lib/libc_r/uthread/uthread_kern.c

   1 /*
   2  * Copyright (c) 1995-1998 John Birrell <jb@cimlogic.com.au>
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by John Birrell.
  16  * 4. Neither the name of the author nor the names of any co-contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  *
  32  * $FreeBSD: src/lib/libc_r/uthread/uthread_kern.c,v 1.28.2.13 2002/10/22 14:44:03 fjoe Exp $
  33  * $DragonFly: src/lib/libc_r/uthread/uthread_kern.c,v 1.2 2003/06/17 04:26:48 dillon Exp $
  34  *
  35  */
  36 #include <errno.h>
  37 #include <poll.h>
  38 #include <stdlib.h>
  39 #include <stdarg.h>
  40 #include <string.h>
  41 #include <unistd.h>
  42 #include <setjmp.h>
  43 #include <sys/param.h>
  44 #include <sys/types.h>
  45 #include <sys/signalvar.h>
  46 #include <sys/stat.h>
  47 #include <sys/time.h>
  48 #include <sys/socket.h>
  49 #include <sys/uio.h>
  50 #include <sys/syscall.h>
  51 #include <fcntl.h>
  52 #include <pthread.h>
  53 #include "pthread_private.h"
  54
  55 /* #define DEBUG_THREAD_KERN */
  56 #ifdef DEBUG_THREAD_KERN
  57 #define DBG_MSG         stdout_debug
  58 #else
  59 #define DBG_MSG(x...)
  60 #endif
  61
  62 /* Static function prototype definitions: */
  63 static void
  64 thread_kern_poll(int wait_reqd);
  65
  66 static void
  67 dequeue_signals(void);
  68
  69 static inline void
  70 thread_run_switch_hook(pthread_t thread_out, pthread_t thread_in);
  71
  72 /* Static variables: */
  73 static int      last_tick = 0;
  74 static int      called_from_handler = 0;
  75
  76 /*
  77  * This is called when a signal handler finishes and wants to
  78  * return to a previous frame.
  79  */
  80 void
  81 _thread_kern_sched_frame(struct pthread_signal_frame *psf)
  82 {
  83         struct pthread  *curthread = _get_curthread();
  84
  85         /*
  86          * Flag the pthread kernel as executing scheduler code
  87          * to avoid a signal from interrupting this execution and
  88          * corrupting the (soon-to-be) current frame.
  89          */
  90         _thread_kern_in_sched = 1;
  91
  92         /* Restore the signal frame: */
  93         _thread_sigframe_restore(curthread, psf);
  94
  95         /* The signal mask was restored; check for any pending signals: */
  96         curthread->check_pending = 1;
  97
  98         /* Switch to the thread scheduler: */
  99         ___longjmp(_thread_kern_sched_jb, 1);
 100 }
 101
 102
 103 void
 104 _thread_kern_sched(ucontext_t *ucp)
 105 {
 106         struct pthread  *curthread = _get_curthread();
 107
 108         /*
 109          * Flag the pthread kernel as executing scheduler code
 110          * to avoid a scheduler signal from interrupting this
 111          * execution and calling the scheduler again.
 112          */
 113         _thread_kern_in_sched = 1;
 114
 115         /* Check if this function was called from the signal handler: */
 116         if (ucp != NULL) {
 117                 /* XXX - Save FP registers? */
 118                 FP_SAVE_UC(ucp);
 119                 called_from_handler = 1;
 120                 DBG_MSG("Entering scheduler due to signal\n");
 121         }
 122
 123         /* Save the state of the current thread: */
 124         if (_setjmp(curthread->ctx.jb) != 0) {
 125                 DBG_MSG("Returned from ___longjmp, thread %p\n",
 126                     curthread);
 127                 /*
 128                  * This point is reached when a longjmp() is called
 129                  * to restore the state of a thread.
 130                  *
 131                  * This is the normal way out of the scheduler.
 132                  */
 133                 _thread_kern_in_sched = 0;
 134
 135                 if (curthread->sig_defer_count == 0) {
 136                         if (((curthread->cancelflags &
 137                             PTHREAD_AT_CANCEL_POINT) == 0) &&
 138                             ((curthread->cancelflags &
 139                             PTHREAD_CANCEL_ASYNCHRONOUS) != 0))
 140                                 /*
 141                                  * Cancellations override signals.
 142                                  *
 143                                  * Stick a cancellation point at the
 144                                  * start of each async-cancellable
 145                                  * thread's resumption.
 146                                  *
 147                                  * We allow threads woken at cancel
 148                                  * points to do their own checks.
 149                                  */
 150                                 pthread_testcancel();
 151                 }
 152
 153                 if (_sched_switch_hook != NULL) {
 154                         /* Run the installed switch hook: */
 155                         thread_run_switch_hook(_last_user_thread, curthread);
 156                 }
 157                 if (ucp == NULL)
 158                         return;
 159                 else {
 160                         /* XXX - Restore FP registers? */
 161                         FP_RESTORE_UC(ucp);
 162
 163                         /*
 164                          * Set the process signal mask in the context; it
 165                          * could have changed by the handler.
