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) 1992-2006, 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 2, or (at your option) any later ver- --
14 -- sion. GNARL 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. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNARL; see file COPYING. If not, write --
19 -- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, --
20 -- Boston, MA 02110-1301, USA. --
22 -- As a special exception, if other files instantiate generics from this --
23 -- unit, or you link this unit with other files to produce an executable, --
24 -- this unit does not by itself cause the resulting executable to be --
25 -- covered by the GNU General Public License. This exception does not --
26 -- however invalidate any other reasons why the executable file might be --
27 -- covered by the GNU Public License. --
29 -- GNARL was developed by the GNARL team at Florida State University. --
30 -- Extensive contributions were provided by Ada Core Technologies, Inc. --
32 ------------------------------------------------------------------------------
35 -- Turn off polling, we do not want ATC polling to take place during
36 -- tasking operations. It causes infinite loops and other problems.
39 -- Used for Raise_Exception
41 with System.Tasking.Debug;
42 -- Used for enabling tasking facilities with gdb
44 with System.Address_Image;
45 -- Used for the function itself
47 with System.Task_Primitives.Operations;
48 -- Used for Finalize_Lock
58 with System.Soft_Links;
59 -- These are procedure pointers to non-tasking routines that use task
60 -- specific data. In the absence of tasking, these routines refer to global
61 -- data. In the presense of tasking, they must be replaced with pointers to
62 -- task-specific versions. Also used for Create_TSD, Destroy_TSD,
63 -- Get_Current_Excep, Finalize_Global_List, Task_Termination, Handler.
65 with System.Tasking.Initialization;
66 -- Used for Remove_From_All_Tasks_List
69 -- Initialization.Poll_Base_Priority_Change
70 -- Finalize_Attributes_Link
71 -- Initialize_Attributes_Link
73 pragma Elaborate_All (System.Tasking.Initialization);
74 -- This insures that tasking is initialized if any tasks are created
76 with System.Tasking.Utilities;
77 -- Used for Make_Passive
81 with System.Tasking.Queuing;
82 -- Used for Dequeue_Head
84 with System.Tasking.Rendezvous;
85 -- Used for Call_Simple
87 with System.OS_Primitives;
88 -- Used for Delay_Modes
90 with System.Secondary_Stack;
93 with System.Storage_Elements;
94 -- Used for Storage_Array
96 with System.Restrictions;
97 -- Used for Abort_Allowed
99 with System.Standard_Library;
100 -- Used for Exception_Trace
102 with System.Traces.Tasking;
103 -- Used for Send_Trace_Info
105 with Unchecked_Deallocation;
106 -- To recover from failure of ATCB initialization
108 with System.Stack_Usage;
110 package body System.Tasking.Stages is
112 package STPO renames System.Task_Primitives.Operations;
113 package SSL renames System.Soft_Links;
114 package SSE renames System.Storage_Elements;
115 package SST renames System.Secondary_Stack;
121 use Task_Primitives.Operations;
125 use System.Traces.Tasking;
127 -----------------------
128 -- Local Subprograms --
129 -----------------------
131 procedure Free is new
132 Unchecked_Deallocation (Ada_Task_Control_Block, Task_Id);
134 procedure Trace_Unhandled_Exception_In_Task (Self_Id : Task_Id);
135 -- This procedure outputs the task specific message for exception
138 procedure Task_Wrapper (Self_ID : Task_Id);
139 pragma Convention (C, Task_Wrapper);
140 -- This is the procedure that is called by the GNULL from the new context
141 -- when a task is created. It waits for activation and then calls the task
142 -- body procedure. When the task body procedure completes, it terminates
145 -- The Task_Wrapper's address will be provided to the underlying threads
146 -- library as the task entry point. Convention C is what makes most sense
147 -- for that purpose (Export C would make the function globally visible,
148 -- and affect the link name on which GDB depends). This will in addition
149 -- trigger an automatic stack alignment suitable for GCC's assumptions if
152 -- "Vulnerable_..." in the procedure names below means they must be called
153 -- with abort deferred.
155 procedure Vulnerable_Complete_Task (Self_ID : Task_Id);
156 -- Complete the calling task. This procedure must be called with
157 -- abort deferred. It should only be called by Complete_Task and
158 -- Finalizate_Global_Tasks (for the environment task).
160 procedure Vulnerable_Complete_Master (Self_ID : Task_Id);
161 -- Complete the current master of the calling task. This procedure
162 -- must be called with abort deferred. It should only be called by
163 -- Vulnerable_Complete_Task and Complete_Master.
165 procedure Vulnerable_Complete_Activation (Self_ID : Task_Id);
166 -- Signal to Self_ID's activator that Self_ID has completed activation.
167 -- This procedure must be called with abort deferred.
169 procedure Abort_Dependents (Self_ID : Task_Id);
170 -- Abort all the direct dependents of Self at its current master
171 -- nesting level, plus all of their dependents, transitively.
172 -- RTS_Lock should be locked by the caller.
174 procedure Vulnerable_Free_Task (T : Task_Id);
175 -- Recover all runtime system storage associated with the task T.
176 -- This should only be called after T has terminated and will no
177 -- longer be referenced.
179 -- For tasks created by an allocator that fails, due to an exception,
180 -- it is called from Expunge_Unactivated_Tasks.
182 -- It is also called from Unchecked_Deallocation, for objects that
183 -- are or contain tasks.
185 -- Different code is used at master completion, in Terminate_Dependents,
186 -- due to a need for tighter synchronization with the master.
188 ----------------------
189 -- Abort_Dependents --
190 ----------------------
192 procedure Abort_Dependents (Self_ID : Task_Id) is
199 P := C.Common.Parent;
203 -- ??? C is supposed to take care of its own dependents, so
204 -- there should be no need to worry about them. Need to double
207 if C.Master_of_Task = Self_ID.Master_Within then
208 Utilities.Abort_One_Task (Self_ID, C);
209 C.Dependents_Aborted := True;
215 P := P.Common.Parent;
218 C := C.Common.All_Tasks_Link;
221 Self_ID.Dependents_Aborted := True;
222 end Abort_Dependents;
228 procedure Abort_Tasks (Tasks : Task_List) is
230 Utilities.Abort_Tasks (Tasks);
237 -- Note that locks of activator and activated task are both locked
238 -- here. This is necessary because C.Common.State and
239 -- Self.Common.Wait_Count have to be synchronized. This is safe from
240 -- deadlock because the activator is always created before the activated
241 -- task. That satisfies our in-order-of-creation ATCB locking policy.
243 -- At one point, we may also lock the parent, if the parent is
244 -- different from the activator. That is also consistent with the
245 -- lock ordering policy, since the activator cannot be created
246 -- before the parent.
248 -- Since we are holding both the activator's lock, and Task_Wrapper
249 -- locks that before it does anything more than initialize the
250 -- low-level ATCB components, it should be safe to wait to update
251 -- the counts until we see that the thread creation is successful.
