lib/libc_r/uthread/uthread_sig.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_sig.c,v 1.25.2.13 2002/10/22 14:44:03 fjoe Exp $
  33  * $DragonFly: src/lib/libc_r/uthread/uthread_sig.c,v 1.5 2007/01/08 21:41:53 dillon Exp $
  34  */
  35 #include <sys/param.h>
  36 #include <sys/types.h>
  37 #include <sys/signalvar.h>
  38 #include <signal.h>
  39 #include <fcntl.h>
  40 #include <unistd.h>
  41 #include <setjmp.h>
  42 #include <errno.h>
  43 #include <pthread.h>
  44 #include "pthread_private.h"
  45
  46 /* Prototypes: */
  47 static void     thread_sig_add(struct pthread *pthread, int sig, int has_args);
  48 static void     thread_sig_check_state(struct pthread *pthread, int sig);
  49 static struct pthread *thread_sig_find(int sig);
  50 static void     thread_sig_handle_special(int sig);
  51 static void     thread_sigframe_add(struct pthread *thread, int sig,
  52                     int has_args);
  53 static void     thread_sigframe_save(struct pthread *thread,
  54                     struct pthread_signal_frame *psf);
  55 static void     thread_sig_invoke_handler(int sig, siginfo_t *info,
  56                     ucontext_t *ucp);
  57
  58 /*#define DEBUG_SIGNAL*/
  59 #ifdef DEBUG_SIGNAL
  60 #define DBG_MSG         stdout_debug
  61 #else
  62 #define DBG_MSG(x...)
  63 #endif
  64
  65 #if defined(_PTHREADS_INVARIANTS)
  66 #define SIG_SET_ACTIVE()        _sig_in_handler = 1
  67 #define SIG_SET_INACTIVE()      _sig_in_handler = 0
  68 #else
  69 #define SIG_SET_ACTIVE()
  70 #define SIG_SET_INACTIVE()
  71 #endif
  72
  73 void
  74 _thread_sig_handler(int sig, siginfo_t *info, ucontext_t *ucp)
  75 {
  76         struct pthread  *curthread = _get_curthread();
  77         struct pthread  *pthread, *pthread_h;
  78         int             in_sched = _thread_kern_in_sched;
  79         char            c;
  80
  81         if (ucp == NULL)
  82                 PANIC("Thread signal handler received null context");
  83         DBG_MSG("Got signal %d, current thread %p\n", sig, curthread);
  84
  85         /* Check if an interval timer signal: */
  86         if (sig == _SCHED_SIGNAL) {
  87                 /* Update the scheduling clock: */
  88                 gettimeofday((struct timeval *)&_sched_tod, NULL);
  89                 _sched_ticks++;
  90
  91                 if (in_sched != 0) {
  92                         /*
  93                          * The scheduler is already running; ignore this
  94                          * signal.
  95                          */
  96                 }
  97                 /*
  98                  * Check if the scheduler interrupt has come when
  99                  * the currently running thread has deferred thread
 100                  * signals.
 101                  */
 102                 else if (curthread->sig_defer_count > 0)
 103                         curthread->yield_on_sig_undefer = 1;
 104                 else {
 105                         /* Schedule the next thread: */
 106                         _thread_kern_sched(ucp);
 107
 108                         /*
 109                          * This point should not be reached, so abort the
 110                          * process:
 111                          */
 112                         PANIC("Returned to signal function from scheduler");
 113                 }
 114         }
 115         /*
 116          * Check if the kernel has been interrupted while the scheduler
 117          * is accessing the scheduling queues or if there is a currently
 118          * running thread that has deferred signals.
 119          */
 120         else if ((in_sched != 0) || (curthread->sig_defer_count > 0)) {
 121                 /* Cast the signal number to a character variable: */
 122                 c = sig;
 123
 124                 /*
 125                  * Write the signal number to the kernel pipe so that it will
 126                  * be ready to read when this signal handler returns.
 127                  */
 128                 if (_queue_signals != 0) {
 129                         __sys_extpwrite(_thread_kern_pipe[1], &c, 1, O_FBLOCKING, -1);
 130                         DBG_MSG("Got signal %d, queueing to kernel pipe\n", sig);
 131                 }
 132                 if (_thread_sigq[sig - 1].blocked == 0) {
 133                         DBG_MSG("Got signal %d, adding to _thread_sigq\n", sig);
 134                         /*
 135                          * Do not block this signal; it will be blocked
 136                          * when the pending signals are run down.
 137                          */
 138                         /* _thread_sigq[sig - 1].blocked = 1; */
 139
 140                         /*
 141                          * Queue the signal, saving siginfo and sigcontext
 142                          * (ucontext).
 143                          *
 144                          * XXX - Do we need to copy siginfo and ucp?
