1------------------------------------------------------------------------------ 2-- -- 3-- GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS -- 4-- -- 5-- S Y S T E M . T A S K I N G . S T A G E S -- 6-- -- 7-- B o d y -- 8-- -- 9-- Copyright (C) 1992-2014, Free Software Foundation, Inc. -- 10-- -- 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. -- 17-- -- 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. -- 21-- -- 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/>. -- 26-- -- 27-- GNARL was developed by the GNARL team at Florida State University. -- 28-- Extensive contributions were provided by Ada Core Technologies, Inc. -- 29-- -- 30------------------------------------------------------------------------------ 31 32pragma Polling (Off); 33-- Turn off polling, we do not want ATC polling to take place during tasking 34-- operations. It causes infinite loops and other problems. 35 36pragma Partition_Elaboration_Policy (Concurrent); 37-- This package only implements the concurrent elaboration policy. This pragma 38-- will enforce it (and detect conflicts with user specified policy). 39 40with Ada.Exceptions; 41with Ada.Unchecked_Deallocation; 42 43with System.Interrupt_Management; 44with System.Tasking.Debug; 45with System.Address_Image; 46with System.Task_Primitives; 47with System.Task_Primitives.Operations; 48with System.Tasking.Utilities; 49with System.Tasking.Queuing; 50with System.Tasking.Rendezvous; 51with System.OS_Primitives; 52with System.Secondary_Stack; 53with System.Storage_Elements; 54with System.Restrictions; 55with System.Standard_Library; 56with System.Traces.Tasking; 57with System.Stack_Usage; 58 59with System.Soft_Links; 60-- These are procedure pointers to non-tasking routines that use task 61-- specific data. In the absence of tasking, these routines refer to global 62-- data. In the presence of tasking, they must be replaced with pointers to 63-- task-specific versions. Also used for Create_TSD, Destroy_TSD, Get_Current 64-- _Excep, Finalize_Library_Objects, Task_Termination, Handler. 65 66with System.Tasking.Initialization; 67pragma Elaborate_All (System.Tasking.Initialization); 68-- This insures that tasking is initialized if any tasks are created 69 70package body System.Tasking.Stages is 71 72 package STPO renames System.Task_Primitives.Operations; 73 package SSL renames System.Soft_Links; 74 package SSE renames System.Storage_Elements; 75 package SST renames System.Secondary_Stack; 76 77 use Ada.Exceptions; 78 79 use Parameters; 80 use Task_Primitives; 81 use Task_Primitives.Operations; 82 use Task_Info; 83 84 use System.Traces; 85 use System.Traces.Tasking; 86 87 ----------------------- 88 -- Local Subprograms -- 89 ----------------------- 90 91 procedure Free is new 92 Ada.Unchecked_Deallocation (Ada_Task_Control_Block, Task_Id); 93 94 procedure Trace_Unhandled_Exception_In_Task (Self_Id : Task_Id); 95 -- This procedure outputs the task specific message for exception 96 -- tracing purposes. 97 98 procedure Task_Wrapper (Self_ID : Task_Id); 99 pragma Convention (C, Task_Wrapper); 100 -- This is the procedure that is called by the GNULL from the new context 101 -- when a task is created. It waits for activation and then calls the task 102 -- body procedure. When the task body procedure completes, it terminates 103 -- the task. 104 -- 105 -- The Task_Wrapper's address will be provided to the underlying threads 106 -- library as the task entry point. Convention C is what makes most sense 107 -- for that purpose (Export C would make the function globally visible, 108 -- and affect the link name on which GDB depends). This will in addition 109 -- trigger an automatic stack alignment suitable for GCC's assumptions if 110 -- need be. 111 112 -- "Vulnerable_..." in the procedure names below means they must be called 113 -- with abort deferred. 114 115 procedure Vulnerable_Complete_Task (Self_ID : Task_Id); 116 -- Complete the calling task. This procedure must be called with 117 -- abort deferred. It should only be called by Complete_Task and 118 -- Finalize_Global_Tasks (for the environment task). 119 120 procedure Vulnerable_Complete_Master (Self_ID : Task_Id); 121 -- Complete the current master of the calling task. This procedure 122 -- must be called with abort deferred. It should only be called by 123 -- Vulnerable_Complete_Task and Complete_Master. 124 125 procedure Vulnerable_Complete_Activation (Self_ID : Task_Id); 126 -- Signal to Self_ID's activator that Self_ID has completed activation. 127 -- This procedure must be called with abort deferred. 128 129 procedure Abort_Dependents (Self_ID : Task_Id); 130 -- Abort all the direct dependents of Self at its current master nesting 131 -- level, plus all of their dependents, transitively. RTS_Lock should be 132 -- locked by the caller. 133 134 procedure Vulnerable_Free_Task (T : Task_Id); 135 -- Recover all runtime system storage associated with the task T. This 136 -- should only be called after T has terminated and will no longer be 137 -- referenced. 138 -- 139 -- For tasks created by an allocator that fails, due to an exception, it is 140 -- called from Expunge_Unactivated_Tasks. 141 -- 142 -- Different code is used at master completion, in Terminate_Dependents, 143 -- due to a need for tighter synchronization with the master. 144 145 ---------------------- 146 -- Abort_Dependents -- 147 ---------------------- 148 149 procedure Abort_Dependents (Self_ID : Task_Id) is 150 C : Task_Id; 151 P : Task_Id; 152 153 -- Each task C will take care of its own dependents, so there is no 154 -- need to worry about them here. In fact, it would be wrong to abort 155 -- indirect dependents here, because we can't distinguish between 156 -- duplicate master ids. For example, suppose we have three nested 157 -- task bodies T1,T2,T3. And suppose T1 also calls P which calls Q (and 158 -- both P and Q are task masters). Q will have the same master id as 159 -- Master_of_Task of T3. Previous versions of this would abort T3 when 160 -- Q calls Complete_Master, which was completely wrong. 161 162 begin 163 C := All_Tasks_List; 164 while C /= null loop 165 P := C.Common.Parent; 166 167 if P = Self_ID then 168 if C.Master_of_Task = Self_ID.Master_Within then 169 pragma Debug 170 (Debug.Trace (Self_ID, "Aborting", 'X', C)); 171 Utilities.Abort_One_Task (Self_ID, C); 172 C.Dependents_Aborted := True; 173 end if; 174 end if; 175 176 C := C.Common.All_Tasks_Link; 177 end loop; 178 179 Self_ID.Dependents_Aborted := True; 180 end Abort_Dependents; 181 182 ----------------- 183 -- Abort_Tasks -- 184 ----------------- 185 186 procedure Abort_Tasks (Tasks : Task_List) is 187 begin 188 Utilities.Abort_Tasks (Tasks); 189 end Abort_Tasks; 190 191 -------------------- 192 -- Activate_Tasks -- 193 -------------------- 194 195 -- Note that locks of activator and activated task are both locked here. 196 -- This is necessary because C.Common.State and Self.Common.Wait_Count have 197 -- to be synchronized. This is safe from deadlock because the activator is 198 -- always created before the activated task. That satisfies our 199 -- in-order-of-creation ATCB locking policy. 200 201 -- At one point, we may also lock the parent, if the parent is different 202 -- from the activator. That is also consistent with the lock ordering 203 -- policy, since the activator cannot be created before the parent. 204 205 -- Since we are holding both the activator's lock, and Task_Wrapper locks 206 -- that before it does anything more than initialize the low-level ATCB 207 -- components, it should be safe to wait to update the counts until we see 208 -- that the thread creation is successful. 209 210 -- If the thread creation fails, we do need to close the entries of the 211 -- task. The first phase, of dequeuing calls, only requires locking the 212 -- acceptor's ATCB, but the waking up of the callers requires locking the 213 -- caller's ATCB. We cannot safely do this while we are holding other 214 -- locks. Therefore, the queue-clearing operation is done in a separate 215 -- pass over the activation chain. 216 217 procedure Activate_Tasks (Chain_Access : Activation_Chain_Access) is 218 Self_ID : constant Task_Id := STPO.Self; 219 P : Task_Id; 220 C : Task_Id; 221 Next_C, Last_C : Task_Id; 222 Activate_Prio : System.Any_Priority; 223 Success : Boolean; 224 All_Elaborated : Boolean := True; 225 226 begin 227 -- If pragma Detect_Blocking is active, then we must check whether this 228 -- potentially blocking operation is called from a protected action. 