253 -- If the thread creation fails, we do need to close the entries
254 -- of the task. The first phase, of dequeuing calls, only requires
255 -- locking the acceptor's ATCB, but the waking up of the callers
256 -- requires locking the caller's ATCB. We cannot safely do this
257 -- while we are holding other locks. Therefore, the queue-clearing
258 -- operation is done in a separate pass over the activation chain.
260 procedure Activate_Tasks (Chain_Access : Activation_Chain_Access) is
261 Self_ID : constant Task_Id := STPO.Self;
264 Next_C, Last_C : Task_Id;
265 Activate_Prio : System.Any_Priority;
267 All_Elaborated : Boolean := True;
270 -- If pragma Detect_Blocking is active, then we must check whether this
271 -- potentially blocking operation is called from a protected action.
273 if System.Tasking.Detect_Blocking
274 and then Self_ID.Common.Protected_Action_Nesting > 0
276 Ada.Exceptions.Raise_Exception
277 (Program_Error'Identity, "potentially blocking operation");
281 (Debug.Trace (Self_ID, "Activate_Tasks", 'C'));
283 Initialization.Defer_Abort_Nestable (Self_ID);
285 pragma Assert (Self_ID.Common.Wait_Count = 0);
287 -- Lock RTS_Lock, to prevent activated tasks from racing ahead before
288 -- we finish activating the chain.
292 -- Check that all task bodies have been elaborated
294 C := Chain_Access.T_ID;
297 if C.Common.Elaborated /= null
298 and then not C.Common.Elaborated.all
300 All_Elaborated := False;
303 -- Reverse the activation chain so that tasks are
304 -- activated in the same order they're declared.
306 Next_C := C.Common.Activation_Link;
307 C.Common.Activation_Link := Last_C;
312 Chain_Access.T_ID := Last_C;
314 if not All_Elaborated then
316 Initialization.Undefer_Abort_Nestable (Self_ID);
318 (Program_Error'Identity, "Some tasks have not been elaborated");
321 -- Activate all the tasks in the chain. Creation of the thread of
322 -- control was deferred until activation. So create it now.
324 C := Chain_Access.T_ID;
326 if C.Common.State /= Terminated then
327 pragma Assert (C.Common.State = Unactivated);
329 P := C.Common.Parent;
333 if C.Common.Base_Priority < Get_Priority (Self_ID) then
334 Activate_Prio := Get_Priority (Self_ID);
336 Activate_Prio := C.Common.Base_Priority;
339 System.Task_Primitives.Operations.Create_Task
340 (C, Task_Wrapper'Address,
342 (C.Common.Compiler_Data.Pri_Stack_Info.Size),
343 Activate_Prio, Success);
345 -- There would be a race between the created task and the
346 -- creator to do the following initialization, if we did not
347 -- have a Lock/Unlock_RTS pair in the task wrapper to prevent
348 -- it from racing ahead.
351 C.Common.State := Runnable;
354 P.Awake_Count := P.Awake_Count + 1;
355 P.Alive_Count := P.Alive_Count + 1;
357 if P.Common.State = Master_Completion_Sleep and then
358 C.Master_of_Task = P.Master_Within
360 pragma Assert (Self_ID /= P);
361 P.Common.Wait_Count := P.Common.Wait_Count + 1;
368 -- No need to set Awake_Count, State, etc. here since the loop
369 -- below will do that for any Unactivated tasks.
373 Self_ID.Common.Activation_Failed := True;
377 C := C.Common.Activation_Link;
380 if not Single_Lock then
384 -- Close the entries of any tasks that failed thread creation,
385 -- and count those that have not finished activation.
387 Write_Lock (Self_ID);
388 Self_ID.Common.State := Activator_Sleep;
390 C := Chain_Access.T_ID;
394 if C.Common.State = Unactivated then
395 C.Common.Activator := null;
396 C.Common.State := Terminated;
398 Utilities.Cancel_Queued_Entry_Calls (C);
400 elsif C.Common.Activator /= null then
401 Self_ID.Common.Wait_Count := Self_ID.Common.Wait_Count + 1;
405 P := C.Common.Activation_Link;
406 C.Common.Activation_Link := null;
410 -- Wait for the activated tasks to complete activation. It is
411 -- unsafe to abort any of these tasks until the count goes to zero.
414 Initialization.Poll_Base_Priority_Change (Self_ID);
415 exit when Self_ID.Common.Wait_Count = 0;
416 Sleep (Self_ID, Activator_Sleep);
419 Self_ID.Common.State := Runnable;
426 -- Remove the tasks from the chain
428 Chain_Access.T_ID := null;
429 Initialization.Undefer_Abort_Nestable (Self_ID);
431 if Self_ID.Common.Activation_Failed then
432 Self_ID.Common.Activation_Failed := False;
433 Raise_Exception (Tasking_Error'Identity,
434 "Failure during activation");
438 -------------------------
439 -- Complete_Activation --
440 -------------------------
442 procedure Complete_Activation is
443 Self_ID : constant Task_Id := STPO.Self;
446 Initialization.Defer_Abort_Nestable (Self_ID);
452 Vulnerable_Complete_Activation (Self_ID);
458 Initialization.Undefer_Abort_Nestable (Self_ID);
461 -- Why do we need to allow for nested deferral here?
463 if Runtime_Traces then
464 Send_Trace_Info (T_Activate);
466 end Complete_Activation;
468 ---------------------
469 -- Complete_Master --
470 ---------------------
472 procedure Complete_Master is
473 Self_ID : constant Task_Id := STPO.Self;
475 pragma Assert (Self_ID.Deferral_Level > 0);
476 Vulnerable_Complete_Master (Self_ID);
483 -- See comments on Vulnerable_Complete_Task for details
485 procedure Complete_Task is
486 Self_ID : constant Task_Id := STPO.Self;
489 pragma Assert (Self_ID.Deferral_Level > 0);
491 Vulnerable_Complete_Task (Self_ID);
493 -- All of our dependents have terminated. Never undefer abort again!
501 -- Compiler interface only. Do not call from within the RTS.
502 -- This must be called to create a new task.
504 procedure Create_Task
506 Size : System.Parameters.Size_Type;
507 Task_Info : System.Task_Info.Task_Info_Type;
508 Num_Entries : Task_Entry_Index;
509 Master : Master_Level;
510 State : Task_Procedure_Access;
511 Discriminants : System.Address;
512 Elaborated : Access_Boolean;
513 Chain : in out Activation_Chain;
515 Created_Task : out Task_Id)
518 Self_ID : constant Task_Id := STPO.Self;
520 Base_Priority : System.Any_Priority;
524 -- If Master is greater than the current master, it means that Master
525 -- has already awaited its dependent tasks. This raises Program_Error,
526 -- by 4.8(10.3/2). See AI-280. Ignore this check for foreign threads.
