gcc/ada/s-taprop-linux.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                GNU ADA 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) 1992-2006, 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 GNU/Linux (GNU/LinuxThreads) version of this package
  35
  36 --  This package contains all the GNULL primitives that interface directly
  37 --  with the underlying OS.
  38
  39 pragma Polling (Off);
  40 --  Turn off polling, we do not want ATC polling to take place during
  41 --  tasking operations. It causes infinite loops and other problems.
  42
  43 with Interfaces.C;
  44 --  used for int
  45 --           size_t
  46
  47 with System.Tasking.Debug;
  48 --  used for Known_Tasks
  49
  50 with System.Interrupt_Management;
  51 --  used for Keep_Unmasked
  52 --           Abort_Task_Interrupt
  53 --           Interrupt_ID
  54
  55 with System.OS_Primitives;
  56 --  used for Delay_Modes
  57
  58 with System.Soft_Links;
  59 --  used for Abort_Defer/Undefer
  60
  61 --  We use System.Soft_Links instead of System.Tasking.Initialization
  62 --  because the later is a higher level package that we shouldn't depend on.
  63 --  For example when using the restricted run time, it is replaced by
  64 --  System.Tasking.Restricted.Stages.
  65
  66 with System.Stack_Checking.Operations;
  67 --  Used for Invalidate_Stack_Cache;
  68
  69 with Ada.Exceptions;
  70 --  used for Raise_Exception
  71 --           Raise_From_Signal_Handler
  72 --           Exception_Id
  73
  74 with Unchecked_Conversion;
  75 with Unchecked_Deallocation;
  76
  77 package body System.Task_Primitives.Operations is
  78
  79    package SSL renames System.Soft_Links;
  80    package SC renames System.Stack_Checking.Operations;
  81
  82    use System.Tasking.Debug;
  83    use System.Tasking;
  84    use Interfaces.C;
  85    use System.OS_Interface;
  86    use System.Parameters;
  87    use System.OS_Primitives;
  88
  89    ----------------
  90    -- Local Data --
  91    ----------------
  92
  93    --  The followings are logically constants, but need to be initialized
  94    --  at run time.
  95
  96    Single_RTS_Lock : aliased RTS_Lock;
  97    --  This is a lock to allow only one thread of control in the RTS at
  98    --  a time; it is used to execute in mutual exclusion from all other tasks.
  99    --  Used mainly in Single_Lock mode, but also to protect All_Tasks_List
 100
 101    ATCB_Key : aliased pthread_key_t;
 102    --  Key used to find the Ada Task_Id associated with a thread
 103
 104    Environment_Task_Id : Task_Id;
 105    --  A variable to hold Task_Id for the environment task
 106
 107    Unblocked_Signal_Mask : aliased sigset_t;
 108    --  The set of signals that should be unblocked in all tasks
 109
 110    --  The followings are internal configuration constants needed
 111
 112    Next_Serial_Number : Task_Serial_Number := 100;
 113    --  We start at 100, to reserve some special values for
 114    --  using in error checking.
 115
 116    Time_Slice_Val : Integer;
 117    pragma Import (C, Time_Slice_Val, "__gl_time_slice_val");
 118
 119    Dispatching_Policy : Character;
 120    pragma Import (C, Dispatching_Policy, "__gl_task_dispatching_policy");
 121
 122    --  The following are effectively constants, but they need to
 123    --  be initialized by calling a pthread_ function.
 124
 125    Mutex_Attr   : aliased pthread_mutexattr_t;
 126    Cond_Attr    : aliased pthread_condattr_t;
 127
 128    Foreign_Task_Elaborated : aliased Boolean := True;
 129    --  Used to identified fake tasks (i.e., non-Ada Threads)
 130
 131    --------------------
 132    -- Local Packages --
 133    --------------------
 134
 135    package Specific is
 136
 137       procedure Initialize (Environment_Task : Task_Id);
 138       pragma Inline (Initialize);
 139       --  Initialize various data needed by this package
 140
 141       function Is_Valid_Task return Boolean;
 142       pragma Inline (Is_Valid_Task);
 143       --  Does executing thread have a TCB?
