1------------------------------------------------------------------------------ 2-- -- 3-- GNU ADA RUN-TIME LIBRARY (GNARL) COMPONENTS -- 4-- -- 5-- S Y S T E M . T A S K I N G . I N I T I A L I Z A T I O N -- 6-- -- 7-- B o d y -- 8-- -- 9-- Copyright (C) 1992-2003, 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 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, 59 Temple Place - Suite 330, Boston, -- 20-- MA 02111-1307, USA. -- 21-- -- 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. -- 28-- -- 29-- GNARL was developed by the GNARL team at Florida State University. -- 30-- Extensive contributions were provided by Ada Core Technologies, Inc. -- 31-- -- 32------------------------------------------------------------------------------ 33 34pragma Style_Checks (All_Checks); 35-- Turn off subprogram alpha ordering check, since we group soft link 36-- bodies and dummy soft link bodies together separately in this unit. 37 38pragma Polling (Off); 39-- Turn polling off for this package. We don't need polling during any 40-- of the routines in this package, and more to the point, if we try 41-- to poll it can cause infinite loops. 42 43with Ada.Exceptions; 44-- used for Exception_Occurrence_Access. 45 46with System.Tasking; 47pragma Elaborate_All (System.Tasking); 48-- ensure that the first step initializations have been performed 49 50with System.Task_Primitives; 51-- used for Lock 52 53with System.Task_Primitives.Operations; 54-- used for Set_Priority 55-- Write_Lock 56-- Unlock 57-- Initialize_Lock 58 59with System.Soft_Links; 60-- used for the non-tasking routines (*_NT) that refer to global data. 61-- They are needed here before the tasking run time has been elaborated. 62 63with System.Tasking.Debug; 64-- used for Trace 65 66with System.Stack_Checking; 67 68with System.Parameters; 69-- used for Single_Lock 70 71package body System.Tasking.Initialization is 72 73 package STPO renames System.Task_Primitives.Operations; 74 package SSL renames System.Soft_Links; 75 package AE renames Ada.Exceptions; 76 77 use Parameters; 78 use Task_Primitives.Operations; 79 80 Global_Task_Lock : aliased System.Task_Primitives.RTS_Lock; 81 -- This is a global lock; it is used to execute in mutual exclusion 82 -- from all other tasks. It is only used by Task_Lock, 83 -- Task_Unlock, and Final_Task_Unlock. 84 85 function Current_Target_Exception return AE.Exception_Occurrence; 86 pragma Import 87 (Ada, Current_Target_Exception, "__gnat_current_target_exception"); 88 -- Import this subprogram from the private part of Ada.Exceptions. 89 90 ----------------------------------------------------------------- 91 -- Tasking versions of services needed by non-tasking programs -- 92 ----------------------------------------------------------------- 93 94 procedure Task_Lock; 95 -- Locks out other tasks. Preceding a section of code by Task_Lock and 96 -- following it by Task_Unlock creates a critical region. This is used 97 -- for ensuring that a region of non-tasking code (such as code used to 98 -- allocate memory) is tasking safe. Note that it is valid for calls to 99 -- Task_Lock/Task_Unlock to be nested, and this must work properly, i.e. 100 -- only the corresponding outer level Task_Unlock will actually unlock. 101 102 procedure Task_Unlock; 103 -- Releases lock previously set by call to Task_Lock. In the nested case, 104 -- all nested locks must be released before other tasks competing for the 105 -- tasking lock are released. 106 107 function Get_Jmpbuf_Address return Address; 108 procedure Set_Jmpbuf_Address (Addr : Address); 109 -- Get/Set Jmpbuf_Address for current task 110 111 function Get_Sec_Stack_Addr return Address; 112 procedure Set_Sec_Stack_Addr (Addr : Address); 113 -- Get/Set location of current task's secondary stack 114 115 function Get_Exc_Stack_Addr return Address; 116 -- Get the exception stack for the current task 117 118 procedure Set_Exc_Stack_Addr (Self_ID : Address; Addr : Address); 119 -- Self_ID is the Task_ID of the task that gets the exception stack. 120 -- For Self_ID = Null_Address, the current task gets the exception stack. 