528 if Self_ID.Master_of_Task /= Foreign_Task_Level
529 and then Master > Self_ID.Master_Within
531 raise Program_Error with
532 "create task after awaiting termination";
535 -- If pragma Detect_Blocking is active must be checked whether
536 -- this potentially blocking operation is called from a
539 if System.Tasking.Detect_Blocking
540 and then Self_ID.Common.Protected_Action_Nesting > 0
542 Ada.Exceptions.Raise_Exception
543 (Program_Error'Identity, "potentially blocking operation");
547 (Debug.Trace (Self_ID, "Create_Task", 'C'));
549 if Priority = Unspecified_Priority then
550 Base_Priority := Self_ID.Common.Base_Priority;
552 Base_Priority := System.Any_Priority (Priority);
555 -- Find parent P of new Task, via master level number
560 while P.Master_of_Task >= Master loop
561 P := P.Common.Parent;
566 Initialization.Defer_Abort_Nestable (Self_ID);
569 T := New_ATCB (Num_Entries);
572 Initialization.Undefer_Abort_Nestable (Self_ID);
573 Raise_Exception (Storage_Error'Identity, "Cannot allocate task");
576 -- RTS_Lock is used by Abort_Dependents and Abort_Tasks.
577 -- Up to this point, it is possible that we may be part of
578 -- a family of tasks that is being aborted.
581 Write_Lock (Self_ID);
583 -- Now, we must check that we have not been aborted.
584 -- If so, we should give up on creating this task,
585 -- and simply return.
587 if not Self_ID.Callable then
588 pragma Assert (Self_ID.Pending_ATC_Level = 0);
589 pragma Assert (Self_ID.Pending_Action);
591 (Chain.T_ID = null or else Chain.T_ID.Common.State = Unactivated);
595 Initialization.Undefer_Abort_Nestable (Self_ID);
597 -- ??? Should never get here
599 pragma Assert (False);
600 raise Standard'Abort_Signal;
603 Initialize_ATCB (Self_ID, State, Discriminants, P, Elaborated,
604 Base_Priority, Task_Info, Size, T, Success);
610 Initialization.Undefer_Abort_Nestable (Self_ID);
612 (Storage_Error'Identity, "Failed to initialize task");
615 T.Master_of_Task := Master;
616 T.Master_Within := T.Master_of_Task + 1;
618 for L in T.Entry_Calls'Range loop
619 T.Entry_Calls (L).Self := T;
620 T.Entry_Calls (L).Level := L;
623 if Task_Image'Length = 0 then
624 T.Common.Task_Image_Len := 0;
627 T.Common.Task_Image (1) := Task_Image (Task_Image'First);
629 -- Remove unwanted blank space generated by 'Image
631 for J in Task_Image'First + 1 .. Task_Image'Last loop
632 if Task_Image (J) /= ' '
633 or else Task_Image (J - 1) /= '('
636 T.Common.Task_Image (Len) := Task_Image (J);
637 exit when Len = T.Common.Task_Image'Last;
641 T.Common.Task_Image_Len := Len;
647 -- Create TSD as early as possible in the creation of a task, since it
648 -- may be used by the operation of Ada code within the task.
650 SSL.Create_TSD (T.Common.Compiler_Data);
651 T.Common.Activation_Link := Chain.T_ID;
653 Initialization.Initialize_Attributes_Link.all (T);
655 Initialization.Undefer_Abort_Nestable (Self_ID);
657 if Runtime_Traces then
658 Send_Trace_Info (T_Create, T);
666 function Current_Master return Master_Level is
668 return STPO.Self.Master_Within;
675 procedure Enter_Master is
676 Self_ID : constant Task_Id := STPO.Self;
678 Self_ID.Master_Within := Self_ID.Master_Within + 1;
681 -------------------------------
682 -- Expunge_Unactivated_Tasks --
683 -------------------------------
685 -- See procedure Close_Entries for the general case
687 procedure Expunge_Unactivated_Tasks (Chain : in out Activation_Chain) is
688 Self_ID : constant Task_Id := STPO.Self;
690 Call : Entry_Call_Link;
695 (Debug.Trace (Self_ID, "Expunge_Unactivated_Tasks", 'C'));
697 Initialization.Defer_Abort_Nestable (Self_ID);
700 -- Experimentation has shown that abort is sometimes (but not
701 -- always) already deferred when this is called.
703 -- That may indicate an error. Find out what is going on
707 pragma Assert (C.Common.State = Unactivated);
709 Temp := C.Common.Activation_Link;
711 if C.Common.State = Unactivated then
715 for J in 1 .. C.Entry_Num loop
716 Queuing.Dequeue_Head (C.Entry_Queues (J), Call);
717 pragma Assert (Call = null);
722 Initialization.Remove_From_All_Tasks_List (C);
725 Vulnerable_Free_Task (C);
731 Initialization.Undefer_Abort_Nestable (Self_ID);
732 end Expunge_Unactivated_Tasks;
734 ---------------------------
735 -- Finalize_Global_Tasks --
736 ---------------------------
739 -- We have a potential problem here if finalization of global
740 -- objects does anything with signals or the timer server, since
741 -- by that time those servers have terminated.
743 -- It is hard to see how that would occur
745 -- However, a better solution might be to do all this finalization
746 -- using the global finalization chain.
748 procedure Finalize_Global_Tasks is
749 Self_ID : constant Task_Id := STPO.Self;
753 if Self_ID.Deferral_Level = 0 then
755 -- In principle, we should be able to predict whether
756 -- abort is already deferred here (and it should not be deferred
757 -- yet but in practice it seems Finalize_Global_Tasks is being
758 -- called sometimes, from RTS code for exceptions, with abort already
761 Initialization.Defer_Abort_Nestable (Self_ID);
763 -- Never undefer again!!!
766 -- This code is only executed by the environment task
768 pragma Assert (Self_ID = Environment_Task);
770 -- Set Environment_Task'Callable to false to notify library-level tasks
771 -- that it is waiting for them (cf 5619-003).
773 Self_ID.Callable := False;
775 -- Exit level 2 master, for normal tasks in library-level packages
779 -- Force termination of "independent" library-level server tasks
783 Abort_Dependents (Self_ID);
785 if not Single_Lock then
789 -- We need to explicitely wait for the task to be terminated here
790 -- because on true concurrent system, we may end this procedure
791 -- before the tasks are really terminated.
793 Write_Lock (Self_ID);
796 exit when Utilities.Independent_Task_Count = 0;
798 -- We used to yield here, but this did not take into account
799 -- low priority tasks that would cause dead lock in some cases.
803 (Self_ID, 0.01, System.OS_Primitives.Relative,
804 Self_ID.Common.State, Ignore, Ignore);
807 -- ??? On multi-processor environments, it seems that the above loop
808 -- isn't sufficient, so we need to add an additional delay.
