src/runtime/thread.c

   1 #include <stdlib.h>
   2 #include <stdio.h>
   3 #include <string.h>
   4 #include <sched.h>
   5 #include <signal.h>
   6 #include <stddef.h>
   7 #include <errno.h>
   8 #include <sys/types.h>
   9 #include <sys/wait.h>
  10
  11 #include "sbcl.h"
  12 #include "runtime.h"
  13 #include "validate.h"           /* for CONTROL_STACK_SIZE etc */
  14 #include "alloc.h"
  15 #include "thread.h"
  16 #include "arch.h"
  17 #include "target-arch-os.h"
  18 #include "os.h"
  19 #include "globals.h"
  20 #include "dynbind.h"
  21 #include "genesis/cons.h"
  22 #include "genesis/fdefn.h"
  23 #include "interr.h"             /* for lose() */
  24 #include "gc-internal.h"
  25
  26 #define ALIEN_STACK_SIZE (1*1024*1024) /* 1Mb size chosen at random */
  27
  28 struct freeable_stack {
  29     os_thread_t os_thread;
  30     os_vm_address_t stack;
  31 };
  32
  33 static struct freeable_stack * volatile freeable_stack = 0;
  34
  35 int dynamic_values_bytes=4096*sizeof(lispobj);  /* same for all threads */
  36 struct thread * volatile all_threads;
  37 extern struct interrupt_data * global_interrupt_data;
  38 extern int linux_no_threads_p;
  39
  40 #ifdef LISP_FEATURE_SB_THREAD
  41
  42 pthread_mutex_t all_threads_lock = PTHREAD_MUTEX_INITIALIZER;
  43
  44 #if defined(LISP_FEATURE_X86) || defined(LISP_FEATURE_X86_64)
  45 extern lispobj call_into_lisp_first_time(lispobj fun, lispobj *args, int nargs);
  46 #endif
  47
  48 #endif
  49
  50 static void
  51 link_thread(struct thread *th)
  52 {
  53     if (all_threads) all_threads->prev=th;
  54     th->next=all_threads;
  55     th->prev=0;
  56     all_threads=th;
  57 }
  58
  59 #ifdef LISP_FEATURE_SB_THREAD
  60 static void
  61 unlink_thread(struct thread *th)
  62 {
  63     if (th->prev)
  64         th->prev->next = th->next;
  65     else
  66         all_threads = th->next;
  67     if (th->next)
  68         th->next->prev = th->prev;
  69 }
  70 #endif
  71
  72 static int
  73 initial_thread_trampoline(struct thread *th)
  74 {
  75     lispobj function;
  76 #if defined(LISP_FEATURE_X86) || defined(LISP_FEATURE_X86_64)
  77     lispobj *args = NULL;
  78 #endif
  79     function = th->no_tls_value_marker;
  80     th->no_tls_value_marker = NO_TLS_VALUE_MARKER_WIDETAG;
  81     if(arch_os_thread_init(th)==0) return 1;
  82     link_thread(th);
  83     th->os_thread=thread_self();
  84     protect_control_stack_guard_page(1);
  85
  86 #if defined(LISP_FEATURE_X86) || defined(LISP_FEATURE_X86_64)
  87     return call_into_lisp_first_time(function,args,0);
  88 #else
  89     return funcall0(function);
  90 #endif
  91 }
  92
  93 #define THREAD_STRUCT_SIZE (THREAD_CONTROL_STACK_SIZE + BINDING_STACK_SIZE + \
  94                             ALIEN_STACK_SIZE + dynamic_values_bytes + \
  95                             32 * SIGSTKSZ)
  96
  97 #ifdef LISP_FEATURE_SB_THREAD
  98
  99 static void
 100 free_thread_stack_later(struct thread *thread_to_be_cleaned_up)
 101 {
 102     struct freeable_stack *new_freeable_stack = 0;
 103     if (thread_to_be_cleaned_up) {
 104         new_freeable_stack = (struct freeable_stack *)
 105             os_validate(0, sizeof(struct freeable_stack));
 106         new_freeable_stack->os_thread = thread_to_be_cleaned_up->os_thread;
 107         new_freeable_stack->stack = (os_vm_address_t)
 108             thread_to_be_cleaned_up->control_stack_start;
 109     }
 110     new_freeable_stack = (struct freeable_stack *)
 111         swap_lispobjs((lispobj *)(void *)&freeable_stack,
 112                       (lispobj)new_freeable_stack);
 113     if (new_freeable_stack) {
 114         FSHOW((stderr,"/reaping %lu\n", new_freeable_stack->os_thread));
 115         /* Under NPTL pthread_join really waits until the thread
 116          * exists and the stack can be safely freed. This is sadly not
 117          * mandated by the pthread spec. */