 166                          */
 167                         ucp->uc_sigmask = _process_sigmask;
 168
 169                         /* Resume the interrupted thread: */
 170                         sigreturn(ucp);
 171                 }
 172         }
 173         /* Switch to the thread scheduler: */
 174         ___longjmp(_thread_kern_sched_jb, 1);
 175 }
 176
 177 void
 178 _thread_kern_sched_sig(void)
 179 {
 180         struct pthread  *curthread = _get_curthread();
 181
 182         curthread->check_pending = 1;
 183         _thread_kern_sched(NULL);
 184 }
 185
 186
 187 void
 188 _thread_kern_scheduler(void)
 189 {
 190         struct timespec ts;
 191         struct timeval  tv;
 192         struct pthread  *curthread = _get_curthread();
 193         pthread_t       pthread, pthread_h;
 194         unsigned int    current_tick;
 195         int             add_to_prioq;
 196
 197         /* If the currently running thread is a user thread, save it: */
 198         if ((curthread->flags & PTHREAD_FLAGS_PRIVATE) == 0)
 199                 _last_user_thread = curthread;
 200
 201         if (called_from_handler != 0) {
 202                 called_from_handler = 0;
 203
 204                 /*
 205                  * We were called from a signal handler; restore the process
 206                  * signal mask.
 207                  */
 208                 if (__sys_sigprocmask(SIG_SETMASK,
 209                     &_process_sigmask, NULL) != 0)
 210                         PANIC("Unable to restore process mask after signal");
 211         }
 212
 213         /*
 214          * Enter a scheduling loop that finds the next thread that is
 215          * ready to run. This loop completes when there are no more threads
 216          * in the global list or when a thread has its state restored by
 217          * either a sigreturn (if the state was saved as a sigcontext) or a
 218          * longjmp (if the state was saved by a setjmp).
 219          */
 220         while (!(TAILQ_EMPTY(&_thread_list))) {
 221                 /* Get the current time of day: */
 222                 GET_CURRENT_TOD(tv);
 223                 TIMEVAL_TO_TIMESPEC(&tv, &ts);
 224                 current_tick = _sched_ticks;
 225
 226                 /*
 227                  * Protect the scheduling queues from access by the signal
 228                  * handler.
 229                  */
 230                 _queue_signals = 1;
 231                 add_to_prioq = 0;
 232
 233                 if (curthread != &_thread_kern_thread) {
 234                         /*
 235                          * This thread no longer needs to yield the CPU.
 236                          */
 237                         curthread->yield_on_sig_undefer = 0;
 238
 239                         if (curthread->state != PS_RUNNING) {
 240                                 /*
 241                                  * Save the current time as the time that the
 242                                  * thread became inactive:
 243                                  */
 244                                 curthread->last_inactive = (long)current_tick;
 245                                 if (curthread->last_inactive <
 246                                     curthread->last_active) {
 247                                         /* Account for a rollover: */
 248                                         curthread->last_inactive =+
 249                                             UINT_MAX + 1;
 250                                 }
 251                         }
 252
 253                         /*
 254                          * Place the currently running thread into the
 255                          * appropriate queue(s).
 256                          */
 257                         switch (curthread->state) {
 258                         case PS_DEAD:
 259                         case PS_STATE_MAX: /* to silence -Wall */
 260                         case PS_SUSPENDED:
 261                                 /*
 262                                  * Dead and suspended threads are not placed
 263                                  * in any queue:
 264                                  */
 265                                 break;
 266
 267                         case PS_RUNNING:
 268                                 /*
 269                                  * Runnable threads can't be placed in the
 270                                  * priority queue until after waiting threads
 271                                  * are polled (to preserve round-robin
 272                                  * scheduling).
 273                                  */
 274                                 add_to_prioq = 1;
 275                                 break;
 276
 277                         /*
 278                          * States which do not depend on file descriptor I/O
 279                          * operations or timeouts:
 280                          */
 281                         case PS_DEADLOCK:
 282                         case PS_FDLR_WAIT:
 283                         case PS_FDLW_WAIT:
 284                         case PS_FILE_WAIT:
 285                         case PS_JOIN:
 286                         case PS_MUTEX_WAIT:
 287                         case PS_SIGSUSPEND:
 288                         case PS_SIGTHREAD:
 289                         case PS_SIGWAIT:
 290                         case PS_WAIT_WAIT:
 291                                 /* No timeouts for these states: */
 292                                 curthread->wakeup_time.tv_sec = -1;
 293                                 curthread->wakeup_time.tv_nsec = -1;
 294
 295                                 /* Restart the time slice: */
 296                                 curthread->slice_usec = -1;
 297
 298                                 /* Insert into the waiting queue: */
 299                                 PTHREAD_WAITQ_INSERT(curthread);
 300                                 break;
 301
 302                         /* States which can timeout: */
 303                         case PS_COND_WAIT:
 304                         case PS_SLEEP_WAIT:
 305                                 /* Restart the time slice: */
 306                                 curthread->slice_usec = -1;
 307
 308                                 /* Insert into the waiting queue: */
 309                                 PTHREAD_WAITQ_INSERT(curthread);
 310                                 break;
 311
 312                         /* States that require periodic work: */
 313                         case PS_SPINBLOCK:
 314                                 /* No timeouts for this state: */
 315                                 curthread->wakeup_time.tv_sec = -1;
 316                                 curthread->wakeup_time.tv_nsec = -1;
 317
 318                                 /* Increment spinblock count: */
 319                                 _spinblock_count++;
 320
 321                                 /* FALLTHROUGH */
 322                         case PS_FDR_WAIT:
 323                         case PS_FDW_WAIT:
 324                         case PS_POLL_WAIT:
 325                         case PS_SELECT_WAIT:
 326                                 /* Restart the time slice: */
 327                                 curthread->slice_usec = -1;
 328
 329                                 /* Insert into the waiting queue: */
 330                                 PTHREAD_WAITQ_INSERT(curthread);
 331
 332                                 /* Insert into the work queue: */
 333                                 PTHREAD_WORKQ_INSERT(curthread);
 334                                 break;
 335                         }
 336
 337                         /*
 338                          * Are there pending signals for this thread?
