gcc/ada/s-taprop-lynxos.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                 GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS                 --
   4 --                                                                          --
   5 --     S Y S T E M . T A S K _ P R I M I T I V E S . O P E R A T I O N S    --
   6 --                                                                          --
   7 --                                  B o d y                                 --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2008, 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,  51  Franklin  Street,  Fifth  Floor, --
  20 -- Boston, MA 02110-1301, 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
  34 --  This is a LynxOS version of this file, adapted to make SCHED_FIFO and
  35 --  ceiling locking (Annex D compliance) work properly.
  36
  37 --  This package contains all the GNULL primitives that interface directly with
  38 --  the underlying OS.
  39
  40 pragma Polling (Off);
  41 --  Turn off polling, we do not want ATC polling to take place during tasking
  42 --  operations. It causes infinite loops and other problems.
  43
  44 with Ada.Unchecked_Deallocation;
  45
  46 with Interfaces.C;
  47
  48 with System.Tasking.Debug;
  49 with System.Interrupt_Management;
  50 with System.OS_Primitives;
  51 with System.Task_Info;
  52
  53 with System.Soft_Links;
  54 --  We use System.Soft_Links instead of System.Tasking.Initialization
  55 --  because the later is a higher level package that we shouldn't depend on.
  56 --  For example when using the restricted run time, it is replaced by
  57 --  System.Tasking.Restricted.Stages.
  58
  59 package body System.Task_Primitives.Operations is
  60
  61    package SSL renames System.Soft_Links;
  62
  63    use System.Tasking.Debug;
  64    use System.Tasking;
  65    use Interfaces.C;
  66    use System.OS_Interface;
  67    use System.Parameters;
  68    use System.OS_Primitives;
  69
  70    ----------------
  71    -- Local Data --
  72    ----------------
  73
  74    --  The followings are logically constants, but need to be initialized
  75    --  at run time.
  76
  77    Single_RTS_Lock : aliased RTS_Lock;
  78    --  This is a lock to allow only one thread of control in the RTS at
  79    --  a time; it is used to execute in mutual exclusion from all other tasks.
  80    --  Used mainly in Single_Lock mode, but also to protect All_Tasks_List
  81
  82    ATCB_Key : aliased pthread_key_t;
  83    --  Key used to find the Ada Task_Id associated with a thread
  84
  85    Environment_Task_Id : Task_Id;
  86    --  A variable to hold Task_Id for the environment task
  87
  88    Locking_Policy : Character;
  89    pragma Import (C, Locking_Policy, "__gl_locking_policy");
  90    --  Value of the pragma Locking_Policy:
  91    --    'C' for Ceiling_Locking
  92    --    'I' for Inherit_Locking
  93    --    ' ' for none.
  94
  95    Unblocked_Signal_Mask : aliased sigset_t;
  96    --  The set of signals that should unblocked in all tasks
  97
  98    --  The followings are internal configuration constants needed
  99
 100    Next_Serial_Number : Task_Serial_Number := 100;
 101    --  We start at 100, to reserve some special values for
 102    --  using in error checking.
 103
 104    Time_Slice_Val : Integer;
 105    pragma Import (C, Time_Slice_Val, "__gl_time_slice_val");
 106
 107    Dispatching_Policy : Character;
 108    pragma Import (C, Dispatching_Policy, "__gl_task_dispatching_policy");
 109
 110    Foreign_Task_Elaborated : aliased Boolean := True;
 111    --  Used to identified fake tasks (i.e., non-Ada Threads)
 112
 113    --------------------
 114    -- Local Packages --
 115    --------------------
 116
 117    package Specific is
 118
 119       procedure Initialize (Environment_Task : Task_Id);
 120       pragma Inline (Initialize);
 121       --  Initialize various data needed by this package
 122
 123       function Is_Valid_Task return Boolean;
 124       pragma Inline (Is_Valid_Task);
 125       --  Does the current thread have an ATCB?
 126
 127       procedure Set (Self_Id : Task_Id);
 128       pragma Inline (Set);
 129       --  Set the self id for the current task
 130
 131       function Self return Task_Id;
 132       pragma Inline (Self);
 133       --  Return a pointer to the Ada Task Control Block of the calling task
 134
 135    end Specific;
 136
 137    package body Specific is separate;
 138    --  The body of this package is target specific
 139
 140    ---------------------------------
 141    -- Support for foreign threads --
 142    ---------------------------------
 143
 144    function Register_Foreign_Thread (Thread : Thread_Id) return Task_Id;
 145    --  Allocate and Initialize a new ATCB for the current Thread
 146
 147    function Register_Foreign_Thread
 148      (Thread : Thread_Id) return Task_Id is separate;
 149
 150    -----------------------
 151    -- Local Subprograms --
 152    -----------------------
 153
 154    procedure Abort_Handler (Sig : Signal);
 155    --  Signal handler used to implement asynchronous abort
 156
 157    procedure Set_OS_Priority (T : Task_Id; Prio : System.Any_Priority);
 158    --  This procedure calls the scheduler of the OS to set thread's priority
 159
 160    -------------------
 161    -- Abort_Handler --
 162    -------------------
 163
 164    procedure Abort_Handler (Sig : Signal) is
 165       pragma Unreferenced (Sig);
 166
 167       T       : constant Task_Id := Self;
 168       Result  : Interfaces.C.int;
 169       Old_Set : aliased sigset_t;
 170
 171    begin
 172       --  It is not safe to raise an exception when using ZCX and the GCC
 173       --  exception handling mechanism.