 145                          */
 146                         _thread_sigq[sig - 1].signo = sig;
 147                         if (info != NULL)
 148                                 memcpy(&_thread_sigq[sig - 1].siginfo, info,
 149                                     sizeof(*info));
 150                         memcpy(&_thread_sigq[sig - 1].uc, ucp, sizeof(*ucp));
 151
 152                         /* Indicate that there are queued signals: */
 153                         _thread_sigq[sig - 1].pending = 1;
 154                         _sigq_check_reqd = 1;
 155                 }
 156                 /* These signals need special handling: */
 157                 else if (sig == SIGCHLD || sig == SIGTSTP ||
 158                     sig == SIGTTIN || sig == SIGTTOU) {
 159                         _thread_sigq[sig - 1].pending = 1;
 160                         _thread_sigq[sig - 1].signo = sig;
 161                         _sigq_check_reqd = 1;
 162                 }
 163                 else
 164                         DBG_MSG("Got signal %d, ignored.\n", sig);
 165         }
 166         /*
 167          * The signal handlers should have been installed so that they
 168          * cannot be interrupted by other signals.
 169          */
 170         else if (_thread_sigq[sig - 1].blocked == 0) {
 171                 /*
 172                  * The signal is not blocked; handle the signal.
 173                  *
 174                  * Ignore subsequent occurrences of this signal
 175                  * until the current signal is handled:
 176                  */
 177                 _thread_sigq[sig - 1].blocked = 1;
 178
 179                 /* This signal will be handled; clear the pending flag: */
 180                 _thread_sigq[sig - 1].pending = 0;
 181
 182                 /*
 183                  * Save siginfo and sigcontext (ucontext).
 184                  *
 185                  * XXX - Do we need to copy siginfo and ucp?
 186                  */
 187                 _thread_sigq[sig - 1].signo = sig;
 188
 189                 if (info != NULL)
 190                         memcpy(&_thread_sigq[sig - 1].siginfo, info,
 191                             sizeof(*info));
 192                 memcpy(&_thread_sigq[sig - 1].uc, ucp, sizeof(*ucp));
 193                 SIG_SET_ACTIVE();
 194
 195                 /* Handle special signals: */
 196                 thread_sig_handle_special(sig);
 197
 198                 pthread_h = NULL;
 199                 if ((pthread = thread_sig_find(sig)) == NULL)
 200                         DBG_MSG("No thread to handle signal %d\n", sig);
 201                 else if (pthread == curthread) {
 202                         /*
 203                          * Unblock the signal and restore the process signal
 204                          * mask in case we don't return from the handler:
 205                          */
 206                         _thread_sigq[sig - 1].blocked = 0;
 207                         __sys_sigprocmask(SIG_SETMASK, &_process_sigmask, NULL);
 208
 209                         /* Call the signal handler for the current thread: */
 210                         thread_sig_invoke_handler(sig, info, ucp);
 211
 212                         /*
 213                          * Set the process signal mask in the context; it
 214                          * could have changed by the handler.
 215                          */
 216                         ucp->uc_sigmask = _process_sigmask;
 217
 218                         /* Resume the interrupted thread: */
 219                         sigreturn(ucp);
 220                 } else {
 221                         DBG_MSG("Got signal %d, adding frame to thread %p\n",
 222                             sig, pthread);
 223
 224                         /* Setup the target thread to receive the signal: */
 225                         thread_sig_add(pthread, sig, /*has_args*/ 1);
 226
 227                         /* Take a peek at the next ready to run thread: */
 228                         pthread_h = PTHREAD_PRIOQ_FIRST();
 229                         DBG_MSG("Finished adding frame, head of prio list %p\n",
 230                             pthread_h);
 231                 }
 232                 SIG_SET_INACTIVE();
 233
 234                 /*
 235                  * Switch to a different context if the currently running
 236                  * thread takes a signal, or if another thread takes a
 237                  * signal and the currently running thread is not in a
 238                  * signal handler.
 239                  */
 240                 if ((pthread_h != NULL) &&
 241                     (pthread_h->active_priority > curthread->active_priority)) {
 242                         /* Enter the kernel scheduler: */
 243                         _thread_kern_sched(ucp);
 244                 }
 245         }
 246         else {
 247                 SIG_SET_ACTIVE();
 248                 thread_sig_handle_special(sig);
 249                 SIG_SET_INACTIVE();
 250         }
 251 }
 252
 253 static void
 254 thread_sig_invoke_handler(int sig, siginfo_t *info, ucontext_t *ucp)
 255  {
 256         struct pthread  *curthread = _get_curthread();
 257         void (*sigfunc)(int, siginfo_t *, void *);
 258         int             saved_seqno;
 259         sigset_t        saved_sigmask;
 260
 261         /* Invoke the signal handler without going through the scheduler:
 262          */
 263         DBG_MSG("Got signal %d, calling handler for current thread %p\n",
 264             sig, curthread);
 265
 266         /* Save the threads signal mask: */
 267         saved_sigmask = curthread->sigmask;
 268         saved_seqno = curthread->sigmask_seqno;
 269
 270         /* Setup the threads signal mask: */
 271         SIGSETOR(curthread->sigmask, _thread_sigact[sig - 1].sa_mask);
 272         sigaddset(&curthread->sigmask, sig);
 273
 274         /*
 275          * Check that a custom handler is installed and if
 276          * the signal is not blocked:
 277          */
 278         sigfunc = _thread_sigact[sig - 1].sa_sigaction;
 279         if (((__sighandler_t *)sigfunc != SIG_DFL) &&
 280             ((__sighandler_t *)sigfunc != SIG_IGN)) {
 281                 if (((_thread_sigact[sig - 1].sa_flags & SA_SIGINFO) != 0) ||
 282                     (info == NULL))
 283                         (*(sigfunc))(sig, info, ucp);
 284                 else
 285                         (*(sigfunc))(sig, (siginfo_t *)info->si_code, ucp);
 286         }
 287         /*
 288          * Only restore the signal mask if it hasn't been changed by the
 289          * application during invocation of the signal handler:
 290          */
 291         if (curthread->sigmask_seqno == saved_seqno)
 292                 curthread->sigmask = saved_sigmask;
 293 }
 294
 295 /*
 296  * Find a thread that can handle the signal.