 339                          *
 340                          * This check has to be performed after the thread
 341                          * has been placed in the queue(s) appropriate for
 342                          * its state.  The process of adding pending signals
 343                          * can change a threads state, which in turn will
 344                          * attempt to add or remove the thread from any
 345                          * scheduling queue to which it belongs.
 346                          */
 347                         if (curthread->check_pending != 0) {
 348                                 curthread->check_pending = 0;
 349                                 _thread_sig_check_pending(curthread);
 350                         }
 351                 }
 352
 353                 /*
 354                  * Avoid polling file descriptors if there are none
 355                  * waiting:
 356                  */
 357                 if (TAILQ_EMPTY(&_workq) != 0) {
 358                 }
 359                 /*
 360                  * Poll file descriptors only if a new scheduling signal
 361                  * has occurred or if we have no more runnable threads.
 362                  */
 363                 else if (((current_tick = _sched_ticks) != last_tick) ||
 364                     ((curthread->state != PS_RUNNING) &&
 365                     (PTHREAD_PRIOQ_FIRST() == NULL))) {
 366                         /* Unprotect the scheduling queues: */
 367                         _queue_signals = 0;
 368
 369                         /*
 370                          * Poll file descriptors to update the state of threads
 371                          * waiting on file I/O where data may be available:
 372                          */
 373                         thread_kern_poll(0);
 374
 375                         /* Protect the scheduling queues: */
 376                         _queue_signals = 1;
 377                 }
 378                 last_tick = current_tick;
 379
 380                 /*
 381                  * Wake up threads that have timedout.  This has to be
 382                  * done after polling in case a thread does a poll or
 383                  * select with zero time.
 384                  */
 385                 PTHREAD_WAITQ_SETACTIVE();
 386                 while (((pthread = TAILQ_FIRST(&_waitingq)) != NULL) &&
 387                     (pthread->wakeup_time.tv_sec != -1) &&
 388                     (((pthread->wakeup_time.tv_sec == 0) &&
 389                     (pthread->wakeup_time.tv_nsec == 0)) ||
 390                     (pthread->wakeup_time.tv_sec < ts.tv_sec) ||
 391                     ((pthread->wakeup_time.tv_sec == ts.tv_sec) &&
 392                     (pthread->wakeup_time.tv_nsec <= ts.tv_nsec)))) {
 393                         switch (pthread->state) {
 394                         case PS_POLL_WAIT:
 395                         case PS_SELECT_WAIT:
 396                                 /* Return zero file descriptors ready: */
 397                                 pthread->data.poll_data->nfds = 0;
 398                                 /* FALLTHROUGH */
 399                         default:
 400                                 /*
 401                                  * Remove this thread from the waiting queue
 402                                  * (and work queue if necessary) and place it
 403                                  * in the ready queue.
 404                                  */
 405                                 PTHREAD_WAITQ_CLEARACTIVE();
 406                                 if (pthread->flags & PTHREAD_FLAGS_IN_WORKQ)
 407                                         PTHREAD_WORKQ_REMOVE(pthread);
 408                                 PTHREAD_NEW_STATE(pthread, PS_RUNNING);
 409                                 PTHREAD_WAITQ_SETACTIVE();
 410                                 break;
 411                         }
 412                         /*
 413                          * Flag the timeout in the thread structure:
 414                          */
 415                         pthread->timeout = 1;
 416                 }
 417                 PTHREAD_WAITQ_CLEARACTIVE();
 418
 419                 /*
 420                  * Check to see if the current thread needs to be added
 421                  * to the priority queue:
 422                  */
 423                 if (add_to_prioq != 0) {
 424                         /*
 425                          * Save the current time as the time that the
 426                          * thread became inactive:
 427                          */
 428                         current_tick = _sched_ticks;
 429                         curthread->last_inactive = (long)current_tick;
 430                         if (curthread->last_inactive <
 431                             curthread->last_active) {
 432                                 /* Account for a rollover: */
 433                                 curthread->last_inactive =+ UINT_MAX + 1;
 434                         }
 435
 436                         if ((curthread->slice_usec != -1) &&
 437                            (curthread->attr.sched_policy != SCHED_FIFO)) {
 438                                 /*
 439                                  * Accumulate the number of microseconds for
 440                                  * which the current thread has run:
 441                                  */
 442                                 curthread->slice_usec +=
 443                                     (curthread->last_inactive -
 444                                     curthread->last_active) *
 445                                     (long)_clock_res_usec;
 446                                 /* Check for time quantum exceeded: */
 447                                 if (curthread->slice_usec > TIMESLICE_USEC)
 448                                         curthread->slice_usec = -1;
 449                         }
 450
 451                         if (curthread->slice_usec == -1) {
 452                                 /*
 453                                  * The thread exceeded its time
 454                                  * quantum or it yielded the CPU;
 455                                  * place it at the tail of the
 456                                  * queue for its priority.
