src/runtime/thread.c

   1 /*
   2  * This software is part of the SBCL system. See the README file for
   3  * more information.
   4  *
   5  * This software is derived from the CMU CL system, which was
   6  * written at Carnegie Mellon University and released into the
   7  * public domain. The software is in the public domain and is
   8  * provided with absolutely no warranty. See the COPYING and CREDITS
   9  * files for more information.
  10  */
  11
  12 #include "sbcl.h"
  13
  14 #include <stdlib.h>
  15 #include <stdio.h>
  16 #include <string.h>
  17 #ifndef LISP_FEATURE_WIN32
  18 #include <sched.h>
  19 #endif
  20 #include <signal.h>
  21 #include <stddef.h>
  22 #include <errno.h>
  23 #include <sys/types.h>
  24 #ifndef LISP_FEATURE_WIN32
  25 #include <sys/wait.h>
  26 #endif
  27
  28 #ifdef LISP_FEATURE_MACH_EXCEPTION_HANDLER
  29 #include <mach/mach.h>
  30 #include <mach/mach_error.h>
  31 #include <mach/mach_types.h>
  32 #endif
  33
  34 #include "runtime.h"
  35 #include "validate.h"           /* for BINDING_STACK_SIZE etc */
  36 #include "alloc.h"
  37 #include "thread.h"
  38 #include "arch.h"
  39 #include "target-arch-os.h"
  40 #include "os.h"
  41 #include "globals.h"
  42 #include "dynbind.h"
  43 #include "genesis/cons.h"
  44 #include "genesis/fdefn.h"
  45 #include "interr.h"             /* for lose() */
  46 #include "gc-internal.h"
  47
  48 #ifdef LISP_FEATURE_WIN32
  49 /*
  50  * Win32 doesn't have SIGSTKSZ, and we're not switching stacks anyway,
  51  * so define it arbitrarily
  52  */
  53 #define SIGSTKSZ 1024
  54 #endif
  55
  56 #if defined(LISP_FEATURE_DARWIN) && defined(LISP_FEATURE_SB_THREAD)
  57 #define DELAY_THREAD_POST_MORTEM 5
  58 #define LOCK_CREATE_THREAD
  59 #endif
  60
  61 #ifdef LISP_FEATURE_FREEBSD
  62 #define CREATE_CLEANUP_THREAD
  63 #define LOCK_CREATE_THREAD
  64 #endif
  65
  66 #ifdef LISP_FEATURE_SB_THREAD
  67 struct thread_post_mortem {
  68 #ifdef DELAY_THREAD_POST_MORTEM
  69     struct thread_post_mortem *next;
  70 #endif
  71     os_thread_t os_thread;
  72     pthread_attr_t *os_attr;
  73     os_vm_address_t os_address;
  74 };
  75
  76 #ifdef DELAY_THREAD_POST_MORTEM
  77 static int pending_thread_post_mortem_count = 0;
  78 pthread_mutex_t thread_post_mortem_lock = PTHREAD_MUTEX_INITIALIZER;
  79 #endif
  80 static struct thread_post_mortem * volatile pending_thread_post_mortem = 0;
  81 #endif
  82
  83 int dynamic_values_bytes=TLS_SIZE*sizeof(lispobj);  /* same for all threads */
  84 struct thread *all_threads;
  85 extern struct interrupt_data * global_interrupt_data;
  86
  87 #ifdef LISP_FEATURE_SB_THREAD
  88 pthread_mutex_t all_threads_lock = PTHREAD_MUTEX_INITIALIZER;
  89 #ifdef LOCK_CREATE_THREAD
  90 static pthread_mutex_t create_thread_lock = PTHREAD_MUTEX_INITIALIZER;
  91 #endif
  92 #ifdef LISP_FEATURE_GCC_TLS
  93 __thread struct thread *current_thread;
  94 #endif
  95 #endif
  96
  97 #if defined(LISP_FEATURE_X86) || defined(LISP_FEATURE_X86_64)
  98 extern lispobj call_into_lisp_first_time(lispobj fun, lispobj *args, int nargs);
  99 #endif
 100
 101 static void
 102 link_thread(struct thread *th)
 103 {
 104     if (all_threads) all_threads->prev=th;
 105     th->next=all_threads;
 106     th->prev=0;
 107     all_threads=th;
 108 }
 109
 110 #ifdef LISP_FEATURE_SB_THREAD
 111 static void
 112 unlink_thread(struct thread *th)
 113 {
 114     if (th->prev)
 115         th->prev->next = th->next;
 116     else
 117         all_threads = th->next;
 118     if (th->next)
 119         th->next->prev = th->prev;
 120 }
 121 #endif
 122
 123 static int
 124 initial_thread_trampoline(struct thread *th)
 125 {
 126     lispobj function;
 127 #if defined(LISP_FEATURE_X86) || defined(LISP_FEATURE_X86_64)
 128     lispobj *args = NULL;
 129 #endif