121 122 function Get_Machine_State_Addr return Address; 123 procedure Set_Machine_State_Addr (Addr : Address); 124 -- Get/Set the address for storing the current task's machine state 125 126 function Get_Current_Excep return SSL.EOA; 127 -- Task-safe version of SSL.Get_Current_Excep 128 129 procedure Timed_Delay_T (Time : Duration; Mode : Integer); 130 -- Task-safe version of SSL.Timed_Delay 131 132 function Get_Stack_Info return Stack_Checking.Stack_Access; 133 -- Get access to the current task's Stack_Info 134 135 procedure Update_Exception 136 (X : AE.Exception_Occurrence := Current_Target_Exception); 137 -- Handle exception setting and check for pending actions 138 139 function Task_Name return String; 140 -- Returns current task's name 141 142 ------------------------ 143 -- Local Subprograms -- 144 ------------------------ 145 146 procedure Do_Pending_Action (Self_ID : Task_ID); 147 -- This is introduced to allow more efficient 148 -- in-line expansion of Undefer_Abort. 149 150 ---------------------------- 151 -- Tasking Initialization -- 152 ---------------------------- 153 154 procedure Gnat_Install_Locks (Lock, Unlock : SSL.No_Param_Proc); 155 pragma Import (C, Gnat_Install_Locks, "__gnatlib_install_locks"); 156 -- Used by Init_RTS to install procedure Lock and Unlock for the 157 -- thread locking. This has no effect on GCC 2. For GCC 3, 158 -- it has an effect only if gcc is configured with 159 -- --enable_threads=gnat. 160 161 procedure Init_RTS; 162 -- This procedure completes the initialization of the GNARL. The first 163 -- part of the initialization is done in the body of System.Tasking. 164 -- It consists of initializing global locks, and installing tasking 165 -- versions of certain operations used by the compiler. Init_RTS is called 166 -- during elaboration. 167 168 -------------------------- 169 -- Change_Base_Priority -- 170 -------------------------- 171 172 -- Call only with abort deferred and holding Self_ID locked. 173 174 procedure Change_Base_Priority (T : Task_ID) is 175 begin 176 if T.Common.Base_Priority /= T.New_Base_Priority then 177 T.Common.Base_Priority := T.New_Base_Priority; 178 Set_Priority (T, T.Common.Base_Priority); 179 end if; 180 end Change_Base_Priority; 181 182 ------------------------ 183 -- Check_Abort_Status -- 184 ------------------------ 185 186 function Check_Abort_Status return Integer is 187 Self_ID : constant Task_ID := Self; 188 begin 189 if Self_ID /= null and then Self_ID.Deferral_Level = 0 190 and then Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level 191 then 192 return 1; 193 else 194 return 0; 195 end if; 196 end Check_Abort_Status; 197 198 ----------------- 199 -- Defer_Abort -- 200 ----------------- 201 202 procedure Defer_Abort (Self_ID : Task_ID) is 203 begin 204 if No_Abort and then not Dynamic_Priority_Support then 205 return; 206 end if; 207 208 pragma Assert (Self_ID.Deferral_Level = 0); 209 210 -- pragma Assert 211 -- (Self_ID.Pending_ATC_Level >= Self_ID.ATC_Nesting_Level); 212 213 -- The above check has been useful in detecting mismatched defer/undefer 214 -- pairs. You may uncomment it when testing on systems that support 215 -- preemptive abort. 216 217 -- If the OS supports preemptive abort (e.g. pthread_kill), it should 218 -- have happened already. A problem is with systems that do not support 219 -- preemptive abort, and so rely on polling. On such systems we may get 220 -- false failures of the assertion, since polling for pending abort does 221 -- no occur until the abort undefer operation. 222 223 -- Even on systems that only poll for abort, the assertion may be useful 224 -- for catching missed abort completion polling points. The operations 225 -- that undefer abort poll for pending aborts. This covers most of the 226 -- places where the core Ada semantics require abort to be caught, 227 -- without any special attention. However, this generally happens on 228 -- exit from runtime system call, which means a pending abort will not 229 -- be noticed on the way into the runtime system. We considered adding a 230 -- check for pending aborts at this point, but chose not to, because of 231 -- the overhead. Instead, we searched for RTS calls where abort 232 -- completion is required and a task could go farther than Ada allows 233 -- before undeferring abort; we then modified the code to ensure the 234 -- abort would be detected. 