 457                                  */
 458                                 PTHREAD_PRIOQ_INSERT_TAIL(curthread);
 459                         } else {
 460                                 /*
 461                                  * The thread hasn't exceeded its
 462                                  * interval.  Place it at the head
 463                                  * of the queue for its priority.
 464                                  */
 465                                 PTHREAD_PRIOQ_INSERT_HEAD(curthread);
 466                         }
 467                 }
 468
 469                 /*
 470                  * Get the highest priority thread in the ready queue.
 471                  */
 472                 pthread_h = PTHREAD_PRIOQ_FIRST();
 473
 474                 /* Check if there are no threads ready to run: */
 475                 if (pthread_h == NULL) {
 476                         /*
 477                          * Lock the pthread kernel by changing the pointer to
 478                          * the running thread to point to the global kernel
 479                          * thread structure:
 480                          */
 481                         _set_curthread(&_thread_kern_thread);
 482                         curthread = &_thread_kern_thread;
 483
 484                         DBG_MSG("No runnable threads, using kernel thread %p\n",
 485                             curthread);
 486
 487                         /* Unprotect the scheduling queues: */
 488                         _queue_signals = 0;
 489
 490                         /*
 491                          * There are no threads ready to run, so wait until
 492                          * something happens that changes this condition:
 493                          */
 494                         thread_kern_poll(1);
 495
 496                         /*
 497                          * This process' usage will likely be very small
 498                          * while waiting in a poll.  Since the scheduling
 499                          * clock is based on the profiling timer, it is
 500                          * unlikely that the profiling timer will fire
 501                          * and update the time of day.  To account for this,
 502                          * get the time of day after polling with a timeout.
 503                          */
 504                         gettimeofday((struct timeval *) &_sched_tod, NULL);
 505
 506                         /* Check once more for a runnable thread: */
 507                         _queue_signals = 1;
 508                         pthread_h = PTHREAD_PRIOQ_FIRST();
 509                         _queue_signals = 0;
 510                 }
 511
 512                 if (pthread_h != NULL) {
 513                         /* Remove the thread from the ready queue: */
 514                         PTHREAD_PRIOQ_REMOVE(pthread_h);
 515
 516                         /* Unprotect the scheduling queues: */
 517                         _queue_signals = 0;
 518
 519                         /*
 520                          * Check for signals queued while the scheduling
 521                          * queues were protected:
 522                          */
 523                         while (_sigq_check_reqd != 0) {
 524                                 /* Clear before handling queued signals: */
 525                                 _sigq_check_reqd = 0;
 526
 527                                 /* Protect the scheduling queues again: */
 528                                 _queue_signals = 1;
 529
 530                                 dequeue_signals();
 531
 532                                 /*
 533                                  * Check for a higher priority thread that
 534                                  * became runnable due to signal handling.
 535                                  */
 536                                 if (((pthread = PTHREAD_PRIOQ_FIRST()) != NULL) &&
 537                                     (pthread->active_priority > pthread_h->active_priority)) {
 538                                         /* Remove the thread from the ready queue: */
 539                                         PTHREAD_PRIOQ_REMOVE(pthread);
 540
 541                                         /*
 542                                          * Insert the lower priority thread
 543                                          * at the head of its priority list:
 544                                          */
 545                                         PTHREAD_PRIOQ_INSERT_HEAD(pthread_h);
 546
 547                                         /* There's a new thread in town: */
 548                                         pthread_h = pthread;
 549                                 }
 550
 551                                 /* Unprotect the scheduling queues: */
 552                                 _queue_signals = 0;
 553                         }
 554
 555                         /* Make the selected thread the current thread: */
 556                         _set_curthread(pthread_h);
 557                         curthread = pthread_h;
 558
 559                         /*
 560                          * Save the current time as the time that the thread
 561                          * became active:
 562                          */
 563                         current_tick = _sched_ticks;
 564                         curthread->last_active = (long) current_tick;
 565
 566                         /*
 567                          * Check if this thread is running for the first time
 568                          * or running again after using its full time slice
 569                          * allocation:
 570                          */
 571                         if (curthread->slice_usec == -1) {
 572                                 /* Reset the accumulated time slice period: */
 573                                 curthread->slice_usec = 0;
 574                         }
 575
 576                         /*
 577                          * If we had a context switch, run any
 578                          * installed switch hooks.