 144
 145       procedure Set (Self_Id : Task_Id);
 146       pragma Inline (Set);
 147       --  Set the self id for the current task
 148
 149       function Self return Task_Id;
 150       pragma Inline (Self);
 151       --  Return a pointer to the Ada Task Control Block of the calling task
 152
 153    end Specific;
 154
 155    package body Specific is separate;
 156    --  The body of this package is target specific
 157
 158    ---------------------------------
 159    -- Support for foreign threads --
 160    ---------------------------------
 161
 162    function Register_Foreign_Thread (Thread : Thread_Id) return Task_Id;
 163    --  Allocate and Initialize a new ATCB for the current Thread
 164
 165    function Register_Foreign_Thread
 166      (Thread : Thread_Id) return Task_Id is separate;
 167
 168    -----------------------
 169    -- Local Subprograms --
 170    -----------------------
 171
 172    subtype unsigned_long is Interfaces.C.unsigned_long;
 173
 174    procedure Abort_Handler (signo : Signal);
 175
 176    function To_pthread_t is new Unchecked_Conversion
 177      (unsigned_long, System.OS_Interface.pthread_t);
 178
 179    -------------------
 180    -- Abort_Handler --
 181    -------------------
 182
 183    procedure Abort_Handler (signo : Signal) is
 184       pragma Unreferenced (signo);
 185
 186       Self_Id : constant Task_Id := Self;
 187       Result  : Interfaces.C.int;
 188       Old_Set : aliased sigset_t;
 189
 190    begin
 191       if ZCX_By_Default and then GCC_ZCX_Support then
 192          return;
 193       end if;
 194
 195       if Self_Id.Deferral_Level = 0
 196         and then Self_Id.Pending_ATC_Level < Self_Id.ATC_Nesting_Level
 197         and then not Self_Id.Aborting
 198       then
 199          Self_Id.Aborting := True;
 200
 201          --  Make sure signals used for RTS internal purpose are unmasked
 202
 203          Result := pthread_sigmask (SIG_UNBLOCK,
 204            Unblocked_Signal_Mask'Unchecked_Access, Old_Set'Unchecked_Access);
 205          pragma Assert (Result = 0);
 206
 207          raise Standard'Abort_Signal;
 208       end if;
 209    end Abort_Handler;
 210
 211    --------------
 212    -- Lock_RTS --
 213    --------------
 214
 215    procedure Lock_RTS is
 216    begin
 217       Write_Lock (Single_RTS_Lock'Access, Global_Lock => True);
 218    end Lock_RTS;
 219
 220    ----------------
 221    -- Unlock_RTS --
 222    ----------------
 223
 224    procedure Unlock_RTS is
 225    begin
 226       Unlock (Single_RTS_Lock'Access, Global_Lock => True);
 227    end Unlock_RTS;
 228
 229    -----------------
 230    -- Stack_Guard --
 231    -----------------
 232
 233    --  The underlying thread system extends the memory (up to 2MB) when needed
 234
 235    procedure Stack_Guard (T : ST.Task_Id; On : Boolean) is
 236       pragma Unreferenced (T);
 237       pragma Unreferenced (On);
 238    begin
 239       null;
 240    end Stack_Guard;
 241
 242    --------------------
 243    -- Get_Thread_Id  --
 244    --------------------
 245
 246    function Get_Thread_Id (T : ST.Task_Id) return OSI.Thread_Id is
 247    begin
 248       return T.Common.LL.Thread;
 249    end Get_Thread_Id;
 250
 251    ----------
 252    -- Self --
 253    ----------
 254
 255    function Self return Task_Id renames Specific.Self;
 256
 257    ---------------------
 258    -- Initialize_Lock --
 259    ---------------------
 260
 261    --  Note: mutexes and cond_variables needed per-task basis are
 262    --  initialized in Initialize_TCB and the Storage_Error is
 263    --  handled. Other mutexes (such as RTS_Lock, Memory_Lock...)
 264    --  used in RTS is initialized before any status change of RTS.
 265    --  Therefore rasing Storage_Error in the following routines
 266    --  should be able to be handled safely.