 297  */
 298 struct pthread *
 299 thread_sig_find(int sig)
 300 {
 301         struct pthread  *curthread = _get_curthread();
 302         int             handler_installed;
 303         struct pthread  *pthread, *pthread_next;
 304         struct pthread  *suspended_thread, *signaled_thread;
 305
 306         DBG_MSG("Looking for thread to handle signal %d\n", sig);
 307         /* Check if the signal requires a dump of thread information: */
 308         if (sig == SIGINFO) {
 309                 /* Dump thread information to file: */
 310                 _thread_dump_info();
 311
 312                 /* Unblock this signal to allow further dumps: */
 313                 _thread_sigq[sig - 1].blocked = 0;
 314         }
 315         /* Check if an interval timer signal: */
 316         else if (sig == _SCHED_SIGNAL) {
 317                 /*
 318                  * This shouldn't ever occur (should this panic?).
 319                  */
 320         } else {
 321                 /*
 322                  * Enter a loop to look for threads that have the signal
 323                  * unmasked.  POSIX specifies that a thread in a sigwait
 324                  * will get the signal over any other threads.  Second
 325                  * preference will be threads in in a sigsuspend.  Third
 326                  * preference will be the current thread.  If none of the
 327                  * above, then the signal is delivered to the first thread
 328                  * that is found.  Note that if a custom handler is not
 329                  * installed, the signal only affects threads in sigwait.
 330                  */
 331                 suspended_thread = NULL;
 332                 if ((curthread != &_thread_kern_thread) &&
 333                     !sigismember(&curthread->sigmask, sig))
 334                         signaled_thread = curthread;
 335                 else
 336                         signaled_thread = NULL;
 337                 if ((_thread_sigact[sig - 1].sa_handler == SIG_IGN) ||
 338                     (_thread_sigact[sig - 1].sa_handler == SIG_DFL))
 339                         handler_installed = 0;
 340                 else
 341                         handler_installed = 1;
 342
 343                 for (pthread = TAILQ_FIRST(&_waitingq);
 344                     pthread != NULL; pthread = pthread_next) {
 345                         /*
 346                          * Grab the next thread before possibly destroying
 347                          * the link entry.
 348                          */
 349                         pthread_next = TAILQ_NEXT(pthread, pqe);
 350
 351                         if ((pthread->state == PS_SIGWAIT) &&
 352                             sigismember(pthread->data.sigwait, sig)) {
 353                                 /* Change the state of the thread to run: */
 354                                 PTHREAD_NEW_STATE(pthread,PS_RUNNING);
 355                                 /*
 356                                  * A signal handler is not invoked for threads
 357                                  * in sigwait.  Clear the blocked and pending
 358                                  * flags.
 359                                  */
 360                                 _thread_sigq[sig - 1].blocked = 0;
 361                                 _thread_sigq[sig - 1].pending = 0;
 362
 363                                 /* Return the signal number: */
 364                                 pthread->signo = sig;
 365
 366                                 /*
 367                                  * POSIX doesn't doesn't specify which thread
 368                                  * will get the signal if there are multiple
 369                                  * waiters, so we give it to the first thread
 370                                  * we find.
 371                                  *
 372                                  * Do not attempt to deliver this signal
 373                                  * to other threads and do not add the signal
 374                                  * to the process pending set.
 375                                  */
 376                                 return (NULL);
 377                         }
 378                         else if ((handler_installed != 0) &&
 379                             !sigismember(&pthread->sigmask, sig) &&
 380                             ((pthread->flags & PTHREAD_FLAGS_SUSPENDED) == 0)) {
 381                                 if (pthread->state == PS_SIGSUSPEND) {
 382                                         if (suspended_thread == NULL)
 383                                                 suspended_thread = pthread;
 384                                 } else if (signaled_thread == NULL)
 385                                         signaled_thread = pthread;
 386                         }
 387                 }
 388
 389                 /*
 390                  * Only perform wakeups and signal delivery if there is a
 391                  * custom handler installed:
 392                  */
 393                 if (handler_installed == 0) {
 394                         /*
 395                          * There is no handler installed.  Unblock the
 396                          * signal so that if a handler _is_ installed, any
 397                          * subsequent signals can be handled.