229 230 if System.Tasking.Detect_Blocking 231 and then Self_ID.Common.Protected_Action_Nesting > 0 232 then 233 raise Program_Error with "potentially blocking operation"; 234 end if; 235 236 pragma Debug 237 (Debug.Trace (Self_ID, "Activate_Tasks", 'C')); 238 239 Initialization.Defer_Abort_Nestable (Self_ID); 240 241 pragma Assert (Self_ID.Common.Wait_Count = 0); 242 243 -- Lock RTS_Lock, to prevent activated tasks from racing ahead before 244 -- we finish activating the chain. 245 246 Lock_RTS; 247 248 -- Check that all task bodies have been elaborated 249 250 C := Chain_Access.T_ID; 251 Last_C := null; 252 while C /= null loop 253 if C.Common.Elaborated /= null 254 and then not C.Common.Elaborated.all 255 then 256 All_Elaborated := False; 257 end if; 258 259 -- Reverse the activation chain so that tasks are activated in the 260 -- same order they're declared. 261 262 Next_C := C.Common.Activation_Link; 263 C.Common.Activation_Link := Last_C; 264 Last_C := C; 265 C := Next_C; 266 end loop; 267 268 Chain_Access.T_ID := Last_C; 269 270 if not All_Elaborated then 271 Unlock_RTS; 272 Initialization.Undefer_Abort_Nestable (Self_ID); 273 raise Program_Error with "Some tasks have not been elaborated"; 274 end if; 275 276 -- Activate all the tasks in the chain. Creation of the thread of 277 -- control was deferred until activation. So create it now. 278 279 C := Chain_Access.T_ID; 280 while C /= null loop 281 if C.Common.State /= Terminated then 282 pragma Assert (C.Common.State = Unactivated); 283 284 P := C.Common.Parent; 285 Write_Lock (P); 286 Write_Lock (C); 287 288 Activate_Prio := 289 (if C.Common.Base_Priority < Get_Priority (Self_ID) 290 then Get_Priority (Self_ID) 291 else C.Common.Base_Priority); 292 293 System.Task_Primitives.Operations.Create_Task 294 (C, Task_Wrapper'Address, 295 Parameters.Size_Type 296 (C.Common.Compiler_Data.Pri_Stack_Info.Size), 297 Activate_Prio, Success); 298 299 -- There would be a race between the created task and the creator 300 -- to do the following initialization, if we did not have a 301 -- Lock/Unlock_RTS pair in the task wrapper to prevent it from 302 -- racing ahead. 303 304 if Success then 305 C.Common.State := Activating; 306 C.Awake_Count := 1; 307 C.Alive_Count := 1; 308 P.Awake_Count := P.Awake_Count + 1; 309 P.Alive_Count := P.Alive_Count + 1; 310 311 if P.Common.State = Master_Completion_Sleep and then 312 C.Master_of_Task = P.Master_Within 313 then 314 pragma Assert (Self_ID /= P); 315 P.Common.Wait_Count := P.Common.Wait_Count + 1; 316 end if; 317 318 for J in System.Tasking.Debug.Known_Tasks'Range loop 319 if System.Tasking.Debug.Known_Tasks (J) = null then 320 System.Tasking.Debug.Known_Tasks (J) := C; 321 C.Known_Tasks_Index := J; 322 exit; 323 end if; 324 end loop; 325 326 if Global_Task_Debug_Event_Set then 327 Debug.Signal_Debug_Event 328 (Debug.Debug_Event_Activating, C); 329 end if; 330 331 C.Common.State := Runnable; 332 333 Unlock (C); 334 Unlock (P); 335 336 else 337 -- No need to set Awake_Count, State, etc. here since the loop 338 -- below will do that for any Unactivated tasks. 339 340 Unlock (C); 341 Unlock (P); 342 Self_ID.Common.Activation_Failed := True; 343 end if; 344 end if; 345 346 C := C.Common.Activation_Link; 347 end loop; 348 349 if not Single_Lock then 350 Unlock_RTS; 351 end if; 352 353 -- Close the entries of any tasks that failed thread creation, and count 354 -- those that have not finished activation. 355 356 Write_Lock (Self_ID); 357 Self_ID.Common.State := Activator_Sleep; 358 359 C := Chain_Access.T_ID; 360 while C /= null loop 361 Write_Lock (C); 362 363 if C.Common.State = Unactivated then 364 C.Common.Activator := null; 365 C.Common.State := Terminated; 366 C.Callable := False; 367 Utilities.Cancel_Queued_Entry_Calls (C); 368 369 elsif C.Common.Activator /= null then 370 Self_ID.Common.Wait_Count := Self_ID.Common.Wait_Count + 1; 371 end if; 372 373 Unlock (C); 374 P := C.Common.Activation_Link; 375 C.Common.Activation_Link := null; 376 C := P; 377 end loop; 378 379 -- Wait for the activated tasks to complete activation. It is 380 -- unsafe to abort any of these tasks until the count goes to zero. 381 382 loop 383 exit when Self_ID.Common.Wait_Count = 0; 384 Sleep (Self_ID, Activator_Sleep); 385 end loop; 386 387 Self_ID.Common.State := Runnable; 388 Unlock (Self_ID); 389 390 if Single_Lock then 391 Unlock_RTS; 392 end if; 393 394 -- Remove the tasks from the chain 395 396 Chain_Access.T_ID := null; 397 Initialization.Undefer_Abort_Nestable (Self_ID); 398 399 if Self_ID.Common.Activation_Failed then 400 Self_ID.Common.Activation_Failed := False; 401 raise Tasking_Error with "Failure during activation"; 402 end if; 403 end Activate_Tasks; 404 405 ------------------------- 406 -- Complete_Activation -- 407 ------------------------- 408 409 procedure Complete_Activation is 410 Self_ID : constant Task_Id := STPO.Self; 411 412 begin 413 Initialization.Defer_Abort_Nestable (Self_ID); 414 415 if Single_Lock then 416 Lock_RTS; 417 end if; 418 419 Vulnerable_Complete_Activation (Self_ID); 420 421 if Single_Lock then 422 Unlock_RTS; 423 end if; 424 425 Initialization.Undefer_Abort_Nestable (Self_ID); 426 427 -- ??? Why do we need to allow for nested deferral here? 428 429 if Runtime_Traces then 430 Send_Trace_Info (T_Activate); 431 end if; 432 end Complete_Activation; 433 434 --------------------- 435 -- Complete_Master -- 436 --------------------- 437 438 procedure Complete_Master is 439 Self_ID : constant Task_Id := STPO.Self; 440 begin 441 pragma Assert 442 (Self_ID.Deferral_Level > 0 443 or else not System.Restrictions.Abort_Allowed); 444 Vulnerable_Complete_Master (Self_ID); 445 end Complete_Master; 446 447 ------------------- 448 -- Complete_Task -- 449 ------------------- 450 451 -- See comments on Vulnerable_Complete_Task for details 452 453 procedure Complete_Task is 454 Self_ID : constant Task_Id := STPO.Self; 455 456 begin 457 pragma Assert 458 (Self_ID.Deferral_Level > 0 459 or else not System.Restrictions.Abort_Allowed); 460 461 Vulnerable_Complete_Task (Self_ID); 462 463 -- All of our dependents have terminated, never undefer abort again 464 465 end Complete_Task; 466 467 ----------------- 468 -- Create_Task -- 469 ----------------- 470 471 -- Compiler interface only. Do not call from within the RTS. This must be 472 -- called to create a new task. 473 474 procedure Create_Task 475 (Priority : Integer; 476 Size : System.Parameters.Size_Type; 477 Task_Info : System.Task_Info.Task_Info_Type; 478 CPU : Integer; 479 Relative_Deadline : Ada.Real_Time.Time_Span; 480 Domain : Dispatching_Domain_Access; 481 Num_Entries : Task_Entry_Index; 482 Master : Master_Level; 483 State : Task_Procedure_Access; 484 Discriminants : System.Address; 485 Elaborated : Access_Boolean; 486 Chain : in out Activation_Chain; 487 Task_Image : String; 488 Created_Task : out Task_Id) 489 is 490 T, P : Task_Id; 491 Self_ID : constant Task_Id := STPO.Self; 492 Success : Boolean; 493 Base_Priority : System.Any_Priority; 494 Len : Natural; 495 Base_CPU : System.Multiprocessors.CPU_Range; 496 497 use type System.Multiprocessors.CPU_Range; 498 499 pragma Unreferenced (Relative_Deadline); 500 -- EDF scheduling is not supported by any of the target platforms so 501 -- this parameter is not passed any further. 502 503 begin 504 -- If Master is greater than the current master, it means that Master 505 -- has already awaited its dependent tasks. This raises Program_Error, 506 -- by 4.8(10.3/2). See AI-280. Ignore this check for foreign threads. 507 508 if Self_ID.Master_of_Task /= Foreign_Task_Level 509 and then Master > Self_ID.Master_Within 510 then 511 raise Program_Error with 512 "create task after awaiting termination"; 513 end if; 514 515 -- If pragma Detect_Blocking is active must be checked whether this 516 -- potentially blocking operation is called from a protected action. 517 518 if System.Tasking.Detect_Blocking 519 and then Self_ID.Common.Protected_Action_Nesting > 0 520 then 521 raise Program_Error with "potentially blocking operation"; 522 end if; 523 524 pragma Debug (Debug.Trace (Self_ID, "Create_Task", 'C')); 525 526 Base_Priority := 527 (if Priority = Unspecified_Priority 528 then Self_ID.Common.Base_Priority 529 else System.Any_Priority (Priority)); 530 531 -- Legal values of CPU are the special Unspecified_CPU value which is 532 -- inserted by the compiler for tasks without CPU aspect, and those in 533 -- the range of CPU_Range but no greater than Number_Of_CPUs. Otherwise 534 -- the task is defined to have failed, and it becomes a completed task 535 -- (RM D.16(14/3)). 