 267
 268    procedure Initialize_Lock
 269      (Prio : System.Any_Priority;
 270       L    : access Lock)
 271    is
 272       pragma Unreferenced (Prio);
 273
 274       Result : Interfaces.C.int;
 275    begin
 276       Result := pthread_mutex_init (L, Mutex_Attr'Access);
 277
 278       pragma Assert (Result = 0 or else Result = ENOMEM);
 279
 280       if Result = ENOMEM then
 281          Ada.Exceptions.Raise_Exception (Storage_Error'Identity,
 282            "Failed to allocate a lock");
 283       end if;
 284    end Initialize_Lock;
 285
 286    procedure Initialize_Lock (L : access RTS_Lock; Level : Lock_Level) is
 287       pragma Unreferenced (Level);
 288
 289       Result : Interfaces.C.int;
 290
 291    begin
 292       Result := pthread_mutex_init (L, Mutex_Attr'Access);
 293
 294       pragma Assert (Result = 0 or else Result = ENOMEM);
 295
 296       if Result = ENOMEM then
 297          raise Storage_Error;
 298       end if;
 299    end Initialize_Lock;
 300
 301    -------------------
 302    -- Finalize_Lock --
 303    -------------------
 304
 305    procedure Finalize_Lock (L : access Lock) is
 306       Result : Interfaces.C.int;
 307    begin
 308       Result := pthread_mutex_destroy (L);
 309       pragma Assert (Result = 0);
 310    end Finalize_Lock;
 311
 312    procedure Finalize_Lock (L : access RTS_Lock) is
 313       Result : Interfaces.C.int;
 314    begin
 315       Result := pthread_mutex_destroy (L);
 316       pragma Assert (Result = 0);
 317    end Finalize_Lock;
 318
 319    ----------------
 320    -- Write_Lock --
 321    ----------------
 322
 323    procedure Write_Lock (L : access Lock; Ceiling_Violation : out Boolean) is
 324       Result : Interfaces.C.int;
 325    begin
 326       Result := pthread_mutex_lock (L);
 327       Ceiling_Violation := Result = EINVAL;
 328
 329       --  Assume the cause of EINVAL is a priority ceiling violation
 330
 331       pragma Assert (Result = 0 or else Result = EINVAL);
 332    end Write_Lock;
 333
 334    procedure Write_Lock
 335      (L           : access RTS_Lock;
 336       Global_Lock : Boolean := False)
 337    is
 338       Result : Interfaces.C.int;
 339    begin
 340       if not Single_Lock or else Global_Lock then
 341          Result := pthread_mutex_lock (L);
 342          pragma Assert (Result = 0);
 343       end if;
 344    end Write_Lock;
 345
 346    procedure Write_Lock (T : Task_Id) is
 347       Result : Interfaces.C.int;
 348    begin
 349       if not Single_Lock then
 350          Result := pthread_mutex_lock (T.Common.LL.L'Access);
 351          pragma Assert (Result = 0);
 352       end if;
 353    end Write_Lock;
 354
 355    ---------------
 356    -- Read_Lock --
 357    ---------------
 358
 359    procedure Read_Lock (L : access Lock; Ceiling_Violation : out Boolean) is
 360    begin
 361       Write_Lock (L, Ceiling_Violation);
 362    end Read_Lock;
 363
 364    ------------
 365    -- Unlock --
 366    ------------
 367
 368    procedure Unlock (L : access Lock) is
 369       Result : Interfaces.C.int;
 370    begin
 371       Result := pthread_mutex_unlock (L);
 372       pragma Assert (Result = 0);
 373    end Unlock;
 374
 375    procedure Unlock (L : access RTS_Lock; Global_Lock : Boolean := False) is
 376       Result : Interfaces.C.int;
 377    begin
 378       if not Single_Lock or else Global_Lock then
 379          Result := pthread_mutex_unlock (L);
 380          pragma Assert (Result = 0);
 381       end if;
 382    end Unlock;
 383
 384    procedure Unlock (T : Task_Id) is
 385       Result : Interfaces.C.int;
 386    begin
 387       if not Single_Lock then
 388          Result := pthread_mutex_unlock (T.Common.LL.L'Access);
 389          pragma Assert (Result = 0);
 390       end if;
 391    end Unlock;
 392
 393    -----------
 394    -- Sleep --
 395    -----------
 396
 397    procedure Sleep
 398      (Self_ID  : Task_Id;
 399       Reason   : System.Tasking.Task_States)
 400    is
 401       pragma Unreferenced (Reason);
 402
 403       Result : Interfaces.C.int;
 404
 405    begin
 406       pragma Assert (Self_ID = Self);
 407
 408       if Single_Lock then
 409          Result := pthread_cond_wait
 410            (Self_ID.Common.LL.CV'Access, Single_RTS_Lock'Access);
 411       else
 412          Result := pthread_cond_wait
 413            (Self_ID.Common.LL.CV'Access, Self_ID.Common.LL.L'Access);
 414       end if;
 415
 416       --  EINTR is not considered a failure
 417
 418       pragma Assert (Result = 0 or else Result = EINTR);
 419    end Sleep;
 420
 421    -----------------
 422    -- Timed_Sleep --
 423    -----------------
 424
 425    --  This is for use within the run-time system, so abort is
 426    --  assumed to be already deferred, and the caller should be
 427    --  holding its own ATCB lock.