 130     function = th->no_tls_value_marker;
 131     th->no_tls_value_marker = NO_TLS_VALUE_MARKER_WIDETAG;
 132     if(arch_os_thread_init(th)==0) return 1;
 133     link_thread(th);
 134     th->os_thread=thread_self();
 135 #ifndef LISP_FEATURE_WIN32
 136     protect_control_stack_hard_guard_page(1, NULL);
 137     protect_binding_stack_hard_guard_page(1, NULL);
 138     protect_alien_stack_hard_guard_page(1, NULL);
 139     protect_control_stack_guard_page(1, NULL);
 140     protect_binding_stack_guard_page(1, NULL);
 141     protect_alien_stack_guard_page(1, NULL);
 142 #endif
 143
 144 #if defined(LISP_FEATURE_X86) || defined(LISP_FEATURE_X86_64)
 145     return call_into_lisp_first_time(function,args,0);
 146 #else
 147     return funcall0(function);
 148 #endif
 149 }
 150
 151 #ifdef LISP_FEATURE_SB_THREAD
 152 #define THREAD_STATE_LOCK_SIZE \
 153     (sizeof(pthread_mutex_t))+(sizeof(pthread_cond_t))
 154 #else
 155 #define THREAD_STATE_LOCK_SIZE 0
 156 #endif
 157
 158 #define THREAD_STRUCT_SIZE (thread_control_stack_size + BINDING_STACK_SIZE + \
 159                             ALIEN_STACK_SIZE +                               \
 160                             THREAD_STATE_LOCK_SIZE +                         \
 161                             dynamic_values_bytes +                           \
 162                             32 * SIGSTKSZ +                                  \
 163                             THREAD_ALIGNMENT_BYTES)
 164
 165 #ifdef LISP_FEATURE_SB_THREAD
 166 /* THREAD POST MORTEM CLEANUP
 167  *
 168  * Memory allocated for the thread stacks cannot be reclaimed while
 169  * the thread is still alive, so we need a mechanism for post mortem
 170  * cleanups. FIXME: We actually have three, for historical reasons as
 171  * the saying goes. Do we really need three? Nikodemus guesses that
 172  * not anymore, now that we properly call pthread_attr_destroy before
 173  * freeing the stack. */
 174
 175 static struct thread_post_mortem *
 176 plan_thread_post_mortem(struct thread *corpse)
 177 {
 178     if (corpse) {
 179         struct thread_post_mortem *post_mortem = malloc(sizeof(struct thread_post_mortem));
 180         gc_assert(post_mortem);
 181         post_mortem->os_thread = corpse->os_thread;
 182         post_mortem->os_attr = corpse->os_attr;
 183         post_mortem->os_address = corpse->os_address;
 184 #ifdef DELAY_THREAD_POST_MORTEM
 185         post_mortem->next = NULL;
 186 #endif
 187         return post_mortem;
 188     } else {
 189         /* FIXME: When does this happen? */
 190         return NULL;
 191     }
 192 }
 193
 194 static void
 195 perform_thread_post_mortem(struct thread_post_mortem *post_mortem)
 196 {
 197 #ifdef CREATE_POST_MORTEM_THREAD
 198     pthread_detach(pthread_self());
 199 #endif
 200     if (post_mortem) {
 201         gc_assert(!pthread_join(post_mortem->os_thread, NULL));
 202         gc_assert(!pthread_attr_destroy(post_mortem->os_attr));
 203         free(post_mortem->os_attr);
 204         os_invalidate(post_mortem->os_address, THREAD_STRUCT_SIZE);
 205         free(post_mortem);
 206     }
 207 }
 208
 209 static void
 210 schedule_thread_post_mortem(struct thread *corpse)
 211 {
 212     struct thread_post_mortem *post_mortem = NULL;
 213     if (corpse) {
 214         post_mortem = plan_thread_post_mortem(corpse);
 215
 216 #ifdef DELAY_THREAD_POST_MORTEM
 217         pthread_mutex_lock(&thread_post_mortem_lock);
 218         /* First stick the new post mortem to the end of the queue. */
 219         if (pending_thread_post_mortem) {
 220             struct thread_post_mortem *next = pending_thread_post_mortem;
 221             while (next->next) {
 222                 next = next->next;
 223             }
 224             next->next = post_mortem;
 225         } else {