 174
 175       if ZCX_By_Default and then GCC_ZCX_Support then
 176          return;
 177       end if;
 178
 179       if T.Deferral_Level = 0
 180         and then T.Pending_ATC_Level < T.ATC_Nesting_Level
 181         and then not T.Aborting
 182       then
 183          T.Aborting := True;
 184
 185          --  Make sure signals used for RTS internal purpose are unmasked
 186
 187          Result :=
 188            pthread_sigmask
 189              (SIG_UNBLOCK,
 190               Unblocked_Signal_Mask'Access,
 191               Old_Set'Access);
 192          pragma Assert (Result = 0);
 193
 194          raise Standard'Abort_Signal;
 195       end if;
 196    end Abort_Handler;
 197
 198    -----------------
 199    -- Stack_Guard --
 200    -----------------
 201
 202    procedure Stack_Guard (T : ST.Task_Id; On : Boolean) is
 203       Stack_Base : constant Address := Get_Stack_Base (T.Common.LL.Thread);
 204       Guard_Page_Address : Address;
 205
 206       Res : Interfaces.C.int;
 207
 208    begin
 209       if Stack_Base_Available then
 210
 211          --  Compute the guard page address
 212
 213          Guard_Page_Address :=
 214            Stack_Base - (Stack_Base mod Get_Page_Size) + Get_Page_Size;
 215
 216          if On then
 217             Res := mprotect (Guard_Page_Address, Get_Page_Size, PROT_ON);
 218          else
 219             Res := mprotect (Guard_Page_Address, Get_Page_Size, PROT_OFF);
 220          end if;
 221
 222          pragma Assert (Res = 0);
 223       end if;
 224    end Stack_Guard;
 225
 226    --------------------
 227    -- Get_Thread_Id  --
 228    --------------------
 229
 230    function Get_Thread_Id (T : ST.Task_Id) return OSI.Thread_Id is
 231    begin
 232       return T.Common.LL.Thread;
 233    end Get_Thread_Id;
 234
 235    ----------
 236    -- Self --
 237    ----------
 238
 239    function Self return Task_Id renames Specific.Self;
 240
 241    ---------------------
 242    -- Initialize_Lock --
 243    ---------------------
 244
 245    procedure Initialize_Lock
 246      (Prio : System.Any_Priority;
 247       L    : not null access Lock)
 248    is
 249       Attributes : aliased pthread_mutexattr_t;
 250       Result : Interfaces.C.int;
 251
 252    begin
 253       Result := pthread_mutexattr_init (Attributes'Access);
 254       pragma Assert (Result = 0 or else Result = ENOMEM);
 255
 256       if Result = ENOMEM then
 257          raise Storage_Error;
 258       end if;
 259
 260       if Locking_Policy = 'C' then
 261          L.Ceiling := Prio;
 262       end if;
 263
 264       Result := pthread_mutex_init (L.Mutex'Access, Attributes'Access);
 265       pragma Assert (Result = 0 or else Result = ENOMEM);
 266
 267       if Result = ENOMEM then
 268          raise Storage_Error;
 269       end if;
 270
 271       Result := pthread_mutexattr_destroy (Attributes'Access);
 272       pragma Assert (Result = 0);
 273    end Initialize_Lock;
 274
 275    procedure Initialize_Lock
 276      (L     : not null access RTS_Lock;
 277       Level : Lock_Level)
 278    is
 279       pragma Unreferenced (Level);
 280
 281       Attributes : aliased pthread_mutexattr_t;
 282       Result     : Interfaces.C.int;
 283
 284    begin
 285       Result := pthread_mutexattr_init (Attributes'Access);
 286       pragma Assert (Result = 0 or else Result = ENOMEM);
 287
 288       if Result = ENOMEM then
 289          raise Storage_Error;
 290       end if;
 291
 292       Result := pthread_mutex_init (L, Attributes'Access);
 293       pragma Assert (Result = 0 or else Result = ENOMEM);
 294
 295       if Result = ENOMEM then
 296          Result := pthread_mutexattr_destroy (Attributes'Access);
 297          raise Storage_Error;
 298       end if;
 299
 300       Result := pthread_mutexattr_destroy (Attributes'Access);
 301       pragma Assert (Result = 0);
 302    end Initialize_Lock;
 303
 304    -------------------
 305    -- Finalize_Lock --
 306    -------------------
 307
 308    procedure Finalize_Lock (L : not null access Lock) is
 309       Result : Interfaces.C.int;
 310    begin
 311       Result := pthread_mutex_destroy (L.Mutex'Access);
 312       pragma Assert (Result = 0);
 313    end Finalize_Lock;
 314
 315    procedure Finalize_Lock (L : not null access RTS_Lock) is
 316       Result : Interfaces.C.int;
 317    begin
 318       Result := pthread_mutex_destroy (L);
 319       pragma Assert (Result = 0);
 320    end Finalize_Lock;
 321
 322    ----------------
 323    -- Write_Lock --
 324    ----------------
 325
 326    procedure Write_Lock
 327      (L                 : not null access Lock;
 328       Ceiling_Violation : out Boolean)
 329    is
 330       Result : Interfaces.C.int;
 331       T      : constant Task_Id := Self;
 332
 333    begin
 334       if Locking_Policy = 'C' then
 335          if T.Common.Current_Priority > L.Ceiling then
 336             Ceiling_Violation := True;
 337             return;
 338          end if;
 339
 340          L.Saved_Priority := T.Common.Current_Priority;
 341
 342          if T.Common.Current_Priority < L.Ceiling then
 343             Set_OS_Priority (T, L.Ceiling);
 344          end if;
 345       end if;
 346
 347       Result := pthread_mutex_lock (L.Mutex'Access);
 348
 349       --  Assume that the cause of EINVAL is a priority ceiling violation
 350
 351       Ceiling_Violation := (Result = EINVAL);
 352       pragma Assert (Result = 0 or else Result = EINVAL);
 353    end Write_Lock;
 354
 355    --  No tricks on RTS_Locks
 356
 357    procedure Write_Lock
 358      (L           : not null access RTS_Lock;
 359       Global_Lock : Boolean := False)
 360    is
 361       Result : Interfaces.C.int;
 362    begin
 363       if not Single_Lock or else Global_Lock then
 364          Result := pthread_mutex_lock (L);
 365          pragma Assert (Result = 0);
 366       end if;
 367    end Write_Lock;