 428
 429    procedure Timed_Sleep
 430      (Self_ID  : Task_Id;
 431       Time     : Duration;
 432       Mode     : ST.Delay_Modes;
 433       Reason   : System.Tasking.Task_States;
 434       Timedout : out Boolean;
 435       Yielded  : out Boolean)
 436    is
 437       pragma Unreferenced (Reason);
 438
 439       Check_Time : constant Duration := Monotonic_Clock;
 440       Abs_Time   : Duration;
 441       Request    : aliased timespec;
 442       Result     : Interfaces.C.int;
 443
 444    begin
 445       Timedout := True;
 446       Yielded := False;
 447
 448       if Mode = Relative then
 449          Abs_Time := Duration'Min (Time, Max_Sensible_Delay) + Check_Time;
 450       else
 451          Abs_Time := Duration'Min (Check_Time + Max_Sensible_Delay, Time);
 452       end if;
 453
 454       if Abs_Time > Check_Time then
 455          Request := To_Timespec (Abs_Time);
 456
 457          loop
 458             exit when Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level
 459               or else Self_ID.Pending_Priority_Change;
 460
 461             if Single_Lock then
 462                Result := pthread_cond_timedwait
 463                  (Self_ID.Common.LL.CV'Access, Single_RTS_Lock'Access,
 464                   Request'Access);
 465
 466             else
 467                Result := pthread_cond_timedwait
 468                  (Self_ID.Common.LL.CV'Access, Self_ID.Common.LL.L'Access,
 469                   Request'Access);
 470             end if;
 471
 472             exit when Abs_Time <= Monotonic_Clock;
 473
 474             if Result = 0 or Result = EINTR then
 475                --  somebody may have called Wakeup for us
 476                Timedout := False;
 477                exit;
 478             end if;
 479
 480             pragma Assert (Result = ETIMEDOUT);
 481          end loop;
 482       end if;
 483    end Timed_Sleep;
 484
 485    -----------------
 486    -- Timed_Delay --
 487    -----------------
 488
 489    --  This is for use in implementing delay statements, so
 490    --  we assume the caller is abort-deferred but is holding
 491    --  no locks.
 492
 493    procedure Timed_Delay
 494      (Self_ID : Task_Id;
 495       Time    : Duration;
 496       Mode    : ST.Delay_Modes)
 497    is
 498       Check_Time : constant Duration := Monotonic_Clock;
 499       Abs_Time   : Duration;
 500       Request    : aliased timespec;
 501
 502       Result : Interfaces.C.int;
 503       pragma Warnings (Off, Result);
 504
 505    begin
 506       if Single_Lock then
 507          Lock_RTS;
 508       end if;
 509
 510       Write_Lock (Self_ID);
 511
 512       if Mode = Relative then
 513          Abs_Time := Time + Check_Time;
 514       else
 515          Abs_Time := Duration'Min (Check_Time + Max_Sensible_Delay, Time);
 516       end if;
 517
 518       if Abs_Time > Check_Time then
 519          Request := To_Timespec (Abs_Time);
 520          Self_ID.Common.State := Delay_Sleep;
 521
 522          loop
 523             if Self_ID.Pending_Priority_Change then
 524                Self_ID.Pending_Priority_Change := False;
 525                Self_ID.Common.Base_Priority := Self_ID.New_Base_Priority;
 526                Set_Priority (Self_ID, Self_ID.Common.Base_Priority);
 527             end if;
 528
 529             exit when Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level;
 530
 531             if Single_Lock then
 532                Result := pthread_cond_timedwait
 533                            (Self_ID.Common.LL.CV'Access,
 534                             Single_RTS_Lock'Access,
 535                             Request'Access);
 536             else
 537                Result := pthread_cond_timedwait
 538                            (Self_ID.Common.LL.CV'Access,
 539                             Self_ID.Common.LL.L'Access,
 540                             Request'Access);
 541             end if;
 542
 543             exit when Abs_Time <= Monotonic_Clock;
 544
 545             pragma Assert (Result = 0 or else
 546               Result = ETIMEDOUT or else
 547               Result = EINTR);
 548          end loop;
 549
 550          Self_ID.Common.State := Runnable;
 551       end if;
 552
 553       Unlock (Self_ID);
 554
 555       if Single_Lock then
 556          Unlock_RTS;
 557       end if;
 558
 559       Result := sched_yield;
 560    end Timed_Delay;
 561
 562    ---------------------
 563    -- Monotonic_Clock --
 564    ---------------------
 565
 566    function Monotonic_Clock return Duration is
 567       TV     : aliased struct_timeval;
 568       Result : Interfaces.C.int;
 569    begin
 570       Result := gettimeofday (TV'Access, System.Null_Address);
 571       pragma Assert (Result = 0);
 572       return To_Duration (TV);
 573    end Monotonic_Clock;
 574
 575    -------------------
 576    -- RT_Resolution --
 577    -------------------
 578
 579    function RT_Resolution return Duration is
 580    begin
 581       return 10#1.0#E-6;
 582    end RT_Resolution;
 583
 584    ------------
 585    -- Wakeup --
 586    ------------
 587
 588    procedure Wakeup (T : Task_Id; Reason : System.Tasking.Task_States) is
 589       pragma Unreferenced (Reason);
 590       Result : Interfaces.C.int;
 591    begin
 592       Result := pthread_cond_signal (T.Common.LL.CV'Access);
 593       pragma Assert (Result = 0);
 594    end Wakeup;
 595
 596    -----------
 597    -- Yield --
 598    -----------
 599
 600    procedure Yield (Do_Yield : Boolean := True) is
 601       Result : Interfaces.C.int;
 602       pragma Unreferenced (Result);
 603    begin
 604       if Do_Yield then
 605          Result := sched_yield;
 606       end if;
 607    end Yield;
 608
 609    ------------------
 610    -- Set_Priority --
 611    ------------------
 612
 613    procedure Set_Priority
 614      (T                   : Task_Id;
 615       Prio                : System.Any_Priority;
 616       Loss_Of_Inheritance : Boolean := False)
 617    is
 618       pragma Unreferenced (Loss_Of_Inheritance);
 619
 620       Result : Interfaces.C.int;
 621       Param  : aliased struct_sched_param;
 622
 623       function Get_Policy (Prio : System.Any_Priority) return Character;
 624       pragma Import (C, Get_Policy, "__gnat_get_specific_dispatching");
 625       --  Get priority specific dispatching policy
 626
 627       Priority_Specific_Policy : constant Character := Get_Policy (Prio);
 628       --  Upper case first character of the policy name corresponding to the
 629       --  task as set by a Priority_Specific_Dispatching pragma.