235 236 Self_ID.Deferral_Level := Self_ID.Deferral_Level + 1; 237 end Defer_Abort; 238 239 -------------------------- 240 -- Defer_Abort_Nestable -- 241 -------------------------- 242 243 procedure Defer_Abort_Nestable (Self_ID : Task_ID) is 244 begin 245 if No_Abort and then not Dynamic_Priority_Support then 246 return; 247 end if; 248 249 -- pragma Assert 250 -- ((Self_ID.Pending_ATC_Level >= Self_ID.ATC_Nesting_Level or else 251 -- Self_ID.Deferral_Level > 0)); 252 253 -- See comment in Defer_Abort on the situations in which it may be 254 -- useful to uncomment the above assertion. 255 256 Self_ID.Deferral_Level := Self_ID.Deferral_Level + 1; 257 end Defer_Abort_Nestable; 258 259 -------------------- 260 -- Defer_Abortion -- 261 -------------------- 262 263 procedure Defer_Abortion is 264 Self_ID : Task_ID; 265 266 begin 267 if No_Abort and then not Dynamic_Priority_Support then 268 return; 269 end if; 270 271 Self_ID := STPO.Self; 272 Self_ID.Deferral_Level := Self_ID.Deferral_Level + 1; 273 end Defer_Abortion; 274 275 ----------------------- 276 -- Do_Pending_Action -- 277 ----------------------- 278 279 -- Call only when holding no locks 280 281 procedure Do_Pending_Action (Self_ID : Task_ID) is 282 use type Ada.Exceptions.Exception_Id; 283 284 begin 285 pragma Assert (Self_ID = Self and then Self_ID.Deferral_Level = 0); 286 287 -- Needs loop to recheck for pending action in case a new one occurred 288 -- while we had abort deferred below. 289 290 loop 291 -- Temporarily defer abortion so that we can lock Self_ID. 292 293 Self_ID.Deferral_Level := Self_ID.Deferral_Level + 1; 294 295 if Single_Lock then 296 Lock_RTS; 297 end if; 298 299 Write_Lock (Self_ID); 300 Self_ID.Pending_Action := False; 301 Poll_Base_Priority_Change (Self_ID); 302 Unlock (Self_ID); 303 304 if Single_Lock then 305 Unlock_RTS; 306 end if; 307 308 -- Restore the original Deferral value. 309 310 Self_ID.Deferral_Level := Self_ID.Deferral_Level - 1; 311 312 if not Self_ID.Pending_Action then 313 if Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level then 314 if not Self_ID.Aborting then 315 Self_ID.Aborting := True; 316 pragma Debug 317 (Debug.Trace (Self_ID, "raise Abort_Signal", 'B')); 318 raise Standard'Abort_Signal; 319 320 pragma Assert (not Self_ID.ATC_Hack); 321 322 elsif Self_ID.ATC_Hack then 323 -- The solution really belongs in the Abort_Signal handler 324 -- for async. entry calls. The present hack is very 325 -- fragile. It relies that the very next point after 326 -- Exit_One_ATC_Level at which the task becomes abortable 327 -- will be the call to Undefer_Abort in the 328 -- Abort_Signal handler. 329 330 Self_ID.ATC_Hack := False; 331 332 pragma Debug 333 (Debug.Trace 334 (Self_ID, "raise Abort_Signal (ATC hack)", 'B')); 335 raise Standard'Abort_Signal; 336 end if; 337 end if; 338 339 return; 340 end if; 341 end loop; 342 end Do_Pending_Action; 343 344 ----------------------- 345 -- Final_Task_Unlock -- 346 ----------------------- 347 348 -- This version is only for use in Terminate_Task, when the task 349 -- is relinquishing further rights to its own ATCB. 350 -- There is a very interesting potential race condition there, where 351 -- the old task may run concurrently with a new task that is allocated 352 -- the old tasks (now reused) ATCB. The critical thing here is to 353 -- not make any reference to the ATCB after the lock is released. 354 -- See also comments on Terminate_Task and Unlock. 