 368
 369    procedure Write_Lock (T : Task_Id) is
 370       Result : Interfaces.C.int;
 371    begin
 372       if not Single_Lock then
 373          Result := pthread_mutex_lock (T.Common.LL.L'Access);
 374          pragma Assert (Result = 0);
 375       end if;
 376    end Write_Lock;
 377
 378    ---------------
 379    -- Read_Lock --
 380    ---------------
 381
 382    procedure Read_Lock
 383      (L                 : not null access Lock;
 384       Ceiling_Violation : out Boolean)
 385    is
 386    begin
 387       Write_Lock (L, Ceiling_Violation);
 388    end Read_Lock;
 389
 390    ------------
 391    -- Unlock --
 392    ------------
 393
 394    procedure Unlock (L : not null access Lock) is
 395       Result : Interfaces.C.int;
 396       T      : constant Task_Id := Self;
 397
 398    begin
 399       Result := pthread_mutex_unlock (L.Mutex'Access);
 400       pragma Assert (Result = 0);
 401
 402       if Locking_Policy = 'C' then
 403          if T.Common.Current_Priority > L.Saved_Priority then
 404             Set_OS_Priority (T, L.Saved_Priority);
 405          end if;
 406       end if;
 407    end Unlock;
 408
 409    procedure Unlock
 410      (L           : not null access RTS_Lock;
 411       Global_Lock : Boolean := False)
 412    is
 413       Result : Interfaces.C.int;
 414    begin
 415       if not Single_Lock or else Global_Lock then
 416          Result := pthread_mutex_unlock (L);
 417          pragma Assert (Result = 0);
 418       end if;
 419    end Unlock;
 420
 421    procedure Unlock (T : Task_Id) is
 422       Result : Interfaces.C.int;
 423    begin
 424       if not Single_Lock then
 425          Result := pthread_mutex_unlock (T.Common.LL.L'Access);
 426          pragma Assert (Result = 0);
 427       end if;
 428    end Unlock;
 429
 430    -----------------
 431    -- Set_Ceiling --
 432    -----------------
 433
 434    --  Dynamic priority ceilings are not supported by the underlying system
 435
 436    procedure Set_Ceiling
 437      (L    : not null access Lock;
 438       Prio : System.Any_Priority)
 439    is
 440       pragma Unreferenced (L, Prio);
 441    begin
 442       null;
 443    end Set_Ceiling;
 444
 445    -----------
 446    -- Sleep --
 447    -----------
 448
 449    procedure Sleep
 450      (Self_ID : Task_Id;
 451       Reason  : System.Tasking.Task_States)
 452    is
 453       pragma Unreferenced (Reason);
 454       Result : Interfaces.C.int;
 455
 456    begin
 457       if Single_Lock then
 458          Result :=
 459            pthread_cond_wait
 460              (Self_ID.Common.LL.CV'Access, Single_RTS_Lock'Access);
 461       else
 462          Result :=
 463            pthread_cond_wait
 464              (Self_ID.Common.LL.CV'Access, Self_ID.Common.LL.L'Access);
 465       end if;
 466
 467       --  EINTR is not considered a failure
 468
 469       pragma Assert (Result = 0 or else Result = EINTR);
 470    end Sleep;
 471
 472    -----------------
 473    -- Timed_Sleep --
 474    -----------------
 475
 476    --  This is for use within the run-time system, so abort is
 477    --  assumed to be already deferred, and the caller should be
 478    --  holding its own ATCB lock.
 479
 480    procedure Timed_Sleep
 481      (Self_ID  : Task_Id;
 482       Time     : Duration;
 483       Mode     : ST.Delay_Modes;
 484       Reason   : Task_States;
 485       Timedout : out Boolean;
 486       Yielded  : out Boolean)
 487    is
 488       pragma Unreferenced (Reason);
 489
 490       Base_Time  : constant Duration := Monotonic_Clock;
 491       Check_Time : Duration := Base_Time;
 492       Rel_Time   : Duration;
 493       Abs_Time   : Duration;
 494       Request    : aliased timespec;
 495       Result     : Interfaces.C.int;
 496
 497    begin
 498       Timedout := True;
 499       Yielded := False;
 500
 501       if Mode = Relative then
 502          Abs_Time := Duration'Min (Time, Max_Sensible_Delay) + Check_Time;
 503
 504          if Relative_Timed_Wait then
 505             Rel_Time := Duration'Min (Max_Sensible_Delay, Time);
 506          end if;
 507
 508       else
 509          Abs_Time := Duration'Min (Check_Time + Max_Sensible_Delay, Time);
 510
 511          if Relative_Timed_Wait then
 512             Rel_Time := Duration'Min (Max_Sensible_Delay, Time - Check_Time);
 513          end if;
 514       end if;
 515
 516       if Abs_Time > Check_Time then
 517          if Relative_Timed_Wait then
 518             Request := To_Timespec (Rel_Time);
 519          else
 520             Request := To_Timespec (Abs_Time);
 521          end if;
 522
 523          loop
 524             exit when Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level;
 525
 526             if Single_Lock then
 527                Result :=
 528                  pthread_cond_timedwait
 529                    (Self_ID.Common.LL.CV'Access, Single_RTS_Lock'Access,
 530                     Request'Access);
 531
 532             else
 533                Result :=
 534                  pthread_cond_timedwait
 535                    (Self_ID.Common.LL.CV'Access, Self_ID.Common.LL.L'Access,
 536                     Request'Access);
 537             end if;
 538
 539             Check_Time := Monotonic_Clock;
 540             exit when Abs_Time <= Check_Time or else Check_Time < Base_Time;
 541
 542             if Result = 0 or Result = EINTR then
 543
 544                --  Somebody may have called Wakeup for us
 545
 546                Timedout := False;
 547                exit;
 548             end if;
 549
 550             pragma Assert (Result = ETIMEDOUT);
 551          end loop;
 552       end if;
 553    end Timed_Sleep;
 554
 555    -----------------
 556    -- Timed_Delay --
 557    -----------------
 558
 559    --  This is for use in implementing delay statements, so we assume
 560    --  the caller is abort-deferred but is holding no locks.