 630
 631    begin
 632       T.Common.Current_Priority := Prio;
 633
 634       --  Priorities are in range 1 .. 99 on GNU/Linux, so we map
 635       --  map 0 .. 98 to 1 .. 99
 636
 637       Param.sched_priority := Interfaces.C.int (Prio) + 1;
 638
 639       if Dispatching_Policy = 'R'
 640         or else Priority_Specific_Policy = 'R'
 641         or else Time_Slice_Val > 0
 642       then
 643          Result := pthread_setschedparam
 644            (T.Common.LL.Thread, SCHED_RR, Param'Access);
 645
 646       elsif Dispatching_Policy = 'F'
 647         or else Priority_Specific_Policy = 'F'
 648         or else Time_Slice_Val = 0
 649       then
 650          Result := pthread_setschedparam
 651            (T.Common.LL.Thread, SCHED_FIFO, Param'Access);
 652
 653       else
 654          Param.sched_priority := 0;
 655          Result := pthread_setschedparam
 656            (T.Common.LL.Thread, SCHED_OTHER, Param'Access);
 657       end if;
 658
 659       pragma Assert (Result = 0 or else Result = EPERM);
 660    end Set_Priority;
 661
 662    ------------------
 663    -- Get_Priority --
 664    ------------------
 665
 666    function Get_Priority (T : Task_Id) return System.Any_Priority is
 667    begin
 668       return T.Common.Current_Priority;
 669    end Get_Priority;
 670
 671    ----------------
 672    -- Enter_Task --
 673    ----------------
 674
 675    procedure Enter_Task (Self_ID : Task_Id) is
 676    begin
 677       Self_ID.Common.LL.Thread := pthread_self;
 678
 679       Specific.Set (Self_ID);
 680
 681       Lock_RTS;
 682
 683       for J in Known_Tasks'Range loop
 684          if Known_Tasks (J) = null then
 685             Known_Tasks (J) := Self_ID;
 686             Self_ID.Known_Tasks_Index := J;
 687             exit;
 688          end if;
 689       end loop;
 690
 691       Unlock_RTS;
 692    end Enter_Task;
 693
 694    --------------
 695    -- New_ATCB --
 696    --------------
 697
 698    function New_ATCB (Entry_Num : Task_Entry_Index) return Task_Id is
 699    begin
 700       return new Ada_Task_Control_Block (Entry_Num);
 701    end New_ATCB;
 702
 703    -------------------
 704    -- Is_Valid_Task --
 705    -------------------
 706
 707    function Is_Valid_Task return Boolean renames Specific.Is_Valid_Task;
 708
 709    -----------------------------
 710    -- Register_Foreign_Thread --
 711    -----------------------------
 712
 713    function Register_Foreign_Thread return Task_Id is
 714    begin
 715       if Is_Valid_Task then
 716          return Self;
 717       else
 718          return Register_Foreign_Thread (pthread_self);
 719       end if;
 720    end Register_Foreign_Thread;
 721
 722    --------------------
 723    -- Initialize_TCB --
 724    --------------------
 725
 726    procedure Initialize_TCB (Self_ID : Task_Id; Succeeded : out Boolean) is
 727       Result : Interfaces.C.int;
 728
 729    begin
 730       --  Give the task a unique serial number
 731
 732       Self_ID.Serial_Number := Next_Serial_Number;
 733       Next_Serial_Number := Next_Serial_Number + 1;
 734       pragma Assert (Next_Serial_Number /= 0);
 735
 736       Self_ID.Common.LL.Thread := To_pthread_t (-1);
 737
 738       if not Single_Lock then
 739          Result := pthread_mutex_init (Self_ID.Common.LL.L'Access,
 740            Mutex_Attr'Access);
 741          pragma Assert (Result = 0 or else Result = ENOMEM);
 742
 743          if Result /= 0 then
 744             Succeeded := False;
 745             return;
 746          end if;
 747       end if;
 748
 749       Result := pthread_cond_init (Self_ID.Common.LL.CV'Access,
 750         Cond_Attr'Access);
 751       pragma Assert (Result = 0 or else Result = ENOMEM);
 752
 753       if Result = 0 then
 754          Succeeded := True;
 755       else
 756          if not Single_Lock then