 226             pending_thread_post_mortem = post_mortem;
 227         }
 228         /* Then, if there are enough things in the queue, clean up one
 229          * from the head -- or increment the count, and null out the
 230          * post_mortem we have. */
 231         if (pending_thread_post_mortem_count > DELAY_THREAD_POST_MORTEM) {
 232             post_mortem = pending_thread_post_mortem;
 233             pending_thread_post_mortem = post_mortem->next;
 234         } else {
 235             pending_thread_post_mortem_count++;
 236             post_mortem = NULL;
 237         }
 238         pthread_mutex_unlock(&thread_post_mortem_lock);
 239         /* Finally run, the cleanup, if any. */
 240         perform_thread_post_mortem(post_mortem);
 241 #elif defined(CREATE_POST_MORTEM_THREAD)
 242         gc_assert(!pthread_create(&thread, NULL, perform_thread_post_mortem, post_mortem));
 243 #else
 244         post_mortem = (struct thread_post_mortem *)
 245             swap_lispobjs((lispobj *)(void *)&pending_thread_post_mortem,
 246                           (lispobj)post_mortem);
 247         perform_thread_post_mortem(post_mortem);
 248 #endif
 249     }
 250 }
 251
 252 /* this is the first thing that runs in the child (which is why the
 253  * silly calling convention).  Basically it calls the user's requested
 254  * lisp function after doing arch_os_thread_init and whatever other
 255  * bookkeeping needs to be done
 256  */
 257 int
 258 new_thread_trampoline(struct thread *th)
 259 {
 260     lispobj function;
 261     int result, lock_ret;
 262
 263     FSHOW((stderr,"/creating thread %lu\n", thread_self()));
 264     check_deferrables_blocked_or_lose(0);
 265     check_gc_signals_unblocked_or_lose(0);
 266     function = th->no_tls_value_marker;
 267     th->no_tls_value_marker = NO_TLS_VALUE_MARKER_WIDETAG;
 268     if(arch_os_thread_init(th)==0) {
 269         /* FIXME: handle error */
 270         lose("arch_os_thread_init failed\n");
 271     }
 272
 273     th->os_thread=thread_self();
 274     protect_control_stack_guard_page(1, NULL);
 275     protect_binding_stack_guard_page(1, NULL);
 276     protect_alien_stack_guard_page(1, NULL);
 277     /* Since GC can only know about this thread from the all_threads
 278      * list and we're just adding this thread to it, there is no
 279      * danger of deadlocking even with SIG_STOP_FOR_GC blocked (which
 280      * it is not). */
 281     lock_ret = pthread_mutex_lock(&all_threads_lock);
 282     gc_assert(lock_ret == 0);
 283     link_thread(th);
 284     lock_ret = pthread_mutex_unlock(&all_threads_lock);
 285     gc_assert(lock_ret == 0);
 286
 287     result = funcall0(function);
 288
 289     /* Block GC */
 290     block_blockable_signals(0, 0);
 291     set_thread_state(th, STATE_DEAD);
 292
 293     /* SIG_STOP_FOR_GC is blocked and GC might be waiting for this
 294      * thread, but since we are already dead it won't wait long. */
 295     lock_ret = pthread_mutex_lock(&all_threads_lock);
 296     gc_assert(lock_ret == 0);
 297
 298     gc_alloc_update_page_tables(BOXED_PAGE_FLAG, &th->alloc_region);
 299     unlink_thread(th);
 300     pthread_mutex_unlock(&all_threads_lock);
 301     gc_assert(lock_ret == 0);
 302
 303     if(th->tls_cookie>=0) arch_os_thread_cleanup(th);
 304     pthread_mutex_destroy(th->state_lock);
 305     pthread_cond_destroy(th->state_cond);
 306
 307     os_invalidate((os_vm_address_t)th->interrupt_data,
 308                   (sizeof (struct interrupt_data)));
 309
 310 #ifdef LISP_FEATURE_MACH_EXCEPTION_HANDLER
 311     FSHOW((stderr, "Deallocating mach port %x\n", THREAD_STRUCT_TO_EXCEPTION_PORT(th)));
 312     mach_port_move_member(mach_task_self(),
 313                           THREAD_STRUCT_TO_EXCEPTION_PORT(th),
 314                           MACH_PORT_NULL);