811 (Self_ID, 0.01, System.OS_Primitives.Relative,
812 Self_ID.Common.State, Ignore, Ignore);
820 -- Complete the environment task
822 Vulnerable_Complete_Task (Self_ID);
824 -- Handle normal task termination by the environment task, but only
825 -- for the normal task termination. In the case of Abnormal and
826 -- Unhandled_Exception they must have been handled before, and the
827 -- task termination soft link must have been changed so the task
828 -- termination routine is not executed twice.
830 SSL.Task_Termination_Handler.all (Ada.Exceptions.Null_Occurrence);
832 -- Finalize the global list for controlled objects if needed
834 SSL.Finalize_Global_List.all;
836 -- Reset the soft links to non-tasking
838 SSL.Abort_Defer := SSL.Abort_Defer_NT'Access;
839 SSL.Abort_Undefer := SSL.Abort_Undefer_NT'Access;
840 SSL.Lock_Task := SSL.Task_Lock_NT'Access;
841 SSL.Unlock_Task := SSL.Task_Unlock_NT'Access;
842 SSL.Get_Jmpbuf_Address := SSL.Get_Jmpbuf_Address_NT'Access;
843 SSL.Set_Jmpbuf_Address := SSL.Set_Jmpbuf_Address_NT'Access;
844 SSL.Get_Sec_Stack_Addr := SSL.Get_Sec_Stack_Addr_NT'Access;
845 SSL.Set_Sec_Stack_Addr := SSL.Set_Sec_Stack_Addr_NT'Access;
846 SSL.Check_Abort_Status := SSL.Check_Abort_Status_NT'Access;
847 SSL.Get_Stack_Info := SSL.Get_Stack_Info_NT'Access;
849 -- Don't bother trying to finalize Initialization.Global_Task_Lock
850 -- and System.Task_Primitives.RTS_Lock.
852 end Finalize_Global_Tasks;
858 procedure Free_Task (T : Task_Id) is
859 Self_Id : constant Task_Id := Self;
862 if T.Common.State = Terminated then
864 -- It is not safe to call Abort_Defer or Write_Lock at this stage
866 Initialization.Task_Lock (Self_Id);
869 Initialization.Remove_From_All_Tasks_List (T);
872 Initialization.Task_Unlock (Self_Id);
874 System.Task_Primitives.Operations.Finalize_TCB (T);
876 -- If the task is not terminated, then we simply ignore the call. This
877 -- happens when a user program attempts an unchecked deallocation on
878 -- a non-terminated task.
885 ---------------------------
886 -- Move_Activation_Chain --
887 ---------------------------
889 procedure Move_Activation_Chain
890 (From, To : Activation_Chain_Access;
891 New_Master : Master_ID)
893 Self_ID : constant Task_Id := STPO.Self;
898 (Debug.Trace (Self_ID, "Move_Activation_Chain", 'C'));
900 -- Nothing to do if From is empty, and we can check that without
909 Initialization.Defer_Abort (Self_ID);
911 -- Loop through the From chain, changing their Master_of_Task
912 -- fields, and to find the end of the chain.
915 C.Master_of_Task := New_Master;
916 exit when C.Common.Activation_Link = null;
917 C := C.Common.Activation_Link;
920 -- Hook From in at the start of To
922 C.Common.Activation_Link := To.all.T_ID;
923 To.all.T_ID := From.all.T_ID;
927 From.all.T_ID := null;
929 Initialization.Undefer_Abort (Self_ID);
930 end Move_Activation_Chain;
936 -- The task wrapper is a procedure that is called first for each task
937 -- task body, and which in turn calls the compiler-generated task body
938 -- procedure. The wrapper's main job is to do initialization for the task.
939 -- It also has some locally declared objects that server as per-task local
940 -- data. Task finalization is done by Complete_Task, which is called from
941 -- an at-end handler that the compiler generates.
943 procedure Task_Wrapper (Self_ID : Task_Id) is
944 use type System.Parameters.Size_Type;
945 use type SSE.Storage_Offset;
946 use System.Standard_Library;
947 use System.Stack_Usage;
949 Bottom_Of_Stack : aliased Integer;
951 Secondary_Stack_Size :
952 constant SSE.Storage_Offset :=
953 Self_ID.Common.Compiler_Data.Pri_Stack_Info.Size *
954 SSE.Storage_Offset (Parameters.Sec_Stack_Ratio) / 100;
957 aliased SSE.Storage_Array
958 (1 .. Secondary_Stack_Size);
960 pragma Warnings (Off);
961 Secondary_Stack_Address : System.Address := Secondary_Stack'Address;
963 Small_Overflow_Guard : constant := 4 * 1024;
964 Big_Overflow_Guard : constant := 16 * 1024;
965 Small_Stack_Limit : constant := 64 * 1024;
966 -- ??? These three values are experimental, and seems to work on most
967 -- platforms. They still need to be analyzed further.
970 Natural := Natural (Self_ID.Common.Compiler_Data.Pri_Stack_Info.Size);
972 pragma Warnings (On);
973 -- Address of secondary stack. In the fixed secondary stack case, this
974 -- value is not modified, causing a warning, hence the bracketing with
975 -- Warnings (Off/On).
977 SEH_Table : aliased SSE.Storage_Array (1 .. 8);
978 -- Structured Exception Registration table (2 words)
980 procedure Install_SEH_Handler (Addr : System.Address);
981 pragma Import (C, Install_SEH_Handler, "__gnat_install_SEH_handler");
982 -- Install the SEH (Structured Exception Handling) handler
984 Cause : Cause_Of_Termination := Normal;
985 -- Indicates the reason why this task terminates. Normal corresponds to
986 -- a task terminating due to completing the last statement of its body,
987 -- or as a result of waiting on a terminate alternative. If the task
988 -- terminates because it is being aborted then Cause will be set to
989 -- Abnormal. If the task terminates because of an exception raised by
990 -- the execution of its task body, then Cause is set to
991 -- Unhandled_Exception.
993 EO : Exception_Occurrence;
994 -- If the task terminates because of an exception raised by the
995 -- execution of its task body, then EO will contain the associated
996 -- exception occurrence. Otherwise, it will contain Null_Occurrence.
