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Sourcecode: sbcl version File versions

thread.c

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <sched.h>
#include <signal.h>
#include <stddef.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/wait.h>

#include "sbcl.h"
#include "runtime.h"
#include "validate.h"         /* for CONTROL_STACK_SIZE etc */
#include "thread.h"
#include "arch.h"
#include "target-arch-os.h"
#include "os.h"
#include "globals.h"
#include "dynbind.h"
#include "genesis/cons.h"
#include "genesis/fdefn.h"
#include "interr.h"             /* for lose() */
#include "gc-internal.h"

#define ALIEN_STACK_SIZE (1*1024*1024) /* 1Mb size chosen at random */

int dynamic_values_bytes=4096*sizeof(lispobj);  /* same for all threads */
struct thread *all_threads;
volatile lispobj all_threads_lock;
extern struct interrupt_data * global_interrupt_data;

int
initial_thread_trampoline(struct thread *th)
{
    lispobj function;
    lispobj *args = NULL;
    function = th->unbound_marker;
    th->unbound_marker = UNBOUND_MARKER_WIDETAG;
    if(arch_os_thread_init(th)==0) return 1;

    if(th->pid < 1) lose("th->pid not set up right");
    th->state=STATE_RUNNING;
#if defined(LISP_FEATURE_X86)
    return call_into_lisp_first_time(function,args,0);
#else
    return funcall0(function);
#endif
}

/* this is the first thing that clone() runs in the child (which is
 * why the silly calling convention).  Basically it calls the user's
 * requested lisp function after doing arch_os_thread_init and
 * whatever other bookkeeping needs to be done
 */

#ifdef LISP_FEATURE_SB_THREAD
int
new_thread_trampoline(struct thread *th)
{
    lispobj function;
    function = th->unbound_marker;
    th->unbound_marker = UNBOUND_MARKER_WIDETAG;
    if(arch_os_thread_init(th)==0) return 1;    

    /* wait here until our thread is linked into all_threads: see below */
    while(th->pid<1) sched_yield();

    th->state=STATE_RUNNING;
    return funcall0(function);
}
#endif /* LISP_FEATURE_SB_THREAD */

/* this is called from any other thread to create the new one, and
 * initialize all parts of it that can be initialized from another 
 * thread 
 */

struct thread * create_thread_struct(lispobj initial_function) {
    union per_thread_data *per_thread;
    struct thread *th=0;      /*  subdue gcc */
    void *spaces=0;

    /* may as well allocate all the spaces at once: it saves us from
     * having to decide what to do if only some of the allocations
     * succeed */
    spaces=os_validate(0,
                   THREAD_CONTROL_STACK_SIZE+
                   BINDING_STACK_SIZE+
                   ALIEN_STACK_SIZE+
                   dynamic_values_bytes+
                   32*SIGSTKSZ
                   );
    if(!spaces) goto cleanup;
    per_thread=(union per_thread_data *)
      (spaces+
       THREAD_CONTROL_STACK_SIZE+
       BINDING_STACK_SIZE+
       ALIEN_STACK_SIZE);

    th=&per_thread->thread;
    if(all_threads) {
      memcpy(per_thread,arch_os_get_current_thread(),
             dynamic_values_bytes);
    } else {
#ifdef LISP_FEATURE_SB_THREAD
      int i;
      for(i=0;i<(dynamic_values_bytes/sizeof(lispobj));i++)
          per_thread->dynamic_values[i]=UNBOUND_MARKER_WIDETAG;
      if(SymbolValue(FREE_TLS_INDEX,0)==UNBOUND_MARKER_WIDETAG) 
          SetSymbolValue
            (FREE_TLS_INDEX,
             make_fixnum(MAX_INTERRUPTS+
                       sizeof(struct thread)/sizeof(lispobj)),
             0);
#define STATIC_TLS_INIT(sym,field) \
  ((struct symbol *)(sym-OTHER_POINTER_LOWTAG))->tls_index= \
  make_fixnum(THREAD_SLOT_OFFSET_WORDS(field))
                          
      STATIC_TLS_INIT(BINDING_STACK_START,binding_stack_start);
      STATIC_TLS_INIT(BINDING_STACK_POINTER,binding_stack_pointer);
      STATIC_TLS_INIT(CONTROL_STACK_START,control_stack_start);
      STATIC_TLS_INIT(CONTROL_STACK_END,control_stack_end);
      STATIC_TLS_INIT(ALIEN_STACK,alien_stack_pointer);
#ifdef LISP_FEATURE_X86
      STATIC_TLS_INIT(PSEUDO_ATOMIC_ATOMIC,pseudo_atomic_atomic);
      STATIC_TLS_INIT(PSEUDO_ATOMIC_INTERRUPTED,pseudo_atomic_interrupted);
#endif
#undef STATIC_TLS_INIT
#endif
    }