 118         gc_assert(pthread_join(new_freeable_stack->os_thread, NULL) == 0);
 119         os_invalidate(new_freeable_stack->stack, THREAD_STRUCT_SIZE);
 120         os_invalidate((os_vm_address_t) new_freeable_stack,
 121                       sizeof(struct freeable_stack));
 122     }
 123 }
 124
 125 /* this is the first thing that runs in the child (which is why the
 126  * silly calling convention).  Basically it calls the user's requested
 127  * lisp function after doing arch_os_thread_init and whatever other
 128  * bookkeeping needs to be done
 129  */
 130 int
 131 new_thread_trampoline(struct thread *th)
 132 {
 133     lispobj function;
 134     int result;
 135     FSHOW((stderr,"/creating thread %lu\n", thread_self()));
 136     function = th->no_tls_value_marker;
 137     th->no_tls_value_marker = NO_TLS_VALUE_MARKER_WIDETAG;
 138     if(arch_os_thread_init(th)==0) {
 139         /* FIXME: handle error */
 140         lose("arch_os_thread_init failed\n");
 141     }
 142
 143     th->os_thread=thread_self();
 144     protect_control_stack_guard_page(1);
 145     /* Since GC can only know about this thread from the all_threads
 146      * list and we're just adding this thread to it there is no danger
 147      * of deadlocking even with SIG_STOP_FOR_GC blocked (which it is
 148      * not). */
 149     pthread_mutex_lock(&all_threads_lock);
 150     link_thread(th);
 151     pthread_mutex_unlock(&all_threads_lock);
 152
 153     result = funcall0(function);
 154     th->state=STATE_DEAD;
 155
 156     /* SIG_STOP_FOR_GC is blocked and GC might be waiting for this
 157      * thread, but since we are already dead it won't wait long. */
 158     pthread_mutex_lock(&all_threads_lock);
 159     gc_alloc_update_page_tables(0, &th->alloc_region);
 160     unlink_thread(th);
 161     pthread_mutex_unlock(&all_threads_lock);
 162
 163     if(th->tls_cookie>=0) arch_os_thread_cleanup(th);
 164     os_invalidate((os_vm_address_t)th->interrupt_data,
 165                   (sizeof (struct interrupt_data)));
 166     free_thread_stack_later(th);
 167     FSHOW((stderr,"/exiting thread %lu\n", thread_self()));
 168     return result;
 169 }
 170
 171 #endif /* LISP_FEATURE_SB_THREAD */
 172
 173 static void
 174 free_thread_struct(struct thread *th)
 175 {
 176     if (th->interrupt_data)
 177         os_invalidate((os_vm_address_t) th->interrupt_data,
 178                       (sizeof (struct interrupt_data)));
 179     os_invalidate((os_vm_address_t) th->control_stack_start,
 180                   THREAD_STRUCT_SIZE);
 181 }
 182
 183 /* this is called from any other thread to create the new one, and
 184  * initialize all parts of it that can be initialized from another
 185  * thread
 186  */
 187
 188 static struct thread *
 189 create_thread_struct(lispobj initial_function) {
 190     union per_thread_data *per_thread;
 191     struct thread *th=0;        /*  subdue gcc */
 192     void *spaces=0;
 193 #ifdef LISP_FEATURE_SB_THREAD
 194     int i;
 195 #endif
 196
 197     /* may as well allocate all the spaces at once: it saves us from
 198      * having to decide what to do if only some of the allocations
 199      * succeed */
 200     spaces=os_validate(0, THREAD_STRUCT_SIZE);
 201     if(!spaces)
 202          return NULL;
 203     per_thread=(union per_thread_data *)
 204         (spaces+
 205          THREAD_CONTROL_STACK_SIZE+
 206          BINDING_STACK_SIZE+
 207          ALIEN_STACK_SIZE);
 208
 209 #ifdef LISP_FEATURE_SB_THREAD
 210     for(i = 0; i < (dynamic_values_bytes / sizeof(lispobj)); i++)
 211         per_thread->dynamic_values[i] = NO_TLS_VALUE_MARKER_WIDETAG;
 212     if (all_threads == 0) {
 213         if(SymbolValue(FREE_TLS_INDEX,0)==UNBOUND_MARKER_WIDETAG) {
 214             SetSymbolValue
 215                 (FREE_TLS_INDEX,
 216                  make_fixnum(MAX_INTERRUPTS+
 217                              sizeof(struct thread)/sizeof(lispobj)),
 218                  0);