536 537 if CPU /= Unspecified_CPU 538 and then (CPU < Integer (System.Multiprocessors.CPU_Range'First) 539 or else 540 CPU > Integer (System.Multiprocessors.Number_Of_CPUs)) 541 then 542 raise Tasking_Error with "CPU not in range"; 543 544 -- Normal CPU affinity 545 546 else 547 -- When the application code says nothing about the task affinity 548 -- (task without CPU aspect) then the compiler inserts the value 549 -- Unspecified_CPU which indicates to the run-time library that 550 -- the task will activate and execute on the same processor as its 551 -- activating task if the activating task is assigned a processor 552 -- (RM D.16(14/3)). 553 554 Base_CPU := 555 (if CPU = Unspecified_CPU 556 then Self_ID.Common.Base_CPU 557 else System.Multiprocessors.CPU_Range (CPU)); 558 end if; 559 560 -- Find parent P of new Task, via master level number. Independent 561 -- tasks should have Parent = Environment_Task, and all tasks created 562 -- by independent tasks are also independent. See, for example, 563 -- s-interr.adb, where Interrupt_Manager does "new Server_Task". The 564 -- access type is at library level, so the parent of the Server_Task 565 -- is Environment_Task. 566 567 P := Self_ID; 568 569 if P.Master_of_Task <= Independent_Task_Level then 570 P := Environment_Task; 571 else 572 while P /= null and then P.Master_of_Task >= Master loop 573 P := P.Common.Parent; 574 end loop; 575 end if; 576 577 Initialization.Defer_Abort_Nestable (Self_ID); 578 579 begin 580 T := New_ATCB (Num_Entries); 581 exception 582 when others => 583 Initialization.Undefer_Abort_Nestable (Self_ID); 584 raise Storage_Error with "Cannot allocate task"; 585 end; 586 587 -- RTS_Lock is used by Abort_Dependents and Abort_Tasks. Up to this 588 -- point, it is possible that we may be part of a family of tasks that 589 -- is being aborted. 590 591 Lock_RTS; 592 Write_Lock (Self_ID); 593 594 -- Now, we must check that we have not been aborted. If so, we should 595 -- give up on creating this task, and simply return. 596 597 if not Self_ID.Callable then 598 pragma Assert (Self_ID.Pending_ATC_Level = 0); 599 pragma Assert (Self_ID.Pending_Action); 600 pragma Assert 601 (Chain.T_ID = null or else Chain.T_ID.Common.State = Unactivated); 602 603 Unlock (Self_ID); 604 Unlock_RTS; 605 Initialization.Undefer_Abort_Nestable (Self_ID); 606 607 -- ??? Should never get here 608 609 pragma Assert (False); 610 raise Standard'Abort_Signal; 611 end if; 612 613 Initialize_ATCB (Self_ID, State, Discriminants, P, Elaborated, 614 Base_Priority, Base_CPU, Domain, Task_Info, Size, T, Success); 615 616 if not Success then 617 Free (T); 618 Unlock (Self_ID); 619 Unlock_RTS; 620 Initialization.Undefer_Abort_Nestable (Self_ID); 621 raise Storage_Error with "Failed to initialize task"; 622 end if; 623 624 if Master = Foreign_Task_Level + 2 then 625 626 -- This should not happen, except when a foreign task creates non 627 -- library-level Ada tasks. In this case, we pretend the master is 628 -- a regular library level task, otherwise the run-time will get 629 -- confused when waiting for these tasks to terminate. 630 631 T.Master_of_Task := Library_Task_Level; 632 633 else 634 T.Master_of_Task := Master; 635 end if; 636 637 T.Master_Within := T.Master_of_Task + 1; 638 639 for L in T.Entry_Calls'Range loop 640 T.Entry_Calls (L).Self := T; 641 T.Entry_Calls (L).Level := L; 642 end loop; 643 644 if Task_Image'Length = 0 then 645 T.Common.Task_Image_Len := 0; 646 else 647 Len := 1; 648 T.Common.Task_Image (1) := Task_Image (Task_Image'First); 649 650 -- Remove unwanted blank space generated by 'Image 651 652 for J in Task_Image'First + 1 .. Task_Image'Last loop 653 if Task_Image (J) /= ' ' 654 or else Task_Image (J - 1) /= '(' 655 then 656 Len := Len + 1; 657 T.Common.Task_Image (Len) := Task_Image (J); 658 exit when Len = T.Common.Task_Image'Last; 659 end if; 660 end loop; 661 662 T.Common.Task_Image_Len := Len; 663 end if; 664 665 -- Note: we used to have code here to initialize T.Commmon.Domain, but 666 -- that is not needed, since this is initialized in System.Tasking. 667 668 Unlock (Self_ID); 669 Unlock_RTS; 670 671 -- The CPU associated to the task (if any) must belong to the 672 -- dispatching domain. 673 674 if Base_CPU /= System.Multiprocessors.Not_A_Specific_CPU 675 and then 676 (Base_CPU not in T.Common.Domain'Range 677 or else not T.Common.Domain (Base_CPU)) 678 then 679 Initialization.Undefer_Abort_Nestable (Self_ID); 680 raise Tasking_Error with "CPU not in dispatching domain"; 681 end if; 682 683 -- To handle the interaction between pragma CPU and dispatching domains 684 -- we need to signal that this task is being allocated to a processor. 685 -- This is needed only for tasks belonging to the system domain (the 686 -- creation of new dispatching domains can only take processors from the 687 -- system domain) and only before the environment task calls the main 688 -- procedure (dispatching domains cannot be created after this). 689 690 if Base_CPU /= System.Multiprocessors.Not_A_Specific_CPU 691 and then T.Common.Domain = System.Tasking.System_Domain 692 and then not System.Tasking.Dispatching_Domains_Frozen 693 then 694 -- Increase the number of tasks attached to the CPU to which this 695 -- task is being moved. 696 697 Dispatching_Domain_Tasks (Base_CPU) := 698 Dispatching_Domain_Tasks (Base_CPU) + 1; 699 end if; 700 701 -- Create TSD as early as possible in the creation of a task, since it 702 -- may be used by the operation of Ada code within the task. 703 704 SSL.Create_TSD (T.Common.Compiler_Data); 705 T.Common.Activation_Link := Chain.T_ID; 706 Chain.T_ID := T; 707 Created_Task := T; 708 Initialization.Undefer_Abort_Nestable (Self_ID); 709 710 if Runtime_Traces then 711 Send_Trace_Info (T_Create, T); 712 end if; 713 714 pragma Debug 715 (Debug.Trace 716 (Self_ID, "Created task in " & T.Master_of_Task'Img, 'C', T)); 717 end Create_Task; 718 719 -------------------- 720 -- Current_Master -- 721 -------------------- 722 723 function Current_Master return Master_Level is 724 begin 725 return STPO.Self.Master_Within; 726 end Current_Master; 727 728 ------------------ 729 -- Enter_Master -- 730 ------------------ 731 732 procedure Enter_Master is 733 Self_ID : constant Task_Id := STPO.Self; 734 begin 735 Self_ID.Master_Within := Self_ID.Master_Within + 1; 736 pragma Debug 737 (Debug.Trace 738 (Self_ID, "Enter_Master ->" & Self_ID.Master_Within'Img, 'M')); 739 end Enter_Master; 740 741 ------------------------------- 742 -- Expunge_Unactivated_Tasks -- 743 ------------------------------- 744 745 -- See procedure Close_Entries for the general case 746 747 procedure Expunge_Unactivated_Tasks (Chain : in out Activation_Chain) is 748 Self_ID : constant Task_Id := STPO.Self; 749 C : Task_Id; 750 Call : Entry_Call_Link; 751 Temp : Task_Id; 752 753 begin 754 pragma Debug 755 (Debug.Trace (Self_ID, "Expunge_Unactivated_Tasks", 'C')); 756 757 Initialization.Defer_Abort_Nestable (Self_ID); 758 759 -- ??? 760 -- Experimentation has shown that abort is sometimes (but not always) 761 -- already deferred when this is called. 762 763 -- That may indicate an error. Find out what is going on 764 765 C := Chain.T_ID; 766 while C /= null loop 767 pragma Assert (C.Common.State = Unactivated); 768 769 Temp := C.Common.Activation_Link; 770 771 if C.Common.State = Unactivated then 772 Lock_RTS; 773 Write_Lock (C); 774 775 for J in 1 .. C.Entry_Num loop 776 Queuing.Dequeue_Head (C.Entry_Queues (J), Call); 777 pragma Assert (Call = null); 778 end loop; 779 780 Unlock (C); 781 782 Initialization.Remove_From_All_Tasks_List (C); 783 Unlock_RTS; 784 785 Vulnerable_Free_Task (C); 786 C := Temp; 787 end if; 788 end loop; 789 790 Chain.T_ID := null; 791 Initialization.Undefer_Abort_Nestable (Self_ID); 792 end Expunge_Unactivated_Tasks; 793 794 --------------------------- 795 -- Finalize_Global_Tasks -- 796 --------------------------- 797 798 -- ??? 799 -- We have a potential problem here if finalization of global objects does 800 -- anything with signals or the timer server, since by that time those 801 -- servers have terminated. 802 803 -- It is hard to see how that would occur 804 805 -- However, a better solution might be to do all this finalization 806 -- using the global finalization chain. 807 808 procedure Finalize_Global_Tasks is 809 Self_ID : constant Task_Id := STPO.Self; 810 811 Ignore_1 : Boolean; 812 Ignore_2 : Boolean; 813 814 function State 815 (Int : System.Interrupt_Management.Interrupt_ID) return Character; 816 pragma Import (C, State, "__gnat_get_interrupt_state"); 817 -- Get interrupt state for interrupt number Int. Defined in init.c 818 819 Default : constant Character := 's'; 820 -- 's' Interrupt_State pragma set state to System (use "default" 821 -- system handler) 822 823 begin 824 if Self_ID.Deferral_Level = 0 then 825 -- ??? 