355 356 procedure Final_Task_Unlock (Self_ID : Task_ID) is 357 begin 358 pragma Assert (Self_ID.Global_Task_Lock_Nesting = 1); 359 Unlock (Global_Task_Lock'Access, Global_Lock => True); 360 end Final_Task_Unlock; 361 362 -------------- 363 -- Init_RTS -- 364 -------------- 365 366 procedure Init_RTS is 367 Self_Id : Task_ID; 368 369 begin 370 -- Terminate run time (regular vs restricted) specific initialization 371 -- of the environment task. 372 373 Self_Id := Environment_Task; 374 Self_Id.Master_of_Task := Environment_Task_Level; 375 Self_Id.Master_Within := Self_Id.Master_of_Task + 1; 376 377 for L in Self_Id.Entry_Calls'Range loop 378 Self_Id.Entry_Calls (L).Self := Self_Id; 379 Self_Id.Entry_Calls (L).Level := L; 380 end loop; 381 382 Self_Id.Awake_Count := 1; 383 Self_Id.Alive_Count := 1; 384 385 Self_Id.Master_Within := Library_Task_Level; 386 -- Normally, a task starts out with internal master nesting level 387 -- one larger than external master nesting level. It is incremented 388 -- to one by Enter_Master, which is called in the task body only if 389 -- the compiler thinks the task may have dependent tasks. There is no 390 -- corresponding call to Enter_Master for the environment task, so we 391 -- would need to increment it to 2 here. Instead, we set it to 3. 392 -- By doing this we reserve the level 2 for server tasks of the runtime 393 -- system. The environment task does not need to wait for these server 394 395 -- Initialize lock used to implement mutual exclusion between all tasks 396 397 Initialize_Lock (Global_Task_Lock'Access, STPO.Global_Task_Level); 398 399 -- Notify that the tasking run time has been elaborated so that 400 -- the tasking version of the soft links can be used. 401 402 if not No_Abort or else Dynamic_Priority_Support then 403 SSL.Abort_Defer := Defer_Abortion'Access; 404 SSL.Abort_Undefer := Undefer_Abortion'Access; 405 end if; 406 407 SSL.Update_Exception := Update_Exception'Access; 408 SSL.Lock_Task := Task_Lock'Access; 409 SSL.Unlock_Task := Task_Unlock'Access; 410 SSL.Get_Jmpbuf_Address := Get_Jmpbuf_Address'Access; 411 SSL.Set_Jmpbuf_Address := Set_Jmpbuf_Address'Access; 412 SSL.Get_Sec_Stack_Addr := Get_Sec_Stack_Addr'Access; 413 SSL.Set_Sec_Stack_Addr := Set_Sec_Stack_Addr'Access; 414 SSL.Get_Exc_Stack_Addr := Get_Exc_Stack_Addr'Access; 415 SSL.Set_Exc_Stack_Addr := Set_Exc_Stack_Addr'Access; 416 SSL.Get_Machine_State_Addr := Get_Machine_State_Addr'Access; 417 SSL.Set_Machine_State_Addr := Set_Machine_State_Addr'Access; 418 SSL.Get_Current_Excep := Get_Current_Excep'Access; 419 SSL.Timed_Delay := Timed_Delay_T'Access; 420 SSL.Check_Abort_Status := Check_Abort_Status'Access; 421 SSL.Get_Stack_Info := Get_Stack_Info'Access; 422 SSL.Task_Name := Task_Name'Access; 423 424 -- No need to create a new Secondary Stack, since we will use the 425 -- default one created in s-secsta.adb 426 427 SSL.Set_Sec_Stack_Addr (SSL.Get_Sec_Stack_Addr_NT); 428 SSL.Set_Exc_Stack_Addr (Null_Address, SSL.Get_Exc_Stack_Addr_NT); 429 SSL.Set_Jmpbuf_Address (SSL.Get_Jmpbuf_Address_NT); 430 SSL.Set_Machine_State_Addr (SSL.Get_Machine_State_Addr_NT); 431 432 -- Install tasking locks in the GCC runtime. 433 434 Gnat_Install_Locks (Task_Lock'Access, Task_Unlock'Access); 435 436 -- Abortion is deferred in a new ATCB, so we need to undefer abortion 437 -- at this stage to make the environment task abortable. 438 439 Undefer_Abort (Environment_Task); 440 end Init_RTS; 441 442 --------------------------- 443 -- Locked_Abort_To_Level-- 444 --------------------------- 445 446 -- Abort a task to the specified ATC nesting level. 447 -- Call this only with T locked. 448 449 -- An earlier version of this code contained a call to Wakeup. That 450 -- should not be necessary here, if Abort_Task is implemented correctly, 451 -- since Abort_Task should include the effect of Wakeup. However, the 452 -- above call was in earlier versions of this file, and at least for 453 -- some targets Abort_Task has not beek doing Wakeup. It should not 454 -- hurt to uncomment the above call, until the error is corrected for 455 -- all targets. 456 457 -- See extended comments in package body System.Tasking.Abortion 458 -- for the overall design of the implementation of task abort. 459 460 -- If the task is sleeping it will be in an abort-deferred region, 461 -- and will not have Abort_Signal raised by Abort_Task. 462 -- Such an "abort deferral" is just to protect the RTS internals, 463 -- and not necessarily required to enforce Ada semantics. 