 219             SetSymbolValue(TLS_INDEX_LOCK,make_fixnum(0),0);
 220         }
 221 #define STATIC_TLS_INIT(sym,field) \
 222   ((struct symbol *)(sym-OTHER_POINTER_LOWTAG))->tls_index= \
 223   make_fixnum(THREAD_SLOT_OFFSET_WORDS(field))
 224
 225         STATIC_TLS_INIT(BINDING_STACK_START,binding_stack_start);
 226         STATIC_TLS_INIT(BINDING_STACK_POINTER,binding_stack_pointer);
 227         STATIC_TLS_INIT(CONTROL_STACK_START,control_stack_start);
 228         STATIC_TLS_INIT(CONTROL_STACK_END,control_stack_end);
 229         STATIC_TLS_INIT(ALIEN_STACK,alien_stack_pointer);
 230 #if defined(LISP_FEATURE_X86) || defined (LISP_FEATURE_X86_64)
 231         STATIC_TLS_INIT(PSEUDO_ATOMIC_ATOMIC,pseudo_atomic_atomic);
 232         STATIC_TLS_INIT(PSEUDO_ATOMIC_INTERRUPTED,pseudo_atomic_interrupted);
 233 #endif
 234 #undef STATIC_TLS_INIT
 235     }
 236 #endif
 237
 238     th=&per_thread->thread;
 239     th->control_stack_start = spaces;
 240     th->binding_stack_start=
 241         (lispobj*)((void*)th->control_stack_start+THREAD_CONTROL_STACK_SIZE);
 242     th->control_stack_end = th->binding_stack_start;
 243     th->alien_stack_start=
 244         (lispobj*)((void*)th->binding_stack_start+BINDING_STACK_SIZE);
 245     th->binding_stack_pointer=th->binding_stack_start;
 246     th->this=th;
 247     th->os_thread=0;
 248     th->state=STATE_RUNNING;
 249 #ifdef LISP_FEATURE_STACK_GROWS_DOWNWARD_NOT_UPWARD
 250     th->alien_stack_pointer=((void *)th->alien_stack_start
 251                              + ALIEN_STACK_SIZE-N_WORD_BYTES);
 252 #else
 253     th->alien_stack_pointer=((void *)th->alien_stack_start);
 254 #endif
 255 #if defined(LISP_FEATURE_X86) || defined (LISP_FEATURE_X86_64)
 256     th->pseudo_atomic_interrupted=0;
 257     th->pseudo_atomic_atomic=0;
 258 #endif
 259 #ifdef LISP_FEATURE_GENCGC
 260     gc_set_region_empty(&th->alloc_region);
 261 #endif
 262
 263 #ifndef LISP_FEATURE_SB_THREAD
 264     /* the tls-points-into-struct-thread trick is only good for threaded
 265      * sbcl, because unithread sbcl doesn't have tls.  So, we copy the
 266      * appropriate values from struct thread here, and make sure that
 267      * we use the appropriate SymbolValue macros to access any of the
 268      * variable quantities from the C runtime.  It's not quite OAOOM,
 269      * it just feels like it */
 270     SetSymbolValue(BINDING_STACK_START,(lispobj)th->binding_stack_start,th);
 271     SetSymbolValue(CONTROL_STACK_START,(lispobj)th->control_stack_start,th);
 272     SetSymbolValue(CONTROL_STACK_END,(lispobj)th->control_stack_end,th);
 273 #if defined(LISP_FEATURE_X86) || defined (LISP_FEATURE_X86_64)
 274     SetSymbolValue(BINDING_STACK_POINTER,(lispobj)th->binding_stack_pointer,th);
 275     SetSymbolValue(ALIEN_STACK,(lispobj)th->alien_stack_pointer,th);
 276     SetSymbolValue(PSEUDO_ATOMIC_ATOMIC,(lispobj)th->pseudo_atomic_atomic,th);
 277     SetSymbolValue(PSEUDO_ATOMIC_INTERRUPTED,th->pseudo_atomic_interrupted,th);
 278 #else
 279     current_binding_stack_pointer=th->binding_stack_pointer;
 280     current_control_stack_pointer=th->control_stack_start;
 281 #endif
 282 #endif
 283     bind_variable(CURRENT_CATCH_BLOCK,make_fixnum(0),th);
 284     bind_variable(CURRENT_UNWIND_PROTECT_BLOCK,make_fixnum(0),th);
 285     bind_variable(FREE_INTERRUPT_CONTEXT_INDEX,make_fixnum(0),th);
 286     bind_variable(INTERRUPT_PENDING, NIL,th);
 287     bind_variable(INTERRUPTS_ENABLED,T,th);
 288     bind_variable(GC_PENDING,NIL,th);
 289 #ifdef LISP_FEATURE_SB_THREAD
 290     bind_variable(STOP_FOR_GC_PENDING,NIL,th);
 291 #endif
 292
 293     th->interrupt_data = (struct interrupt_data *)
 294         os_validate(0,(sizeof (struct interrupt_data)));
 295     if (!th->interrupt_data) {
 296         free_thread_struct(th);
 297         return 0;
 298     }
 299     th->interrupt_data->pending_handler = 0;
 300     th->no_tls_value_marker=initial_function;
