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     th->os_thread=thread_self();
  54     if (all_threads) all_threads->prev=th;
  55     th->next=all_threads;
  56     th->prev=0;
  57     all_threads=th;
  58     protect_control_stack_guard_page(1);
  59 }
  60
  61 #ifdef LISP_FEATURE_SB_THREAD
  62 static void
  63 unlink_thread(struct thread *th)
  64 {
  65     if (th->prev)
  66         th->prev->next = th->next;
  67     else
  68         all_threads = th->next;
  69     if (th->next)
  70         th->next->prev = th->prev;
  71 }
  72 #endif
  73
  74 static int
  75 initial_thread_trampoline(struct thread *th)
  76 {
  77     lispobj function;
  78 #if defined(LISP_FEATURE_X86) || defined(LISP_FEATURE_X86_64)
  79     lispobj *args = NULL;
  80 #endif
  81     function = th->no_tls_value_marker;
  82     th->no_tls_value_marker = NO_TLS_VALUE_MARKER_WIDETAG;
  83     if(arch_os_thread_init(th)==0) return 1;
  84     link_thread(th);
  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     /* Since GC can only know about this thread from the all_threads
 144      * list and we're just adding this thread to it there is no danger
 145      * of deadlocking even with SIG_STOP_FOR_GC blocked. */
 146     pthread_mutex_lock(&all_threads_lock);
 147     link_thread(th);
 148     pthread_mutex_unlock(&all_threads_lock);
 149
 150     result = funcall0(function);
 151     th->state=STATE_DEAD;
 152
 153     /* SIG_STOP_FOR_GC is blocked and GC might be waiting for this
 154      * thread, but since we are already dead it won't wait long. */
 155     pthread_mutex_lock(&all_threads_lock);
 156     unlink_thread(th);
 157     pthread_mutex_unlock(&all_threads_lock);
 158
 159     gc_alloc_update_page_tables(0, &th->alloc_region);
 160     if(th->tls_cookie>=0) arch_os_thread_cleanup(th);
 161     os_invalidate((os_vm_address_t)th->interrupt_data,
 162                   (sizeof (struct interrupt_data)));
 163     free_thread_stack_later(th);
 164     FSHOW((stderr,"/exiting thread %lu\n", thread_self()));
 165     return result;
 166 }
 167
 168 #endif /* LISP_FEATURE_SB_THREAD */
 169
 170 static void
 171 free_thread_struct(struct thread *th)
 172 {
 173     if (th->interrupt_data)
 174         os_invalidate((os_vm_address_t) th->interrupt_data,
 175                       (sizeof (struct interrupt_data)));
 176     os_invalidate((os_vm_address_t) th->control_stack_start,
 177                   THREAD_STRUCT_SIZE);
 178 }
 179
 180 /* this is called from any other thread to create the new one, and
 181  * initialize all parts of it that can be initialized from another
 182  * thread
 183  */
 184
 185 static struct thread *
 186 create_thread_struct(lispobj initial_function) {
 187     union per_thread_data *per_thread;
 188     struct thread *th=0;        /*  subdue gcc */
 189     void *spaces=0;
 190
 191     /* may as well allocate all the spaces at once: it saves us from
 192      * having to decide what to do if only some of the allocations
 193      * succeed */
 194     spaces=os_validate(0, THREAD_STRUCT_SIZE);
 195     if(!spaces)
 196          return NULL;
 197     per_thread=(union per_thread_data *)
 198         (spaces+
 199          THREAD_CONTROL_STACK_SIZE+
 200          BINDING_STACK_SIZE+
 201          ALIEN_STACK_SIZE);
 202
 203     if(all_threads) {
 204         memcpy(per_thread,arch_os_get_current_thread(),
 205                dynamic_values_bytes);
 206     } else {
 207 #ifdef LISP_FEATURE_SB_THREAD
 208         int i;
 209         for(i=0;i<(dynamic_values_bytes/sizeof(lispobj));i++)
 210             per_thread->dynamic_values[i]=NO_TLS_VALUE_MARKER_WIDETAG;
 211         if(SymbolValue(FREE_TLS_INDEX,0)==UNBOUND_MARKER_WIDETAG) {
 212             SetSymbolValue
 213                 (FREE_TLS_INDEX,
 214                  make_fixnum(MAX_INTERRUPTS+