464 -- Abort_Task should wake the task up and let it decide if it wants 465 -- to complete the aborted construct immediately. 466 467 -- Note that the effect of the lowl-level Abort_Task is not persistent. 468 -- If the target task is not blocked, this wakeup will be missed. 469 470 -- We don't bother calling Abort_Task if this task is aborting itself, 471 -- since we are inside the RTS and have abort deferred. Similarly, We 472 -- don't bother to call Abort_Task if T is terminated, since there is 473 -- no need to abort a terminated task, and it could be dangerous to try 474 -- if the task has stopped executing. 475 476 -- Note that an earlier version of this code had some false reasoning 477 -- about being able to reliably wake up a task that had suspended on 478 -- a blocking system call that does not atomically relase the task's 479 -- lock (e.g., UNIX nanosleep, which we once thought could be used to 480 -- implement delays). That still left the possibility of missed 481 -- wakeups. 482 483 -- We cannot safely call Vulnerable_Complete_Activation here, 484 -- since that requires locking Self_ID.Parent. The anti-deadlock 485 -- lock ordering rules would then require us to release the lock 486 -- on Self_ID first, which would create a timing window for other 487 -- tasks to lock Self_ID. This is significant for tasks that may be 488 -- aborted before their execution can enter the task body, and so 489 -- they do not get a chance to call Complete_Task. The actual work 490 -- for this case is done in Terminate_Task. 491 492 procedure Locked_Abort_To_Level 493 (Self_ID : Task_ID; 494 T : Task_ID; 495 L : ATC_Level) 496 is 497 begin 498 if not T.Aborting and then T /= Self_ID then 499 case T.Common.State is 500 when Unactivated | Terminated => 501 pragma Assert (False); 502 null; 503 504 when Runnable => 505 -- This is needed to cancel an asynchronous protected entry 506 -- call during a requeue with abort. 507 508 T.Entry_Calls 509 (T.ATC_Nesting_Level).Cancellation_Attempted := True; 510 511 when Interrupt_Server_Blocked_On_Event_Flag => 512 null; 513 514 when Delay_Sleep | 515 Async_Select_Sleep | 516 Interrupt_Server_Idle_Sleep | 517 Interrupt_Server_Blocked_Interrupt_Sleep | 518 Timer_Server_Sleep | 519 AST_Server_Sleep => 520 Wakeup (T, T.Common.State); 521 522 when Acceptor_Sleep => 523 T.Open_Accepts := null; 524 Wakeup (T, T.Common.State); 525 526 when Entry_Caller_Sleep => 527 T.Entry_Calls 528 (T.ATC_Nesting_Level).Cancellation_Attempted := True; 529 Wakeup (T, T.Common.State); 530 531 when Activator_Sleep | 532 Master_Completion_Sleep | 533 Master_Phase_2_Sleep | 534 Asynchronous_Hold => 535 null; 536 end case; 537 end if; 538 539 if T.Pending_ATC_Level > L then 540 T.Pending_ATC_Level := L; 541 T.Pending_Action := True; 542 543 if L = 0 then 544 T.Callable := False; 545 end if; 546 547 -- This prevents aborted task from accepting calls 548 549 if T.Aborting then 550 551 -- The test above is just a heuristic, to reduce wasteful 552 -- calls to Abort_Task. We are holding T locked, and this 553 -- value will not be set to False except with T also locked, 554 -- inside Exit_One_ATC_Level, so we should not miss wakeups. 555 556 if T.Common.State = Acceptor_Sleep then 557 T.Open_Accepts := null; 558 end if; 559 560 elsif T /= Self_ID and then 561 (T.Common.State = Runnable 562 or else T.Common.State = Interrupt_Server_Blocked_On_Event_Flag) 563 -- The task is blocked on a system call waiting for the 564 -- completion event. In this case Abort_Task may need to take 565 -- special action in order to succeed. Example system: VMS. 566 567 then 568 Abort_Task (T); 569 end if; 570 end if; 571 end Locked_Abort_To_Level; 572 573 ------------------------------- 574 -- Poll_Base_Priority_Change -- 575 ------------------------------- 576 577 -- Poll for pending base priority change and for held tasks. 578 -- This should always be called with (only) Self_ID locked. 