 398                          */
 399                         _thread_sigq[sig - 1].blocked = 0;
 400                 } else {
 401                         /*
 402                          * If we didn't find a thread in the waiting queue,
 403                          * check the all threads queue:
 404                          */
 405                         if (suspended_thread == NULL &&
 406                             signaled_thread == NULL) {
 407                                 /*
 408                                  * Enter a loop to look for other threads
 409                                  * capable of receiving the signal:
 410                                  */
 411                                 TAILQ_FOREACH(pthread, &_thread_list, tle) {
 412                                         if (!sigismember(&pthread->sigmask,
 413                                             sig)) {
 414                                                 signaled_thread = pthread;
 415                                                 break;
 416                                         }
 417                                 }
 418                         }
 419
 420                         if (suspended_thread == NULL &&
 421                             signaled_thread == NULL)
 422                                 /*
 423                                  * Add it to the set of signals pending
 424                                  * on the process:
 425                                  */
 426                                 sigaddset(&_process_sigpending, sig);
 427                         else {
 428                                 /*
 429                                  * We only deliver the signal to one thread;
 430                                  * give preference to the suspended thread:
 431                                  */
 432                                 if (suspended_thread != NULL)
 433                                         pthread = suspended_thread;
 434                                 else
 435                                         pthread = signaled_thread;
 436                                 return (pthread);
 437                         }
 438                 }
 439         }
 440
 441         /* Returns nothing. */
 442         return (NULL);
 443 }
 444
 445 void
 446 _thread_sig_check_pending(struct pthread *pthread)
 447 {
 448         sigset_t        sigset;
 449         int             i;
 450
 451         /*
 452          * Check if there are pending signals for the running
 453          * thread or process that aren't blocked:
 454          */
 455         sigset = pthread->sigpend;
 456         SIGSETOR(sigset, _process_sigpending);
 457         SIGSETNAND(sigset, pthread->sigmask);
 458         if (SIGNOTEMPTY(sigset)) {
 459                 for (i = 1; i < NSIG; i++) {
 460                         if (sigismember(&sigset, i) != 0) {
 461                                 if (sigismember(&pthread->sigpend, i) != 0)
 462                                         thread_sig_add(pthread, i,
 463                                             /*has_args*/ 0);
 464                                 else {
 465                                         thread_sig_add(pthread, i,
 466                                             /*has_args*/ 1);
 467                                         sigdelset(&_process_sigpending, i);
 468                                 }
 469                         }
 470                 }
 471         }
 472 }
 473
 474 /*
 475  * This can only be called from the kernel scheduler.  It assumes that
 476  * all thread contexts are saved and that a signal frame can safely be
 477  * added to any user thread.
 478  */
 479 void
 480 _thread_sig_handle_pending(void)
 481 {
 482         struct pthread  *pthread;
 483         int             i, sig;
 484
 485         PTHREAD_ASSERT(_thread_kern_in_sched != 0,
 486             "_thread_sig_handle_pending called from outside kernel schedule");
 487         /*
 488          * Check the array of pending signals:
 489          */
 490         for (i = 0; i < NSIG; i++) {
 491                 if (_thread_sigq[i].pending != 0) {
 492                         /* This signal is no longer pending. */
 493                         _thread_sigq[i].pending = 0;
 494
 495                         sig = _thread_sigq[i].signo;
 496
 497                         /* Some signals need special handling: */
 498                         thread_sig_handle_special(sig);
 499
 500                         if (_thread_sigq[i].blocked == 0) {
 501                                 /*
 502                                  * Block future signals until this one
 503                                  * is handled:
 504                                  */
 505                                 _thread_sigq[i].blocked = 1;
 506
 507                                 if ((pthread = thread_sig_find(sig)) != NULL) {
 508                                         /*
 509                                          * Setup the target thread to receive
 510                                          * the signal:
 511                                          */
 512                                         thread_sig_add(pthread, sig,
 513                                             /*has_args*/ 1);
 514                                 }
 515                         }
 516                 }
 517         }
 518 }
 519
 520 static void
 521 thread_sig_handle_special(int sig)
 522 {
 523         struct pthread  *pthread, *pthread_next;
 524         int             i;
 525
 526         switch (sig) {
 527         case SIGCHLD:
 528                 /*
 529                  * Go through the file list and set all files
 530                  * to non-blocking again in case the child
 531                  * set some of them to block. Sigh.
 532                  */
 533                 for (i = 0; i < _thread_dtablesize; i++) {
 534                         /* Check if this file is used: */
 535                         if (_thread_fd_table[i] != NULL) {
 536                                 /*
 537                                  * Set the file descriptor to non-blocking:
 538                                  */
 539                                 __sys_fcntl(i, F_SETFL,
 540                                     _thread_fd_getflags(i) | O_NONBLOCK);
 541                         }
 542                 }
 543                 /*
 544                  * Enter a loop to wake up all threads waiting
 545                  * for a process to complete:
 546                  */
 547                 for (pthread = TAILQ_FIRST(&_waitingq);
 548                     pthread != NULL; pthread = pthread_next) {
 549                         /*
 550                          * Grab the next thread before possibly
 551                          * destroying the link entry:
 552                          */
 553                         pthread_next = TAILQ_NEXT(pthread, pqe);
 554
 555                         /*
 556                          * If this thread is waiting for a child
 557                          * process to complete, wake it up:
 558                          */
 559                         if (pthread->state == PS_WAIT_WAIT) {
 560                                 /* Make the thread runnable: */
 561                                 PTHREAD_NEW_STATE(pthread,PS_RUNNING);
 562
 563                                 /* Return the signal number: */
 564                                 pthread->signo = sig;
 565                         }
 566                 }
 567                 break;
 568
 569         /*
 570          * POSIX says that pending SIGCONT signals are
 571          * discarded when one of these signals occurs.