 315     mach_port_deallocate(mach_task_self(),
 316                          THREAD_STRUCT_TO_EXCEPTION_PORT(th));
 317     mach_port_destroy(mach_task_self(),
 318                       THREAD_STRUCT_TO_EXCEPTION_PORT(th));
 319 #endif
 320
 321     schedule_thread_post_mortem(th);
 322     FSHOW((stderr,"/exiting thread %lu\n", thread_self()));
 323     return result;
 324 }
 325
 326 #endif /* LISP_FEATURE_SB_THREAD */
 327
 328 static void
 329 free_thread_struct(struct thread *th)
 330 {
 331     if (th->interrupt_data)
 332         os_invalidate((os_vm_address_t) th->interrupt_data,
 333                       (sizeof (struct interrupt_data)));
 334     os_invalidate((os_vm_address_t) th->os_address,
 335                   THREAD_STRUCT_SIZE);
 336 }
 337
 338 /* this is called from any other thread to create the new one, and
 339  * initialize all parts of it that can be initialized from another
 340  * thread
 341  */
 342
 343 static struct thread *
 344 create_thread_struct(lispobj initial_function) {
 345     union per_thread_data *per_thread;
 346     struct thread *th=0;        /*  subdue gcc */
 347     void *spaces=0;
 348     void *aligned_spaces=0;
 349 #ifdef LISP_FEATURE_SB_THREAD
 350     unsigned int i;
 351 #endif
 352
 353     /* May as well allocate all the spaces at once: it saves us from
 354      * having to decide what to do if only some of the allocations
 355      * succeed. SPACES must be appropriately aligned, since the GC
 356      * expects the control stack to start at a page boundary -- and
 357      * the OS may have even more rigorous requirements. We can't rely
 358      * on the alignment passed from os_validate, since that might
 359      * assume the current (e.g. 4k) pagesize, while we calculate with
 360      * the biggest (e.g. 64k) pagesize allowed by the ABI. */
 361     spaces=os_validate(0, THREAD_STRUCT_SIZE);
 362     if(!spaces)
 363         return NULL;
 364     /* Aligning up is safe as THREAD_STRUCT_SIZE has
 365      * THREAD_ALIGNMENT_BYTES padding. */
 366     aligned_spaces = (void *)((((unsigned long)(char *)spaces)
 367                                + THREAD_ALIGNMENT_BYTES-1)
 368                               &~(unsigned long)(THREAD_ALIGNMENT_BYTES-1));
 369     per_thread=(union per_thread_data *)
 370         (aligned_spaces+
 371          thread_control_stack_size+
 372          BINDING_STACK_SIZE+
 373          ALIEN_STACK_SIZE +
 374          THREAD_STATE_LOCK_SIZE);
 375
 376 #ifdef LISP_FEATURE_SB_THREAD
 377     for(i = 0; i < (dynamic_values_bytes / sizeof(lispobj)); i++)
 378         per_thread->dynamic_values[i] = NO_TLS_VALUE_MARKER_WIDETAG;
 379     if (all_threads == 0) {
 380         if(SymbolValue(FREE_TLS_INDEX,0)==UNBOUND_MARKER_WIDETAG) {
 381             SetSymbolValue
 382                 (FREE_TLS_INDEX,
 383                  /* FIXME: should be MAX_INTERRUPTS -1 ? */
 384                  make_fixnum(MAX_INTERRUPTS+
 385                              sizeof(struct thread)/sizeof(lispobj)),
 386                  0);
 387             SetSymbolValue(TLS_INDEX_LOCK,make_fixnum(0),0);
 388         }
 389 #define STATIC_TLS_INIT(sym,field) \
 390   ((struct symbol *)(sym-OTHER_POINTER_LOWTAG))->tls_index= \
 391   make_fixnum(THREAD_SLOT_OFFSET_WORDS(field))
 392
 393         STATIC_TLS_INIT(BINDING_STACK_START,binding_stack_start);
 394         STATIC_TLS_INIT(BINDING_STACK_POINTER,binding_stack_pointer);
 395         STATIC_TLS_INIT(CONTROL_STACK_START,control_stack_start);
 396         STATIC_TLS_INIT(CONTROL_STACK_END,control_stack_end);
 397         STATIC_TLS_INIT(ALIEN_STACK,alien_stack_pointer);
 398 #if defined(LISP_FEATURE_X86) || defined (LISP_FEATURE_X86_64)
 399         STATIC_TLS_INIT(PSEUDO_ATOMIC_BITS,pseudo_atomic_bits);
 400 #endif
 401 #undef STATIC_TLS_INIT
 402     }
 403 #endif