826 -- In principle, we should be able to predict whether abort is 827 -- already deferred here (and it should not be deferred yet but in 828 -- practice it seems Finalize_Global_Tasks is being called sometimes, 829 -- from RTS code for exceptions, with abort already deferred. 830 831 Initialization.Defer_Abort_Nestable (Self_ID); 832 833 -- Never undefer again 834 end if; 835 836 -- This code is only executed by the environment task 837 838 pragma Assert (Self_ID = Environment_Task); 839 840 -- Set Environment_Task'Callable to false to notify library-level tasks 841 -- that it is waiting for them. 842 843 Self_ID.Callable := False; 844 845 -- Exit level 2 master, for normal tasks in library-level packages 846 847 Complete_Master; 848 849 -- Force termination of "independent" library-level server tasks 850 851 Lock_RTS; 852 853 Abort_Dependents (Self_ID); 854 855 if not Single_Lock then 856 Unlock_RTS; 857 end if; 858 859 -- We need to explicitly wait for the task to be terminated here 860 -- because on true concurrent system, we may end this procedure before 861 -- the tasks are really terminated. 862 863 Write_Lock (Self_ID); 864 865 -- If the Abort_Task signal is set to system, it means that we may 866 -- not have been able to abort all independent tasks (in particular, 867 -- Server_Task may be blocked, waiting for a signal), in which case, do 868 -- not wait for Independent_Task_Count to go down to 0. We arbitrarily 869 -- limit the number of loop iterations; if an independent task does not 870 -- terminate, we do not want to hang here. In that case, the thread will 871 -- be terminated when the process exits. 872 873 if State (System.Interrupt_Management.Abort_Task_Interrupt) /= Default 874 then 875 for J in 1 .. 10 loop 876 exit when Utilities.Independent_Task_Count = 0; 877 878 -- We used to yield here, but this did not take into account low 879 -- priority tasks that would cause dead lock in some cases (true 880 -- FIFO scheduling). 881 882 Timed_Sleep 883 (Self_ID, 0.01, System.OS_Primitives.Relative, 884 Self_ID.Common.State, Ignore_1, Ignore_2); 885 end loop; 886 end if; 887 888 -- ??? On multi-processor environments, it seems that the above loop 889 -- isn't sufficient, so we need to add an additional delay. 890 891 Timed_Sleep 892 (Self_ID, 0.01, System.OS_Primitives.Relative, 893 Self_ID.Common.State, Ignore_1, Ignore_2); 894 895 Unlock (Self_ID); 896 897 if Single_Lock then 898 Unlock_RTS; 899 end if; 900 901 -- Complete the environment task 902 903 Vulnerable_Complete_Task (Self_ID); 904 905 -- Handle normal task termination by the environment task, but only 906 -- for the normal task termination. In the case of Abnormal and 907 -- Unhandled_Exception they must have been handled before, and the 908 -- task termination soft link must have been changed so the task 909 -- termination routine is not executed twice. 910 911 SSL.Task_Termination_Handler.all (Ada.Exceptions.Null_Occurrence); 912 913 -- Finalize all library-level controlled objects 914 915 if not SSL."=" (SSL.Finalize_Library_Objects, null) then 916 SSL.Finalize_Library_Objects.all; 917 end if; 918 919 -- Reset the soft links to non-tasking 920 921 SSL.Abort_Defer := SSL.Abort_Defer_NT'Access; 922 SSL.Abort_Undefer := SSL.Abort_Undefer_NT'Access; 923 SSL.Lock_Task := SSL.Task_Lock_NT'Access; 924 SSL.Unlock_Task := SSL.Task_Unlock_NT'Access; 925 SSL.Get_Jmpbuf_Address := SSL.Get_Jmpbuf_Address_NT'Access; 926 SSL.Set_Jmpbuf_Address := SSL.Set_Jmpbuf_Address_NT'Access; 927 SSL.Get_Sec_Stack_Addr := SSL.Get_Sec_Stack_Addr_NT'Access; 928 SSL.Set_Sec_Stack_Addr := SSL.Set_Sec_Stack_Addr_NT'Access; 929 SSL.Check_Abort_Status := SSL.Check_Abort_Status_NT'Access; 930 SSL.Get_Stack_Info := SSL.Get_Stack_Info_NT'Access; 931 932 -- Don't bother trying to finalize Initialization.Global_Task_Lock 933 -- and System.Task_Primitives.RTS_Lock. 934 935 end Finalize_Global_Tasks; 936 937 --------------- 938 -- Free_Task -- 939 --------------- 940 941 procedure Free_Task (T : Task_Id) is 942 Self_Id : constant Task_Id := Self; 943 944 begin 945 if T.Common.State = Terminated then 946 947 -- It is not safe to call Abort_Defer or Write_Lock at this stage 948 949 Initialization.Task_Lock (Self_Id); 950 951 Lock_RTS; 952 Initialization.Finalize_Attributes (T); 953 Initialization.Remove_From_All_Tasks_List (T); 954 Unlock_RTS; 955 956 Initialization.Task_Unlock (Self_Id); 957 958 System.Task_Primitives.Operations.Finalize_TCB (T); 959 960 else 961 -- If the task is not terminated, then mark the task as to be freed 962 -- upon termination. 963 964 T.Free_On_Termination := True; 965 end if; 966 end Free_Task; 967 968 --------------------------- 969 -- Move_Activation_Chain -- 970 --------------------------- 971 972 procedure Move_Activation_Chain 973 (From, To : Activation_Chain_Access; 974 New_Master : Master_ID) 975 is 976 Self_ID : constant Task_Id := STPO.Self; 977 C : Task_Id; 978 979 begin 980 pragma Debug 981 (Debug.Trace (Self_ID, "Move_Activation_Chain", 'C')); 982 983 -- Nothing to do if From is empty, and we can check that without 984 -- deferring aborts. 985 986 C := From.all.T_ID; 987 988 if C = null then 989 return; 990 end if; 991 992 Initialization.Defer_Abort_Nestable (Self_ID); 993 994 -- Loop through the From chain, changing their Master_of_Task fields, 995 -- and to find the end of the chain. 996 997 loop 998 C.Master_of_Task := New_Master; 999 exit when C.Common.Activation_Link = null; 1000 C := C.Common.Activation_Link; 1001 end loop; 1002 1003 -- Hook From in at the start of To 1004 1005 C.Common.Activation_Link := To.all.T_ID; 1006 To.all.T_ID := From.all.T_ID; 1007 1008 -- Set From to empty 1009 1010 From.all.T_ID := null; 1011 1012 Initialization.Undefer_Abort_Nestable (Self_ID); 1013 end Move_Activation_Chain; 1014 1015 ------------------ 1016 -- Task_Wrapper -- 1017 ------------------ 1018 1019 -- The task wrapper is a procedure that is called first for each task body 1020 -- and which in turn calls the compiler-generated task body procedure. 1021 -- The wrapper's main job is to do initialization for the task. It also 1022 -- has some locally declared objects that serve as per-task local data. 1023 -- Task finalization is done by Complete_Task, which is called from an 1024 -- at-end handler that the compiler generates. 1025 1026 procedure Task_Wrapper (Self_ID : Task_Id) is 1027 use type SSE.Storage_Offset; 1028 use System.Standard_Library; 1029 use System.Stack_Usage; 1030 1031 Bottom_Of_Stack : aliased Integer; 1032 1033 Task_Alternate_Stack : 1034 aliased SSE.Storage_Array (1 .. Alternate_Stack_Size); 1035 -- The alternate signal stack for this task, if any 1036 1037 Use_Alternate_Stack : constant Boolean := Alternate_Stack_Size /= 0; 1038 -- Whether to use above alternate signal stack for stack overflows 1039 1040 Secondary_Stack_Size : 1041 constant SSE.Storage_Offset := 1042 Self_ID.Common.Compiler_Data.Pri_Stack_Info.Size * 1043 SSE.Storage_Offset (Parameters.Sec_Stack_Percentage) / 100; 1044 1045 Secondary_Stack : aliased SSE.Storage_Array (1 .. Secondary_Stack_Size); 1046 for Secondary_Stack'Alignment use Standard'Maximum_Alignment; 1047 -- Actual area allocated for secondary stack. Note that it is critical 1048 -- that this have maximum alignment, since any kind of data can be 1049 -- allocated here. 1050 1051 Secondary_Stack_Address : System.Address := Secondary_Stack'Address; 1052 -- Address of secondary stack. In the fixed secondary stack case, this 1053 -- value is not modified, causing a warning, hence the bracketing with 1054 -- Warnings (Off/On). But why is so much *more* bracketed??? 1055 1056 SEH_Table : aliased SSE.Storage_Array (1 .. 8); 1057 -- Structured Exception Registration table (2 words) 1058 1059 procedure Install_SEH_Handler (Addr : System.Address); 1060 pragma Import (C, Install_SEH_Handler, "__gnat_install_SEH_handler"); 1061 -- Install the SEH (Structured Exception Handling) handler 1062 1063 Cause : Cause_Of_Termination := Normal; 1064 -- Indicates the reason why this task terminates. Normal corresponds to 1065 -- a task terminating due to completing the last statement of its body, 1066 -- or as a result of waiting on a terminate alternative. If the task 1067 -- terminates because it is being aborted then Cause will be set 1068 -- to Abnormal. If the task terminates because of an exception 1069 -- raised by the execution of its task body, then Cause is set 1070 -- to Unhandled_Exception. 1071 1072 EO : Exception_Occurrence; 1073 -- If the task terminates because of an exception raised by the 1074 -- execution of its task body, then EO will contain the associated 1075 -- exception occurrence. Otherwise, it will contain Null_Occurrence. 1076 1077 TH : Termination_Handler := null; 1078 -- Pointer to the protected procedure to be executed upon task 1079 -- termination. 