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 int dynamic_values_bytes=4096*sizeof(lispobj);  /* same for all threads */
  29 struct thread *all_threads;
  30 volatile lispobj all_threads_lock;
  31 extern struct interrupt_data * global_interrupt_data;
  32 extern int linux_no_threads_p;
  33
  34 /* When trying to get all_threads_lock one should make sure that
  35  * sig_stop_for_gc is not blocked. Else there would be a possible
  36  * deadlock: gc locks it, other thread blocks signals, gc sends stop
  37  * request to other thread and waits, other thread blocks on lock. */
  38 void check_sig_stop_for_gc_can_arrive_or_lose()
  39 {
  40     /* Get the current sigmask, by blocking the empty set. */
  41     sigset_t empty,current;
  42     sigemptyset(&empty);
  43     thread_sigmask(SIG_BLOCK, &empty, &current);
  44     if (sigismember(&current,SIG_STOP_FOR_GC))
  45         lose("SIG_STOP_FOR_GC is blocked\n");
  46     if (SymbolValue(INTERRUPTS_ENABLED,arch_os_get_current_thread()) == NIL)
  47         lose("interrupts disabled\n");
  48     if (arch_pseudo_atomic_atomic(NULL))
  49         lose("n pseudo atomic\n");
  50 }
  51
  52 #ifdef QSHOW_SIGNALS
  53 #define FSHOW_SIGNAL FSHOW
  54 #else
  55 #define FSHOW_SIGNAL(args)
  56 #endif
  57
  58 #define GET_ALL_THREADS_LOCK(name) \
  59     { \
  60         sigset_t _newset,_oldset; \
  61         sigemptyset(&_newset); \
  62         sigaddset_blockable(&_newset); \
  63         sigdelset(&_newset,SIG_STOP_FOR_GC); \
  64         thread_sigmask(SIG_BLOCK, &_newset, &_oldset); \
  65         check_sig_stop_for_gc_can_arrive_or_lose(); \
  66         FSHOW_SIGNAL((stderr,"/%s:waiting on lock=%ld, thread=%ld\n",name, \
  67                all_threads_lock,arch_os_get_current_thread()->os_thread)); \
  68         get_spinlock(&all_threads_lock,(long)arch_os_get_current_thread()); \
  69         FSHOW_SIGNAL((stderr,"/%s:got lock, thread=%ld\n", \
  70                name,arch_os_get_current_thread()->os_thread));
  71
  72 #define RELEASE_ALL_THREADS_LOCK(name) \
  73         FSHOW_SIGNAL((stderr,"/%s:released lock\n",name)); \
  74         release_spinlock(&all_threads_lock); \
  75         thread_sigmask(SIG_SETMASK,&_oldset,0); \
  76     }
  77
  78 int
  79 initial_thread_trampoline(struct thread *th)
  80 {
  81     lispobj function;
  82 #if defined(LISP_FEATURE_X86) || defined(LISP_FEATURE_X86_64)
  83     lispobj *args = NULL;
  84 #endif
  85
  86     function = th->unbound_marker;
  87     th->unbound_marker = UNBOUND_MARKER_WIDETAG;
  88     if(arch_os_thread_init(th)==0) return 1;
  89
  90     if(th->os_thread < 1) lose("th->os_thread not set up right");
  91     th->state=STATE_RUNNING;
  92 #if defined(LISP_FEATURE_X86) || defined(LISP_FEATURE_X86_64)
  93     return call_into_lisp_first_time(function,args,0);
  94 #else
  95     return funcall0(function);
  96 #endif
  97 }
  98
  99 #ifdef LISP_FEATURE_SB_THREAD
 100
 101 /* this is the first thing that runs in the child (which is why the
 102  * silly calling convention).  Basically it calls the user's requested
 103  * lisp function after doing arch_os_thread_init and whatever other
 104  * bookkeeping needs to be done
 105  */
 106 int
 107 new_thread_trampoline(struct thread *th)
 108 {
 109     lispobj function;
 110     function = th->unbound_marker;
 111     th->unbound_marker = UNBOUND_MARKER_WIDETAG;
 112     if(arch_os_thread_init(th)==0) return 1;
 113
 114     /* wait here until our thread is linked into all_threads: see below */
 115     while(th->os_thread<1) sched_yield();
 116
 117     th->state=STATE_RUNNING;
 118     return funcall0(function);
 119 }
 120 #endif /* LISP_FEATURE_SB_THREAD */