 404
 405     th=&per_thread->thread;
 406     th->os_address = spaces;
 407     th->control_stack_start = aligned_spaces;
 408     th->binding_stack_start=
 409         (lispobj*)((void*)th->control_stack_start+thread_control_stack_size);
 410     th->control_stack_end = th->binding_stack_start;
 411     th->alien_stack_start=
 412         (lispobj*)((void*)th->binding_stack_start+BINDING_STACK_SIZE);
 413     th->binding_stack_pointer=th->binding_stack_start;
 414     th->this=th;
 415     th->os_thread=0;
 416 #ifdef LISP_FEATURE_SB_THREAD
 417     th->os_attr=malloc(sizeof(pthread_attr_t));
 418     th->state_lock=(pthread_mutex_t *)((void *)th->alien_stack_start +
 419                                        ALIEN_STACK_SIZE);
 420     pthread_mutex_init(th->state_lock, NULL);
 421     th->state_cond=(pthread_cond_t *)((void *)th->state_lock +
 422                                       (sizeof(pthread_mutex_t)));
 423     pthread_cond_init(th->state_cond, NULL);
 424 #endif
 425     th->state=STATE_RUNNING;
 426 #ifdef LISP_FEATURE_STACK_GROWS_DOWNWARD_NOT_UPWARD
 427     th->alien_stack_pointer=((void *)th->alien_stack_start
 428                              + ALIEN_STACK_SIZE-N_WORD_BYTES);
 429 #else
 430     th->alien_stack_pointer=((void *)th->alien_stack_start);
 431 #endif
 432 #if defined(LISP_FEATURE_X86) || defined (LISP_FEATURE_X86_64)
 433     th->pseudo_atomic_bits=0;
 434 #endif
 435 #ifdef LISP_FEATURE_GENCGC
 436     gc_set_region_empty(&th->alloc_region);
 437 #endif
 438
 439 #ifndef LISP_FEATURE_SB_THREAD
 440     /* the tls-points-into-struct-thread trick is only good for threaded
 441      * sbcl, because unithread sbcl doesn't have tls.  So, we copy the
 442      * appropriate values from struct thread here, and make sure that
 443      * we use the appropriate SymbolValue macros to access any of the
 444      * variable quantities from the C runtime.  It's not quite OAOOM,
 445      * it just feels like it */
 446     SetSymbolValue(BINDING_STACK_START,(lispobj)th->binding_stack_start,th);
 447     SetSymbolValue(CONTROL_STACK_START,(lispobj)th->control_stack_start,th);
 448     SetSymbolValue(CONTROL_STACK_END,(lispobj)th->control_stack_end,th);
 449 #if defined(LISP_FEATURE_X86) || defined (LISP_FEATURE_X86_64)
 450     SetSymbolValue(BINDING_STACK_POINTER,(lispobj)th->binding_stack_pointer,th);
 451     SetSymbolValue(ALIEN_STACK,(lispobj)th->alien_stack_pointer,th);
 452     SetSymbolValue(PSEUDO_ATOMIC_BITS,(lispobj)th->pseudo_atomic_bits,th);
 453 #else
 454     current_binding_stack_pointer=th->binding_stack_pointer;
 455     current_control_stack_pointer=th->control_stack_start;
 456 #endif
 457 #endif
 458     bind_variable(CURRENT_CATCH_BLOCK,make_fixnum(0),th);
 459     bind_variable(CURRENT_UNWIND_PROTECT_BLOCK,make_fixnum(0),th);
 460     bind_variable(FREE_INTERRUPT_CONTEXT_INDEX,make_fixnum(0),th);
 461     bind_variable(INTERRUPT_PENDING, NIL,th);
 462     bind_variable(INTERRUPTS_ENABLED,T,th);
 463     bind_variable(ALLOW_WITH_INTERRUPTS,T,th);
 464     bind_variable(GC_PENDING,NIL,th);
 465     bind_variable(ALLOC_SIGNAL,NIL,th);
 466 #ifdef LISP_FEATURE_SB_THREAD
 467     bind_variable(STOP_FOR_GC_PENDING,NIL,th);
 468 #endif
 469
 470     th->interrupt_data = (struct interrupt_data *)
 471         os_validate(0,(sizeof (struct interrupt_data)));
 472     if (!th->interrupt_data) {
 473         free_thread_struct(th);
 474         return 0;
 475     }
 476     th->interrupt_data->pending_handler = 0;
 477     th->interrupt_data->gc_blocked_deferrables = 0;
 478 #ifdef LISP_FEATURE_PPC
 479     th->interrupt_data->allocation_trap_context = 0;
 480 #endif
 481     th->no_tls_value_marker=initial_function;
 482
 483     th->stepping = NIL;
 484     return th;
 485 }
 486
 487 #ifdef LISP_FEATURE_MACH_EXCEPTION_HANDLER