1080 1081 procedure Search_Fall_Back_Handler (ID : Task_Id); 1082 -- Procedure that searches recursively a fall-back handler through the 1083 -- master relationship. If the handler is found, its pointer is stored 1084 -- in TH. It stops when the handler is found or when the ID is null. 1085 1086 ------------------------------ 1087 -- Search_Fall_Back_Handler -- 1088 ------------------------------ 1089 1090 procedure Search_Fall_Back_Handler (ID : Task_Id) is 1091 begin 1092 -- A null Task_Id indicates that we have reached the root of the 1093 -- task hierarchy and no handler has been found. 1094 1095 if ID = null then 1096 return; 1097 1098 -- If there is a fall back handler, store its pointer for later 1099 -- execution. 1100 1101 elsif ID.Common.Fall_Back_Handler /= null then 1102 TH := ID.Common.Fall_Back_Handler; 1103 1104 -- Otherwise look for a fall back handler in the parent 1105 1106 else 1107 Search_Fall_Back_Handler (ID.Common.Parent); 1108 end if; 1109 end Search_Fall_Back_Handler; 1110 1111 -- Start of processing for Task_Wrapper 1112 1113 begin 1114 pragma Assert (Self_ID.Deferral_Level = 1); 1115 1116 Debug.Master_Hook 1117 (Self_ID, Self_ID.Common.Parent, Self_ID.Master_of_Task); 1118 1119 -- Assume a size of the stack taken at this stage 1120 1121 if not Parameters.Sec_Stack_Dynamic then 1122 Self_ID.Common.Compiler_Data.Sec_Stack_Addr := 1123 Secondary_Stack'Address; 1124 SST.SS_Init (Secondary_Stack_Address, Integer (Secondary_Stack'Last)); 1125 end if; 1126 1127 if Use_Alternate_Stack then 1128 Self_ID.Common.Task_Alternate_Stack := Task_Alternate_Stack'Address; 1129 end if; 1130 1131 -- Set the guard page at the bottom of the stack. The call to unprotect 1132 -- the page is done in Terminate_Task 1133 1134 Stack_Guard (Self_ID, True); 1135 1136 -- Initialize low-level TCB components, that cannot be initialized by 1137 -- the creator. Enter_Task sets Self_ID.LL.Thread. 1138 1139 Enter_Task (Self_ID); 1140 1141 -- Initialize dynamic stack usage 1142 1143 if System.Stack_Usage.Is_Enabled then 1144 declare 1145 Guard_Page_Size : constant := 16 * 1024; 1146 -- Part of the stack used as a guard page. This is an OS dependent 1147 -- value, so we need to use the maximum. This value is only used 1148 -- when the stack address is known, that is currently Windows. 1149 1150 Small_Overflow_Guard : constant := 12 * 1024; 1151 -- Note: this used to be 4K, but was changed to 12K, since 1152 -- smaller values resulted in segmentation faults from dynamic 1153 -- stack analysis. 1154 1155 Big_Overflow_Guard : constant := 64 * 1024 + 8 * 1024; 1156 Small_Stack_Limit : constant := 64 * 1024; 1157 -- ??? These three values are experimental, and seem to work on 1158 -- most platforms. They still need to be analyzed further. They 1159 -- also need documentation, what are they and why does the logic 1160 -- differ depending on whether the stack is large or small??? 1161 1162 Pattern_Size : Natural := 1163 Natural (Self_ID.Common. 1164 Compiler_Data.Pri_Stack_Info.Size); 1165 -- Size of the pattern 1166 1167 Stack_Base : Address; 1168 -- Address of the base of the stack 1169 1170 begin 1171 Stack_Base := Self_ID.Common.Compiler_Data.Pri_Stack_Info.Base; 1172 1173 if Stack_Base = Null_Address then 1174 1175 -- On many platforms, we don't know the real stack base 1176 -- address. Estimate it using an address in the frame. 1177 1178 Stack_Base := Bottom_Of_Stack'Address; 1179 1180 -- Also reduce the size of the stack to take into account the 1181 -- secondary stack array declared in this frame. This is for 1182 -- sure very conservative. 1183 1184 if not Parameters.Sec_Stack_Dynamic then 1185 Pattern_Size := 1186 Pattern_Size - Natural (Secondary_Stack_Size); 1187 end if; 1188 1189 -- Adjustments for inner frames 1190 1191 Pattern_Size := Pattern_Size - 1192 (if Pattern_Size < Small_Stack_Limit 1193 then Small_Overflow_Guard 1194 else Big_Overflow_Guard); 1195 else 1196 -- Reduce by the size of the final guard page 1197 1198 Pattern_Size := Pattern_Size - Guard_Page_Size; 1199 end if; 1200 1201 STPO.Lock_RTS; 1202 Initialize_Analyzer 1203 (Self_ID.Common.Analyzer, 1204 Self_ID.Common.Task_Image (1 .. Self_ID.Common.Task_Image_Len), 1205 Natural (Self_ID.Common.Compiler_Data.Pri_Stack_Info.Size), 1206 SSE.To_Integer (Stack_Base), 1207 Pattern_Size); 1208 STPO.Unlock_RTS; 1209 Fill_Stack (Self_ID.Common.Analyzer); 1210 end; 1211 end if; 1212 1213 -- We setup the SEH (Structured Exception Handling) handler if supported 1214 -- on the target. 1215 1216 Install_SEH_Handler (SEH_Table'Address); 1217 1218 -- Initialize exception occurrence 1219 1220 Save_Occurrence (EO, Ada.Exceptions.Null_Occurrence); 1221 1222 -- We lock RTS_Lock to wait for activator to finish activating the rest 1223 -- of the chain, so that everyone in the chain comes out in priority 1224 -- order. 1225 1226 -- This also protects the value of 1227 -- Self_ID.Common.Activator.Common.Wait_Count. 1228 1229 Lock_RTS; 1230 Unlock_RTS; 1231 1232 if not System.Restrictions.Abort_Allowed then 1233 1234 -- If Abort is not allowed, reset the deferral level since it will 1235 -- not get changed by the generated code. Keeping a default value 1236 -- of one would prevent some operations (e.g. select or delay) to 1237 -- proceed successfully. 1238 1239 Self_ID.Deferral_Level := 0; 1240 end if; 1241 1242 if Global_Task_Debug_Event_Set then 1243 Debug.Signal_Debug_Event (Debug.Debug_Event_Run, Self_ID); 1244 end if; 1245 1246 begin 1247 -- We are separating the following portion of the code in order to 1248 -- place the exception handlers in a different block. In this way, 1249 -- we do not call Set_Jmpbuf_Address (which needs Self) before we 1250 -- set Self in Enter_Task 1251 1252 -- Call the task body procedure 1253 1254 -- The task body is called with abort still deferred. That 1255 -- eliminates a dangerous window, for which we had to patch-up in 1256 -- Terminate_Task. 1257 1258 -- During the expansion of the task body, we insert an RTS-call 1259 -- to Abort_Undefer, at the first point where abort should be 1260 -- allowed. 1261 1262 Self_ID.Common.Task_Entry_Point (Self_ID.Common.Task_Arg); 1263 Initialization.Defer_Abort_Nestable (Self_ID); 1264 1265 exception 1266 -- We can't call Terminate_Task in the exception handlers below, 1267 -- since there may be (e.g. in the case of GCC exception handling) 1268 -- clean ups associated with the exception handler that need to 1269 -- access task specific data. 1270 1271 -- Defer abort so that this task can't be aborted while exiting 1272 1273 when Standard'Abort_Signal => 1274 Initialization.Defer_Abort_Nestable (Self_ID); 1275 1276 -- Update the cause that motivated the task termination so that 1277 -- the appropriate information is passed to the task termination 1278 -- procedure. Task termination as a result of waiting on a 1279 -- terminate alternative is a normal termination, although it is 1280 -- implemented using the abort mechanisms. 1281 1282 if Self_ID.Terminate_Alternative then 1283 Cause := Normal; 1284 1285 if Global_Task_Debug_Event_Set then 1286 Debug.Signal_Debug_Event 1287 (Debug.Debug_Event_Terminated, Self_ID); 1288 end if; 1289 else 1290 Cause := Abnormal; 1291 1292 if Global_Task_Debug_Event_Set then 1293 Debug.Signal_Debug_Event 1294 (Debug.Debug_Event_Abort_Terminated, Self_ID); 1295 end if; 1296 end if; 1297 1298 when others => 1299 -- ??? Using an E : others here causes CD2C11A to fail on Tru64 1300 1301 Initialization.Defer_Abort_Nestable (Self_ID); 1302 1303 -- Perform the task specific exception tracing duty. We handle 1304 -- these outputs here and not in the common notification routine 1305 -- because we need access to tasking related data and we don't 1306 -- want to drag dependencies against tasking related units in the 1307 -- the common notification units. Additionally, no trace is ever 1308 -- triggered from the common routine for the Unhandled_Raise case 1309 -- in tasks, since an exception never appears unhandled in this 1310 -- context because of this handler. 1311 1312 if Exception_Trace = Unhandled_Raise then 1313 Trace_Unhandled_Exception_In_Task (Self_ID); 1314 end if; 1315 1316 -- Update the cause that motivated the task termination so that 1317 -- the appropriate information is passed to the task termination 1318 -- procedure, as well as the associated Exception_Occurrence. 1319 1320 Cause := Unhandled_Exception; 1321 1322 Save_Occurrence (EO, SSL.Get_Current_Excep.all.all); 1323 1324 if Global_Task_Debug_Event_Set then 1325 Debug.Signal_Debug_Event 1326 (Debug.Debug_Event_Exception_Terminated, Self_ID); 1327 end if; 1328 end; 1329 1330 -- Look for a task termination handler. This code is for all tasks but 1331 -- the environment task. The task termination code for the environment 1332 -- task is executed by SSL.Task_Termination_Handler. 