 757             Result := pthread_mutex_destroy (Self_ID.Common.LL.L'Access);
 758             pragma Assert (Result = 0);
 759          end if;
 760
 761          Succeeded := False;
 762       end if;
 763    end Initialize_TCB;
 764
 765    -----------------
 766    -- Create_Task --
 767    -----------------
 768
 769    procedure Create_Task
 770      (T          : Task_Id;
 771       Wrapper    : System.Address;
 772       Stack_Size : System.Parameters.Size_Type;
 773       Priority   : System.Any_Priority;
 774       Succeeded  : out Boolean)
 775    is
 776       Attributes : aliased pthread_attr_t;
 777       Result     : Interfaces.C.int;
 778
 779    begin
 780       Result := pthread_attr_init (Attributes'Access);
 781       pragma Assert (Result = 0 or else Result = ENOMEM);
 782
 783       if Result /= 0 then
 784          Succeeded := False;
 785          return;
 786       end if;
 787
 788       Result :=
 789         pthread_attr_setstacksize
 790           (Attributes'Access, Interfaces.C.size_t (Stack_Size));
 791       pragma Assert (Result = 0);
 792
 793       Result :=
 794         pthread_attr_setdetachstate
 795           (Attributes'Access, PTHREAD_CREATE_DETACHED);
 796       pragma Assert (Result = 0);
 797
 798       --  Since the initial signal mask of a thread is inherited from the
 799       --  creator, and the Environment task has all its signals masked, we
 800       --  do not need to manipulate caller's signal mask at this point.
 801       --  All tasks in RTS will have All_Tasks_Mask initially.
 802
 803       Result := pthread_create
 804         (T.Common.LL.Thread'Access,
 805          Attributes'Access,
 806          Thread_Body_Access (Wrapper),
 807          To_Address (T));
 808       pragma Assert (Result = 0 or else Result = EAGAIN);
 809
 810       Succeeded := Result = 0;
 811
 812       Result := pthread_attr_destroy (Attributes'Access);
 813       pragma Assert (Result = 0);
 814
 815       Set_Priority (T, Priority);
 816    end Create_Task;
 817
 818    ------------------
 819    -- Finalize_TCB --
 820    ------------------
 821
 822    procedure Finalize_TCB (T : Task_Id) is
 823       Result  : Interfaces.C.int;
 824       Tmp     : Task_Id := T;
 825       Is_Self : constant Boolean := T = Self;
 826
 827       procedure Free is new
 828         Unchecked_Deallocation (Ada_Task_Control_Block, Task_Id);
 829
 830    begin
 831       if not Single_Lock then
 832          Result := pthread_mutex_destroy (T.Common.LL.L'Access);
 833          pragma Assert (Result = 0);
 834       end if;
 835
 836       Result := pthread_cond_destroy (T.Common.LL.CV'Access);
 837       pragma Assert (Result = 0);
 838
 839       if T.Known_Tasks_Index /= -1 then
 840          Known_Tasks (T.Known_Tasks_Index) := null;
 841       end if;
 842       SC.Invalidate_Stack_Cache (T.Common.Compiler_Data.Pri_Stack_Info'Access);
 843       Free (Tmp);
 844
 845       if Is_Self then
 846          Specific.Set (null);
 847       end if;
 848    end Finalize_TCB;
 849
 850    ---------------
 851    -- Exit_Task --
 852    ---------------
 853
 854    procedure Exit_Task is
 855    begin
 856       Specific.Set (null);
 857    end Exit_Task;
 858
 859    ----------------
 860    -- Abort_Task --
 861    ----------------
 862
 863    procedure Abort_Task (T : Task_Id) is
 864       Result : Interfaces.C.int;
 865    begin
 866       Result := pthread_kill (T.Common.LL.Thread,
 867         Signal (System.Interrupt_Management.Abort_Task_Interrupt));
 868       pragma Assert (Result = 0);
 869    end Abort_Task;
 870
 871    ----------------
 872    -- Initialize --
 873    ----------------
 874
 875    procedure Initialize (S : in out Suspension_Object) is
 876       Result : Interfaces.C.int;
 877    begin
 878       --  Initialize internal state. It is always initialized to False (ARM
 879       --  D.10 par. 6).