998 TH : Termination_Handler := null;
999 -- Pointer to the protected procedure to be executed upon task
1002 procedure Search_Fall_Back_Handler (ID : Task_Id);
1003 -- Procedure that searches recursively a fall-back handler through the
1004 -- master relationship. If the handler is found, its pointer is stored
1007 procedure Search_Fall_Back_Handler (ID : Task_Id) is
1009 -- If there is a fall back handler, store its pointer for later
1012 if ID.Common.Fall_Back_Handler /= null then
1013 TH := ID.Common.Fall_Back_Handler;
1015 -- Otherwise look for a fall back handler in the parent
1017 elsif ID.Common.Parent /= null then
1018 Search_Fall_Back_Handler (ID.Common.Parent);
1020 -- Otherwise, do nothing
1025 end Search_Fall_Back_Handler;
1028 pragma Assert (Self_ID.Deferral_Level = 1);
1030 -- Assume a size of the stack taken at this stage
1032 if Size < Small_Stack_Limit then
1033 Size := Size - Small_Overflow_Guard;
1035 Size := Size - Big_Overflow_Guard;
1038 if not Parameters.Sec_Stack_Dynamic then
1039 Self_ID.Common.Compiler_Data.Sec_Stack_Addr :=
1040 Secondary_Stack'Address;
1041 SST.SS_Init (Secondary_Stack_Address, Integer (Secondary_Stack'Last));
1042 Size := Size - Natural (Secondary_Stack_Size);
1045 if System.Stack_Usage.Is_Enabled then
1047 Initialize_Analyzer (Self_ID.Common.Analyzer,
1048 Self_ID.Common.Task_Image
1049 (1 .. Self_ID.Common.Task_Image_Len),
1051 SSE.To_Integer (Bottom_Of_Stack'Address));
1053 Fill_Stack (Self_ID.Common.Analyzer);
1056 -- Set the guard page at the bottom of the stack. The call to unprotect
1057 -- the page is done in Terminate_Task
1059 Stack_Guard (Self_ID, True);
1061 -- Initialize low-level TCB components, that cannot be initialized
1062 -- by the creator. Enter_Task sets Self_ID.Known_Tasks_Index and
1063 -- also Self_ID.LL.Thread
1065 Enter_Task (Self_ID);
1067 -- We setup the SEH (Structured Exception Handling) handler if supported
1070 Install_SEH_Handler (SEH_Table'Address);
1072 -- Initialize exception occurrence
1074 Save_Occurrence (EO, Ada.Exceptions.Null_Occurrence);
1076 -- We lock RTS_Lock to wait for activator to finish activating the rest
1077 -- of the chain, so that everyone in the chain comes out in priority
1080 -- This also protects the value of
1081 -- Self_ID.Common.Activator.Common.Wait_Count.
1086 if not System.Restrictions.Abort_Allowed then
1088 -- If Abort is not allowed, reset the deferral level since it will
1089 -- not get changed by the generated code. Keeping a default value
1090 -- of one would prevent some operations (e.g. select or delay) to
1091 -- proceed successfully.
1093 Self_ID.Deferral_Level := 0;
1097 -- We are separating the following portion of the code in order to
1098 -- place the exception handlers in a different block. In this way,
1099 -- we do not call Set_Jmpbuf_Address (which needs Self) before we
1100 -- set Self in Enter_Task
1102 -- Call the task body procedure
1104 -- The task body is called with abort still deferred. That
1105 -- eliminates a dangerous window, for which we had to patch-up in
1108 -- During the expansion of the task body, we insert an RTS-call
1109 -- to Abort_Undefer, at the first point where abort should be
1112 Self_ID.Common.Task_Entry_Point (Self_ID.Common.Task_Arg);
1113 Initialization.Defer_Abort_Nestable (Self_ID);
1116 -- We can't call Terminate_Task in the exception handlers below,
1117 -- since there may be (e.g. in the case of GCC exception handling)
1118 -- clean ups associated with the exception handler that need to
1119 -- access task specific data.
1121 -- Defer abort so that this task can't be aborted while exiting
1123 when Standard'Abort_Signal =>
1124 Initialization.Defer_Abort_Nestable (Self_ID);
1126 -- Update the cause that motivated the task termination so that
1127 -- the appropriate information is passed to the task termination
1128 -- procedure. Task termination as a result of waiting on a
1129 -- terminate alternative is a normal termination, although it is
1130 -- implemented using the abort mechanisms.
1132 if Self_ID.Terminate_Alternative then
1138 -- ??? Using an E : others here causes CD2C11A to fail on
1139 -- DEC Unix, see 7925-005.
1141 Initialization.Defer_Abort_Nestable (Self_ID);
1143 -- Perform the task specific exception tracing duty. We handle
1144 -- these outputs here and not in the common notification routine
1145 -- because we need access to tasking related data and we don't
1146 -- want to drag dependencies against tasking related units in the
1147 -- the common notification units. Additionally, no trace is ever
1148 -- triggered from the common routine for the Unhandled_Raise case
1149 -- in tasks, since an exception never appears unhandled in this
1150 -- context because of this handler.
1152 if Exception_Trace = Unhandled_Raise then
1153 Trace_Unhandled_Exception_In_Task (Self_ID);
1156 -- Update the cause that motivated the task termination so that
1157 -- the appropriate information is passed to the task termination
1158 -- procedure, as well as the associated Exception_Occurrence.
1160 Cause := Unhandled_Exception;
1161 Save_Occurrence (EO, SSL.Get_Current_Excep.all.all);
1164 -- Look for a task termination handler. This code is for all tasks but
1165 -- the environment task. The task termination code for the environment
1166 -- task is executed by SSL.Task_Termination_Handler.
1172 Write_Lock (Self_ID);
1174 if Self_ID.Common.Specific_Handler /= null then
1175 TH := Self_ID.Common.Specific_Handler;
1177 -- Look for a fall-back handler following the master relationship
1180 Search_Fall_Back_Handler (Self_ID);
1189 -- Execute the task termination handler if we found it
1192 TH.all (Cause, Self_ID, EO);
1195 if System.Stack_Usage.Is_Enabled then
1196 Compute_Result (Self_ID.Common.Analyzer);
1197 Report_Result (Self_ID.Common.Analyzer);
1200 Terminate_Task (Self_ID);
1203 --------------------
1204 -- Terminate_Task --
1205 --------------------
1207 -- Before we allow the thread to exit, we must clean up. This is a
1208 -- a delicate job. We must wake up the task's master, who may immediately
1209 -- try to deallocate the ATCB out from under the current task WHILE IT IS
1212 -- To avoid this, the parent task must be blocked up to the latest
1213 -- statement executed. The trouble is that we have another step that we
1214 -- also want to postpone to the very end, i.e., calling SSL.Destroy_TSD.
1215 -- We have to postpone that until the end because compiler-generated code
1216 -- is likely to try to access that data at just about any point.
1218 -- We can't call Destroy_TSD while we are holding any other locks, because
1219 -- it locks Global_Task_Lock, and our deadlock prevention rules require
1220 -- that to be the outermost lock. Our first "solution" was to just lock
1221 -- Global_Task_Lock in addition to the other locks, and force the parent to
1222 -- also lock this lock between its wakeup and its freeing of the ATCB. See
1223 -- Complete_Task for the parent-side of the code that has the matching
1224 -- calls to Task_Lock and Task_Unlock. That was not really a solution,
1225 -- since the operation Task_Unlock continued to access the ATCB after
1226 -- unlocking, after which the parent was observed to race ahead, deallocate
1227 -- the ATCB, and then reallocate it to another task. The call to
1228 -- Undefer_Abortion in Task_Unlock by the "terminated" task was overwriting
1229 -- the data of the new task that reused the ATCB! To solve this problem, we
1230 -- introduced the new operation Final_Task_Unlock.