 579                          */
 580                         if ((_sched_switch_hook != NULL) &&
 581                             (_last_user_thread != curthread)) {
 582                                 thread_run_switch_hook(_last_user_thread,
 583                                     curthread);
 584                         }
 585                         /*
 586                          * Continue the thread at its current frame:
 587                          */
 588 #if NOT_YET
 589                         _setcontext(&curthread->ctx.uc);
 590 #else
 591                         ___longjmp(curthread->ctx.jb, 1);
 592 #endif
 593                         /* This point should not be reached. */
 594                         PANIC("Thread has returned from sigreturn or longjmp");
 595                 }
 596         }
 597
 598         /* There are no more threads, so exit this process: */
 599         exit(0);
 600 }
 601
 602 void
 603 _thread_kern_sched_state(enum pthread_state state, char *fname, int lineno)
 604 {
 605         struct pthread  *curthread = _get_curthread();
 606
 607         /*
 608          * Flag the pthread kernel as executing scheduler code
 609          * to avoid a scheduler signal from interrupting this
 610          * execution and calling the scheduler again.
 611          */
 612         _thread_kern_in_sched = 1;
 613
 614         /*
 615          * Prevent the signal handler from fiddling with this thread
 616          * before its state is set and is placed into the proper queue.
 617          */
 618         _queue_signals = 1;
 619
 620         /* Change the state of the current thread: */
 621         curthread->state = state;
 622         curthread->fname = fname;
 623         curthread->lineno = lineno;
 624
 625         /* Schedule the next thread that is ready: */
 626         _thread_kern_sched(NULL);
 627 }
 628
 629 void
 630 _thread_kern_sched_state_unlock(enum pthread_state state,
 631     spinlock_t *lock, char *fname, int lineno)
 632 {
 633         struct pthread  *curthread = _get_curthread();
 634
 635         /*
 636          * Flag the pthread kernel as executing scheduler code
 637          * to avoid a scheduler signal from interrupting this
 638          * execution and calling the scheduler again.
 639          */
 640         _thread_kern_in_sched = 1;
 641
 642         /*
 643          * Prevent the signal handler from fiddling with this thread
 644          * before its state is set and it is placed into the proper
 645          * queue(s).
 646          */
 647         _queue_signals = 1;
 648
 649         /* Change the state of the current thread: */
 650         curthread->state = state;
 651         curthread->fname = fname;
 652         curthread->lineno = lineno;
 653
 654         _SPINUNLOCK(lock);
 655
 656         /* Schedule the next thread that is ready: */
 657         _thread_kern_sched(NULL);
 658 }
 659
 660 static void
 661 thread_kern_poll(int wait_reqd)
 662 {
 663         int             count = 0;
 664         int             i, found;
 665         int             kern_pipe_added = 0;
 666         int             nfds = 0;
 667         int             timeout_ms = 0;
 668         struct pthread  *pthread;
 669         struct timespec ts;
 670         struct timeval  tv;
 671
 672         /* Check if the caller wants to wait: */
 673         if (wait_reqd == 0) {
 674                 timeout_ms = 0;
 675         }
 676         else {
 677                 /* Get the current time of day: */
 678                 GET_CURRENT_TOD(tv);
 679                 TIMEVAL_TO_TIMESPEC(&tv, &ts);
 680
 681                 _queue_signals = 1;
 682                 pthread = TAILQ_FIRST(&_waitingq);
 683                 _queue_signals = 0;
 684
 685                 if ((pthread == NULL) || (pthread->wakeup_time.tv_sec == -1)) {
 686                         /*
 687                          * Either there are no threads in the waiting queue,
 688                          * or there are no threads that can timeout.
 689                          */
 690                         timeout_ms = INFTIM;
 691                 }
 692                 else if (pthread->wakeup_time.tv_sec - ts.tv_sec > 60000)
 693                         /* Limit maximum timeout to prevent rollover. */
 694                         timeout_ms = 60000;
 695                 else {
 696                         /*
 697                          * Calculate the time left for the next thread to
 698                          * timeout:
 699                          */
 700                         timeout_ms = ((pthread->wakeup_time.tv_sec - ts.tv_sec) *
 701                             1000) + ((pthread->wakeup_time.tv_nsec - ts.tv_nsec) /
 702                             1000000);
 703                         /*
 704                          * Don't allow negative timeouts:
 705                          */
 706                         if (timeout_ms < 0)
 707                                 timeout_ms = 0;
 708                 }
 709         }
 710
 711         /* Protect the scheduling queues: */
 712         _queue_signals = 1;
 713
 714         /*
 715          * Check to see if the signal queue needs to be walked to look
 716          * for threads awoken by a signal while in the scheduler.
 717          */
 718         if (_sigq_check_reqd != 0) {
 719                 /* Reset flag before handling queued signals: */
 720                 _sigq_check_reqd = 0;
 721
 722                 dequeue_signals();
 723         }
 724
 725         /*
 726          * Check for a thread that became runnable due to a signal:
 727          */
 728         if (PTHREAD_PRIOQ_FIRST() != NULL) {
 729                 /*
 730                  * Since there is at least one runnable thread,
 731                  * disable the wait.