 488 mach_port_t setup_mach_exception_handling_thread();
 489 kern_return_t mach_thread_init(mach_port_t thread_exception_port);
 490
 491 #endif
 492
 493 void create_initial_thread(lispobj initial_function) {
 494     struct thread *th=create_thread_struct(initial_function);
 495     if(th) {
 496 #ifdef LISP_FEATURE_MACH_EXCEPTION_HANDLER
 497         setup_mach_exception_handling_thread();
 498 #endif
 499         initial_thread_trampoline(th); /* no return */
 500     } else lose("can't create initial thread\n");
 501 }
 502
 503 #ifdef LISP_FEATURE_SB_THREAD
 504
 505 #ifndef __USE_XOPEN2K
 506 extern int pthread_attr_setstack (pthread_attr_t *__attr, void *__stackaddr,
 507                                   size_t __stacksize);
 508 #endif
 509
 510 boolean create_os_thread(struct thread *th,os_thread_t *kid_tid)
 511 {
 512     /* The new thread inherits the restrictive signal mask set here,
 513      * and enables signals again when it is set up properly. */
 514     sigset_t oldset;
 515     boolean r=1;
 516     int retcode = 0, initcode;
 517
 518     FSHOW_SIGNAL((stderr,"/create_os_thread: creating new thread\n"));
 519
 520     /* Blocking deferrable signals is enough, no need to block
 521      * SIG_STOP_FOR_GC because the child process is not linked onto
 522      * all_threads until it's ready. */
 523     block_deferrable_signals(0, &oldset);
 524
 525 #ifdef LOCK_CREATE_THREAD
 526     retcode = pthread_mutex_lock(&create_thread_lock);
 527     gc_assert(retcode == 0);
 528     FSHOW_SIGNAL((stderr,"/create_os_thread: got lock\n"));
 529 #endif
 530
 531     if((initcode = pthread_attr_init(th->os_attr)) ||
 532        /* call_into_lisp_first_time switches the stack for the initial
 533         * thread. For the others, we use this. */
 534        (pthread_attr_setstack(th->os_attr,th->control_stack_start,
 535                               thread_control_stack_size)) ||
 536        (retcode = pthread_create
 537         (kid_tid,th->os_attr,(void *(*)(void *))new_thread_trampoline,th))) {
 538         FSHOW_SIGNAL((stderr, "init = %d\n", initcode));
 539         FSHOW_SIGNAL((stderr, "pthread_create returned %d, errno %d\n",
 540                       retcode, errno));
 541         if(retcode < 0) {
 542             perror("create_os_thread");
 543         }
 544         r=0;
 545     }
 546
 547 #ifdef LOCK_CREATE_THREAD
 548     retcode = pthread_mutex_unlock(&create_thread_lock);
 549     gc_assert(retcode == 0);
 550     FSHOW_SIGNAL((stderr,"/create_os_thread: released lock\n"));
 551 #endif
 552     thread_sigmask(SIG_SETMASK,&oldset,0);
 553     return r;
 554 }
 555
 556 os_thread_t create_thread(lispobj initial_function) {
 557     struct thread *th, *thread = arch_os_get_current_thread();
 558     os_thread_t kid_tid = 0;
 559
 560     /* Must defend against async unwinds. */
 561     if (SymbolValue(INTERRUPTS_ENABLED, thread) != NIL)
 562         lose("create_thread is not safe when interrupts are enabled.\n");
 563
 564     /* Assuming that a fresh thread struct has no lisp objects in it,
 565      * linking it to all_threads can be left to the thread itself
 566      * without fear of gc lossage. initial_function violates this
 567      * assumption and must stay pinned until the child starts up. */
 568     th = create_thread_struct(initial_function);
 569     if (th && !create_os_thread(th,&kid_tid)) {
 570         free_thread_struct(th);
 571         kid_tid = 0;
 572     }
 573     return kid_tid;
 574 }
 575
 576 /* stopping the world is a two-stage process.  From this thread we signal
 577  * all the others with SIG_STOP_FOR_GC.  The handler for this signal does
 578  * the usual pseudo-atomic checks (we don't want to stop a thread while
 579  * it's in the middle of allocation) then waits for another SIG_STOP_FOR_GC.
