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