 732                  */
 733                 timeout_ms = 0;
 734         }
 735
 736         /*
 737          * Form the poll table:
 738          */
 739         nfds = 0;
 740         if (timeout_ms != 0) {
 741                 /* Add the kernel pipe to the poll table: */
 742                 _thread_pfd_table[nfds].fd = _thread_kern_pipe[0];
 743                 _thread_pfd_table[nfds].events = POLLRDNORM;
 744                 _thread_pfd_table[nfds].revents = 0;
 745                 nfds++;
 746                 kern_pipe_added = 1;
 747         }
 748
 749         PTHREAD_WAITQ_SETACTIVE();
 750         TAILQ_FOREACH(pthread, &_workq, qe) {
 751                 switch (pthread->state) {
 752                 case PS_SPINBLOCK:
 753                         /*
 754                          * If the lock is available, let the thread run.
 755                          */
 756                         if (pthread->data.spinlock->access_lock == 0) {
 757                                 PTHREAD_WAITQ_CLEARACTIVE();
 758                                 PTHREAD_WORKQ_REMOVE(pthread);
 759                                 PTHREAD_NEW_STATE(pthread,PS_RUNNING);
 760                                 PTHREAD_WAITQ_SETACTIVE();
 761                                 /* One less thread in a spinblock state: */
 762                                 _spinblock_count--;
 763                                 /*
 764                                  * Since there is at least one runnable
 765                                  * thread, disable the wait.
 766                                  */
 767                                 timeout_ms = 0;
 768                         }
 769                         break;
 770
 771                 /* File descriptor read wait: */
 772                 case PS_FDR_WAIT:
 773                         /* Limit number of polled files to table size: */
 774                         if (nfds < _thread_dtablesize) {
 775                                 _thread_pfd_table[nfds].events = POLLRDNORM;
 776                                 _thread_pfd_table[nfds].fd = pthread->data.fd.fd;
 777                                 nfds++;
 778                         }
 779                         break;
 780
 781                 /* File descriptor write wait: */
 782                 case PS_FDW_WAIT:
 783                         /* Limit number of polled files to table size: */
 784                         if (nfds < _thread_dtablesize) {
 785                                 _thread_pfd_table[nfds].events = POLLWRNORM;
 786                                 _thread_pfd_table[nfds].fd = pthread->data.fd.fd;
 787                                 nfds++;
 788                         }
 789                         break;
 790
 791                 /* File descriptor poll or select wait: */
 792                 case PS_POLL_WAIT:
 793                 case PS_SELECT_WAIT:
 794                         /* Limit number of polled files to table size: */
 795                         if (pthread->data.poll_data->nfds + nfds <
 796                             _thread_dtablesize) {
 797                                 for (i = 0; i < pthread->data.poll_data->nfds; i++) {
 798                                         _thread_pfd_table[nfds + i].fd =
 799                                             pthread->data.poll_data->fds[i].fd;
 800                                         _thread_pfd_table[nfds + i].events =
 801                                             pthread->data.poll_data->fds[i].events;
 802                                 }
 803                                 nfds += pthread->data.poll_data->nfds;
 804                         }
 805                         break;
 806
 807                 /* Other states do not depend on file I/O. */
 808                 default:
 809                         break;
 810                 }
 811         }
 812         PTHREAD_WAITQ_CLEARACTIVE();
 813
 814         /*
 815          * Wait for a file descriptor to be ready for read, write, or
 816          * an exception, or a timeout to occur:
 817          */
 818         count = __sys_poll(_thread_pfd_table, nfds, timeout_ms);
 819
 820         if (kern_pipe_added != 0)
 821                 /*
 822                  * Remove the pthread kernel pipe file descriptor
 823                  * from the pollfd table:
 824                  */
 825                 nfds = 1;
 826         else
 827                 nfds = 0;
 828
 829         /*
 830          * Check if it is possible that there are bytes in the kernel
 831          * read pipe waiting to be read:
 832          */
 833         if (count < 0 || ((kern_pipe_added != 0) &&
 834             (_thread_pfd_table[0].revents & POLLRDNORM))) {
 835                 /*
 836                  * If the kernel read pipe was included in the
 837                  * count:
 838                  */
 839                 if (count > 0) {
 840                         /* Decrement the count of file descriptors: */
 841                         count--;
 842                 }
 843
 844                 if (_sigq_check_reqd != 0) {
 845                         /* Reset flag before handling signals: */
 846                         _sigq_check_reqd = 0;
 847
 848                         dequeue_signals();
 849                 }
 850         }
 851
 852         /*
 853          * Check if any file descriptors are ready:
 854          */
 855         if (count > 0) {
 856                 /*
 857                  * Enter a loop to look for threads waiting on file
 858                  * descriptors that are flagged as available by the
 859                  * _poll syscall:
 860                  */
 861                 PTHREAD_WAITQ_SETACTIVE();
 862                 TAILQ_FOREACH(pthread, &_workq, qe) {
 863                         switch (pthread->state) {
 864                         case PS_SPINBLOCK:
 865                                 /*
 866                                  * If the lock is available, let the thread run.