 580  */
 581
 582 /* To avoid deadlocks when gc stops the world all clients of each
 583  * mutex must enable or disable SIG_STOP_FOR_GC for the duration of
 584  * holding the lock, but they must agree on which. */
 585 void gc_stop_the_world()
 586 {
 587     struct thread *p,*th=arch_os_get_current_thread();
 588     int status, lock_ret;
 589 #ifdef LOCK_CREATE_THREAD
 590     /* KLUDGE: Stopping the thread during pthread_create() causes deadlock
 591      * on FreeBSD. */
 592     FSHOW_SIGNAL((stderr,"/gc_stop_the_world:waiting on create_thread_lock\n"));
 593     lock_ret = pthread_mutex_lock(&create_thread_lock);
 594     gc_assert(lock_ret == 0);
 595     FSHOW_SIGNAL((stderr,"/gc_stop_the_world:got create_thread_lock\n"));
 596 #endif
 597     FSHOW_SIGNAL((stderr,"/gc_stop_the_world:waiting on lock\n"));
 598     /* keep threads from starting while the world is stopped. */
 599     lock_ret = pthread_mutex_lock(&all_threads_lock);      \
 600     gc_assert(lock_ret == 0);
 601
 602     FSHOW_SIGNAL((stderr,"/gc_stop_the_world:got lock\n"));
 603     /* stop all other threads by sending them SIG_STOP_FOR_GC */
 604     for(p=all_threads; p; p=p->next) {
 605         gc_assert(p->os_thread != 0);
 606         FSHOW_SIGNAL((stderr,"/gc_stop_the_world: thread=%lu, state=%x\n",
 607                       p->os_thread, thread_state(p)));
 608         if((p!=th) && ((thread_state(p)==STATE_RUNNING))) {
 609             FSHOW_SIGNAL((stderr,"/gc_stop_the_world: suspending thread %lu\n",
 610                           p->os_thread));
 611             /* We already hold all_thread_lock, P can become DEAD but
 612              * cannot exit, ergo it's safe to use pthread_kill. */
 613             status=pthread_kill(p->os_thread,SIG_STOP_FOR_GC);
 614             if (status==ESRCH) {
 615                 /* This thread has exited. */
 616                 gc_assert(thread_state(p)==STATE_DEAD);
 617             } else if (status) {
 618                 lose("cannot send suspend thread=%lu: %d, %s\n",
 619                      p->os_thread,status,strerror(status));
 620             }
 621         }
 622     }
 623     FSHOW_SIGNAL((stderr,"/gc_stop_the_world:signals sent\n"));
 624     for(p=all_threads;p;p=p->next) {
 625         if (p!=th) {
 626             FSHOW_SIGNAL
 627                 ((stderr,
 628                   "/gc_stop_the_world: waiting for thread=%lu: state=%x\n",
 629                   p->os_thread, thread_state(p)));
 630             wait_for_thread_state_change(p, STATE_RUNNING);
 631             if (p->state == STATE_RUNNING)
 632                 lose("/gc_stop_the_world: unexpected state");
 633         }
 634     }
 635     FSHOW_SIGNAL((stderr,"/gc_stop_the_world:end\n"));
 636 }
 637
 638 void gc_start_the_world()
 639 {
 640     struct thread *p,*th=arch_os_get_current_thread();
 641     int lock_ret;
 642     /* if a resumed thread creates a new thread before we're done with
 643      * this loop, the new thread will get consed on the front of
 644      * all_threads, but it won't have been stopped so won't need
 645      * restarting */
 646     FSHOW_SIGNAL((stderr,"/gc_start_the_world:begin\n"));
 647     for(p=all_threads;p;p=p->next) {
 648         gc_assert(p->os_thread!=0);
 649         if (p!=th) {
 650             lispobj state = thread_state(p);
 651             if (state != STATE_DEAD) {
 652                 if(state != STATE_SUSPENDED) {
 653                     lose("gc_start_the_world: wrong thread state is %d\n",