 301     return th;
 302 }
 303
 304 void create_initial_thread(lispobj initial_function) {
 305     struct thread *th=create_thread_struct(initial_function);
 306     if(th) {
 307         initial_thread_trampoline(th); /* no return */
 308     } else lose("can't create initial thread");
 309 }
 310
 311 #ifdef LISP_FEATURE_SB_THREAD
 312
 313 #ifndef __USE_XOPEN2K
 314 extern int pthread_attr_setstack (pthread_attr_t *__attr, void *__stackaddr,
 315                                   size_t __stacksize);
 316 #endif
 317
 318 boolean create_os_thread(struct thread *th,os_thread_t *kid_tid)
 319 {
 320     /* The new thread inherits the restrictive signal mask set here,
 321      * and enables signals again when it is set up properly. */
 322     pthread_attr_t attr;
 323     sigset_t newset,oldset;
 324     boolean r=1;
 325     sigemptyset(&newset);
 326     /* Blocking deferrable signals is enough, no need to block
 327      * SIG_STOP_FOR_GC because the child process is not linked onto
 328      * all_threads until it's ready. */
 329     sigaddset_deferrable(&newset);
 330     thread_sigmask(SIG_BLOCK, &newset, &oldset);
 331
 332     if((pthread_attr_init(&attr)) ||
 333        (pthread_attr_setstack(&attr,th->control_stack_start,
 334                               THREAD_CONTROL_STACK_SIZE-16)) ||
 335        (pthread_create
 336         (kid_tid,&attr,(void *(*)(void *))new_thread_trampoline,th)))
 337         r=0;
 338     thread_sigmask(SIG_SETMASK,&oldset,0);
 339     return r;
 340 }
 341
 342 os_thread_t create_thread(lispobj initial_function) {
 343     struct thread *th;
 344     os_thread_t kid_tid;
 345
 346     if(linux_no_threads_p) return 0;
 347
 348     /* Assuming that a fresh thread struct has no lisp objects in it,
 349      * linking it to all_threads can be left to the thread itself
 350      * without fear of gc lossage. initial_function violates this
 351      * assumption and must stay pinned until the child starts up. */
 352     th = create_thread_struct(initial_function);
 353     if(th==0) return 0;
 354
 355     if (create_os_thread(th,&kid_tid)) {
 356         return kid_tid;
 357     } else {
 358         free_thread_struct(th);
 359         return 0;
 360     }
 361 }
 362
 363 /* Send the signo to os_thread, retry if the rt signal queue is
 364  * full. */
 365 static int kill_thread_safely(os_thread_t os_thread, int signo)
 366 {
 367     int r;
 368     /* The man page does not mention EAGAIN as a valid return value
 369      * for either pthread_kill or kill. But that's theory, this is
 370      * practice. By waiting here we assume that the delivery of this
 371      * signal is not necessary for the delivery of the signals in the
 372      * queue. In other words, we _assume_ there are no deadlocks. */
 373     while ((r=pthread_kill(os_thread,signo))==EAGAIN) {
 374         /* wait a bit then try again in the hope of the rt signal
 375          * queue not being full */
 376         FSHOW_SIGNAL((stderr,"/rt signal queue full\n"));
 377         /* FIXME: some kind of backoff (random, exponential) would be
 378          * nice. */
 379         sleep(1);
 380     }
 381     return r;
 382 }
 383
 384 int signal_interrupt_thread(os_thread_t os_thread)
 385 {
 386     int status = kill_thread_safely(os_thread, SIG_INTERRUPT_THREAD);
 387     if (status == 0) {
 388         return 0;
 389     } else if (status == ESRCH) {
 390         return -1;
 391     } else {
 392         lose("cannot send SIG_INTERRUPT_THREAD to thread=%lu: %d, %s",
 393              os_thread, status, strerror(status));
 394     }
 395 }
 396
 397 /* stopping the world is a two-stage process.  From this thread we signal
 398  * all the others with SIG_STOP_FOR_GC.  The handler for this signal does
 399  * the usual pseudo-atomic checks (we don't want to stop a thread while
 400  * it's in the middle of allocation) then waits for another SIG_STOP_FOR_GC.