 121
 122 /* this is called from any other thread to create the new one, and
 123  * initialize all parts of it that can be initialized from another
 124  * thread
 125  */
 126
 127 struct thread * create_thread_struct(lispobj initial_function) {
 128     union per_thread_data *per_thread;
 129     struct thread *th=0;        /*  subdue gcc */
 130     void *spaces=0;
 131
 132     /* may as well allocate all the spaces at once: it saves us from
 133      * having to decide what to do if only some of the allocations
 134      * succeed */
 135     spaces=os_validate(0,
 136                        THREAD_CONTROL_STACK_SIZE+
 137                        BINDING_STACK_SIZE+
 138                        ALIEN_STACK_SIZE+
 139                        dynamic_values_bytes+
 140                        32*SIGSTKSZ);
 141     if(!spaces)
 142          return NULL;
 143     per_thread=(union per_thread_data *)
 144         (spaces+
 145          THREAD_CONTROL_STACK_SIZE+
 146          BINDING_STACK_SIZE+
 147          ALIEN_STACK_SIZE);
 148
 149     if(all_threads) {
 150         memcpy(per_thread,arch_os_get_current_thread(),
 151                dynamic_values_bytes);
 152     } else {
 153 #ifdef LISP_FEATURE_SB_THREAD
 154         int i;
 155         for(i=0;i<(dynamic_values_bytes/sizeof(lispobj));i++)
 156             per_thread->dynamic_values[i]=UNBOUND_MARKER_WIDETAG;
 157         if(SymbolValue(FREE_TLS_INDEX,0)==UNBOUND_MARKER_WIDETAG)
 158             SetSymbolValue
 159                 (FREE_TLS_INDEX,
 160                  make_fixnum(MAX_INTERRUPTS+
 161                              sizeof(struct thread)/sizeof(lispobj)),
 162                  0);
 163 #define STATIC_TLS_INIT(sym,field) \
 164   ((struct symbol *)(sym-OTHER_POINTER_LOWTAG))->tls_index= \
 165   make_fixnum(THREAD_SLOT_OFFSET_WORDS(field))
 166
 167         STATIC_TLS_INIT(BINDING_STACK_START,binding_stack_start);
 168         STATIC_TLS_INIT(BINDING_STACK_POINTER,binding_stack_pointer);
 169         STATIC_TLS_INIT(CONTROL_STACK_START,control_stack_start);
 170         STATIC_TLS_INIT(CONTROL_STACK_END,control_stack_end);
 171         STATIC_TLS_INIT(ALIEN_STACK,alien_stack_pointer);
 172 #ifdef LISP_FEATURE_X86
 173         STATIC_TLS_INIT(PSEUDO_ATOMIC_ATOMIC,pseudo_atomic_atomic);
 174         STATIC_TLS_INIT(PSEUDO_ATOMIC_INTERRUPTED,pseudo_atomic_interrupted);
 175 #endif
 176 #undef STATIC_TLS_INIT
 177 #endif
 178     }
 179
 180     th=&per_thread->thread;
 181     th->control_stack_start = spaces;
 182     th->binding_stack_start=
 183         (lispobj*)((void*)th->control_stack_start+THREAD_CONTROL_STACK_SIZE);
 184     th->control_stack_end = th->binding_stack_start;
 185     th->alien_stack_start=
 186         (lispobj*)((void*)th->binding_stack_start+BINDING_STACK_SIZE);
 187     th->binding_stack_pointer=th->binding_stack_start;
 188     th->this=th;
 189     th->os_thread=0;
 190     th->interrupt_fun=NIL;
 191     th->interrupt_fun_lock=0;
 192     th->state=STATE_STARTING;
 193 #ifdef LISP_FEATURE_STACK_GROWS_DOWNWARD_NOT_UPWARD
 194     th->alien_stack_pointer=((void *)th->alien_stack_start
 195                              + ALIEN_STACK_SIZE-N_WORD_BYTES);
 196 #else
 197     th->alien_stack_pointer=((void *)th->alien_stack_start);
 198 #endif
 199 #if defined(LISP_FEATURE_X86) || defined (LISP_FEATURE_X86_64)
 200     th->pseudo_atomic_interrupted=0;
 201     th->pseudo_atomic_atomic=0;
 202 #endif
 203 #ifdef LISP_FEATURE_GENCGC
 204     gc_set_region_empty(&th->alloc_region);
 205 #endif
 206
 207 #ifndef LISP_FEATURE_SB_THREAD
 208     /* the tls-points-into-struct-thread trick is only good for threaded