1333 1334 if Single_Lock then 1335 Lock_RTS; 1336 end if; 1337 1338 Write_Lock (Self_ID); 1339 1340 if Self_ID.Common.Specific_Handler /= null then 1341 TH := Self_ID.Common.Specific_Handler; 1342 else 1343 -- Look for a fall-back handler following the master relationship 1344 -- for the task. As specified in ARM C.7.3 par. 9/2, "the fall-back 1345 -- handler applies only to the dependent tasks of the task". Hence, 1346 -- if the terminating tasks (Self_ID) had a fall-back handler, it 1347 -- would not apply to itself, so we start the search with the parent. 1348 1349 Search_Fall_Back_Handler (Self_ID.Common.Parent); 1350 end if; 1351 1352 Unlock (Self_ID); 1353 1354 if Single_Lock then 1355 Unlock_RTS; 1356 end if; 1357 1358 -- Execute the task termination handler if we found it 1359 1360 if TH /= null then 1361 begin 1362 TH.all (Cause, Self_ID, EO); 1363 1364 exception 1365 1366 -- RM-C.7.3 requires all exceptions raised here to be ignored 1367 1368 when others => 1369 null; 1370 end; 1371 end if; 1372 1373 if System.Stack_Usage.Is_Enabled then 1374 Compute_Result (Self_ID.Common.Analyzer); 1375 Report_Result (Self_ID.Common.Analyzer); 1376 end if; 1377 1378 Terminate_Task (Self_ID); 1379 end Task_Wrapper; 1380 1381 -------------------- 1382 -- Terminate_Task -- 1383 -------------------- 1384 1385 -- Before we allow the thread to exit, we must clean up. This is a delicate 1386 -- job. We must wake up the task's master, who may immediately try to 1387 -- deallocate the ATCB from the current task WHILE IT IS STILL EXECUTING. 1388 1389 -- To avoid this, the parent task must be blocked up to the latest 1390 -- statement executed. The trouble is that we have another step that we 1391 -- also want to postpone to the very end, i.e., calling SSL.Destroy_TSD. 1392 -- We have to postpone that until the end because compiler-generated code 1393 -- is likely to try to access that data at just about any point. 1394 1395 -- We can't call Destroy_TSD while we are holding any other locks, because 1396 -- it locks Global_Task_Lock, and our deadlock prevention rules require 1397 -- that to be the outermost lock. Our first "solution" was to just lock 1398 -- Global_Task_Lock in addition to the other locks, and force the parent to 1399 -- also lock this lock between its wakeup and its freeing of the ATCB. See 1400 -- Complete_Task for the parent-side of the code that has the matching 1401 -- calls to Task_Lock and Task_Unlock. That was not really a solution, 1402 -- since the operation Task_Unlock continued to access the ATCB after 1403 -- unlocking, after which the parent was observed to race ahead, deallocate 1404 -- the ATCB, and then reallocate it to another task. The call to 1405 -- Undefer_Abort in Task_Unlock by the "terminated" task was overwriting 1406 -- the data of the new task that reused the ATCB. To solve this problem, we 1407 -- introduced the new operation Final_Task_Unlock. 1408 1409 procedure Terminate_Task (Self_ID : Task_Id) is 1410 Environment_Task : constant Task_Id := STPO.Environment_Task; 1411 Master_of_Task : Integer; 1412 Deallocate : Boolean; 1413 1414 begin 1415 Debug.Task_Termination_Hook; 1416 1417 if Runtime_Traces then 1418 Send_Trace_Info (T_Terminate); 1419 end if; 1420 1421 -- Since GCC cannot allocate stack chunks efficiently without reordering 1422 -- some of the allocations, we have to handle this unexpected situation 1423 -- here. Normally we never have to call Vulnerable_Complete_Task here. 1424 1425 if Self_ID.Common.Activator /= null then 1426 Vulnerable_Complete_Task (Self_ID); 1427 end if; 1428 1429 Initialization.Task_Lock (Self_ID); 1430 1431 if Single_Lock then 1432 Lock_RTS; 1433 end if; 1434 1435 Master_of_Task := Self_ID.Master_of_Task; 1436 1437 -- Check if the current task is an independent task If so, decrement 1438 -- the Independent_Task_Count value. 1439 1440 if Master_of_Task = Independent_Task_Level then 1441 if Single_Lock then 1442 Utilities.Independent_Task_Count := 1443 Utilities.Independent_Task_Count - 1; 1444 1445 else 1446 Write_Lock (Environment_Task); 1447 Utilities.Independent_Task_Count := 1448 Utilities.Independent_Task_Count - 1; 1449 Unlock (Environment_Task); 1450 end if; 1451 end if; 1452 1453 -- Unprotect the guard page if needed 1454 1455 Stack_Guard (Self_ID, False); 1456 1457 Utilities.Make_Passive (Self_ID, Task_Completed => True); 1458 Deallocate := Self_ID.Free_On_Termination; 1459 1460 if Single_Lock then 1461 Unlock_RTS; 1462 end if; 1463 1464 pragma Assert (Check_Exit (Self_ID)); 1465 1466 SSL.Destroy_TSD (Self_ID.Common.Compiler_Data); 1467 Initialization.Final_Task_Unlock (Self_ID); 1468 1469 -- WARNING: past this point, this thread must assume that the ATCB has 1470 -- been deallocated, and can't access it anymore (which is why we have 1471 -- saved the Free_On_Termination flag in a temporary variable). 1472 1473 if Deallocate then 1474 Free_Task (Self_ID); 1475 end if; 1476 1477 if Master_of_Task > 0 then 1478 STPO.Exit_Task; 1479 end if; 1480 end Terminate_Task; 1481 1482 ---------------- 1483 -- Terminated -- 1484 ---------------- 1485 1486 function Terminated (T : Task_Id) return Boolean is 1487 Self_ID : constant Task_Id := STPO.Self; 1488 Result : Boolean; 1489 1490 begin 1491 Initialization.Defer_Abort_Nestable (Self_ID); 1492 1493 if Single_Lock then 1494 Lock_RTS; 1495 end if; 1496 1497 Write_Lock (T); 1498 Result := T.Common.State = Terminated; 1499 Unlock (T); 1500 1501 if Single_Lock then 1502 Unlock_RTS; 1503 end if; 1504 1505 Initialization.Undefer_Abort_Nestable (Self_ID); 1506 return Result; 1507 end Terminated; 1508 1509 ---------------------------------------- 1510 -- Trace_Unhandled_Exception_In_Task -- 1511 ---------------------------------------- 1512 1513 procedure Trace_Unhandled_Exception_In_Task (Self_Id : Task_Id) is 1514 procedure To_Stderr (S : String); 1515 pragma Import (Ada, To_Stderr, "__gnat_to_stderr"); 1516 1517 use System.Soft_Links; 1518 use System.Standard_Library; 1519 1520 function To_Address is new 1521 Ada.Unchecked_Conversion 1522 (Task_Id, System.Task_Primitives.Task_Address); 1523 1524 Excep : constant Exception_Occurrence_Access := 1525 SSL.Get_Current_Excep.all; 1526 1527 begin 1528 -- This procedure is called by the task outermost handler in 1529 -- Task_Wrapper below, so only once the task stack has been fully 1530 -- unwound. The common notification routine has been called at the 1531 -- raise point already. 1532 1533 -- Lock to prevent unsynchronized output 1534 1535 Initialization.Task_Lock (Self_Id); 1536 To_Stderr ("task "); 1537 1538 if Self_Id.Common.Task_Image_Len /= 0 then 1539 To_Stderr 1540 (Self_Id.Common.Task_Image (1 .. Self_Id.Common.Task_Image_Len)); 1541 To_Stderr ("_"); 1542 end if; 1543 1544 To_Stderr (System.Address_Image (To_Address (Self_Id))); 1545 To_Stderr (" terminated by unhandled exception"); 1546 To_Stderr ((1 => ASCII.LF)); 1547 To_Stderr (Exception_Information (Excep.all)); 1548 Initialization.Task_Unlock (Self_Id); 1549 end Trace_Unhandled_Exception_In_Task; 1550 1551 ------------------------------------ 1552 -- Vulnerable_Complete_Activation -- 1553 ------------------------------------ 1554 1555 -- As in several other places, the locks of the activator and activated 1556 -- task are both locked here. This follows our deadlock prevention lock 1557 -- ordering policy, since the activated task must be created after the 1558 -- activator. 1559 1560 procedure Vulnerable_Complete_Activation (Self_ID : Task_Id) is 1561 Activator : constant Task_Id := Self_ID.Common.Activator; 1562 1563 begin 1564 pragma Debug (Debug.Trace (Self_ID, "V_Complete_Activation", 'C')); 1565 1566 Write_Lock (Activator); 1567 Write_Lock (Self_ID); 1568 1569 pragma Assert (Self_ID.Common.Activator /= null); 1570 1571 -- Remove dangling reference to Activator, since a task may outlive its 1572 -- activator. 1573 1574 Self_ID.Common.Activator := null; 1575 1576 -- Wake up the activator, if it is waiting for a chain of tasks to 1577 -- activate, and we are the last in the chain to complete activation. 1578 1579 if Activator.Common.State = Activator_Sleep then 1580 Activator.Common.Wait_Count := Activator.Common.Wait_Count - 1; 1581 1582 if Activator.Common.Wait_Count = 0 then 1583 Wakeup (Activator, Activator_Sleep); 1584 end if; 1585 end if; 1586 1587 -- The activator raises a Tasking_Error if any task it is activating 1588 -- is completed before the activation is done. However, if the reason 1589 -- for the task completion is an abort, we do not raise an exception. 