579 -- It may temporarily release Self_ID's lock. 580 581 -- The call to Yield is to force enqueuing at the 582 -- tail of the dispatching queue. 583 584 -- We must unlock Self_ID for this to take effect, 585 -- since we are inheriting high active priority from the lock. 586 587 -- See also Poll_Base_Priority_Change_At_Entry_Call, 588 -- in package System.Tasking.Entry_Calls. 589 590 -- In this version, we check if the task is held too because 591 -- doing this only in Do_Pending_Action is not enough. 592 593 procedure Poll_Base_Priority_Change (Self_ID : Task_ID) is 594 begin 595 if Dynamic_Priority_Support and then Self_ID.Pending_Priority_Change then 596 597 -- Check for ceiling violations ??? 598 599 Self_ID.Pending_Priority_Change := False; 600 601 if Self_ID.Common.Base_Priority = Self_ID.New_Base_Priority then 602 if Single_Lock then 603 Unlock_RTS; 604 Yield; 605 Lock_RTS; 606 else 607 Unlock (Self_ID); 608 Yield; 609 Write_Lock (Self_ID); 610 end if; 611 612 elsif Self_ID.Common.Base_Priority < Self_ID.New_Base_Priority then 613 Self_ID.Common.Base_Priority := Self_ID.New_Base_Priority; 614 Set_Priority (Self_ID, Self_ID.Common.Base_Priority); 615 616 else 617 -- Lowering priority 618 619 Self_ID.Common.Base_Priority := Self_ID.New_Base_Priority; 620 Set_Priority (Self_ID, Self_ID.Common.Base_Priority); 621 622 if Single_Lock then 623 Unlock_RTS; 624 Yield; 625 Lock_RTS; 626 else 627 Unlock (Self_ID); 628 Yield; 629 Write_Lock (Self_ID); 630 end if; 631 end if; 632 end if; 633 end Poll_Base_Priority_Change; 634 635 -------------------------------- 636 -- Remove_From_All_Tasks_List -- 637 -------------------------------- 638 639 procedure Remove_From_All_Tasks_List (T : Task_ID) is 640 C : Task_ID; 641 Previous : Task_ID; 642 643 begin 644 pragma Debug 645 (Debug.Trace (Self, "Remove_From_All_Tasks_List", 'C')); 646 647 Previous := Null_Task; 648 C := All_Tasks_List; 649 650 while C /= Null_Task loop 651 if C = T then 652 if Previous = Null_Task then 653 All_Tasks_List := 654 All_Tasks_List.Common.All_Tasks_Link; 655 else 656 Previous.Common.All_Tasks_Link := C.Common.All_Tasks_Link; 657 end if; 658 659 return; 660 end if; 661 662 Previous := C; 663 C := C.Common.All_Tasks_Link; 664 end loop; 665 666 pragma Assert (False); 667 end Remove_From_All_Tasks_List; 668 669 --------------- 670 -- Task_Lock -- 671 --------------- 672 673 procedure Task_Lock (Self_ID : Task_ID) is 674 begin 675 Self_ID.Global_Task_Lock_Nesting := Self_ID.Global_Task_Lock_Nesting + 1; 676 677 if Self_ID.Global_Task_Lock_Nesting = 1 then 678 Defer_Abort_Nestable (Self_ID); 679 Write_Lock (Global_Task_Lock'Access, Global_Lock => True); 680 end if; 681 end Task_Lock; 682 683 procedure Task_Lock is 684 begin 685 Task_Lock (STPO.Self); 686 end Task_Lock; 687 688 --------------- 689 -- Task_Name -- 690 --------------- 691 692 function Task_Name return String is 693 Self_Id : constant Task_ID := STPO.Self; 694 695 begin 696 return Self_Id.Common.Task_Image (1 .. Self_Id.Common.Task_Image_Len); 697 end Task_Name; 698 699 ----------------- 700 -- Task_Unlock -- 701 ----------------- 702 703 procedure Task_Unlock (Self_ID : Task_ID) is 704 begin 705 pragma Assert (Self_ID.Global_Task_Lock_Nesting > 0); 706 Self_ID.Global_Task_Lock_Nesting := Self_ID.Global_Task_Lock_Nesting - 1; 707 708 if Self_ID.Global_Task_Lock_Nesting = 0 then 709 Unlock (Global_Task_Lock'Access, Global_Lock => True); 710 Undefer_Abort_Nestable (Self_ID); 711 end if; 712 end Task_Unlock; 713 714 procedure Task_Unlock is 715 begin 716 Task_Unlock (STPO.Self); 717 end Task_Unlock; 718 719 ------------------- 720 -- Undefer_Abort -- 721 ------------------- 722 723 -- Precondition : Self does not hold any locks! 724 725 -- Undefer_Abort is called on any abortion completion point (aka. 726 -- synchronization point). It performs the following actions if they 727 -- are pending: (1) change the base priority, (2) abort the task. 728 729 -- The priority change has to occur before abortion. Otherwise, it would 730 -- take effect no earlier than the next abortion completion point. 