 209      * sbcl, because unithread sbcl doesn't have tls.  So, we copy the
 210      * appropriate values from struct thread here, and make sure that
 211      * we use the appropriate SymbolValue macros to access any of the
 212      * variable quantities from the C runtime.  It's not quite OAOOM,
 213      * it just feels like it */
 214     SetSymbolValue(BINDING_STACK_START,(lispobj)th->binding_stack_start,th);
 215     SetSymbolValue(CONTROL_STACK_START,(lispobj)th->control_stack_start,th);
 216     SetSymbolValue(CONTROL_STACK_END,(lispobj)th->control_stack_end,th);
 217 #if defined(LISP_FEATURE_X86) || defined (LISP_FEATURE_X86_64)
 218     SetSymbolValue(BINDING_STACK_POINTER,(lispobj)th->binding_stack_pointer,th);
 219     SetSymbolValue(ALIEN_STACK,(lispobj)th->alien_stack_pointer,th);
 220     SetSymbolValue(PSEUDO_ATOMIC_ATOMIC,(lispobj)th->pseudo_atomic_atomic,th);
 221     SetSymbolValue(PSEUDO_ATOMIC_INTERRUPTED,th->pseudo_atomic_interrupted,th);
 222 #else
 223     current_binding_stack_pointer=th->binding_stack_pointer;
 224     current_control_stack_pointer=th->control_stack_start;
 225 #endif
 226 #endif
 227     bind_variable(CURRENT_CATCH_BLOCK,make_fixnum(0),th);
 228     bind_variable(CURRENT_UNWIND_PROTECT_BLOCK,make_fixnum(0),th);
 229     bind_variable(FREE_INTERRUPT_CONTEXT_INDEX,make_fixnum(0),th);
 230     bind_variable(INTERRUPT_PENDING, NIL,th);
 231     bind_variable(INTERRUPTS_ENABLED,T,th);
 232
 233     th->interrupt_data = (struct interrupt_data *)
 234         os_validate(0,(sizeof (struct interrupt_data)));
 235     if(all_threads)
 236         memcpy(th->interrupt_data,
 237                arch_os_get_current_thread()->interrupt_data,
 238                sizeof (struct interrupt_data));
 239     else
 240         memcpy(th->interrupt_data,global_interrupt_data,
 241                sizeof (struct interrupt_data));
 242
 243     th->unbound_marker=initial_function;
 244     return th;
 245 }
 246
 247 void link_thread(struct thread *th,os_thread_t kid_tid)
 248 {
 249     if (all_threads) all_threads->prev=th;
 250     th->next=all_threads;
 251     th->prev=0;
 252     all_threads=th;
 253     /* note that th->os_thread is 0 at this time.  We rely on
 254      * all_threads_lock to ensure that we don't have >1 thread with
 255      * os_thread=0 on the list at once
 256      */
 257     protect_control_stack_guard_page(th,1);
 258     /* child will not start until this is set */
 259     th->os_thread=kid_tid;
 260 }
 261
 262 void create_initial_thread(lispobj initial_function) {
 263     struct thread *th=create_thread_struct(initial_function);
 264     os_thread_t kid_tid=thread_self();
 265     if(th && kid_tid>0) {
 266         link_thread(th,kid_tid);
 267         initial_thread_trampoline(all_threads); /* no return */
 268     } else lose("can't create initial thread");
 269 }
 270
 271 #ifdef LISP_FEATURE_SB_THREAD
 272
 273 boolean create_os_thread(struct thread *th,os_thread_t *kid_tid)
 274 {
 275     /* The new thread inherits the restrictive signal mask set here,
 276      * and enables signals again when it is set up properly. */
 277     pthread_attr_t attr;
 278     sigset_t newset,oldset;
 279     boolean r=1;
 280     sigemptyset(&newset);
 281     sigaddset_blockable(&newset);
 282     thread_sigmask(SIG_BLOCK, &newset, &oldset);
 283
 284     if((pthread_attr_init(&attr)) ||
 285        (pthread_attr_setstack(&attr,th->control_stack_start,
 286                               THREAD_CONTROL_STACK_SIZE-16)) ||
 287        (pthread_create
 288         (kid_tid,&attr,(void *(*)(void *))new_thread_trampoline,th)))
 289         r=0;
 290     thread_sigmask(SIG_SETMASK,&oldset,0);