1590 -- See RM 9.2(5). 1591 1592 if not Self_ID.Callable and then Self_ID.Pending_ATC_Level /= 0 then 1593 Activator.Common.Activation_Failed := True; 1594 end if; 1595 1596 Unlock (Self_ID); 1597 Unlock (Activator); 1598 1599 -- After the activation, active priority should be the same as base 1600 -- priority. We must unlock the Activator first, though, since it 1601 -- should not wait if we have lower priority. 1602 1603 if Get_Priority (Self_ID) /= Self_ID.Common.Base_Priority then 1604 Write_Lock (Self_ID); 1605 Set_Priority (Self_ID, Self_ID.Common.Base_Priority); 1606 Unlock (Self_ID); 1607 end if; 1608 end Vulnerable_Complete_Activation; 1609 1610 -------------------------------- 1611 -- Vulnerable_Complete_Master -- 1612 -------------------------------- 1613 1614 procedure Vulnerable_Complete_Master (Self_ID : Task_Id) is 1615 C : Task_Id; 1616 P : Task_Id; 1617 CM : constant Master_Level := Self_ID.Master_Within; 1618 T : aliased Task_Id; 1619 1620 To_Be_Freed : Task_Id; 1621 -- This is a list of ATCBs to be freed, after we have released all RTS 1622 -- locks. This is necessary because of the locking order rules, since 1623 -- the storage manager uses Global_Task_Lock. 1624 1625 pragma Warnings (Off); 1626 function Check_Unactivated_Tasks return Boolean; 1627 pragma Warnings (On); 1628 -- Temporary error-checking code below. This is part of the checks 1629 -- added in the new run time. Call it only inside a pragma Assert. 1630 1631 ----------------------------- 1632 -- Check_Unactivated_Tasks -- 1633 ----------------------------- 1634 1635 function Check_Unactivated_Tasks return Boolean is 1636 begin 1637 if not Single_Lock then 1638 Lock_RTS; 1639 end if; 1640 1641 Write_Lock (Self_ID); 1642 1643 C := All_Tasks_List; 1644 while C /= null loop 1645 if C.Common.Activator = Self_ID and then C.Master_of_Task = CM then 1646 return False; 1647 end if; 1648 1649 if C.Common.Parent = Self_ID and then C.Master_of_Task = CM then 1650 Write_Lock (C); 1651 1652 if C.Common.State = Unactivated then 1653 return False; 1654 end if; 1655 1656 Unlock (C); 1657 end if; 1658 1659 C := C.Common.All_Tasks_Link; 1660 end loop; 1661 1662 Unlock (Self_ID); 1663 1664 if not Single_Lock then 1665 Unlock_RTS; 1666 end if; 1667 1668 return True; 1669 end Check_Unactivated_Tasks; 1670 1671 -- Start of processing for Vulnerable_Complete_Master 1672 1673 begin 1674 pragma Debug 1675 (Debug.Trace (Self_ID, "V_Complete_Master(" & CM'Img & ")", 'C')); 1676 1677 pragma Assert (Self_ID.Common.Wait_Count = 0); 1678 pragma Assert 1679 (Self_ID.Deferral_Level > 0 1680 or else not System.Restrictions.Abort_Allowed); 1681 1682 -- Count how many active dependent tasks this master currently has, and 1683 -- record this in Wait_Count. 1684 1685 -- This count should start at zero, since it is initialized to zero for 1686 -- new tasks, and the task should not exit the sleep-loops that use this 1687 -- count until the count reaches zero. 1688 1689 -- While we're counting, if we run across any unactivated tasks that 1690 -- belong to this master, we summarily terminate them as required by 1691 -- RM-9.2(6). 1692 1693 Lock_RTS; 1694 Write_Lock (Self_ID); 1695 1696 C := All_Tasks_List; 1697 while C /= null loop 1698 1699 -- Terminate unactivated (never-to-be activated) tasks 1700 1701 if C.Common.Activator = Self_ID and then C.Master_of_Task = CM then 1702 1703 -- Usually, C.Common.Activator = Self_ID implies C.Master_of_Task 1704 -- = CM. The only case where C is pending activation by this 1705 -- task, but the master of C is not CM is in Ada 2005, when C is 1706 -- part of a return object of a build-in-place function. 1707 1708 pragma Assert (C.Common.State = Unactivated); 1709 1710 Write_Lock (C); 1711 C.Common.Activator := null; 1712 C.Common.State := Terminated; 1713 C.Callable := False; 1714 Utilities.Cancel_Queued_Entry_Calls (C); 1715 Unlock (C); 1716 end if; 1717 1718 -- Count it if directly dependent on this master 1719 1720 if C.Common.Parent = Self_ID and then C.Master_of_Task = CM then 1721 Write_Lock (C); 1722 1723 if C.Awake_Count /= 0 then 1724 Self_ID.Common.Wait_Count := Self_ID.Common.Wait_Count + 1; 1725 end if; 1726 1727 Unlock (C); 1728 end if; 1729 1730 C := C.Common.All_Tasks_Link; 1731 end loop; 1732 1733 Self_ID.Common.State := Master_Completion_Sleep; 1734 Unlock (Self_ID); 1735 1736 if not Single_Lock then 1737 Unlock_RTS; 1738 end if; 1739 1740 -- Wait until dependent tasks are all terminated or ready to terminate. 1741 -- While waiting, the task may be awakened if the task's priority needs 1742 -- changing, or this master is aborted. In the latter case, we abort the 1743 -- dependents, and resume waiting until Wait_Count goes to zero. 1744 1745 Write_Lock (Self_ID); 1746 1747 loop 1748 exit when Self_ID.Common.Wait_Count = 0; 1749 1750 -- Here is a difference as compared to Complete_Master 1751 1752 if Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level 1753 and then not Self_ID.Dependents_Aborted 1754 then 1755 if Single_Lock then 1756 Abort_Dependents (Self_ID); 1757 else 1758 Unlock (Self_ID); 1759 Lock_RTS; 1760 Abort_Dependents (Self_ID); 1761 Unlock_RTS; 1762 Write_Lock (Self_ID); 1763 end if; 1764 else 1765 pragma Debug 1766 (Debug.Trace (Self_ID, "master_completion_sleep", 'C')); 1767 Sleep (Self_ID, Master_Completion_Sleep); 1768 end if; 1769 end loop; 1770 1771 Self_ID.Common.State := Runnable; 1772 Unlock (Self_ID); 1773 1774 -- Dependents are all terminated or on terminate alternatives. Now, 1775 -- force those on terminate alternatives to terminate, by aborting them. 1776 1777 pragma Assert (Check_Unactivated_Tasks); 1778 1779 if Self_ID.Alive_Count > 1 then 1780 -- ??? 1781 -- Consider finding a way to skip the following extra steps if there 1782 -- are no dependents with terminate alternatives. This could be done 1783 -- by adding another count to the ATCB, similar to Awake_Count, but 1784 -- keeping track of tasks that are on terminate alternatives. 1785 1786 pragma Assert (Self_ID.Common.Wait_Count = 0); 1787 1788 -- Force any remaining dependents to terminate by aborting them 1789 1790 if not Single_Lock then 1791 Lock_RTS; 1792 end if; 1793 1794 Abort_Dependents (Self_ID); 1795 1796 -- Above, when we "abort" the dependents we are simply using this 1797 -- operation for convenience. We are not required to support the full 1798 -- abort-statement semantics; in particular, we are not required to 1799 -- immediately cancel any queued or in-service entry calls. That is 1800 -- good, because if we tried to cancel a call we would need to lock 1801 -- the caller, in order to wake the caller up. Our anti-deadlock 1802 -- rules prevent us from doing that without releasing the locks on C 1803 -- and Self_ID. Releasing and retaking those locks would be wasteful 1804 -- at best, and should not be considered further without more 1805 -- detailed analysis of potential concurrent accesses to the ATCBs 1806 -- of C and Self_ID. 1807 1808 -- Count how many "alive" dependent tasks this master currently has, 1809 -- and record this in Wait_Count. This count should start at zero, 1810 -- since it is initialized to zero for new tasks, and the task should 1811 -- not exit the sleep-loops that use this count until the count 1812 -- reaches zero. 1813 1814 pragma Assert (Self_ID.Common.Wait_Count = 0); 1815 1816 Write_Lock (Self_ID); 1817 1818 C := All_Tasks_List; 1819 while C /= null loop 1820 if C.Common.Parent = Self_ID and then C.Master_of_Task = CM then 1821 Write_Lock (C); 1822 1823 pragma Assert (C.Awake_Count = 0); 1824 1825 if C.Alive_Count > 0 then 1826 pragma Assert (C.Terminate_Alternative); 1827 Self_ID.Common.Wait_Count := Self_ID.Common.Wait_Count + 1; 1828 end if; 1829 1830 Unlock (C); 1831 end if; 1832 1833 C := C.Common.All_Tasks_Link; 1834 end loop; 1835 1836 Self_ID.Common.State := Master_Phase_2_Sleep; 1837 Unlock (Self_ID); 1838 1839 if not Single_Lock then 1840 Unlock_RTS; 1841 end if; 1842 1843 -- Wait for all counted tasks to finish terminating themselves 1844 1845 Write_Lock (Self_ID); 1846 1847 loop 1848 exit when Self_ID.Common.Wait_Count = 0; 1849 Sleep (Self_ID, Master_Phase_2_Sleep); 1850 end loop; 1851 1852 Self_ID.Common.State := Runnable; 1853 Unlock (Self_ID); 1854 end if; 1855 1856 -- We don't wake up for abort here. We are already terminating just as 1857 -- fast as we can, so there is no point. 1858 1859 -- Remove terminated tasks from the list of Self_ID's dependents, but 1860 -- don't free their ATCBs yet, because of lock order restrictions, which 1861 -- don't allow us to call "free" or "malloc" while holding any other 1862 -- locks. Instead, we put those ATCBs to be freed onto a temporary list, 1863 -- called To_Be_Freed. 