1232 procedure Terminate_Task (Self_ID : Task_Id) is
1233 Environment_Task : constant Task_Id := STPO.Environment_Task;
1234 Master_of_Task : Integer;
1237 Debug.Task_Termination_Hook;
1239 if Runtime_Traces then
1240 Send_Trace_Info (T_Terminate);
1243 -- Since GCC cannot allocate stack chunks efficiently without reordering
1244 -- some of the allocations, we have to handle this unexpected situation
1245 -- here. We should normally never have to call Vulnerable_Complete_Task
1246 -- here. See 6602-003 for more details.
1248 if Self_ID.Common.Activator /= null then
1249 Vulnerable_Complete_Task (Self_ID);
1252 Initialization.Task_Lock (Self_ID);
1258 Master_of_Task := Self_ID.Master_of_Task;
1260 -- Check if the current task is an independent task If so, decrement
1261 -- the Independent_Task_Count value.
1263 if Master_of_Task = 2 then
1265 Utilities.Independent_Task_Count :=
1266 Utilities.Independent_Task_Count - 1;
1268 Write_Lock (Environment_Task);
1269 Utilities.Independent_Task_Count :=
1270 Utilities.Independent_Task_Count - 1;
1271 Unlock (Environment_Task);
1275 -- Unprotect the guard page if needed
1277 Stack_Guard (Self_ID, False);
1279 Utilities.Make_Passive (Self_ID, Task_Completed => True);
1285 pragma Assert (Check_Exit (Self_ID));
1287 SSL.Destroy_TSD (Self_ID.Common.Compiler_Data);
1288 Initialization.Final_Task_Unlock (Self_ID);
1290 -- WARNING: past this point, this thread must assume that the ATCB
1291 -- has been deallocated. It should not be accessed again.
1293 if Master_of_Task > 0 then
1302 function Terminated (T : Task_Id) return Boolean is
1303 Self_ID : constant Task_Id := STPO.Self;
1307 Initialization.Defer_Abort_Nestable (Self_ID);
1314 Result := T.Common.State = Terminated;
1321 Initialization.Undefer_Abort_Nestable (Self_ID);
1325 ----------------------------------------
1326 -- Trace_Unhandled_Exception_In_Task --
1327 ----------------------------------------
1329 procedure Trace_Unhandled_Exception_In_Task (Self_Id : Task_Id) is
1330 procedure To_Stderr (S : String);
1331 pragma Import (Ada, To_Stderr, "__gnat_to_stderr");
1333 use System.Soft_Links;
1334 use System.Standard_Library;
1336 function To_Address is new
1337 Unchecked_Conversion (Task_Id, System.Address);
1339 function Tailored_Exception_Information
1340 (E : Exception_Occurrence) return String;
1342 (Ada, Tailored_Exception_Information,
1343 "__gnat_tailored_exception_information");
1345 Excep : constant Exception_Occurrence_Access :=
1346 SSL.Get_Current_Excep.all;
1349 -- This procedure is called by the task outermost handler in
1350 -- Task_Wrapper below, so only once the task stack has been fully
1351 -- unwound. The common notification routine has been called at the
1352 -- raise point already.
1354 To_Stderr ("task ");
1356 if Self_Id.Common.Task_Image_Len /= 0 then
1358 (Self_Id.Common.Task_Image (1 .. Self_Id.Common.Task_Image_Len));
1362 To_Stderr (System.Address_Image (To_Address (Self_Id)));
1363 To_Stderr (" terminated by unhandled exception");
1364 To_Stderr ((1 => ASCII.LF));
1365 To_Stderr (Tailored_Exception_Information (Excep.all));
1366 end Trace_Unhandled_Exception_In_Task;
1368 ------------------------------------
1369 -- Vulnerable_Complete_Activation --
1370 ------------------------------------
1372 -- As in several other places, the locks of the activator and activated
1373 -- task are both locked here. This follows our deadlock prevention lock
1374 -- ordering policy, since the activated task must be created after the
1377 procedure Vulnerable_Complete_Activation (Self_ID : Task_Id) is
1378 Activator : constant Task_Id := Self_ID.Common.Activator;
1381 pragma Debug (Debug.Trace (Self_ID, "V_Complete_Activation", 'C'));
1383 Write_Lock (Activator);
1384 Write_Lock (Self_ID);
1386 pragma Assert (Self_ID.Common.Activator /= null);
1388 -- Remove dangling reference to Activator, since a task may
1389 -- outlive its activator.
1391 Self_ID.Common.Activator := null;
1393 -- Wake up the activator, if it is waiting for a chain of tasks to
1394 -- activate, and we are the last in the chain to complete activation.
1396 if Activator.Common.State = Activator_Sleep then
1397 Activator.Common.Wait_Count := Activator.Common.Wait_Count - 1;
1399 if Activator.Common.Wait_Count = 0 then
1400 Wakeup (Activator, Activator_Sleep);
1404 -- The activator raises a Tasking_Error if any task it is activating
1405 -- is completed before the activation is done. However, if the reason
1406 -- for the task completion is an abort, we do not raise an exception.
1409 if not Self_ID.Callable and then Self_ID.Pending_ATC_Level /= 0 then
1410 Activator.Common.Activation_Failed := True;
1416 -- After the activation, active priority should be the same
1417 -- as base priority. We must unlock the Activator first,
1418 -- though, since it should not wait if we have lower priority.
1420 if Get_Priority (Self_ID) /= Self_ID.Common.Base_Priority then
1421 Write_Lock (Self_ID);
1422 Set_Priority (Self_ID, Self_ID.Common.Base_Priority);
1425 end Vulnerable_Complete_Activation;
1427 --------------------------------
1428 -- Vulnerable_Complete_Master --
1429 --------------------------------
1431 procedure Vulnerable_Complete_Master (Self_ID : Task_Id) is
1434 CM : constant Master_Level := Self_ID.Master_Within;
1435 T : aliased Task_Id;
1437 To_Be_Freed : Task_Id;
1438 -- This is a list of ATCBs to be freed, after we have released
1439 -- all RTS locks. This is necessary because of the locking order
1440 -- rules, since the storage manager uses Global_Task_Lock.
1442 pragma Warnings (Off);
1443 function Check_Unactivated_Tasks return Boolean;
1444 pragma Warnings (On);
1445 -- Temporary error-checking code below. This is part of the checks
1446 -- added in the new run time. Call it only inside a pragma Assert.
1448 -----------------------------
1449 -- Check_Unactivated_Tasks --
1450 -----------------------------
1452 function Check_Unactivated_Tasks return Boolean is
1454 if not Single_Lock then
1458 Write_Lock (Self_ID);
1460 C := All_Tasks_List;
1461 while C /= null loop
1462 if C.Common.Activator = Self_ID and then C.Master_of_Task = CM then
1466 if C.Common.Parent = Self_ID and then C.Master_of_Task = CM then
1469 if C.Common.State = Unactivated then
1476 C := C.Common.All_Tasks_Link;
1481 if not Single_Lock then
1486 end Check_Unactivated_Tasks;
1488 -- Start of processing for Vulnerable_Complete_Master
1492 (Debug.Trace (Self_ID, "V_Complete_Master", 'C'));
1494 pragma Assert (Self_ID.Common.Wait_Count = 0);
1495 pragma Assert (Self_ID.Deferral_Level > 0);
1497 -- Count how many active dependent tasks this master currently
1498 -- has, and record this in Wait_Count.