    th->control_stack_start = spaces;
    th->binding_stack_start=
      (lispobj*)((void*)th->control_stack_start+THREAD_CONTROL_STACK_SIZE);
    th->control_stack_end = th->binding_stack_start;
    th->alien_stack_start=
      (lispobj*)((void*)th->binding_stack_start+BINDING_STACK_SIZE);
    th->binding_stack_pointer=th->binding_stack_start;
    th->this=th;
    th->pid=0;
    th->state=STATE_STOPPED;
#ifdef LISP_FEATURE_STACK_GROWS_DOWNWARD_NOT_UPWARD
    th->alien_stack_pointer=((void *)th->alien_stack_start
                       + ALIEN_STACK_SIZE-4); /* naked 4.  FIXME */
#else
    th->alien_stack_pointer=((void *)th->alien_stack_start);
#endif
#ifdef LISP_FEATURE_X86
    th->pseudo_atomic_interrupted=0;
    th->pseudo_atomic_atomic=0;
#endif
#ifdef LISP_FEATURE_GENCGC
    gc_set_region_empty(&th->alloc_region);
#endif

#ifndef LISP_FEATURE_SB_THREAD
    /* the tls-points-into-struct-thread trick is only good for threaded
     * sbcl, because unithread sbcl doesn't have tls.  So, we copy the
     * appropriate values from struct thread here, and make sure that 
     * we use the appropriate SymbolValue macros to access any of the
     * variable quantities from the C runtime.  It's not quite OAOOM,
     * it just feels like it */
    SetSymbolValue(BINDING_STACK_START,(lispobj)th->binding_stack_start,th);
    SetSymbolValue(CONTROL_STACK_START,(lispobj)th->control_stack_start,th);
    SetSymbolValue(CONTROL_STACK_END,(lispobj)th->control_stack_end,th);
#ifdef LISP_FEATURE_X86
    SetSymbolValue(BINDING_STACK_POINTER,(lispobj)th->binding_stack_pointer,th);
    SetSymbolValue(ALIEN_STACK,(lispobj)th->alien_stack_pointer,th);
    SetSymbolValue(PSEUDO_ATOMIC_ATOMIC,(lispobj)th->pseudo_atomic_atomic,th);
    SetSymbolValue(PSEUDO_ATOMIC_INTERRUPTED,th->pseudo_atomic_interrupted,th);
#else
    current_binding_stack_pointer=th->binding_stack_pointer;
    current_control_stack_pointer=th->control_stack_start;
#endif
#endif    
    bind_variable(CURRENT_CATCH_BLOCK,make_fixnum(0),th);
    bind_variable(CURRENT_UNWIND_PROTECT_BLOCK,make_fixnum(0),th); 
    bind_variable(FREE_INTERRUPT_CONTEXT_INDEX,make_fixnum(0),th);
    bind_variable(INTERRUPT_PENDING, NIL,th);
    bind_variable(INTERRUPTS_ENABLED,T,th);

    th->interrupt_data=os_validate(0,(sizeof (struct interrupt_data)));
    if(all_threads) 
      memcpy(th->interrupt_data,
             arch_os_get_current_thread()->interrupt_data,
             sizeof (struct interrupt_data));
    else 
      memcpy(th->interrupt_data,global_interrupt_data,
             sizeof (struct interrupt_data));

    th->unbound_marker=initial_function;
    return th;
 cleanup:
    /* if(th && th->tls_cookie>=0) os_free_tls_pointer(th); */
    if(spaces) os_invalidate(spaces,
                       THREAD_CONTROL_STACK_SIZE+BINDING_STACK_SIZE+
                       ALIEN_STACK_SIZE+dynamic_values_bytes);
    return 0;
}

void link_thread(struct thread *th,pid_t kid_pid)
{
    sigset_t newset,oldset;
    sigemptyset(&newset);
    sigaddset_blockable(&newset);
    sigprocmask(SIG_BLOCK, &newset, &oldset); 

    get_spinlock(&all_threads_lock,kid_pid);
    th->next=all_threads;
    all_threads=th;
    /* note that th->pid is 0 at this time.  We rely on all_threads_lock
     * to ensure that we don't have >1 thread with pid=0 on the list at once
     */
    protect_control_stack_guard_page(th->pid,1);
    release_spinlock(&all_threads_lock);

    sigprocmask(SIG_SETMASK,&oldset,0);
    th->pid=kid_pid;          /* child will not start until this is set */
}

void create_initial_thread(lispobj initial_function) {
    struct thread *th=create_thread_struct(initial_function);
    pid_t kid_pid=getpid();
    if(th && kid_pid>0) {
      link_thread(th,kid_pid);
      initial_thread_trampoline(all_threads); /* no return */
    } else lose("can't create initial thread");
}