 867                                  */
 868                                 if (pthread->data.spinlock->access_lock == 0) {
 869                                         PTHREAD_WAITQ_CLEARACTIVE();
 870                                         PTHREAD_WORKQ_REMOVE(pthread);
 871                                         PTHREAD_NEW_STATE(pthread,PS_RUNNING);
 872                                         PTHREAD_WAITQ_SETACTIVE();
 873
 874                                         /*
 875                                          * One less thread in a spinblock state:
 876                                          */
 877                                         _spinblock_count--;
 878                                 }
 879                                 break;
 880
 881                         /* File descriptor read wait: */
 882                         case PS_FDR_WAIT:
 883                                 if ((nfds < _thread_dtablesize) &&
 884                                     ((_thread_pfd_table[nfds].revents
 885                                     & (POLLRDNORM | POLLHUP
 886                                       | POLLERR | POLLNVAL)) != 0)) {
 887                                         PTHREAD_WAITQ_CLEARACTIVE();
 888                                         PTHREAD_WORKQ_REMOVE(pthread);
 889                                         PTHREAD_NEW_STATE(pthread,PS_RUNNING);
 890                                         PTHREAD_WAITQ_SETACTIVE();
 891                                 }
 892                                 nfds++;
 893                                 break;
 894
 895                         /* File descriptor write wait: */
 896                         case PS_FDW_WAIT:
 897                                 if ((nfds < _thread_dtablesize) &&
 898                                     ((_thread_pfd_table[nfds].revents
 899                                     & (POLLWRNORM | POLLHUP
 900                                       | POLLERR | POLLNVAL)) != 0)) {
 901                                         PTHREAD_WAITQ_CLEARACTIVE();
 902                                         PTHREAD_WORKQ_REMOVE(pthread);
 903                                         PTHREAD_NEW_STATE(pthread,PS_RUNNING);
 904                                         PTHREAD_WAITQ_SETACTIVE();
 905                                 }
 906                                 nfds++;
 907                                 break;
 908
 909                         /* File descriptor poll or select wait: */
 910                         case PS_POLL_WAIT:
 911                         case PS_SELECT_WAIT:
 912                                 if (pthread->data.poll_data->nfds + nfds <
 913                                     _thread_dtablesize) {
 914                                         /*
 915                                          * Enter a loop looking for I/O
 916                                          * readiness:
 917                                          */
 918                                         found = 0;
 919                                         for (i = 0; i < pthread->data.poll_data->nfds; i++) {
 920                                                 if (_thread_pfd_table[nfds + i].revents != 0) {
 921                                                         pthread->data.poll_data->fds[i].revents =
 922                                                             _thread_pfd_table[nfds + i].revents;
 923                                                         found++;
 924                                                 }
 925                                         }
 926
 927                                         /* Increment before destroying: */
 928                                         nfds += pthread->data.poll_data->nfds;
 929
 930                                         if (found != 0) {
 931                                                 pthread->data.poll_data->nfds = found;
 932                                                 PTHREAD_WAITQ_CLEARACTIVE();
 933                                                 PTHREAD_WORKQ_REMOVE(pthread);
 934                                                 PTHREAD_NEW_STATE(pthread,PS_RUNNING);
 935                                                 PTHREAD_WAITQ_SETACTIVE();
 936                                         }
 937                                 }
 938                                 else
 939                                         nfds += pthread->data.poll_data->nfds;
 940                                 break;
 941
 942                         /* Other states do not depend on file I/O. */
 943                         default:
 944                                 break;
 945                         }
 946                 }
 947                 PTHREAD_WAITQ_CLEARACTIVE();
 948         }
 949         else if (_spinblock_count != 0) {
 950                 /*
 951                  * Enter a loop to look for threads waiting on a spinlock
 952                  * that is now available.
 953                  */
 954                 PTHREAD_WAITQ_SETACTIVE();
 955                 TAILQ_FOREACH(pthread, &_workq, qe) {
 956                         if (pthread->state == PS_SPINBLOCK) {
 957                                 /*
 958                                  * If the lock is available, let the thread run.
 959                                  */
 960                                 if (pthread->data.spinlock->access_lock == 0) {
 961                                         PTHREAD_WAITQ_CLEARACTIVE();
 962                                         PTHREAD_WORKQ_REMOVE(pthread);
 963                                         PTHREAD_NEW_STATE(pthread,PS_RUNNING);
 964                                         PTHREAD_WAITQ_SETACTIVE();
 965
 966                                         /*
 967                                          * One less thread in a spinblock state:
 968                                          */
 969                                         _spinblock_count--;
 970                                 }
 971                         }
 972                 }
 973                 PTHREAD_WAITQ_CLEARACTIVE();
 974         }