 561
 562    procedure Timed_Delay
 563      (Self_ID : Task_Id;
 564       Time    : Duration;
 565       Mode    : ST.Delay_Modes)
 566    is
 567       Base_Time  : constant Duration := Monotonic_Clock;
 568       Check_Time : Duration := Base_Time;
 569       Abs_Time   : Duration;
 570       Rel_Time   : Duration;
 571       Request    : aliased timespec;
 572
 573       Result : Interfaces.C.int;
 574       pragma Warnings (Off, Result);
 575
 576    begin
 577       if Single_Lock then
 578          Lock_RTS;
 579       end if;
 580
 581       --  Comments needed in code below ???
 582
 583       Write_Lock (Self_ID);
 584
 585       if Mode = Relative then
 586          Abs_Time := Duration'Min (Time, Max_Sensible_Delay) + Check_Time;
 587
 588          if Relative_Timed_Wait then
 589             Rel_Time := Duration'Min (Max_Sensible_Delay, Time);
 590          end if;
 591
 592       else
 593          Abs_Time := Duration'Min (Check_Time + Max_Sensible_Delay, Time);
 594
 595          if Relative_Timed_Wait then
 596             Rel_Time := Duration'Min (Max_Sensible_Delay, Time - Check_Time);
 597          end if;
 598       end if;
 599
 600       if Abs_Time > Check_Time then
 601          if Relative_Timed_Wait then
 602             Request := To_Timespec (Rel_Time);
 603          else
 604             Request := To_Timespec (Abs_Time);
 605          end if;
 606
 607          Self_ID.Common.State := Delay_Sleep;
 608
 609          loop
 610             exit when Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level;
 611
 612             if Single_Lock then
 613                Result :=
 614                  pthread_cond_timedwait
 615                    (Self_ID.Common.LL.CV'Access,
 616                     Single_RTS_Lock'Access,
 617                     Request'Access);
 618             else
 619                Result :=
 620                  pthread_cond_timedwait
 621                    (Self_ID.Common.LL.CV'Access,
 622                     Self_ID.Common.LL.L'Access,
 623                     Request'Access);
 624             end if;
 625
 626             Check_Time := Monotonic_Clock;
 627             exit when Abs_Time <= Check_Time or else Check_Time < Base_Time;
 628
 629             pragma Assert (Result = 0         or else
 630                            Result = ETIMEDOUT or else
 631                            Result = EINTR);
 632          end loop;
 633
 634          Self_ID.Common.State := Runnable;
 635       end if;
 636
 637       Unlock (Self_ID);
 638
 639       if Single_Lock then
 640          Unlock_RTS;
 641       end if;
 642
 643       Result := sched_yield;
 644    end Timed_Delay;
 645
 646    ---------------------
 647    -- Monotonic_Clock --
 648    ---------------------
 649
 650    function Monotonic_Clock return Duration is
 651       TS     : aliased timespec;
 652       Result : Interfaces.C.int;
 653    begin
 654       Result :=
 655         clock_gettime
 656           (clock_id => CLOCK_REALTIME, tp => TS'Unchecked_Access);
 657       pragma Assert (Result = 0);
 658       return To_Duration (TS);
 659    end Monotonic_Clock;
 660
 661    -------------------
 662    -- RT_Resolution --
 663    -------------------
 664
 665    function RT_Resolution return Duration is
 666       Res    : aliased timespec;
 667       Result : Interfaces.C.int;
 668    begin
 669       Result :=
 670         clock_getres
 671           (clock_id => CLOCK_REALTIME, res => Res'Unchecked_Access);
 672       pragma Assert (Result = 0);
 673       return To_Duration (Res);
 674    end RT_Resolution;
 675
 676    ------------
 677    -- Wakeup --
 678    ------------
 679
 680    procedure Wakeup (T : Task_Id; Reason : System.Tasking.Task_States) is
 681       pragma Unreferenced (Reason);
 682       Result : Interfaces.C.int;
 683    begin
 684       Result := pthread_cond_signal (T.Common.LL.CV'Access);
 685       pragma Assert (Result = 0);
 686    end Wakeup;
 687
 688    -----------
 689    -- Yield --
 690    -----------
 691
 692    procedure Yield (Do_Yield : Boolean := True) is
 693       Result : Interfaces.C.int;
 694       pragma Unreferenced (Result);
 695    begin
 696       if Do_Yield then
 697          Result := sched_yield;
 698       end if;
 699    end Yield;
 700
 701    ------------------
 702    -- Set_Priority --
 703    ------------------
 704
 705    procedure Set_OS_Priority (T : Task_Id; Prio : System.Any_Priority) is
 706       Result : Interfaces.C.int;
 707       Param  : aliased struct_sched_param;
 708
 709       function Get_Policy (Prio : System.Any_Priority) return Character;
 710       pragma Import (C, Get_Policy, "__gnat_get_specific_dispatching");
 711       --  Get priority specific dispatching policy
 712
 713       Priority_Specific_Policy : constant Character := Get_Policy (Prio);
 714       --  Upper case first character of the policy name corresponding to the
 715       --  task as set by a Priority_Specific_Dispatching pragma.