 215                              sizeof(struct thread)/sizeof(lispobj)),
 216                  0);
 217             SetSymbolValue(TLS_INDEX_LOCK,make_fixnum(0),0);
 218         }
 219 #define STATIC_TLS_INIT(sym,field) \
 220   ((struct symbol *)(sym-OTHER_POINTER_LOWTAG))->tls_index= \
 221   make_fixnum(THREAD_SLOT_OFFSET_WORDS(field))
 222
 223         STATIC_TLS_INIT(BINDING_STACK_START,binding_stack_start);
 224         STATIC_TLS_INIT(BINDING_STACK_POINTER,binding_stack_pointer);
 225         STATIC_TLS_INIT(CONTROL_STACK_START,control_stack_start);
 226         STATIC_TLS_INIT(CONTROL_STACK_END,control_stack_end);
 227         STATIC_TLS_INIT(ALIEN_STACK,alien_stack_pointer);
 228 #if defined(LISP_FEATURE_X86) || defined (LISP_FEATURE_X86_64)
 229         STATIC_TLS_INIT(PSEUDO_ATOMIC_ATOMIC,pseudo_atomic_atomic);
 230         STATIC_TLS_INIT(PSEUDO_ATOMIC_INTERRUPTED,pseudo_atomic_interrupted);
 231 #endif
 232 #undef STATIC_TLS_INIT
 233 #endif
 234     }
 235
 236     th=&per_thread->thread;
 237     th->control_stack_start = spaces;
 238     th->binding_stack_start=
 239         (lispobj*)((void*)th->control_stack_start+THREAD_CONTROL_STACK_SIZE);
 240     th->control_stack_end = th->binding_stack_start;
 241     th->alien_stack_start=
 242         (lispobj*)((void*)th->binding_stack_start+BINDING_STACK_SIZE);
 243     th->binding_stack_pointer=th->binding_stack_start;
 244     th->this=th;
 245     th->os_thread=0;
 246     th->state=STATE_RUNNING;
 247 #ifdef LISP_FEATURE_STACK_GROWS_DOWNWARD_NOT_UPWARD
 248     th->alien_stack_pointer=((void *)th->alien_stack_start
 249                              + ALIEN_STACK_SIZE-N_WORD_BYTES);
 250 #else
 251     th->alien_stack_pointer=((void *)th->alien_stack_start);
 252 #endif
 253 #if defined(LISP_FEATURE_X86) || defined (LISP_FEATURE_X86_64)
 254     th->pseudo_atomic_interrupted=0;
 255     th->pseudo_atomic_atomic=0;
 256 #endif
 257 #ifdef LISP_FEATURE_GENCGC
 258     gc_set_region_empty(&th->alloc_region);
 259 #endif
 260
 261 #ifndef LISP_FEATURE_SB_THREAD
 262     /* the tls-points-into-struct-thread trick is only good for threaded
 263      * sbcl, because unithread sbcl doesn't have tls.  So, we copy the
 264      * appropriate values from struct thread here, and make sure that
 265      * we use the appropriate SymbolValue macros to access any of the
 266      * variable quantities from the C runtime.  It's not quite OAOOM,
 267      * it just feels like it */
 268     SetSymbolValue(BINDING_STACK_START,(lispobj)th->binding_stack_start,th);
 269     SetSymbolValue(CONTROL_STACK_START,(lispobj)th->control_stack_start,th);
 270     SetSymbolValue(CONTROL_STACK_END,(lispobj)th->control_stack_end,th);
 271 #if defined(LISP_FEATURE_X86) || defined (LISP_FEATURE_X86_64)
 272     SetSymbolValue(BINDING_STACK_POINTER,(lispobj)th->binding_stack_pointer,th);
 273     SetSymbolValue(ALIEN_STACK,(lispobj)th->alien_stack_pointer,th);
 274     SetSymbolValue(PSEUDO_ATOMIC_ATOMIC,(lispobj)th->pseudo_atomic_atomic,th);
 275     SetSymbolValue(PSEUDO_ATOMIC_INTERRUPTED,th->pseudo_atomic_interrupted,th);
 276 #else
 277     current_binding_stack_pointer=th->binding_stack_pointer;
 278     current_control_stack_pointer=th->control_stack_start;
 279 #endif
 280 #endif
 281     bind_variable(CURRENT_CATCH_BLOCK,make_fixnum(0),th);
 282     bind_variable(CURRENT_UNWIND_PROTECT_BLOCK,make_fixnum(0),th);
 283     bind_variable(FREE_INTERRUPT_CONTEXT_INDEX,make_fixnum(0),th);
 284     bind_variable(INTERRUPT_PENDING, NIL,th);
 285     bind_variable(INTERRUPTS_ENABLED,T,th);
 286     bind_variable(GC_PENDING,NIL,th);
 287 #ifdef LISP_FEATURE_SB_THREAD
 288     bind_variable(STOP_FOR_GC_PENDING,NIL,th);
 289 #endif
 290
 291     th->interrupt_data = (struct interrupt_data *)
 292         os_validate(0,(sizeof (struct interrupt_data)));