1500 -- This count should start at zero, since it is initialized to
1501 -- zero for new tasks, and the task should not exit the
1502 -- sleep-loops that use this count until the count reaches zero.
1504 -- While we're counting, if we run across any unactivated tasks that
1505 -- belong to this master, we summarily terminate them as required by
1509 Write_Lock (Self_ID);
1511 C := All_Tasks_List;
1512 while C /= null loop
1514 -- Terminate unactivated (never-to-be activated) tasks
1516 if C.Common.Activator = Self_ID and then C.Master_of_Task = CM then
1517 pragma Assert (C.Common.State = Unactivated);
1518 -- Usually, C.Common.Activator = Self_ID implies C.Master_of_Task
1519 -- = CM. The only case where C is pending activation by this
1520 -- task, but the master of C is not CM is in Ada 2005, when C is
1521 -- part of a return object of a build-in-place function.
1524 C.Common.Activator := null;
1525 C.Common.State := Terminated;
1526 C.Callable := False;
1527 Utilities.Cancel_Queued_Entry_Calls (C);
1531 -- Count it if dependent on this master
1533 if C.Common.Parent = Self_ID and then C.Master_of_Task = CM then
1536 if C.Awake_Count /= 0 then
1537 Self_ID.Common.Wait_Count := Self_ID.Common.Wait_Count + 1;
1543 C := C.Common.All_Tasks_Link;
1546 Self_ID.Common.State := Master_Completion_Sleep;
1549 if not Single_Lock then
1553 -- Wait until dependent tasks are all terminated or ready to terminate.
1554 -- While waiting, the task may be awakened if the task's priority needs
1555 -- changing, or this master is aborted. In the latter case, we want
1556 -- to abort the dependents, and resume waiting until Wait_Count goes
1559 Write_Lock (Self_ID);
1562 Initialization.Poll_Base_Priority_Change (Self_ID);
1563 exit when Self_ID.Common.Wait_Count = 0;
1565 -- Here is a difference as compared to Complete_Master
1567 if Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level
1568 and then not Self_ID.Dependents_Aborted
1571 Abort_Dependents (Self_ID);
1575 Abort_Dependents (Self_ID);
1577 Write_Lock (Self_ID);
1580 Sleep (Self_ID, Master_Completion_Sleep);
1584 Self_ID.Common.State := Runnable;
1587 -- Dependents are all terminated or on terminate alternatives.
1588 -- Now, force those on terminate alternatives to terminate, by
1591 pragma Assert (Check_Unactivated_Tasks);
1593 if Self_ID.Alive_Count > 1 then
1595 -- Consider finding a way to skip the following extra steps if there
1596 -- are no dependents with terminate alternatives. This could be done
1597 -- by adding another count to the ATCB, similar to Awake_Count, but
1598 -- keeping track of tasks that are on terminate alternatives.
1600 pragma Assert (Self_ID.Common.Wait_Count = 0);
1602 -- Force any remaining dependents to terminate by aborting them
1604 if not Single_Lock then
1608 Abort_Dependents (Self_ID);
1610 -- Above, when we "abort" the dependents we are simply using this
1611 -- operation for convenience. We are not required to support the full
1612 -- abort-statement semantics; in particular, we are not required to
1613 -- immediately cancel any queued or in-service entry calls. That is
1614 -- good, because if we tried to cancel a call we would need to lock
1615 -- the caller, in order to wake the caller up. Our anti-deadlock
1616 -- rules prevent us from doing that without releasing the locks on C
1617 -- and Self_ID. Releasing and retaking those locks would be wasteful
1618 -- at best, and should not be considered further without more
1619 -- detailed analysis of potential concurrent accesses to the
1620 -- ATCBs of C and Self_ID.
1622 -- Count how many "alive" dependent tasks this master currently
1623 -- has, and record this in Wait_Count. This count should start at
1624 -- zero, since it is initialized to zero for new tasks, and the
1625 -- task should not exit the sleep-loops that use this count until
1626 -- the count reaches zero.
1628 pragma Assert (Self_ID.Common.Wait_Count = 0);
1630 Write_Lock (Self_ID);
1632 C := All_Tasks_List;
1633 while C /= null loop
1634 if C.Common.Parent = Self_ID and then C.Master_of_Task = CM then
1637 pragma Assert (C.Awake_Count = 0);
1639 if C.Alive_Count > 0 then
1640 pragma Assert (C.Terminate_Alternative);
1641 Self_ID.Common.Wait_Count := Self_ID.Common.Wait_Count + 1;
1647 C := C.Common.All_Tasks_Link;
1650 Self_ID.Common.State := Master_Phase_2_Sleep;
1653 if not Single_Lock then
1657 -- Wait for all counted tasks to finish terminating themselves
1659 Write_Lock (Self_ID);
1662 Initialization.Poll_Base_Priority_Change (Self_ID);
1663 exit when Self_ID.Common.Wait_Count = 0;
1664 Sleep (Self_ID, Master_Phase_2_Sleep);
1667 Self_ID.Common.State := Runnable;
1671 -- We don't wake up for abort here. We are already terminating just as
1672 -- fast as we can, so there is no point.
1674 -- Remove terminated tasks from the list of Self_ID's dependents, but
1675 -- don't free their ATCBs yet, because of lock order restrictions,
1676 -- which don't allow us to call "free" or "malloc" while holding any
1677 -- other locks. Instead, we put those ATCBs to be freed onto a
1678 -- temporary list, called To_Be_Freed.
1680 if not Single_Lock then
1684 C := All_Tasks_List;
1686 while C /= null loop
1687 if C.Common.Parent = Self_ID and then C.Master_of_Task >= CM then
1689 P.Common.All_Tasks_Link := C.Common.All_Tasks_Link;
1691 All_Tasks_List := C.Common.All_Tasks_Link;
1694 T := C.Common.All_Tasks_Link;
1695 C.Common.All_Tasks_Link := To_Be_Freed;
1701 C := C.Common.All_Tasks_Link;
1707 -- Free all the ATCBs on the list To_Be_Freed
1709 -- The ATCBs in the list are no longer in All_Tasks_List, and after
1710 -- any interrupt entries are detached from them they should no longer
1713 -- Global_Task_Lock (Task_Lock/Unlock) is locked in the loop below to
1714 -- avoid a race between a terminating task and its parent. The parent
1715 -- might try to deallocate the ACTB out from underneath the exiting
1716 -- task. Note that Free will also lock Global_Task_Lock, but that is
1717 -- OK, since this is the *one* lock for which we have a mechanism to
1718 -- support nested locking. See Task_Wrapper and its finalizer for more
1722 -- The check "T.Common.Parent /= null ..." below is to prevent dangling
1723 -- references to terminated library-level tasks, which could
1724 -- otherwise occur during finalization of library-level objects.