 291     return r;
 292 }
 293
 294 struct thread *create_thread(lispobj initial_function) {
 295     struct thread *th;
 296     os_thread_t kid_tid=0;
 297     boolean success;
 298
 299     if(linux_no_threads_p) return 0;
 300
 301     th=create_thread_struct(initial_function);
 302     if(th==0) return 0;
 303
 304     /* we must not be interrupted here after a successful
 305      * create_os_thread, because the kid will be waiting for its
 306      * thread struct to be linked */
 307     GET_ALL_THREADS_LOCK("create_thread")
 308
 309     success=create_os_thread(th,&kid_tid);
 310     if (success)
 311         link_thread(th,kid_tid);
 312     else
 313         os_invalidate((os_vm_address_t) th->control_stack_start,
 314                       ((sizeof (lispobj))
 315                        * (th->control_stack_end-th->control_stack_start)) +
 316                       BINDING_STACK_SIZE+ALIEN_STACK_SIZE+dynamic_values_bytes+
 317                       32*SIGSTKSZ);
 318
 319     RELEASE_ALL_THREADS_LOCK("create_thread")
 320
 321     if (success)
 322         return th;
 323     else
 324         return 0;
 325 }
 326 #endif
 327
 328 #if defined LISP_FEATURE_SB_THREAD
 329 /* This is not needed unless #+SB-THREAD, as there's a trivial null
 330  * unithread definition. */
 331
 332 /* called from lisp from the thread object finalizer */
 333 void reap_dead_thread(struct thread *th)
 334 {
 335     if(th->state!=STATE_DEAD)
 336         lose("thread %lx is not joinable, state=%d\n",th,th->state);
 337 #ifdef LISP_FEATURE_GENCGC
 338     {
 339         sigset_t newset,oldset;
 340         sigemptyset(&newset);
 341         sigaddset_blockable(&newset);
 342         thread_sigmask(SIG_BLOCK, &newset, &oldset);
 343         gc_alloc_update_page_tables(0, &th->alloc_region);
 344         release_spinlock(&all_threads_lock);
 345         thread_sigmask(SIG_SETMASK,&oldset,0);
 346     }
 347 #endif
 348     GET_ALL_THREADS_LOCK("reap_dead_thread")
 349     FSHOW((stderr,"/reap_dead_thread: reaping %ld\n",th->os_thread));
 350     if(th->prev)
 351         th->prev->next=th->next;
 352     else all_threads=th->next;
 353     if(th->next)
 354         th->next->prev=th->prev;
 355     RELEASE_ALL_THREADS_LOCK("reap_dead_thread")
 356     if(th->tls_cookie>=0) arch_os_thread_cleanup(th);
 357     gc_assert(pthread_join(th->os_thread,NULL)==0);
 358     os_invalidate((os_vm_address_t) th->control_stack_start,
 359                   ((sizeof (lispobj))
 360                    * (th->control_stack_end-th->control_stack_start)) +
 361                   BINDING_STACK_SIZE+ALIEN_STACK_SIZE+dynamic_values_bytes+
 362                   32*SIGSTKSZ);
 363 }
 364
 365 int interrupt_thread(struct thread *th, lispobj function)
 366 {
 367     /* A thread may also become dead after this test. */
 368     if ((th->state != STATE_DEAD)) {
 369         /* In clone_threads, if A and B both interrupt C at
 370          * approximately the same time, it does not matter: the
 371          * second signal will be masked until the handler has
 372          * returned from the first one.  In pthreads though, we
 373          * can't put the knowledge of what function to call into
 374          * the siginfo, so we have to store it in the destination
 375          * thread, and do it in such a way that A won't clobber
 376          * B's interrupt.  Hence this stupid linked list.
 377          *
 378          * This does depend on SIG_INTERRUPT_THREAD being queued
 379          * (as POSIX RT signals are): we need to keep
 380          * interrupt_fun data for exactly as many signals as are
 381          * going to be received by the destination thread.