 293     if (!th->interrupt_data) {
 294         free_thread_struct(th);
 295         return 0;
 296     }
 297     th->interrupt_data->pending_handler = 0;
 298     th->no_tls_value_marker=initial_function;
 299     return th;
 300 }
 301
 302 void create_initial_thread(lispobj initial_function) {
 303     struct thread *th=create_thread_struct(initial_function);
 304     if(th) {
 305         initial_thread_trampoline(th); /* no return */
 306     } else lose("can't create initial thread");
 307 }
 308
 309 #ifdef LISP_FEATURE_SB_THREAD
 310
 311 #ifndef __USE_XOPEN2K
 312 extern int pthread_attr_setstack (pthread_attr_t *__attr, void *__stackaddr,
 313                                   size_t __stacksize);
 314 #endif
 315
 316 boolean create_os_thread(struct thread *th,os_thread_t *kid_tid)
 317 {
 318     /* The new thread inherits the restrictive signal mask set here,
 319      * and enables signals again when it is set up properly. */
 320     pthread_attr_t attr;
 321     sigset_t newset,oldset;
 322     boolean r=1;
 323     sigemptyset(&newset);
 324     /* Blocking deferrable signals is enough, no need to block
 325      * SIG_STOP_FOR_GC because the child process is not linked onto
 326      * all_threads until it's ready. */
 327     sigaddset_deferrable(&newset);
 328     thread_sigmask(SIG_BLOCK, &newset, &oldset);
 329
 330     if((pthread_attr_init(&attr)) ||
 331        (pthread_attr_setstack(&attr,th->control_stack_start,
 332                               THREAD_CONTROL_STACK_SIZE-16)) ||
 333        (pthread_create
 334         (kid_tid,&attr,(void *(*)(void *))new_thread_trampoline,th)))
 335         r=0;
 336     thread_sigmask(SIG_SETMASK,&oldset,0);
 337     return r;
 338 }
 339
 340 os_thread_t create_thread(lispobj initial_function) {
 341     struct thread *th;
 342     os_thread_t kid_tid;
 343
 344     if(linux_no_threads_p) return 0;
 345
 346     th=create_thread_struct(initial_function);
 347     if(th==0) return 0;
 348
 349     if (create_os_thread(th,&kid_tid)) {
 350         return kid_tid;
 351     } else {
 352         free_thread_struct(th);
 353         return 0;
 354     }
 355 }
 356
 357 /* Send the signo to os_thread, retry if the rt signal queue is
 358  * full. */
 359 static int kill_thread_safely(os_thread_t os_thread, int signo)
 360 {
 361     int r;
 362     /* The man page does not mention EAGAIN as a valid return value
 363      * for either pthread_kill or kill. But that's theory, this is
 364      * practice. By waiting here we assume that the delivery of this
 365      * signal is not necessary for the delivery of the signals in the
 366      * queue. In other words, we _assume_ there are no deadlocks. */
 367     while ((r=pthread_kill(os_thread,signo))==EAGAIN) {
 368         /* wait a bit then try again in the hope of the rt signal
 369          * queue not being full */
 370         FSHOW_SIGNAL((stderr,"/rt signal queue full\n"));
 371         /* FIXME: some kind of backoff (random, exponential) would be
 372          * nice. */
 373         sleep(1);
 374     }
 375     return r;
 376 }
 377
 378 int signal_interrupt_thread(os_thread_t os_thread)
 379 {
 380     int status = kill_thread_safely(os_thread, SIG_INTERRUPT_THREAD);
 381     if (status == 0) {
 382         return 0;
 383     } else if (status == ESRCH) {
 384         return -1;
 385     } else {
 386         lose("cannot send SIG_INTERRUPT_THREAD to thread=%lu: %d, %s",
 387              os_thread, status, strerror(status));
 388     }
 389 }
 390
 391 /* stopping the world is a two-stage process.  From this thread we signal
 392  * all the others with SIG_STOP_FOR_GC.  The handler for this signal does
 393  * the usual pseudo-atomic checks (we don't want to stop a thread while
 394  * it's in the middle of allocation) then waits for another SIG_STOP_FOR_GC.