 975
 976         /* Unprotect the scheduling queues: */
 977         _queue_signals = 0;
 978
 979         while (_sigq_check_reqd != 0) {
 980                 /* Handle queued signals: */
 981                 _sigq_check_reqd = 0;
 982
 983                 /* Protect the scheduling queues: */
 984                 _queue_signals = 1;
 985
 986                 dequeue_signals();
 987
 988                 /* Unprotect the scheduling queues: */
 989                 _queue_signals = 0;
 990         }
 991 }
 992
 993 void
 994 _thread_kern_set_timeout(const struct timespec * timeout)
 995 {
 996         struct pthread  *curthread = _get_curthread();
 997         struct timespec current_time;
 998         struct timeval  tv;
 999
1000         /* Reset the timeout flag for the running thread: */
1001         curthread->timeout = 0;
1002
1003         /* Check if the thread is to wait forever: */
1004         if (timeout == NULL) {
1005                 /*
1006                  * Set the wakeup time to something that can be recognised as
1007                  * different to an actual time of day:
1008                  */
1009                 curthread->wakeup_time.tv_sec = -1;
1010                 curthread->wakeup_time.tv_nsec = -1;
1011         }
1012         /* Check if no waiting is required: */
1013         else if (timeout->tv_sec == 0 && timeout->tv_nsec == 0) {
1014                 /* Set the wake up time to 'immediately': */
1015                 curthread->wakeup_time.tv_sec = 0;
1016                 curthread->wakeup_time.tv_nsec = 0;
1017         } else {
1018                 /* Get the current time: */
1019                 GET_CURRENT_TOD(tv);
1020                 TIMEVAL_TO_TIMESPEC(&tv, &current_time);
1021
1022                 /* Calculate the time for the current thread to wake up: */
1023                 curthread->wakeup_time.tv_sec = current_time.tv_sec + timeout->tv_sec;
1024                 curthread->wakeup_time.tv_nsec = current_time.tv_nsec + timeout->tv_nsec;
1025
1026                 /* Check if the nanosecond field needs to wrap: */
1027                 if (curthread->wakeup_time.tv_nsec >= 1000000000) {
1028                         /* Wrap the nanosecond field: */
1029                         curthread->wakeup_time.tv_sec += 1;
1030                         curthread->wakeup_time.tv_nsec -= 1000000000;
1031                 }
1032         }
1033 }
1034
1035 void
1036 _thread_kern_sig_defer(void)
1037 {
1038         struct pthread  *curthread = _get_curthread();
1039
1040         /* Allow signal deferral to be recursive. */
1041         curthread->sig_defer_count++;
1042 }
1043
1044 void
1045 _thread_kern_sig_undefer(void)
1046 {
1047         struct pthread  *curthread = _get_curthread();
1048
1049         /*
1050          * Perform checks to yield only if we are about to undefer
1051          * signals.
1052          */
1053         if (curthread->sig_defer_count > 1) {
1054                 /* Decrement the signal deferral count. */
1055                 curthread->sig_defer_count--;
1056         }
1057         else if (curthread->sig_defer_count == 1) {
1058                 /* Reenable signals: */
1059                 curthread->sig_defer_count = 0;
1060
1061                 /*
1062                  * Check if there are queued signals:
1063                  */
1064                 if (_sigq_check_reqd != 0)
1065                         _thread_kern_sched(NULL);
1066
1067                 /*
1068                  * Check for asynchronous cancellation before delivering any
1069                  * pending signals:
1070                  */
1071                 if (((curthread->cancelflags & PTHREAD_AT_CANCEL_POINT) == 0) &&
1072                     ((curthread->cancelflags & PTHREAD_CANCEL_ASYNCHRONOUS) != 0))
1073                         pthread_testcancel();
1074
1075                 /*
1076                  * If there are pending signals or this thread has
1077                  * to yield the CPU, call the kernel scheduler:
1078                  *
1079                  * XXX - Come back and revisit the pending signal problem
1080                  */
1081                 if ((curthread->yield_on_sig_undefer != 0) ||
1082                     SIGNOTEMPTY(curthread->sigpend)) {
1083                         curthread->yield_on_sig_undefer = 0;
1084                         _thread_kern_sched(NULL);
1085                 }
1086         }
1087 }
1088
1089 static void
1090 dequeue_signals(void)
1091 {
1092         char    bufr[128];
1093         int     num;
1094
1095         /*
1096          * Enter a loop to clear the pthread kernel pipe:
1097          */
1098         while (((num = __sys_read(_thread_kern_pipe[0], bufr,
1099             sizeof(bufr))) > 0) || (num == -1 && errno == EINTR)) {
1100         }
1101         if ((num < 0) && (errno != EAGAIN)) {
1102                 /*
1103                  * The only error we should expect is if there is
1104                  * no data to read.
1105                  */
1106                 PANIC("Unable to read from thread kernel pipe");
1107         }
1108         /* Handle any pending signals: */
1109         _thread_sig_handle_pending();
1110 }
1111
1112 static inline void
1113 thread_run_switch_hook(pthread_t thread_out, pthread_t thread_in)
1114 {
1115         pthread_t tid_out = thread_out;
1116         pthread_t tid_in = thread_in;
1117
1118         if ((tid_out != NULL) &&
1119             (tid_out->flags & PTHREAD_FLAGS_PRIVATE) != 0)
1120                 tid_out = NULL;
1121         if ((tid_in != NULL) &&
1122             (tid_in->flags & PTHREAD_FLAGS_PRIVATE) != 0)
1123                 tid_in = NULL;
1124
1125         if ((_sched_switch_hook != NULL) && (tid_out != tid_in)) {
1126                 /* Run the scheduler switch hook: */
1127                 _sched_switch_hook(tid_out, tid_in);
1128         }
1129 }
1130
1131 struct pthread *
1132 _get_curthread(void)
1133 {
1134         if (_thread_initial == NULL)
1135                 _thread_init();
1136
1137         return (_thread_run);
1138 }
1139
1140 void
1141 _set_curthread(struct pthread *newthread)
1142 {
1143         _thread_run = newthread;
1144 }