 572          */
 573         case SIGTSTP:
 574         case SIGTTIN:
 575         case SIGTTOU:
 576                 /*
 577                  * Enter a loop to discard pending SIGCONT
 578                  * signals:
 579                  */
 580                 TAILQ_FOREACH(pthread, &_thread_list, tle) {
 581                         sigdelset(&pthread->sigpend, SIGCONT);
 582                 }
 583                 break;
 584
 585         default:
 586                 break;
 587         }
 588 }
 589
 590 /*
 591  * Perform thread specific actions in response to a signal.
 592  * This function is only called if there is a handler installed
 593  * for the signal, and if the target thread has the signal
 594  * unmasked.
 595  */
 596 static void
 597 thread_sig_add(struct pthread *pthread, int sig, int has_args)
 598 {
 599         int     restart;
 600         int     suppress_handler = 0;
 601         int     thread_is_active = 0;
 602
 603         restart = _thread_sigact[sig - 1].sa_flags & SA_RESTART;
 604
 605         /* Make sure this signal isn't still in the pending set: */
 606         sigdelset(&pthread->sigpend, sig);
 607
 608         /*
 609          * Process according to thread state:
 610          */
 611         switch (pthread->state) {
 612         /*
 613          * States which do not change when a signal is trapped:
 614          */
 615         case PS_DEAD:
 616         case PS_DEADLOCK:
 617         case PS_STATE_MAX:
 618         case PS_SIGTHREAD:
 619                 /*
 620                  * You can't call a signal handler for threads in these
 621                  * states.
 622                  */
 623                 suppress_handler = 1;
 624                 break;
 625
 626         /*
 627          * States which do not need any cleanup handling when signals
 628          * occur:
 629          */
 630         case PS_RUNNING:
 631                 /*
 632                  * Remove the thread from the queue before changing its
 633                  * priority:
 634                  */
 635                 if ((pthread->flags & PTHREAD_FLAGS_IN_PRIOQ) != 0)
 636                         PTHREAD_PRIOQ_REMOVE(pthread);
 637                 else
 638                         /*
 639                          * This thread is running; avoid placing it in
 640                          * the run queue:
 641                          */
 642                         thread_is_active = 1;
 643                 break;
 644
 645         case PS_SUSPENDED:
 646                 break;
 647
 648         case PS_SPINBLOCK:
 649                 /* Remove the thread from the workq and waitq: */
 650                 PTHREAD_WORKQ_REMOVE(pthread);
 651                 PTHREAD_WAITQ_REMOVE(pthread);
 652                 /* Make the thread runnable: */
 653                 PTHREAD_SET_STATE(pthread, PS_RUNNING);
 654                 break;
 655
 656         case PS_SIGWAIT:
 657                 /* The signal handler is not called for threads in SIGWAIT. */
 658                 suppress_handler = 1;
 659                 /* Wake up the thread if the signal is blocked. */
 660                 if (sigismember(pthread->data.sigwait, sig)) {
 661                         /* Change the state of the thread to run: */
 662                         PTHREAD_NEW_STATE(pthread, PS_RUNNING);
 663
 664                         /* Return the signal number: */
 665                         pthread->signo = sig;
 666                 } else
 667                         /* Increment the pending signal count. */
 668                         sigaddset(&pthread->sigpend, sig);
 669                 break;
 670
 671         /*
 672          * The wait state is a special case due to the handling of
 673          * SIGCHLD signals.
 674          */
 675         case PS_WAIT_WAIT:
 676                 if (sig == SIGCHLD) {
 677                         /* Change the state of the thread to run: */
 678                         PTHREAD_WAITQ_REMOVE(pthread);
 679                         PTHREAD_SET_STATE(pthread, PS_RUNNING);
 680
 681                         /* Return the signal number: */
 682                         pthread->signo = sig;
 683                 }
 684                 else {
 685                         /*
 686                          * Mark the thread as interrupted only if the
 687                          * restart flag is not set on the signal action:
 688                          */
 689                         if (restart == 0)
 690                                 pthread->interrupted = 1;
 691                         PTHREAD_WAITQ_REMOVE(pthread);
 692                         PTHREAD_SET_STATE(pthread, PS_RUNNING);
 693                 }
 694                 break;
 695
 696         /*
 697          * States which cannot be interrupted but still require the
 698          * signal handler to run:
 699          */
 700         case PS_COND_WAIT:
 701         case PS_MUTEX_WAIT:
 702                 /*
 703                  * Remove the thread from the wait queue.  It will
 704                  * be added back to the wait queue once all signal
 705                  * handlers have been invoked.
 706                  */
 707                 PTHREAD_WAITQ_REMOVE(pthread);
 708                 break;
 709
 710         case PS_JOIN:
 711                 /*
 712                  * Remove the thread from the wait queue.  It will
 713                  * be added back to the wait queue once all signal
 714                  * handlers have been invoked.
 715                  */
 716                 PTHREAD_WAITQ_REMOVE(pthread);
 717                 /* Make the thread runnable: */
 718                 PTHREAD_SET_STATE(pthread, PS_RUNNING);
 719                 break;
 720
 721         /*
 722          * States which are interruptible but may need to be removed
 723          * from queues before any signal handler is called.