 395  */
 396
 397 /* To avoid deadlocks when gc stops the world all clients of each
 398  * mutex must enable or disable SIG_STOP_FOR_GC for the duration of
 399  * holding the lock, but they must agree on which. */
 400 void gc_stop_the_world()
 401 {
 402     struct thread *p,*th=arch_os_get_current_thread();
 403     int status;
 404     FSHOW_SIGNAL((stderr,"/gc_stop_the_world:waiting on lock, thread=%lu\n",
 405                   th->os_thread));
 406     /* keep threads from starting while the world is stopped. */
 407     pthread_mutex_lock(&all_threads_lock); \
 408     FSHOW_SIGNAL((stderr,"/gc_stop_the_world:got lock, thread=%lu\n",
 409                   th->os_thread));
 410     /* stop all other threads by sending them SIG_STOP_FOR_GC */
 411     for(p=all_threads; p; p=p->next) {
 412         if((p!=th) && ((p->state==STATE_RUNNING))) {
 413             FSHOW_SIGNAL((stderr,"/gc_stop_the_world: suspending %lu\n",
 414                           p->os_thread));
 415             status=kill_thread_safely(p->os_thread,SIG_STOP_FOR_GC);
 416             if (status==ESRCH) {
 417                 /* This thread has exited. */
 418                 gc_assert(p->state==STATE_DEAD);
 419             } else if (status) {
 420                 lose("cannot send suspend thread=%lu: %d, %s",
 421                      p->os_thread,status,strerror(status));
 422             }
 423         }
 424     }
 425     FSHOW_SIGNAL((stderr,"/gc_stop_the_world:signals sent\n"));
 426     /* wait for the running threads to stop or finish */
 427     for(p=all_threads;p;) {
 428         gc_assert(p->os_thread!=0);
 429         if((p==th) || (p->state==STATE_SUSPENDED) ||
 430            (p->state==STATE_DEAD)) {
 431             p=p->next;
 432         } else {
 433             sched_yield();
 434         }
 435     }
 436     FSHOW_SIGNAL((stderr,"/gc_stop_the_world:end\n"));
 437 }
 438
 439 void gc_start_the_world()
 440 {
 441     struct thread *p,*th=arch_os_get_current_thread();
 442     int status;
 443     /* if a resumed thread creates a new thread before we're done with
 444      * this loop, the new thread will get consed on the front of
 445      * all_threads, but it won't have been stopped so won't need
 446      * restarting */
 447     FSHOW_SIGNAL((stderr,"/gc_start_the_world:begin\n"));
 448     for(p=all_threads;p;p=p->next) {
 449         gc_assert(p->os_thread!=0);
 450         if((p!=th) && (p->state!=STATE_DEAD)) {
 451             if(p->state!=STATE_SUSPENDED) {
 452                 lose("gc_start_the_world: wrong thread state is %d\n",
 453                      fixnum_value(p->state));
 454             }
 455             FSHOW_SIGNAL((stderr, "/gc_start_the_world: resuming %lu\n",
 456                           p->os_thread));
 457             p->state=STATE_RUNNING;
 458             status=kill_thread_safely(p->os_thread,SIG_STOP_FOR_GC);
 459             if (status) {
 460                 lose("cannot resume thread=%lu: %d, %s",
 461                      p->os_thread,status,strerror(status));
 462             }
 463         }
 464     }
 465     /* If we waited here until all threads leave STATE_SUSPENDED, then
 466      * SIG_STOP_FOR_GC wouldn't need to be a rt signal. That has some
 467      * performance implications, but does away with the 'rt signal
 468      * queue full' problem. */
 469     pthread_mutex_unlock(&all_threads_lock); \
 470     FSHOW_SIGNAL((stderr,"/gc_start_the_world:end\n"));
 471 }
 472 #endif