731 732 procedure Undefer_Abort (Self_ID : Task_ID) is 733 begin 734 if No_Abort and then not Dynamic_Priority_Support then 735 return; 736 end if; 737 738 pragma Assert (Self_ID.Deferral_Level = 1); 739 740 Self_ID.Deferral_Level := Self_ID.Deferral_Level - 1; 741 742 if Self_ID.Deferral_Level = 0 then 743 pragma Assert (Check_No_Locks (Self_ID)); 744 745 if Self_ID.Pending_Action then 746 Do_Pending_Action (Self_ID); 747 end if; 748 end if; 749 end Undefer_Abort; 750 751 ---------------------------- 752 -- Undefer_Abort_Nestable -- 753 ---------------------------- 754 755 -- An earlier version would re-defer abort if an abort is in progress. 756 -- Then, we modified the effect of the raise statement so that it defers 757 -- abort until control reaches a handler. That was done to prevent 758 -- "skipping over" a handler if another asynchronous abort occurs during 759 -- the propagation of the abort to the handler. 760 761 -- There has been talk of reversing that decision, based on a newer 762 -- implementation of exception propagation. Care must be taken to evaluate 763 -- how such a change would interact with the above code and all the places 764 -- where abort-deferral is used to bridge over critical transitions, such 765 -- as entry to the scope of a region with a finalizer and entry into the 766 -- body of an accept-procedure. 767 768 procedure Undefer_Abort_Nestable (Self_ID : Task_ID) is 769 begin 770 if No_Abort and then not Dynamic_Priority_Support then 771 return; 772 end if; 773 774 pragma Assert (Self_ID.Deferral_Level > 0); 775 776 Self_ID.Deferral_Level := Self_ID.Deferral_Level - 1; 777 778 if Self_ID.Deferral_Level = 0 then 779 780 pragma Assert (Check_No_Locks (Self_ID)); 781 782 if Self_ID.Pending_Action then 783 Do_Pending_Action (Self_ID); 784 end if; 785 end if; 786 end Undefer_Abort_Nestable; 787 788 ---------------------- 789 -- Undefer_Abortion -- 790 ---------------------- 791 792 -- Phase out RTS-internal use of Undefer_Abortion 793 -- to reduce overhead due to multiple calls to Self. 794 795 procedure Undefer_Abortion is 796 Self_ID : Task_ID; 797 798 begin 799 if No_Abort and then not Dynamic_Priority_Support then 800 return; 801 end if; 802 803 Self_ID := STPO.Self; 804 pragma Assert (Self_ID.Deferral_Level > 0); 805 806 Self_ID.Deferral_Level := Self_ID.Deferral_Level - 1; 807 808 if Self_ID.Deferral_Level = 0 then 809 pragma Assert (Check_No_Locks (Self_ID)); 810 811 if Self_ID.Pending_Action then 812 Do_Pending_Action (Self_ID); 813 end if; 814 end if; 815 end Undefer_Abortion; 816 817 ---------------------- 818 -- Update_Exception -- 819 ---------------------- 820 821 -- Call only when holding no locks. 822 823 procedure Update_Exception 824 (X : AE.Exception_Occurrence := Current_Target_Exception) 825 is 826 Self_Id : constant Task_ID := Self; 827 use Ada.Exceptions; 828 829 begin 830 Save_Occurrence (Self_Id.Common.Compiler_Data.Current_Excep, X); 831 832 if Self_Id.Deferral_Level = 0 then 833 if Self_Id.Pending_Action then 834 Self_Id.Pending_Action := False; 835 Self_Id.Deferral_Level := Self_Id.Deferral_Level + 1; 836 837 if Single_Lock then 838 Lock_RTS; 839 end if; 840 841 Write_Lock (Self_Id); 842 Self_Id.Pending_Action := False; 843 Poll_Base_Priority_Change (Self_Id); 844 Unlock (Self_Id); 845 846 if Single_Lock then 847 Unlock_RTS; 848 end if; 849 850 Self_Id.Deferral_Level := Self_Id.Deferral_Level - 1; 851 852 if Self_Id.Pending_ATC_Level < Self_Id.ATC_Nesting_Level then 853 if not Self_Id.Aborting then 854 Self_Id.Aborting := True; 855 raise Standard'Abort_Signal; 856 end if; 857 end if; 858 end if; 859 end if; 860 end Update_Exception; 861 862 -------------------------- 863 -- Wakeup_Entry_Caller -- 864 -------------------------- 865 866 -- This is called at the end of service of an entry call, to abort the 867 -- caller if he is in an abortable part, and to wake up the caller if it 868 -- is on Entry_Caller_Sleep. It assumes that the call is already off-queue. 869 870 -- (This enforces the rule that a task must be off-queue if its state is 871 -- Done or Cancelled.) Call it holding the lock of Entry_Call.Self. 872 873 -- Timed_Call or Simple_Call: 874 -- The caller is waiting on Entry_Caller_Sleep, in 875 -- Wait_For_Completion, or Wait_For_Completion_With_Timeout. 