 382          */
 383         struct cons *c=alloc_cons(function,NIL);
 384         int kill_status;
 385         /* interrupt_thread_handler locks this spinlock with
 386          * interrupts blocked and it does so for the sake of
 387          * arrange_return_to_lisp_function, so we must also block
 388          * them. */
 389         sigset_t newset,oldset;
 390         sigemptyset(&newset);
 391         sigaddset_blockable(&newset);
 392         thread_sigmask(SIG_BLOCK, &newset, &oldset);
 393         get_spinlock(&th->interrupt_fun_lock,
 394                      (long)arch_os_get_current_thread());
 395         kill_status=thread_kill(th->os_thread,SIG_INTERRUPT_THREAD);
 396         if(kill_status==0) {
 397             ((struct cons *)native_pointer(c))->cdr=th->interrupt_fun;
 398             th->interrupt_fun=c;
 399         }
 400         release_spinlock(&th->interrupt_fun_lock);
 401         thread_sigmask(SIG_SETMASK,&oldset,0);
 402         return (kill_status ? -1 : 0);
 403     }
 404     errno=EPERM; return -1;
 405 }
 406
 407 /* stopping the world is a two-stage process.  From this thread we signal
 408  * all the others with SIG_STOP_FOR_GC.  The handler for this signal does
 409  * the usual pseudo-atomic checks (we don't want to stop a thread while
 410  * it's in the middle of allocation) then waits for another SIG_STOP_FOR_GC.
 411  */
 412
 413 /* To avoid deadlocks when gc stops the world all clients of each
 414  * mutex must enable or disable SIG_STOP_FOR_GC for the duration of
 415  * holding the lock, but they must agree on which. */
 416 void gc_stop_the_world()
 417 {
 418     struct thread *p,*th=arch_os_get_current_thread();
 419     FSHOW_SIGNAL((stderr,"/gc_stop_the_world:waiting on lock, thread=%ld\n",
 420                   th->os_thread));
 421     /* keep threads from starting while the world is stopped. */
 422     get_spinlock(&all_threads_lock,(long)th);
 423     FSHOW_SIGNAL((stderr,"/gc_stop_the_world:got lock, thread=%ld\n",
 424                   th->os_thread));
 425     /* stop all other threads by sending them SIG_STOP_FOR_GC */
 426     for(p=all_threads; p; p=p->next) {
 427         while(p->state==STATE_STARTING) sched_yield();
 428         if((p!=th) && (p->state==STATE_RUNNING)) {
 429             FSHOW_SIGNAL((stderr,"/gc_stop_the_world:sending sig_stop to %ld\n",
 430                           p->os_thread));
 431             if(thread_kill(p->os_thread,SIG_STOP_FOR_GC)==-1) {
 432                 /* we can't kill the thread; assume because it died
 433                  * since we last checked */
 434                 p->state=STATE_DEAD;
 435                 FSHOW_SIGNAL((stderr,"/gc_stop_the_world:assuming %ld dead\n",
 436                    p->os_thread));
 437             }
 438         }
 439     }
 440     FSHOW_SIGNAL((stderr,"/gc_stop_the_world:signals sent\n"));
 441     /* wait for the running threads to stop or finish */
 442     for(p=all_threads;p;) {
 443         gc_assert(p->os_thread!=0);
 444         gc_assert(p->state!=STATE_STARTING);
 445         if((p==th) || (p->state==STATE_SUSPENDED) ||
 446            (p->state==STATE_DEAD)) {
 447             p=p->next;
 448         }
 449     }
 450     FSHOW_SIGNAL((stderr,"/gc_stop_the_world:end\n"));
 451 }
 452
 453 void gc_start_the_world()
 454 {
 455     struct thread *p,*th=arch_os_get_current_thread();
 456     /* if a resumed thread creates a new thread before we're done with
 457      * this loop, the new thread will get consed on the front of
 458      * all_threads, but it won't have been stopped so won't need
 459      * restarting */
 460     FSHOW_SIGNAL((stderr,"/gc_start_the_world:begin\n"));
 461     for(p=all_threads;p;p=p->next) {
 462         gc_assert(p->os_thread!=0);
 463         if((p!=th) && (p->state!=STATE_DEAD)) {
 464             if(p->state!=STATE_SUSPENDED) {
 465                 lose("gc_start_the_world: wrong thread state is %ld\n",
 466                      fixnum_value(p->state));
 467             }
 468             thread_kill(p->os_thread,SIG_STOP_FOR_GC);
 469         }
 470     }
 471     /* we must wait for all threads to leave stopped state else we
 472      * risk signal accumulation and lose any meaning of
 473      * thread->state */
 474     for(p=all_threads;p;) {
 475         if((p==th) || (p->state!=STATE_SUSPENDED)) {
 476             p=p->next;
 477         }
 478     }
 479     release_spinlock(&all_threads_lock);
 480     FSHOW_SIGNAL((stderr,"/gc_start_the_world:end\n"));
 481 }
 482 #endif