1725 -- A better solution might be to hook task objects into the
1726 -- finalization chain and deallocate the ATCB when the task
1727 -- object is deallocated. However, this change is not likely
1728 -- to gain anything significant, since all this storage should
1729 -- be recovered en-masse when the process exits.
1731 while To_Be_Freed /= null loop
1733 To_Be_Freed := T.Common.All_Tasks_Link;
1735 -- ??? On SGI there is currently no Interrupt_Manager, that's
1736 -- why we need to check if the Interrupt_Manager_ID is null
1738 if T.Interrupt_Entry and Interrupt_Manager_ID /= null then
1740 Detach_Interrupt_Entries_Index : constant Task_Entry_Index := 1;
1741 -- Corresponds to the entry index of System.Interrupts.
1742 -- Interrupt_Manager.Detach_Interrupt_Entries.
1743 -- Be sure to update this value when changing
1744 -- Interrupt_Manager specs.
1746 type Param_Type is access all Task_Id;
1748 Param : aliased Param_Type := T'Access;
1751 System.Tasking.Rendezvous.Call_Simple
1752 (Interrupt_Manager_ID, Detach_Interrupt_Entries_Index,
1757 if (T.Common.Parent /= null
1758 and then T.Common.Parent.Common.Parent /= null)
1759 or else T.Master_of_Task > 3
1761 Initialization.Task_Lock (Self_ID);
1763 -- If Sec_Stack_Addr is not null, it means that Destroy_TSD
1764 -- has not been called yet (case of an unactivated task).
1766 if T.Common.Compiler_Data.Sec_Stack_Addr /= Null_Address then
1767 SSL.Destroy_TSD (T.Common.Compiler_Data);
1770 Vulnerable_Free_Task (T);
1771 Initialization.Task_Unlock (Self_ID);
1775 -- It might seem nice to let the terminated task deallocate its own
1776 -- ATCB. That would not cover the case of unactivated tasks. It also
1777 -- would force us to keep the underlying thread around past termination,
1778 -- since references to the ATCB are possible past termination.
1779 -- Currently, we get rid of the thread as soon as the task terminates,
1780 -- and let the parent recover the ATCB later.
1782 -- Some day, if we want to recover the ATCB earlier, at task
1783 -- termination, we could consider using "fat task IDs", that include the
1784 -- serial number with the ATCB pointer, to catch references to tasks
1785 -- that no longer have ATCBs. It is not clear how much this would gain,
1786 -- since the user-level task object would still be occupying storage.
1788 -- Make next master level up active.
1789 -- We don't need to lock the ATCB, since the value is only updated by
1790 -- each task for itself.
1792 Self_ID.Master_Within := CM - 1;
1793 end Vulnerable_Complete_Master;
1795 ------------------------------
1796 -- Vulnerable_Complete_Task --
1797 ------------------------------
1799 -- Complete the calling task
1801 -- This procedure must be called with abort deferred. It should only be
1802 -- called by Complete_Task and Finalize_Global_Tasks (for the environment
1805 -- The effect is similar to that of Complete_Master. Differences include
1806 -- the closing of entries here, and computation of the number of active
1807 -- dependent tasks in Complete_Master.
1809 -- We don't lock Self_ID before the call to Vulnerable_Complete_Activation,
1810 -- because that does its own locking, and because we do not need the lock
1811 -- to test Self_ID.Common.Activator. That value should only be read and
1812 -- modified by Self.
1814 procedure Vulnerable_Complete_Task (Self_ID : Task_Id) is
1816 pragma Assert (Self_ID.Deferral_Level > 0);
1817 pragma Assert (Self_ID = Self);
1818 pragma Assert (Self_ID.Master_Within = Self_ID.Master_of_Task + 1
1820 Self_ID.Master_Within = Self_ID.Master_of_Task + 2);
1821 pragma Assert (Self_ID.Common.Wait_Count = 0);
1822 pragma Assert (Self_ID.Open_Accepts = null);
1823 pragma Assert (Self_ID.ATC_Nesting_Level = 1);
1825 pragma Debug (Debug.Trace (Self_ID, "V_Complete_Task", 'C'));
1831 Write_Lock (Self_ID);
1832 Self_ID.Callable := False;
1834 -- In theory, Self should have no pending entry calls left on its
1835 -- call-stack. Each async. select statement should clean its own call,
1836 -- and blocking entry calls should defer abort until the calls are
1837 -- cancelled, then clean up.
1839 Utilities.Cancel_Queued_Entry_Calls (Self_ID);
1842 if Self_ID.Common.Activator /= null then
1843 Vulnerable_Complete_Activation (Self_ID);
1850 -- If Self_ID.Master_Within = Self_ID.Master_of_Task + 2
1851 -- we may have dependent tasks for which we need to wait.
1852 -- Otherwise, we can just exit.
1854 if Self_ID.Master_Within = Self_ID.Master_of_Task + 2 then
1855 Vulnerable_Complete_Master (Self_ID);
1857 end Vulnerable_Complete_Task;
1859 --------------------------
1860 -- Vulnerable_Free_Task --
1861 --------------------------
1863 -- Recover all runtime system storage associated with the task T.
1864 -- This should only be called after T has terminated and will no
1865 -- longer be referenced.
1867 -- For tasks created by an allocator that fails, due to an exception,
1868 -- it is called from Expunge_Unactivated_Tasks.
1870 -- For tasks created by elaboration of task object declarations it
1871 -- is called from the finalization code of the Task_Wrapper procedure.
1872 -- It is also called from Unchecked_Deallocation, for objects that
1873 -- are or contain tasks.
1875 procedure Vulnerable_Free_Task (T : Task_Id) is
1877 pragma Debug (Debug.Trace (Self, "Vulnerable_Free_Task", 'C', T));
1884 Initialization.Finalize_Attributes_Link.all (T);
1891 System.Task_Primitives.Operations.Finalize_TCB (T);
1892 end Vulnerable_Free_Task;
1894 -- Package elaboration code
1897 -- Establish the Adafinal softlink
1899 -- This is not done inside the central RTS initialization routine
1900 -- to avoid with-ing this package from System.Tasking.Initialization.
1902 SSL.Adafinal := Finalize_Global_Tasks'Access;
1904 -- Establish soft links for subprograms that manipulate master_id's.
1905 -- This cannot be done when the RTS is initialized, because of various
1906 -- elaboration constraints.
1908 SSL.Current_Master := Stages.Current_Master'Access;
1909 SSL.Enter_Master := Stages.Enter_Master'Access;
1910 SSL.Complete_Master := Stages.Complete_Master'Access;
1911 end System.Tasking.Stages;