 880
 881       S.State := False;
 882       S.Waiting := False;
 883
 884       --  Initialize internal mutex
 885
 886       Result := pthread_mutex_init (S.L'Access, Mutex_Attr'Access);
 887
 888       pragma Assert (Result = 0 or else Result = ENOMEM);
 889
 890       if Result = ENOMEM then
 891          raise Storage_Error;
 892       end if;
 893
 894       --  Initialize internal condition variable
 895
 896       Result := pthread_cond_init (S.CV'Access, Cond_Attr'Access);
 897
 898       pragma Assert (Result = 0 or else Result = ENOMEM);
 899
 900       if Result /= 0 then
 901          Result := pthread_mutex_destroy (S.L'Access);
 902          pragma Assert (Result = 0);
 903
 904          if Result = ENOMEM then
 905             raise Storage_Error;
 906          end if;
 907       end if;
 908    end Initialize;
 909
 910    --------------
 911    -- Finalize --
 912    --------------
 913
 914    procedure Finalize (S : in out Suspension_Object) is
 915       Result  : Interfaces.C.int;
 916    begin
 917       --  Destroy internal mutex
 918
 919       Result := pthread_mutex_destroy (S.L'Access);
 920       pragma Assert (Result = 0);
 921
 922       --  Destroy internal condition variable
 923
 924       Result := pthread_cond_destroy (S.CV'Access);
 925       pragma Assert (Result = 0);
 926    end Finalize;
 927
 928    -------------------
 929    -- Current_State --
 930    -------------------
 931
 932    function Current_State (S : Suspension_Object) return Boolean is
 933    begin
 934       --  We do not want to use lock on this read operation. State is marked
 935       --  as Atomic so that we ensure that the value retrieved is correct.
 936
 937       return S.State;
 938    end Current_State;
 939
 940    ---------------
 941    -- Set_False --
 942    ---------------
 943
 944    procedure Set_False (S : in out Suspension_Object) is
 945       Result  : Interfaces.C.int;
 946    begin
 947       SSL.Abort_Defer.all;
 948
 949       Result := pthread_mutex_lock (S.L'Access);
 950       pragma Assert (Result = 0);
 951
 952       S.State := False;
 953
 954       Result := pthread_mutex_unlock (S.L'Access);
 955       pragma Assert (Result = 0);
 956
 957       SSL.Abort_Undefer.all;
 958    end Set_False;
 959
 960    --------------
 961    -- Set_True --
 962    --------------
 963
 964    procedure Set_True (S : in out Suspension_Object) is
 965       Result : Interfaces.C.int;
 966    begin
 967       SSL.Abort_Defer.all;
 968
 969       Result := pthread_mutex_lock (S.L'Access);
 970       pragma Assert (Result = 0);
 971
 972       --  If there is already a task waiting on this suspension object then
 973       --  we resume it, leaving the state of the suspension object to False,
 974       --  as it is specified in ARM D.10 par. 9. Otherwise, it just leaves
 975       --  the state to True.
 976
 977       if S.Waiting then
 978          S.Waiting := False;
 979          S.State := False;
 980
 981          Result := pthread_cond_signal (S.CV'Access);
 982          pragma Assert (Result = 0);
 983       else
 984          S.State := True;
 985       end if;
 986
 987       Result := pthread_mutex_unlock (S.L'Access);
 988       pragma Assert (Result = 0);
 989
 990       SSL.Abort_Undefer.all;
 991    end Set_True;
 992
 993    ------------------------
 994    -- Suspend_Until_True --
 995    ------------------------
 996
 997    procedure Suspend_Until_True (S : in out Suspension_Object) is
 998       Result : Interfaces.C.int;
 999    begin
1000       SSL.Abort_Defer.all;
1001
1002       Result := pthread_mutex_lock (S.L'Access);
1003       pragma Assert (Result = 0);
1004
1005       if S.Waiting then
1006          --  Program_Error must be raised upon calling Suspend_Until_True
1007          --  if another task is already waiting on that suspension object
1008          --  (ARM D.10 par. 10).
1009
1010          Result := pthread_mutex_unlock (S.L'Access);
1011          pragma Assert (Result = 0);
1012
1013          SSL.Abort_Undefer.all;
1014
1015          raise Program_Error;
1016       else
1017          --  Suspend the task if the state is False. Otherwise, the task
1018          --  continues its execution, and the state of the suspension object
1019          --  is set to False (ARM D.10 par. 9).