 724          *
 725          * XXX - We may not need to handle this condition, but will
 726          *       mark it as a potential problem.
 727          */
 728         case PS_FDLR_WAIT:
 729         case PS_FDLW_WAIT:
 730                 if (restart == 0)
 731                         pthread->interrupted = 1;
 732                 /*
 733                  * Remove the thread from the wait queue.  Our
 734                  * signal handler hook will remove this thread
 735                  * from the fd or file queue before invoking
 736                  * the actual handler.
 737                  */
 738                 PTHREAD_WAITQ_REMOVE(pthread);
 739                 break;
 740
 741         /*
 742          * States which are interruptible:
 743          */
 744         case PS_FDR_WAIT:
 745         case PS_FDW_WAIT:
 746                 if (restart == 0) {
 747                         /*
 748                          * Flag the operation as interrupted and
 749                          * set the state to running:
 750                          */
 751                         pthread->interrupted = 1;
 752                         PTHREAD_SET_STATE(pthread, PS_RUNNING);
 753                 }
 754                 PTHREAD_WORKQ_REMOVE(pthread);
 755                 PTHREAD_WAITQ_REMOVE(pthread);
 756                 break;
 757
 758         case PS_POLL_WAIT:
 759         case PS_SELECT_WAIT:
 760         case PS_SLEEP_WAIT:
 761                 /*
 762                  * Unmasked signals always cause poll, select, and sleep
 763                  * to terminate early, regardless of SA_RESTART:
 764                  */
 765                 pthread->interrupted = 1;
 766                 /* Remove threads in poll and select from the workq: */
 767                 if ((pthread->flags & PTHREAD_FLAGS_IN_WORKQ) != 0)
 768                         PTHREAD_WORKQ_REMOVE(pthread);
 769                 PTHREAD_WAITQ_REMOVE(pthread);
 770                 PTHREAD_SET_STATE(pthread, PS_RUNNING);
 771                 break;
 772
 773         case PS_SIGSUSPEND:
 774                 PTHREAD_WAITQ_REMOVE(pthread);
 775                 PTHREAD_SET_STATE(pthread, PS_RUNNING);
 776                 break;
 777         }
 778
 779         if (suppress_handler == 0) {
 780                 /* Setup a signal frame and save the current threads state: */
 781                 thread_sigframe_add(pthread, sig, has_args);
 782
 783                 /*
 784                  * Signals are deferred until just before the threads
 785                  * signal handler is invoked:
 786                  */
 787                 pthread->sig_defer_count = 1;
 788
 789                 /* Make sure the thread is runnable: */
 790                 if (pthread->state != PS_RUNNING)
 791                         PTHREAD_SET_STATE(pthread, PS_RUNNING);
 792                 /*
 793                  * The thread should be removed from all scheduling
 794                  * queues at this point.  Raise the priority and place
 795                  * the thread in the run queue.  It is also possible
 796                  * for a signal to be sent to a suspended thread,
 797                  * mostly via pthread_kill().  If a thread is suspended,
 798                  * don't insert it into the priority queue; just set
 799                  * its state to suspended and it will run the signal
 800                  * handler when it is resumed.
 801                  */
 802                 pthread->active_priority |= PTHREAD_SIGNAL_PRIORITY;
 803                 if ((pthread->flags & PTHREAD_FLAGS_SUSPENDED) != 0)
 804                         PTHREAD_SET_STATE(pthread, PS_SUSPENDED);
 805                 else if (thread_is_active == 0)
 806                         PTHREAD_PRIOQ_INSERT_TAIL(pthread);
 807         }
 808 }
 809
 810 static void
 811 thread_sig_check_state(struct pthread *pthread, int sig)
 812 {
 813         /*
 814          * Process according to thread state:
 815          */
 816         switch (pthread->state) {
 817         /*
 818          * States which do not change when a signal is trapped:
 819          */
 820         case PS_DEAD:
 821         case PS_DEADLOCK:
 822         case PS_STATE_MAX:
 823         case PS_SIGTHREAD:
 824         case PS_RUNNING:
 825         case PS_SUSPENDED:
 826         case PS_SPINBLOCK:
 827         case PS_COND_WAIT:
 828         case PS_JOIN:
 829         case PS_MUTEX_WAIT:
 830                 break;
 831
 832         case PS_SIGWAIT:
 833                 /* Wake up the thread if the signal is blocked. */
 834                 if (sigismember(pthread->data.sigwait, sig)) {
 835                         /* Change the state of the thread to run: */
 836                         PTHREAD_NEW_STATE(pthread, PS_RUNNING);
 837
 838                         /* Return the signal number: */
 839                         pthread->signo = sig;
 840                 } else
 841                         /* Increment the pending signal count. */
 842                         sigaddset(&pthread->sigpend, sig);
 843                 break;
 844
 845         /*
 846          * The wait state is a special case due to the handling of
 847          * SIGCHLD signals.