 716
 717    begin
 718       Param.sched_priority := Interfaces.C.int (Prio);
 719
 720       if Time_Slice_Supported
 721         and then (Dispatching_Policy = 'R'
 722                    or else Priority_Specific_Policy = 'R'
 723                    or else Time_Slice_Val > 0)
 724       then
 725          Result :=
 726            pthread_setschedparam
 727              (T.Common.LL.Thread, SCHED_RR, Param'Access);
 728
 729       elsif Dispatching_Policy = 'F'
 730         or else Priority_Specific_Policy = 'F'
 731         or else Time_Slice_Val = 0
 732       then
 733          Result :=
 734            pthread_setschedparam
 735              (T.Common.LL.Thread, SCHED_FIFO, Param'Access);
 736
 737       else
 738          Result :=
 739            pthread_setschedparam
 740              (T.Common.LL.Thread, SCHED_OTHER, Param'Access);
 741       end if;
 742
 743       pragma Assert (Result = 0);
 744    end Set_OS_Priority;
 745
 746    type Prio_Array_Type is array (System.Any_Priority) of Integer;
 747    pragma Atomic_Components (Prio_Array_Type);
 748    Prio_Array : Prio_Array_Type;
 749    --  Comments needed for these declarations ???
 750
 751    procedure Set_Priority
 752      (T                   : Task_Id;
 753       Prio                : System.Any_Priority;
 754       Loss_Of_Inheritance : Boolean := False)
 755    is
 756       Array_Item : Integer;
 757
 758    begin
 759       Set_OS_Priority (T, Prio);
 760
 761       if Locking_Policy = 'C' then
 762
 763          --  Annex D requirements: loss of inheritance puts task at the start
 764          --  of the queue for that prio; copied from 5ztaprop (VxWorks).
 765
 766          if Loss_Of_Inheritance
 767            and then Prio < T.Common.Current_Priority then
 768
 769             Array_Item := Prio_Array (T.Common.Base_Priority) + 1;
 770             Prio_Array (T.Common.Base_Priority) := Array_Item;
 771
 772             loop
 773                Yield;
 774                exit when Array_Item = Prio_Array (T.Common.Base_Priority)
 775                  or else Prio_Array (T.Common.Base_Priority) = 1;
 776             end loop;
 777
 778             Prio_Array (T.Common.Base_Priority) :=
 779               Prio_Array (T.Common.Base_Priority) - 1;
 780          end if;
 781       end if;
 782
 783       T.Common.Current_Priority := Prio;
 784    end Set_Priority;
 785
 786    ------------------
 787    -- Get_Priority --
 788    ------------------
 789
 790    function Get_Priority (T : Task_Id) return System.Any_Priority is
 791    begin
 792       return T.Common.Current_Priority;
 793    end Get_Priority;
 794
 795    ----------------
 796    -- Enter_Task --
 797    ----------------
 798
 799    procedure Enter_Task (Self_ID : Task_Id) is
 800    begin
 801       Self_ID.Common.LL.Thread := pthread_self;
 802       Self_ID.Common.LL.LWP := lwp_self;
 803
 804       Specific.Set (Self_ID);
 805
 806       Lock_RTS;
 807
 808       for J in Known_Tasks'Range loop
 809          if Known_Tasks (J) = null then
 810             Known_Tasks (J) := Self_ID;
 811             Self_ID.Known_Tasks_Index := J;
 812             exit;
 813          end if;
 814       end loop;
 815
 816       Unlock_RTS;
 817    end Enter_Task;
 818
 819    --------------
 820    -- New_ATCB --
 821    --------------
 822
 823    function New_ATCB (Entry_Num : Task_Entry_Index) return Task_Id is
 824    begin
 825       return new Ada_Task_Control_Block (Entry_Num);
 826    end New_ATCB;
 827
 828    -------------------
 829    -- Is_Valid_Task --
 830    -------------------
 831
 832    function Is_Valid_Task return Boolean renames Specific.Is_Valid_Task;
 833
 834    -----------------------------
 835    -- Register_Foreign_Thread --
 836    -----------------------------
 837
 838    function Register_Foreign_Thread return Task_Id is
 839    begin
 840       if Is_Valid_Task then
 841          return Self;
 842       else
 843          return Register_Foreign_Thread (pthread_self);
 844       end if;
 845    end Register_Foreign_Thread;
 846
 847    --------------------
 848    -- Initialize_TCB --
 849    --------------------
 850
 851    procedure Initialize_TCB (Self_ID : Task_Id; Succeeded : out Boolean) is
 852       Mutex_Attr : aliased pthread_mutexattr_t;
 853       Result     : Interfaces.C.int;
 854       Cond_Attr  : aliased pthread_condattr_t;
 855
 856    begin
 857       --  Give the task a unique serial number
 858
 859       Self_ID.Serial_Number := Next_Serial_Number;
 860       Next_Serial_Number := Next_Serial_Number + 1;
 861       pragma Assert (Next_Serial_Number /= 0);
 862
 863       if not Single_Lock then
 864          Result := pthread_mutexattr_init (Mutex_Attr'Access);
 865          pragma Assert (Result = 0 or else Result = ENOMEM);
 866
 867          if Result = 0 then
 868             Result :=
 869               pthread_mutex_init
 870                 (Self_ID.Common.LL.L'Access, Mutex_Attr'Access);
 871             pragma Assert (Result = 0 or else Result = ENOMEM);
 872          end if;
 873
 874          if Result /= 0 then
 875             Succeeded := False;
 876             return;
 877          end if;
 878
 879          Result := pthread_mutexattr_destroy (Mutex_Attr'Access);
 880          pragma Assert (Result = 0);
 881       end if;
 882
 883       Result := pthread_condattr_init (Cond_Attr'Access);
 884       pragma Assert (Result = 0 or else Result = ENOMEM);
 885
 886       if Result = 0 then
 887          Result :=
 888            pthread_cond_init (Self_ID.Common.LL.CV'Access, Cond_Attr'Access);
 889          pragma Assert (Result = 0 or else Result = ENOMEM);
 890       end if;
 891
 892       if Result = 0 then
 893          Succeeded := True;
 894       else
 895          if not Single_Lock then
 896             Result := pthread_mutex_destroy (Self_ID.Common.LL.L'Access);
 897             pragma Assert (Result = 0);
 898          end if;
 899
 900          Succeeded := False;
 901       end if;
 902
 903       Result := pthread_condattr_destroy (Cond_Attr'Access);
 904       pragma Assert (Result = 0);
 905    end Initialize_TCB;
 906
 907    -----------------
 908    -- Create_Task --
 909    -----------------
 910
 911    procedure Create_Task
 912      (T          : Task_Id;
 913       Wrapper    : System.Address;
 914       Stack_Size : System.Parameters.Size_Type;
 915       Priority   : System.Any_Priority;
 916       Succeeded  : out Boolean)
 917    is
 918       Attributes          : aliased pthread_attr_t;
 919       Adjusted_Stack_Size : Interfaces.C.size_t;
 920       Result              : Interfaces.C.int;
 921
 922       use System.Task_Info;
 923
 924    begin
 925       Adjusted_Stack_Size := Interfaces.C.size_t (Stack_Size);
 926
 927       if Stack_Base_Available then
 928
 929          --  If Stack Checking is supported then allocate 2 additional pages:
 930
 931          --  In the worst case, stack is allocated at something like
 932          --  N * Get_Page_Size - epsilon, we need to add the size for 2 pages
 933          --  to be sure the effective stack size is greater than what
 934          --  has been asked.