1020
1021          if S.State then
1022             S.State := False;
1023          else
1024             S.Waiting := True;
1025             Result := pthread_cond_wait (S.CV'Access, S.L'Access);
1026          end if;
1027
1028          Result := pthread_mutex_unlock (S.L'Access);
1029          pragma Assert (Result = 0);
1030
1031          SSL.Abort_Undefer.all;
1032       end if;
1033    end Suspend_Until_True;
1034
1035    ----------------
1036    -- Check_Exit --
1037    ----------------
1038
1039    --  Dummy version
1040
1041    function Check_Exit (Self_ID : ST.Task_Id) return Boolean is
1042       pragma Unreferenced (Self_ID);
1043    begin
1044       return True;
1045    end Check_Exit;
1046
1047    --------------------
1048    -- Check_No_Locks --
1049    --------------------
1050
1051    function Check_No_Locks (Self_ID : ST.Task_Id) return Boolean is
1052       pragma Unreferenced (Self_ID);
1053    begin
1054       return True;
1055    end Check_No_Locks;
1056
1057    ----------------------
1058    -- Environment_Task --
1059    ----------------------
1060
1061    function Environment_Task return Task_Id is
1062    begin
1063       return Environment_Task_Id;
1064    end Environment_Task;
1065
1066    ------------------
1067    -- Suspend_Task --
1068    ------------------
1069
1070    function Suspend_Task
1071      (T           : ST.Task_Id;
1072       Thread_Self : Thread_Id) return Boolean
1073    is
1074    begin
1075       if T.Common.LL.Thread /= Thread_Self then
1076          return pthread_kill (T.Common.LL.Thread, SIGSTOP) = 0;
1077       else
1078          return True;
1079       end if;
1080    end Suspend_Task;
1081
1082    -----------------
1083    -- Resume_Task --
1084    -----------------
1085
1086    function Resume_Task
1087      (T           : ST.Task_Id;
1088       Thread_Self : Thread_Id) return Boolean
1089    is
1090    begin
1091       if T.Common.LL.Thread /= Thread_Self then
1092          return pthread_kill (T.Common.LL.Thread, SIGCONT) = 0;
1093       else
1094          return True;
1095       end if;
1096    end Resume_Task;
1097
1098    ----------------
1099    -- Initialize --
1100    ----------------
1101
1102    procedure Initialize (Environment_Task : Task_Id) is
1103       act     : aliased struct_sigaction;
1104       old_act : aliased struct_sigaction;
1105       Tmp_Set : aliased sigset_t;
1106       Result  : Interfaces.C.int;
1107
1108       function State
1109         (Int : System.Interrupt_Management.Interrupt_ID) return Character;
1110       pragma Import (C, State, "__gnat_get_interrupt_state");
1111       --  Get interrupt state.  Defined in a-init.c
1112       --  The input argument is the interrupt number,
1113       --  and the result is one of the following:
1114
1115       Default : constant Character := 's';
1116       --    'n'   this interrupt not set by any Interrupt_State pragma
1117       --    'u'   Interrupt_State pragma set state to User
1118       --    'r'   Interrupt_State pragma set state to Runtime
1119       --    's'   Interrupt_State pragma set state to System (use "default"
1120       --           system handler)
1121
1122    begin
1123       Environment_Task_Id := Environment_Task;
1124
1125       Interrupt_Management.Initialize;
1126
1127       --  Prepare the set of signals that should be unblocked in all tasks
1128
1129       Result := sigemptyset (Unblocked_Signal_Mask'Access);
1130       pragma Assert (Result = 0);
1131
1132       for J in Interrupt_Management.Interrupt_ID loop
1133          if System.Interrupt_Management.Keep_Unmasked (J) then
1134             Result := sigaddset (Unblocked_Signal_Mask'Access, Signal (J));
1135             pragma Assert (Result = 0);
1136          end if;
1137       end loop;
1138
1139       Result := pthread_mutexattr_init (Mutex_Attr'Access);
1140       pragma Assert (Result = 0);
1141
1142       Result := pthread_condattr_init (Cond_Attr'Access);
1143       pragma Assert (Result = 0);
1144
1145       Initialize_Lock (Single_RTS_Lock'Access, RTS_Lock_Level);
1146
1147       --  Initialize the global RTS lock
1148
1149       Specific.Initialize (Environment_Task);
1150
1151       Enter_Task (Environment_Task);
1152
1153       --  Install the abort-signal handler
1154
1155       if State (System.Interrupt_Management.Abort_Task_Interrupt)
1156         /= Default
1157       then
1158          act.sa_flags := 0;
1159          act.sa_handler := Abort_Handler'Address;
1160
1161          Result := sigemptyset (Tmp_Set'Access);
1162          pragma Assert (Result = 0);
1163          act.sa_mask := Tmp_Set;
1164
1165          Result :=
1166            sigaction
1167            (Signal (Interrupt_Management.Abort_Task_Interrupt),
1168             act'Unchecked_Access,
1169             old_act'Unchecked_Access);
1170          pragma Assert (Result = 0);
1171       end if;
1172    end Initialize;
1173
1174 end System.Task_Primitives.Operations;