 848          */
 849         case PS_WAIT_WAIT:
 850                 if (sig == SIGCHLD) {
 851                         /*
 852                          * Remove the thread from the wait queue and
 853                          * make it runnable:
 854                          */
 855                         PTHREAD_NEW_STATE(pthread, PS_RUNNING);
 856
 857                         /* Return the signal number: */
 858                         pthread->signo = sig;
 859                 }
 860                 break;
 861
 862         case PS_FDLR_WAIT:
 863         case PS_FDLW_WAIT:
 864         case PS_SIGSUSPEND:
 865         case PS_SLEEP_WAIT:
 866                 /*
 867                  * Remove the thread from the wait queue and make it
 868                  * runnable:
 869                  */
 870                 PTHREAD_NEW_STATE(pthread, PS_RUNNING);
 871
 872                 /* Flag the operation as interrupted: */
 873                 pthread->interrupted = 1;
 874                 break;
 875
 876         /*
 877          * These states are additionally in the work queue:
 878          */
 879         case PS_FDR_WAIT:
 880         case PS_FDW_WAIT:
 881         case PS_POLL_WAIT:
 882         case PS_SELECT_WAIT:
 883                 /*
 884                  * Remove the thread from the wait and work queues, and
 885                  * make it runnable:
 886                  */
 887                 PTHREAD_WORKQ_REMOVE(pthread);
 888                 PTHREAD_NEW_STATE(pthread, PS_RUNNING);
 889
 890                 /* Flag the operation as interrupted: */
 891                 pthread->interrupted = 1;
 892                 break;
 893         }
 894 }
 895
 896 /*
 897  * Send a signal to a specific thread (ala pthread_kill):
 898  */
 899 void
 900 _thread_sig_send(struct pthread *pthread, int sig)
 901 {
 902         struct pthread  *curthread = _get_curthread();
 903
 904         /* Check for signals whose actions are SIG_DFL: */
 905         if (_thread_sigact[sig - 1].sa_handler == SIG_DFL) {
 906                 /*
 907                  * Check to see if a temporary signal handler is
 908                  * installed for sigwaiters:
 909                  */
 910                 if (_thread_dfl_count[sig] == 0)
 911                         /*
 912                          * Deliver the signal to the process if a handler
 913                          * is not installed:
 914                          */
 915                         kill(getpid(), sig);
 916                 /*
 917                  * Assuming we're still running after the above kill(),
 918                  * make any necessary state changes to the thread:
 919                  */
 920                 thread_sig_check_state(pthread, sig);
 921         }
 922         /*
 923          * Check that the signal is not being ignored:
 924          */
 925         else if (_thread_sigact[sig - 1].sa_handler != SIG_IGN) {
 926                 if (pthread->state == PS_SIGWAIT &&
 927                     sigismember(pthread->data.sigwait, sig)) {
 928                         /* Change the state of the thread to run: */
 929                         PTHREAD_NEW_STATE(pthread, PS_RUNNING);
 930
 931                         /* Return the signal number: */
 932                         pthread->signo = sig;
 933                 } else if (sigismember(&pthread->sigmask, sig))
 934                         /* Add the signal to the pending set: */
 935                         sigaddset(&pthread->sigpend, sig);
 936                 else if (pthread == curthread)
 937                         /* Call the signal handler for the current thread: */
 938                         thread_sig_invoke_handler(sig, NULL, NULL);
 939                 else {
 940                         /* Protect the scheduling queues: */
 941                         _thread_kern_sig_defer();
 942                         /*
 943                          * Perform any state changes due to signal
 944                          * arrival:
 945                          */
 946                         thread_sig_add(pthread, sig, /* has args */ 0);
 947                         /* Unprotect the scheduling queues: */
 948                         _thread_kern_sig_undefer();
 949                 }
 950         }
 951 }
 952
 953 /*
 954  * User thread signal handler wrapper.
 955  *
 956  *   thread - current running thread
 957  */
 958 void
 959 _thread_sig_wrapper(void)
 960 {
 961         struct pthread_signal_frame *psf;
 962         struct pthread  *thread = _get_curthread();
 963
 964         /* Get the current frame and state: */
 965         psf = thread->curframe;
 966         thread->curframe = NULL;
 967         PTHREAD_ASSERT(psf != NULL, "Invalid signal frame in signal handler");
 968
 969         /*
 970          * We're coming from the kernel scheduler; clear the in
 971          * scheduler flag:
 972          */
 973         _thread_kern_in_sched = 0;
 974
 975         /* Check the threads previous state: */
 976         if (psf->saved_state.psd_state != PS_RUNNING) {
 977                 /*
 978                  * Do a little cleanup handling for those threads in
 979                  * queues before calling the signal handler.  Signals
 980                  * for these threads are temporarily blocked until
 981                  * after cleanup handling.