 935
 936          Adjusted_Stack_Size := Adjusted_Stack_Size + 2 * Get_Page_Size;
 937       end if;
 938
 939       Result := pthread_attr_init (Attributes'Access);
 940       pragma Assert (Result = 0 or else Result = ENOMEM);
 941
 942       if Result /= 0 then
 943          Succeeded := False;
 944          return;
 945       end if;
 946
 947       Result :=
 948         pthread_attr_setdetachstate
 949           (Attributes'Access, PTHREAD_CREATE_DETACHED);
 950       pragma Assert (Result = 0);
 951
 952       Result :=
 953         pthread_attr_setstacksize
 954           (Attributes'Access, Adjusted_Stack_Size);
 955       pragma Assert (Result = 0);
 956
 957       if T.Common.Task_Info /= Default_Scope then
 958
 959          --  We are assuming that Scope_Type has the same values than the
 960          --  corresponding C macros
 961
 962          Result :=
 963            pthread_attr_setscope
 964              (Attributes'Access, Task_Info_Type'Pos (T.Common.Task_Info));
 965          pragma Assert (Result = 0);
 966       end if;
 967
 968       --  Since the initial signal mask of a thread is inherited from the
 969       --  creator, and the Environment task has all its signals masked, we
 970       --  do not need to manipulate caller's signal mask at this point.
 971       --  All tasks in RTS will have All_Tasks_Mask initially.
 972
 973       Result :=
 974         pthread_create
 975           (T.Common.LL.Thread'Access,
 976            Attributes'Access,
 977            Thread_Body_Access (Wrapper),
 978            To_Address (T));
 979       pragma Assert (Result = 0 or else Result = EAGAIN);
 980
 981       Succeeded := Result = 0;
 982
 983       Result := pthread_attr_destroy (Attributes'Access);
 984       pragma Assert (Result = 0);
 985
 986       if Succeeded then
 987          Set_Priority (T, Priority);
 988       end if;
 989    end Create_Task;
 990
 991    ------------------
 992    -- Finalize_TCB --
 993    ------------------
 994
 995    procedure Finalize_TCB (T : Task_Id) is
 996       Result : Interfaces.C.int;
 997       Tmp    : Task_Id := T;
 998       Is_Self : constant Boolean := T = Self;
 999
1000       procedure Free is new
1001         Ada.Unchecked_Deallocation (Ada_Task_Control_Block, Task_Id);
1002
1003    begin
1004       if not Single_Lock then
1005          Result := pthread_mutex_destroy (T.Common.LL.L'Access);
1006          pragma Assert (Result = 0);
1007       end if;
1008
1009       Result := pthread_cond_destroy (T.Common.LL.CV'Access);
1010       pragma Assert (Result = 0);
1011
1012       if T.Known_Tasks_Index /= -1 then
1013          Known_Tasks (T.Known_Tasks_Index) := null;
1014       end if;
1015
1016       Free (Tmp);
1017
1018       if Is_Self then
1019          Result := st_setspecific (ATCB_Key, System.Null_Address);
1020          pragma Assert (Result = 0);
1021       end if;
1022    end Finalize_TCB;
1023
1024    ---------------
1025    -- Exit_Task --
1026    ---------------
1027
1028    procedure Exit_Task is
1029    begin
1030       Specific.Set (null);
1031    end Exit_Task;
1032
1033    ----------------
1034    -- Abort_Task --
1035    ----------------
1036
1037    procedure Abort_Task (T : Task_Id) is
1038       Result : Interfaces.C.int;
1039    begin
1040       Result :=
1041         pthread_kill
1042           (T.Common.LL.Thread,
1043            Signal (System.Interrupt_Management.Abort_Task_Interrupt));
1044       pragma Assert (Result = 0);
1045    end Abort_Task;
1046
1047    ----------------
1048    -- Initialize --
1049    ----------------
1050
1051    procedure Initialize (S : in out Suspension_Object) is
1052       Mutex_Attr : aliased pthread_mutexattr_t;
1053       Cond_Attr  : aliased pthread_condattr_t;
1054       Result     : Interfaces.C.int;
1055
1056    begin
1057       --  Initialize internal state (always to False (RM D.10(6)))
1058
1059       S.State := False;
1060       S.Waiting := False;
1061
1062       --  Initialize internal mutex
1063
1064       Result := pthread_mutexattr_init (Mutex_Attr'Access);
1065       pragma Assert (Result = 0 or else Result = ENOMEM);
1066
1067       if Result = ENOMEM then
1068          raise Storage_Error;
1069       end if;
1070
1071       Result := pthread_mutex_init (S.L'Access, Mutex_Attr'Access);
1072       pragma Assert (Result = 0 or else Result = ENOMEM);
1073
1074       if Result = ENOMEM then
1075          Result := pthread_mutexattr_destroy (Mutex_Attr'Access);
1076          pragma Assert (Result = 0);
1077
1078          raise Storage_Error;
1079       end if;
1080
1081       Result := pthread_mutexattr_destroy (Mutex_Attr'Access);