1864 1865 if not Single_Lock then 1866 Lock_RTS; 1867 end if; 1868 1869 C := All_Tasks_List; 1870 P := null; 1871 while C /= null loop 1872 1873 -- If Free_On_Termination is set, do nothing here, and let the 1874 -- task free itself if not already done, otherwise we risk a race 1875 -- condition where Vulnerable_Free_Task is called in the loop below, 1876 -- while the task calls Free_Task itself, in Terminate_Task. 1877 1878 if C.Common.Parent = Self_ID 1879 and then C.Master_of_Task >= CM 1880 and then not C.Free_On_Termination 1881 then 1882 if P /= null then 1883 P.Common.All_Tasks_Link := C.Common.All_Tasks_Link; 1884 else 1885 All_Tasks_List := C.Common.All_Tasks_Link; 1886 end if; 1887 1888 T := C.Common.All_Tasks_Link; 1889 C.Common.All_Tasks_Link := To_Be_Freed; 1890 To_Be_Freed := C; 1891 C := T; 1892 1893 else 1894 P := C; 1895 C := C.Common.All_Tasks_Link; 1896 end if; 1897 end loop; 1898 1899 Unlock_RTS; 1900 1901 -- Free all the ATCBs on the list To_Be_Freed 1902 1903 -- The ATCBs in the list are no longer in All_Tasks_List, and after 1904 -- any interrupt entries are detached from them they should no longer 1905 -- be referenced. 1906 1907 -- Global_Task_Lock (Task_Lock/Unlock) is locked in the loop below to 1908 -- avoid a race between a terminating task and its parent. The parent 1909 -- might try to deallocate the ACTB out from underneath the exiting 1910 -- task. Note that Free will also lock Global_Task_Lock, but that is 1911 -- OK, since this is the *one* lock for which we have a mechanism to 1912 -- support nested locking. See Task_Wrapper and its finalizer for more 1913 -- explanation. 1914 1915 -- ??? 1916 -- The check "T.Common.Parent /= null ..." below is to prevent dangling 1917 -- references to terminated library-level tasks, which could otherwise 1918 -- occur during finalization of library-level objects. A better solution 1919 -- might be to hook task objects into the finalization chain and 1920 -- deallocate the ATCB when the task object is deallocated. However, 1921 -- this change is not likely to gain anything significant, since all 1922 -- this storage should be recovered en-masse when the process exits. 1923 1924 while To_Be_Freed /= null loop 1925 T := To_Be_Freed; 1926 To_Be_Freed := T.Common.All_Tasks_Link; 1927 1928 -- ??? On SGI there is currently no Interrupt_Manager, that's why we 1929 -- need to check if the Interrupt_Manager_ID is null. 1930 1931 if T.Interrupt_Entry and then Interrupt_Manager_ID /= null then 1932 declare 1933 Detach_Interrupt_Entries_Index : constant Task_Entry_Index := 1; 1934 -- Corresponds to the entry index of System.Interrupts. 1935 -- Interrupt_Manager.Detach_Interrupt_Entries. Be sure 1936 -- to update this value when changing Interrupt_Manager specs. 1937 1938 type Param_Type is access all Task_Id; 1939 1940 Param : aliased Param_Type := T'Access; 1941 1942 begin 1943 System.Tasking.Rendezvous.Call_Simple 1944 (Interrupt_Manager_ID, Detach_Interrupt_Entries_Index, 1945 Param'Address); 1946 end; 1947 end if; 1948 1949 if (T.Common.Parent /= null 1950 and then T.Common.Parent.Common.Parent /= null) 1951 or else T.Master_of_Task > Library_Task_Level 1952 then 1953 Initialization.Task_Lock (Self_ID); 1954 1955 -- If Sec_Stack_Addr is not null, it means that Destroy_TSD 1956 -- has not been called yet (case of an unactivated task). 1957 1958 if T.Common.Compiler_Data.Sec_Stack_Addr /= Null_Address then 1959 SSL.Destroy_TSD (T.Common.Compiler_Data); 1960 end if; 1961 1962 Vulnerable_Free_Task (T); 1963 Initialization.Task_Unlock (Self_ID); 1964 end if; 1965 end loop; 1966 1967 -- It might seem nice to let the terminated task deallocate its own 1968 -- ATCB. That would not cover the case of unactivated tasks. It also 1969 -- would force us to keep the underlying thread around past termination, 1970 -- since references to the ATCB are possible past termination. 1971 1972 -- Currently, we get rid of the thread as soon as the task terminates, 1973 -- and let the parent recover the ATCB later. 1974 1975 -- Some day, if we want to recover the ATCB earlier, at task 1976 -- termination, we could consider using "fat task IDs", that include the 1977 -- serial number with the ATCB pointer, to catch references to tasks 1978 -- that no longer have ATCBs. It is not clear how much this would gain, 1979 -- since the user-level task object would still be occupying storage. 1980 1981 -- Make next master level up active. We don't need to lock the ATCB, 1982 -- since the value is only updated by each task for itself. 1983 1984 Self_ID.Master_Within := CM - 1; 1985 1986 Debug.Master_Completed_Hook (Self_ID, CM); 1987 end Vulnerable_Complete_Master; 1988 1989 ------------------------------ 1990 -- Vulnerable_Complete_Task -- 1991 ------------------------------ 1992 1993 -- Complete the calling task 1994 1995 -- This procedure must be called with abort deferred. It should only be 1996 -- called by Complete_Task and Finalize_Global_Tasks (for the environment 1997 -- task). 1998 1999 -- The effect is similar to that of Complete_Master. Differences include 2000 -- the closing of entries here, and computation of the number of active 2001 -- dependent tasks in Complete_Master. 2002 2003 -- We don't lock Self_ID before the call to Vulnerable_Complete_Activation, 2004 -- because that does its own locking, and because we do not need the lock 2005 -- to test Self_ID.Common.Activator. That value should only be read and 2006 -- modified by Self. 2007 2008 procedure Vulnerable_Complete_Task (Self_ID : Task_Id) is 2009 begin 2010 pragma Assert 2011 (Self_ID.Deferral_Level > 0 2012 or else not System.Restrictions.Abort_Allowed); 2013 pragma Assert (Self_ID = Self); 2014 pragma Assert 2015 (Self_ID.Master_Within in 2016 Self_ID.Master_of_Task + 1 .. Self_ID.Master_of_Task + 3); 2017 pragma Assert (Self_ID.Common.Wait_Count = 0); 2018 pragma Assert (Self_ID.Open_Accepts = null); 2019 pragma Assert (Self_ID.ATC_Nesting_Level = 1); 2020 2021 pragma Debug (Debug.Trace (Self_ID, "V_Complete_Task", 'C')); 2022 2023 if Single_Lock then 2024 Lock_RTS; 2025 end if; 2026 2027 Write_Lock (Self_ID); 2028 Self_ID.Callable := False; 2029 2030 -- In theory, Self should have no pending entry calls left on its 2031 -- call-stack. Each async. select statement should clean its own call, 2032 -- and blocking entry calls should defer abort until the calls are 2033 -- cancelled, then clean up. 2034 2035 Utilities.Cancel_Queued_Entry_Calls (Self_ID); 2036 Unlock (Self_ID); 2037 2038 if Self_ID.Common.Activator /= null then 2039 Vulnerable_Complete_Activation (Self_ID); 2040 end if; 2041 2042 if Single_Lock then 2043 Unlock_RTS; 2044 end if; 2045 2046 -- If Self_ID.Master_Within = Self_ID.Master_of_Task + 2 we may have 2047 -- dependent tasks for which we need to wait. Otherwise we just exit. 2048 2049 if Self_ID.Master_Within = Self_ID.Master_of_Task + 2 then 2050 Vulnerable_Complete_Master (Self_ID); 2051 end if; 2052 end Vulnerable_Complete_Task; 2053 2054 -------------------------- 2055 -- Vulnerable_Free_Task -- 2056 -------------------------- 2057 2058 -- Recover all runtime system storage associated with the task T. This 2059 -- should only be called after T has terminated and will no longer be 2060 -- referenced. 2061 2062 -- For tasks created by an allocator that fails, due to an exception, it 2063 -- is called from Expunge_Unactivated_Tasks. 2064 2065 -- For tasks created by elaboration of task object declarations it is 2066 -- called from the finalization code of the Task_Wrapper procedure. 2067 2068 procedure Vulnerable_Free_Task (T : Task_Id) is 2069 begin 2070 pragma Debug (Debug.Trace (Self, "Vulnerable_Free_Task", 'C', T)); 2071 2072 if Single_Lock then 2073 Lock_RTS; 2074 end if; 2075 2076 Write_Lock (T); 2077 Initialization.Finalize_Attributes (T); 2078 Unlock (T); 2079 2080 if Single_Lock then 2081 Unlock_RTS; 2082 end if; 2083 2084 System.Task_Primitives.Operations.Finalize_TCB (T); 2085 end Vulnerable_Free_Task; 2086 2087-- Package elaboration code 2088 2089begin 2090 -- Establish the Adafinal softlink 2091 2092 -- This is not done inside the central RTS initialization routine 2093 -- to avoid with'ing this package from System.Tasking.Initialization. 2094 2095 SSL.Adafinal := Finalize_Global_Tasks'Access; 2096 2097 -- Establish soft links for subprograms that manipulate master_id's. 2098 -- This cannot be done when the RTS is initialized, because of various 2099 -- elaboration constraints. 2100 2101 SSL.Current_Master := Stages.Current_Master'Access; 2102 SSL.Enter_Master := Stages.Enter_Master'Access; 2103 SSL.Complete_Master := Stages.Complete_Master'Access; 2104end System.Tasking.Stages; 2105