 654                          fixnum_value(state));
 655                 }
 656                 FSHOW_SIGNAL((stderr, "/gc_start_the_world: resuming %lu\n",
 657                               p->os_thread));
 658                 set_thread_state(p, STATE_RUNNING);
 659             }
 660         }
 661     }
 662
 663     lock_ret = pthread_mutex_unlock(&all_threads_lock);
 664     gc_assert(lock_ret == 0);
 665 #ifdef LOCK_CREATE_THREAD
 666     lock_ret = pthread_mutex_unlock(&create_thread_lock);
 667     gc_assert(lock_ret == 0);
 668 #endif
 669
 670     FSHOW_SIGNAL((stderr,"/gc_start_the_world:end\n"));
 671 }
 672 #endif
 673
 674 int
 675 thread_yield()
 676 {
 677 #ifdef LISP_FEATURE_SB_THREAD
 678     return sched_yield();
 679 #else
 680     return 0;
 681 #endif
 682 }
 683
 684 /* If the thread id given does not belong to a running thread (it has
 685  * exited or never even existed) pthread_kill _may_ fail with ESRCH,
 686  * but it is also allowed to just segfault, see
 687  * <http://udrepper.livejournal.com/16844.html>.
 688  *
 689  * Relying on thread ids can easily backfire since ids are recycled
 690  * (NPTL recycles them extremely fast) so a signal can be sent to
 691  * another process if the one it was sent to exited.
 692  *
 693  * We send signals in two places: signal_interrupt_thread sends a
 694  * signal that's harmless if delivered to another thread, but
 695  * SIG_STOP_FOR_GC is fatal.
 696  *
 697  * For these reasons, we must make sure that the thread is still alive
 698  * when the pthread_kill is called and return if the thread is
 699  * exiting. */
 700 int
 701 kill_safely(os_thread_t os_thread, int signal)
 702 {
 703     FSHOW_SIGNAL((stderr,"/kill_safely: %lu, %d\n", os_thread, signal));
 704     {
 705 #ifdef LISP_FEATURE_SB_THREAD
 706         sigset_t oldset;
 707         struct thread *thread;
 708         /* pthread_kill is not async signal safe and we don't want to be
 709          * interrupted while holding the lock. */
 710         block_deferrable_signals(0, &oldset);
 711         pthread_mutex_lock(&all_threads_lock);
 712         for (thread = all_threads; thread; thread = thread->next) {
 713             if (thread->os_thread == os_thread) {
 714                 int status = pthread_kill(os_thread, signal);
 715                 if (status)
 716                     lose("kill_safely: pthread_kill failed with %d\n", status);
 717                 break;
 718             }
 719         }
 720         pthread_mutex_unlock(&all_threads_lock);
 721         thread_sigmask(SIG_SETMASK,&oldset,0);
 722         if (thread)
 723             return 0;
 724         else
 725             return -1;
 726 #else
 727         int status;
 728         if (os_thread != 0)
 729             lose("kill_safely: who do you want to kill? %d?\n", os_thread);
 730         /* Dubious (as in don't know why it works) workaround for the
 731          * signal sometimes not being generated on darwin. */
 732 #ifdef LISP_FEATURE_DARWIN
 733         {
 734             sigset_t oldset;
 735             sigprocmask(SIG_BLOCK, &deferrable_sigset, &oldset);
 736             status = raise(signal);
 737             sigprocmask(SIG_SETMASK,&oldset,0);
 738         }
 739 #else
 740         status = raise(signal);
 741 #endif
 742         if (status == 0) {
 743             return 0;
 744         } else {
 745             lose("cannot raise signal %d, %d %s\n",
 746                  signal, status, strerror(errno));
 747         }
 748 #endif
 749     }
 750 }