives.Operations.Finalize_TCB (T);
1968 end Vulnerable_Free_Task;
1970 -- Package elaboration code
1973 -- Establish the Adafinal oftlink
1975 -- This is not done inside the central RTS initialization routine
1976 -- to avoid with-ing this package from System.Tasking.Initialization.
1978 SSL.Adafinal := Finalize_Global_Tasks'Access;
1980 -- Establish soft links for subprograms that manipulate master_id's.
1981 -- This cannot be done when the RTS is initialized, because of various
1982 -- elaboration constraints.
1984 SSL.Current_Master := Stages.Current_Master'Access;
1985 SSL.Enter_Master := Stages.Enter_Master'Access;
1986 SSL.Complete_Master := Stages.Complete_Master'Access;
1987 end System.Tasking.Stages;