 982                  */
 983                 switch (psf->saved_state.psd_state) {
 984                 case PS_FDLR_WAIT:
 985                 case PS_FDLW_WAIT:
 986                         _fd_lock_backout(thread);
 987                         psf->saved_state.psd_state = PS_RUNNING;
 988                         break;
 989
 990                 case PS_COND_WAIT:
 991                         _cond_wait_backout(thread);
 992                         psf->saved_state.psd_state = PS_RUNNING;
 993                         break;
 994
 995                 case PS_MUTEX_WAIT:
 996                         _mutex_lock_backout(thread);
 997                         psf->saved_state.psd_state = PS_RUNNING;
 998                         break;
 999
1000                 default:
1001                         break;
1002                 }
1003         }
1004
1005         /* Unblock the signal in case we don't return from the handler: */
1006         _thread_sigq[psf->signo - 1].blocked = 0;
1007
1008         /*
1009          * Lower the priority before calling the handler in case
1010          * it never returns (longjmps back):
1011          */
1012         thread->active_priority &= ~PTHREAD_SIGNAL_PRIORITY;
1013
1014         /*
1015          * Reenable interruptions without checking for the need to
1016          * context switch:
1017          */
1018         thread->sig_defer_count = 0;
1019
1020         /*
1021          * Dispatch the signal via the custom signal handler:
1022          */
1023         if (psf->sig_has_args == 0)
1024                 thread_sig_invoke_handler(psf->signo, NULL, NULL);
1025         else
1026                 thread_sig_invoke_handler(psf->signo, &psf->siginfo, &psf->uc);
1027
1028         /*
1029          * Call the kernel scheduler to safely restore the frame and
1030          * schedule the next thread:
1031          */
1032         _thread_kern_sched_frame(psf);
1033 }
1034
1035 static void
1036 thread_sigframe_add(struct pthread *thread, int sig, int has_args)
1037 {
1038         struct pthread_signal_frame *psf = NULL;
1039         unsigned long   stackp;
1040
1041         /* Get the top of the threads stack: */
1042         stackp = GET_STACK_JB(thread->ctx.jb);
1043
1044         /*
1045          * Leave a little space on the stack and round down to the
1046          * nearest aligned word:
1047          */
1048         stackp -= sizeof(double);
1049         stackp &= ~0x3UL;
1050
1051         /* Allocate room on top of the stack for a new signal frame: */
1052         stackp -= sizeof(struct pthread_signal_frame);
1053
1054         psf = (struct pthread_signal_frame *) stackp;
1055
1056         /* Save the current context in the signal frame: */
1057         thread_sigframe_save(thread, psf);
1058
1059         /* Set handler specific information: */
1060         psf->sig_has_args = has_args;
1061         psf->signo = sig;
1062         if (has_args) {
1063                 /* Copy the signal handler arguments to the signal frame: */
1064                 memcpy(&psf->uc, &_thread_sigq[psf->signo - 1].uc,
1065                     sizeof(psf->uc));
1066                 memcpy(&psf->siginfo, &_thread_sigq[psf->signo - 1].siginfo,
1067                     sizeof(psf->siginfo));
1068         }
1069
1070         /* Setup the signal mask: */
1071         SIGSETOR(thread->sigmask, _thread_sigact[sig - 1].sa_mask);
1072         sigaddset(&thread->sigmask, sig);
1073
1074         /* Set up the new frame: */
1075         thread->curframe = psf;
1076         thread->flags &= PTHREAD_FLAGS_PRIVATE | PTHREAD_FLAGS_TRACE |
1077             PTHREAD_FLAGS_IN_SYNCQ;
1078         /*
1079          * Set up the context:
1080          */
1081         stackp -= sizeof(double);
1082         _setjmp(thread->ctx.jb);
1083         SET_STACK_JB(thread->ctx.jb, stackp);
1084         SET_RETURN_ADDR_JB(thread->ctx.jb, _thread_sig_wrapper);
1085 }
1086
1087 void
1088 _thread_sigframe_restore(struct pthread *thread,
1089     struct pthread_signal_frame *psf)
1090 {
1091         memcpy(&thread->ctx, &psf->ctx, sizeof(thread->ctx));
1092         /*
1093          * Only restore the signal mask if it hasn't been changed
1094          * by the application during invocation of the signal handler:
1095          */
1096         if (thread->sigmask_seqno == psf->saved_state.psd_sigmask_seqno)
1097                 thread->sigmask = psf->saved_state.psd_sigmask;
1098         thread->curframe = psf->saved_state.psd_curframe;
1099         thread->wakeup_time = psf->saved_state.psd_wakeup_time;
1100         thread->data = psf->saved_state.psd_wait_data;
1101         thread->state = psf->saved_state.psd_state;
1102         thread->flags = psf->saved_state.psd_flags;
1103         thread->interrupted = psf->saved_state.psd_interrupted;
1104         thread->signo = psf->saved_state.psd_signo;
1105         thread->sig_defer_count = psf->saved_state.psd_sig_defer_count;
1106 }
1107
1108 static void
1109 thread_sigframe_save(struct pthread *thread, struct pthread_signal_frame *psf)
1110 {
1111         memcpy(&psf->ctx, &thread->ctx, sizeof(thread->ctx));
1112         psf->saved_state.psd_sigmask = thread->sigmask;
1113         psf->saved_state.psd_curframe = thread->curframe;
1114         psf->saved_state.psd_wakeup_time = thread->wakeup_time;
1115         psf->saved_state.psd_wait_data = thread->data;
1116         psf->saved_state.psd_state = thread->state;
1117         psf->saved_state.psd_flags = thread->flags &
1118             (PTHREAD_FLAGS_PRIVATE | PTHREAD_FLAGS_TRACE);
1119         psf->saved_state.psd_interrupted = thread->interrupted;
1120         psf->saved_state.psd_sigmask_seqno = thread->sigmask_seqno;
1121         psf->saved_state.psd_signo = thread->signo;
1122         psf->saved_state.psd_sig_defer_count = thread->sig_defer_count;
1123 }
1124