1082       pragma Assert (Result = 0);
1083
1084       --  Initialize internal condition variable
1085
1086       Result := pthread_condattr_init (Cond_Attr'Access);
1087       pragma Assert (Result = 0 or else Result = ENOMEM);
1088
1089       if Result /= 0 then
1090          Result := pthread_mutex_destroy (S.L'Access);
1091          pragma Assert (Result = 0);
1092
1093          if Result = ENOMEM then
1094             raise Storage_Error;
1095          end if;
1096       end if;
1097
1098       Result := pthread_cond_init (S.CV'Access, Cond_Attr'Access);
1099       pragma Assert (Result = 0 or else Result = ENOMEM);
1100
1101       if Result /= 0 then
1102          Result := pthread_mutex_destroy (S.L'Access);
1103          pragma Assert (Result = 0);
1104
1105          if Result = ENOMEM then
1106             Result := pthread_condattr_destroy (Cond_Attr'Access);
1107             pragma Assert (Result = 0);
1108
1109             raise Storage_Error;
1110          end if;
1111       end if;
1112
1113       Result := pthread_condattr_destroy (Cond_Attr'Access);
1114       pragma Assert (Result = 0);
1115    end Initialize;
1116
1117    --------------
1118    -- Finalize --
1119    --------------
1120
1121    procedure Finalize (S : in out Suspension_Object) is
1122       Result : Interfaces.C.int;
1123
1124    begin
1125       --  Destroy internal mutex
1126
1127       Result := pthread_mutex_destroy (S.L'Access);
1128       pragma Assert (Result = 0);
1129
1130       --  Destroy internal condition variable
1131
1132       Result := pthread_cond_destroy (S.CV'Access);
1133       pragma Assert (Result = 0);
1134    end Finalize;
1135
1136    -------------------
1137    -- Current_State --
1138    -------------------
1139
1140    function Current_State (S : Suspension_Object) return Boolean is
1141    begin
1142       --  We do not want to use lock on this read operation. State is marked
1143       --  as Atomic so that we ensure that the value retrieved is correct.
1144
1145       return S.State;
1146    end Current_State;
1147
1148    ---------------
1149    -- Set_False --
1150    ---------------
1151
1152    procedure Set_False (S : in out Suspension_Object) is
1153       Result : Interfaces.C.int;
1154
1155    begin
1156       SSL.Abort_Defer.all;
1157
1158       Result := pthread_mutex_lock (S.L'Access);
1159       pragma Assert (Result = 0);
1160
1161       S.State := False;
1162
1163       Result := pthread_mutex_unlock (S.L'Access);
1164       pragma Assert (Result = 0);
1165
1166       SSL.Abort_Undefer.all;
1167    end Set_False;
1168
1169    --------------
1170    -- Set_True --
1171    --------------
1172
1173    procedure Set_True (S : in out Suspension_Object) is
1174       Result : Interfaces.C.int;
1175
1176    begin
1177       SSL.Abort_Defer.all;
1178
1179       Result := pthread_mutex_lock (S.L'Access);
1180       pragma Assert (Result = 0);
1181
1182       --  If there is already a task waiting on this suspension object then
1183       --  we resume it, leaving the state of the suspension object to False,
1184       --  as specified in (RM D.10(9)). Otherwise, just leave state set True.
1185
1186       if S.Waiting then
1187          S.Waiting := False;
1188          S.State := False;
1189
1190          Result := pthread_cond_signal (S.CV'Access);
1191          pragma Assert (Result = 0);
1192
1193       else
1194          S.State := True;
1195       end if;
1196
1197       Result := pthread_mutex_unlock (S.L'Access);
1198       pragma Assert (Result = 0);
1199
1200       SSL.Abort_Undefer.all;
1201    end Set_True;
1202
1203    ------------------------
1204    -- Suspend_Until_True --
1205    ------------------------
1206
1207    procedure Suspend_Until_True (S : in out Suspension_Object) is
1208       Result : Interfaces.C.int;
1209
1210    begin
1211       SSL.Abort_Defer.all;
1212
1213       Result := pthread_mutex_lock (S.L'Access);
1214       pragma Assert (Result = 0);
1215
1216       if S.Waiting then
1217
1218          --  Program_Error must be raised upon calling Suspend_Until_True
1219          --  if another task is already waiting on that suspension object
1220          --  (RM D.10 (10)).
1221
1222          Result := pthread_mutex_unlock (S.L'Access);
1223          pragma Assert (Result = 0);
1224
1225          SSL.Abort_Undefer.all;
1226
1227          raise Program_Error;
1228
1229       else
1230          --  Suspend the task if the state is False. Otherwise, the task
1231          --  continues its execution, and the state of the suspension object
1232          --  is set to False (RM D.10(9)).