 401  */
 402
 403 /* To avoid deadlocks when gc stops the world all clients of each
 404  * mutex must enable or disable SIG_STOP_FOR_GC for the duration of
 405  * holding the lock, but they must agree on which. */
 406 void gc_stop_the_world()
 407 {
 408     struct thread *p,*th=arch_os_get_current_thread();
 409     int status;
 410     FSHOW_SIGNAL((stderr,"/gc_stop_the_world:waiting on lock, thread=%lu\n",
 411                   th->os_thread));
 412     /* keep threads from starting while the world is stopped. */
 413     pthread_mutex_lock(&all_threads_lock); \
 414     FSHOW_SIGNAL((stderr,"/gc_stop_the_world:got lock, thread=%lu\n",
 415                   th->os_thread));
 416     /* stop all other threads by sending them SIG_STOP_FOR_GC */
 417     for(p=all_threads; p; p=p->next) {
 418         gc_assert(p->os_thread != 0);
 419         if((p!=th) && ((p->state==STATE_RUNNING))) {
 420             FSHOW_SIGNAL((stderr,"/gc_stop_the_world: suspending %lu\n",
 421                           p->os_thread));
 422             status=kill_thread_safely(p->os_thread,SIG_STOP_FOR_GC);
 423             if (status==ESRCH) {
 424                 /* This thread has exited. */
 425                 gc_assert(p->state==STATE_DEAD);
 426             } else if (status) {
 427                 lose("cannot send suspend thread=%lu: %d, %s",
 428                      p->os_thread,status,strerror(status));
 429             }
 430         }
 431     }
 432     FSHOW_SIGNAL((stderr,"/gc_stop_the_world:signals sent\n"));
 433     /* wait for the running threads to stop or finish */
 434     for(p=all_threads;p;) {
 435         if((p!=th) && (p->state==STATE_RUNNING)) {
 436             sched_yield();
 437         } else {
 438             p=p->next;
 439         }
 440     }
 441     FSHOW_SIGNAL((stderr,"/gc_stop_the_world:end\n"));
 442 }
 443
 444 void gc_start_the_world()
 445 {
 446     struct thread *p,*th=arch_os_get_current_thread();
 447     int status;
 448     /* if a resumed thread creates a new thread before we're done with
 449      * this loop, the new thread will get consed on the front of
 450      * all_threads, but it won't have been stopped so won't need
 451      * restarting */
 452     FSHOW_SIGNAL((stderr,"/gc_start_the_world:begin\n"));
 453     for(p=all_threads;p;p=p->next) {
 454         gc_assert(p->os_thread!=0);
 455         if((p!=th) && (p->state!=STATE_DEAD)) {
 456             if(p->state!=STATE_SUSPENDED) {
 457                 lose("gc_start_the_world: wrong thread state is %d\n",
 458                      fixnum_value(p->state));
 459             }
 460             FSHOW_SIGNAL((stderr, "/gc_start_the_world: resuming %lu\n",
 461                           p->os_thread));
 462             p->state=STATE_RUNNING;
 463             status=kill_thread_safely(p->os_thread,SIG_STOP_FOR_GC);
 464             if (status) {
 465                 lose("cannot resume thread=%lu: %d, %s",
 466                      p->os_thread,status,strerror(status));
 467             }
 468         }
 469     }
 470     /* If we waited here until all threads leave STATE_SUSPENDED, then
 471      * SIG_STOP_FOR_GC wouldn't need to be a rt signal. That has some
 472      * performance implications, but does away with the 'rt signal
 473      * queue full' problem. */
 474     pthread_mutex_unlock(&all_threads_lock); \
 475     FSHOW_SIGNAL((stderr,"/gc_start_the_world:end\n"));
 476 }
 477 #endif