876 877 -- Conditional_Call: 878 -- The caller might be in Wait_For_Completion, 879 -- waiting for a rendezvous (possibly requeued without abort) 880 -- to complete. 881 882 -- Asynchronous_Call: 883 -- The caller may be executing in the abortable part o 884 -- an async. select, or on a time delay, 885 -- if Entry_Call.State >= Was_Abortable. 886 887 procedure Wakeup_Entry_Caller 888 (Self_ID : Task_ID; 889 Entry_Call : Entry_Call_Link; 890 New_State : Entry_Call_State) 891 is 892 Caller : constant Task_ID := Entry_Call.Self; 893 894 begin 895 pragma Debug (Debug.Trace 896 (Self_ID, "Wakeup_Entry_Caller", 'E', Caller)); 897 pragma Assert (New_State = Done or else New_State = Cancelled); 898 899 pragma Assert 900 (Caller.Common.State /= Terminated 901 and then Caller.Common.State /= Unactivated); 902 903 Entry_Call.State := New_State; 904 905 if Entry_Call.Mode = Asynchronous_Call then 906 907 -- Abort the caller in his abortable part, 908 -- but do so only if call has been queued abortably 909 910 if Entry_Call.State >= Was_Abortable or else New_State = Done then 911 Locked_Abort_To_Level (Self_ID, Caller, Entry_Call.Level - 1); 912 end if; 913 914 elsif Caller.Common.State = Entry_Caller_Sleep then 915 Wakeup (Caller, Entry_Caller_Sleep); 916 end if; 917 end Wakeup_Entry_Caller; 918 919 ---------------------- 920 -- Soft-Link Bodies -- 921 ---------------------- 922 923 function Get_Current_Excep return SSL.EOA is 924 begin 925 return STPO.Self.Common.Compiler_Data.Current_Excep'Access; 926 end Get_Current_Excep; 927 928 function Get_Exc_Stack_Addr return Address is 929 begin 930 return STPO.Self.Common.Compiler_Data.Exc_Stack_Addr; 931 end Get_Exc_Stack_Addr; 932 933 function Get_Jmpbuf_Address return Address is 934 begin 935 return STPO.Self.Common.Compiler_Data.Jmpbuf_Address; 936 end Get_Jmpbuf_Address; 937 938 function Get_Machine_State_Addr return Address is 939 begin 940 return STPO.Self.Common.Compiler_Data.Machine_State_Addr; 941 end Get_Machine_State_Addr; 942 943 function Get_Sec_Stack_Addr return Address is 944 begin 945 return STPO.Self.Common.Compiler_Data.Sec_Stack_Addr; 946 end Get_Sec_Stack_Addr; 947 948 function Get_Stack_Info return Stack_Checking.Stack_Access is 949 begin 950 return STPO.Self.Common.Compiler_Data.Pri_Stack_Info'Access; 951 end Get_Stack_Info; 952 953 procedure Set_Exc_Stack_Addr (Self_ID : Address; Addr : Address) is 954 Me : Task_ID := To_Task_Id (Self_ID); 955 956 begin 957 if Me = Null_Task then 958 Me := STPO.Self; 959 end if; 960 961 Me.Common.Compiler_Data.Exc_Stack_Addr := Addr; 962 end Set_Exc_Stack_Addr; 963 964 procedure Set_Jmpbuf_Address (Addr : Address) is 965 begin 966 STPO.Self.Common.Compiler_Data.Jmpbuf_Address := Addr; 967 end Set_Jmpbuf_Address; 968 969 procedure Set_Machine_State_Addr (Addr : Address) is 970 begin 971 STPO.Self.Common.Compiler_Data.Machine_State_Addr := Addr; 972 end Set_Machine_State_Addr; 973 974 procedure Set_Sec_Stack_Addr (Addr : Address) is 975 begin 976 STPO.Self.Common.Compiler_Data.Sec_Stack_Addr := Addr; 977 end Set_Sec_Stack_Addr; 978 979 procedure Timed_Delay_T (Time : Duration; Mode : Integer) is 980 begin 981 STPO.Timed_Delay (STPO.Self, Time, Mode); 982 end Timed_Delay_T; 983 984 ----------------------- 985 -- Soft-Link Dummies -- 986 ----------------------- 987 988 -- These are dummies for subprograms that are only needed by certain 989 -- optional run-time system packages. If they are needed, the soft 990 -- links will be redirected to the real subprogram by elaboration of 991 -- the subprogram body where the real subprogram is declared. 992 993 procedure Finalize_Attributes (T : Task_ID) is 994 pragma Warnings (Off, T); 995 996 begin 997 null; 998 end Finalize_Attributes; 999 1000 procedure Initialize_Attributes (T : Task_ID) is 1001 pragma Warnings (Off, T); 1002 1003 begin 1004 null; 1005 end Initialize_Attributes; 1006 1007begin 1008 Init_RTS; 1009end System.Tasking.Initialization; 1010