1233
1234          if S.State then
1235             S.State := False;
1236          else
1237             S.Waiting := True;
1238             Result := pthread_cond_wait (S.CV'Access, S.L'Access);
1239          end if;
1240
1241          Result := pthread_mutex_unlock (S.L'Access);
1242          pragma Assert (Result = 0);
1243
1244          SSL.Abort_Undefer.all;
1245       end if;
1246    end Suspend_Until_True;
1247
1248    ----------------
1249    -- Check_Exit --
1250    ----------------
1251
1252    --  Dummy version
1253
1254    function Check_Exit (Self_ID : ST.Task_Id) return Boolean is
1255       pragma Unreferenced (Self_ID);
1256    begin
1257       return True;
1258    end Check_Exit;
1259
1260    --------------------
1261    -- Check_No_Locks --
1262    --------------------
1263
1264    function Check_No_Locks (Self_ID : ST.Task_Id) return Boolean is
1265       pragma Unreferenced (Self_ID);
1266    begin
1267       return True;
1268    end Check_No_Locks;
1269
1270    ----------------------
1271    -- Environment_Task --
1272    ----------------------
1273
1274    function Environment_Task return Task_Id is
1275    begin
1276       return Environment_Task_Id;
1277    end Environment_Task;
1278
1279    --------------
1280    -- Lock_RTS --
1281    --------------
1282
1283    procedure Lock_RTS is
1284    begin
1285       Write_Lock (Single_RTS_Lock'Access, Global_Lock => True);
1286    end Lock_RTS;
1287
1288    ----------------
1289    -- Unlock_RTS --
1290    ----------------
1291
1292    procedure Unlock_RTS is
1293    begin
1294       Unlock (Single_RTS_Lock'Access, Global_Lock => True);
1295    end Unlock_RTS;
1296
1297    ------------------
1298    -- Suspend_Task --
1299    ------------------
1300
1301    function Suspend_Task
1302      (T           : ST.Task_Id;
1303       Thread_Self : Thread_Id) return Boolean
1304    is
1305       pragma Unreferenced (T);
1306       pragma Unreferenced (Thread_Self);
1307    begin
1308       return False;
1309    end Suspend_Task;
1310
1311    -----------------
1312    -- Resume_Task --
1313    -----------------
1314
1315    function Resume_Task
1316      (T           : ST.Task_Id;
1317       Thread_Self : Thread_Id) return Boolean
1318    is
1319       pragma Unreferenced (T);
1320       pragma Unreferenced (Thread_Self);
1321    begin
1322       return False;
1323    end Resume_Task;
1324
1325    --------------------
1326    -- Stop_All_Tasks --
1327    --------------------
1328
1329    procedure Stop_All_Tasks is
1330    begin
1331       null;
1332    end Stop_All_Tasks;
1333
1334    ---------------
1335    -- Stop_Task --
1336    ---------------
1337
1338    function Stop_Task (T : ST.Task_Id) return Boolean is
1339       pragma Unreferenced (T);
1340    begin
1341       return False;
1342    end Stop_Task;
1343
1344    -------------------
1345    -- Continue_Task --
1346    -------------------
1347
1348    function Continue_Task (T : ST.Task_Id) return Boolean is
1349       pragma Unreferenced (T);
1350    begin
1351       return False;
1352    end Continue_Task;
1353
1354    ----------------
1355    -- Initialize --
1356    ----------------
1357
1358    procedure Initialize (Environment_Task : Task_Id) is
1359       act     : aliased struct_sigaction;
1360       old_act : aliased struct_sigaction;
1361       Tmp_Set : aliased sigset_t;
1362       Result  : Interfaces.C.int;
1363
1364       function State
1365         (Int  : System.Interrupt_Management.Interrupt_ID) return Character;
1366       pragma Import (C, State, "__gnat_get_interrupt_state");
1367       --  Get interrupt state.  Defined in a-init.c
1368       --  The input argument is the interrupt number,
1369       --  and the result is one of the following:
1370
1371       Default : constant Character := 's';
1372       --    'n'   this interrupt not set by any Interrupt_State pragma
1373       --    'u'   Interrupt_State pragma set state to User
1374       --    'r'   Interrupt_State pragma set state to Runtime
1375       --    's'   Interrupt_State pragma set state to System (use "default"
1376       --           system handler)
1377
1378    begin
1379       Environment_Task_Id := Environment_Task;
1380
1381       Interrupt_Management.Initialize;
1382
1383       --  Prepare the set of signals that should unblocked in all tasks
1384
1385       Result := sigemptyset (Unblocked_Signal_Mask'Access);
1386       pragma Assert (Result = 0);
1387
1388       for J in Interrupt_Management.Interrupt_ID loop
1389          if System.Interrupt_Management.Keep_Unmasked (J) then
1390             Result := sigaddset (Unblocked_Signal_Mask'Access, Signal (J));
1391             pragma Assert (Result = 0);
1392          end if;
1393       end loop;
1394
1395       --  Initialize the lock used to synchronize chain of all ATCBs
1396
1397       Initialize_Lock (Single_RTS_Lock'Access, RTS_Lock_Level);
1398
1399       Specific.Initialize (Environment_Task);
1400
1401       Enter_Task (Environment_Task);
1402
1403       --  Install the abort-signal handler
1404
1405       if State
1406           (System.Interrupt_Management.Abort_Task_Interrupt) /= Default
1407       then
1408          act.sa_flags := 0;
1409          act.sa_handler := Abort_Handler'Address;
1410
1411          Result := sigemptyset (Tmp_Set'Access);
1412          pragma Assert (Result = 0);
1413          act.sa_mask := Tmp_Set;
1414
1415          Result :=
1416            sigaction
1417              (Signal (System.Interrupt_Management.Abort_Task_Interrupt),
1418               act'Unchecked_Access,
1419               old_act'Unchecked_Access);
1420
1421          pragma Assert (Result = 0);
1422       end if;
1423    end Initialize;
1424
1425 end System.Task_Primitives.Operations;