#ifdef LISP_FEATURE_SB_THREAD
pid_t create_thread(lispobj initial_function) {
    struct thread *th=create_thread_struct(initial_function);
    pid_t kid_pid=0;

    if(th==0) return 0;
    kid_pid=clone(new_thread_trampoline,
              (((void*)th->control_stack_start)+
               THREAD_CONTROL_STACK_SIZE-4),
              CLONE_FILES|SIG_THREAD_EXIT|CLONE_VM,th);
    
    if(kid_pid>0) {
      link_thread(th,kid_pid);
      return th->pid;
    } else {
      os_invalidate((os_vm_address_t) th->control_stack_start,
                  ((sizeof (lispobj))
                   * (th->control_stack_end-th->control_stack_start)) +
                  BINDING_STACK_SIZE+ALIEN_STACK_SIZE+dynamic_values_bytes+
                  32*SIGSTKSZ);
      return 0;
    }
}
#endif

/* unused */
void destroy_thread (struct thread *th)
{
    /* precondition: the unix task has already been killed and exited.
     * This is called by the parent or some other thread */
#ifdef LISP_FEATURE_GENCGC
    gc_alloc_update_page_tables(0, &th->alloc_region);
#endif
    get_spinlock(&all_threads_lock,th->pid);
    th->unbound_marker=0;     /* for debugging */
    if(th==all_threads) 
      all_threads=th->next;
    else {
      struct thread *th1=all_threads;
      while(th1 && th1->next!=th) th1=th1->next;
      if(th1)     th1->next=th->next;     /* unlink */
    }
    release_spinlock(&all_threads_lock);
    if(th && th->tls_cookie>=0) arch_os_thread_cleanup(th); 
    os_invalidate((os_vm_address_t) th->control_stack_start,
              ((sizeof (lispobj))
               * (th->control_stack_end-th->control_stack_start)) +
              BINDING_STACK_SIZE+ALIEN_STACK_SIZE+dynamic_values_bytes+
              32*SIGSTKSZ);
}

struct thread *find_thread_by_pid(pid_t pid) 
{
    struct thread *th;
    for_each_thread(th)
      if(th->pid==pid) return th;
    return 0;
}

#if defined LISP_FEATURE_SB_THREAD
/* This is not needed unless #+SB-THREAD, as there's a trivial null
 * unithread definition. */

void mark_dead_threads() 
{
    pid_t kid;
    int status;
    while(1) {
      kid=waitpid(-1,&status,__WALL|WNOHANG);
      if(kid<=0) break;
      if(WIFEXITED(status) || WIFSIGNALED(status)) {
          struct thread *th=find_thread_by_pid(kid);
          if(th) th->state=STATE_DEAD;
      }
    }
}

void reap_dead_threads() 
{
    struct thread *th,*next,*prev=0;
    th=all_threads;
    while(th) {
      next=th->next;
      if(th->state==STATE_DEAD) {
          funcall1(SymbolFunction(HANDLE_THREAD_EXIT),make_fixnum(th->pid));
#ifdef LISP_FEATURE_GENCGC
          gc_alloc_update_page_tables(0, &th->alloc_region);
#endif
          get_spinlock(&all_threads_lock,th->pid);
          if(prev) prev->next=next;
          else all_threads=next;
          release_spinlock(&all_threads_lock);
          if(th->tls_cookie>=0) arch_os_thread_cleanup(th); 
          os_invalidate((os_vm_address_t) th->control_stack_start,
                    ((sizeof (lispobj))
                     * (th->control_stack_end-th->control_stack_start)) +
                    BINDING_STACK_SIZE+ALIEN_STACK_SIZE+dynamic_values_bytes+
                    32*SIGSTKSZ);
      } else 
          prev=th;
      th=next;
    }
}

/* These are not needed unless #+SB-THREAD, and since sigwaitinfo()
 * doesn't seem to be easily available everywhere (OpenBSD...) it's
 * more trouble than it's worth to compile it when not needed. */
void block_sigcont(void)
{
    /* don't allow ourselves to receive SIGCONT while we're in the
     * "ambiguous" state of being on the queue but not actually stopped.
     */
    sigset_t newset;
    sigemptyset(&newset);
    sigaddset(&newset,SIG_DEQUEUE);
    sigprocmask(SIG_BLOCK, &newset, 0); 
}

void unblock_sigcont_and_sleep(void)
{
    sigset_t set;
    sigemptyset(&set);
    sigaddset(&set,SIG_DEQUEUE);
    do {
      errno=0;
      sigwaitinfo(&set,0);
    }while(errno==EINTR);
    sigprocmask(SIG_UNBLOCK,&set,0);
}

int interrupt_thread(pid_t pid, lispobj function)
{
    union sigval sigval;
    struct thread *th;
    sigval.sival_int=function;
    for_each_thread(th) 
      if((th->pid==pid) && (th->state != STATE_DEAD))
          return sigqueue(pid, SIG_INTERRUPT_THREAD, sigval);
    errno=EPERM; return -1;
}

int signal_thread_to_dequeue (pid_t pid)
{
    return kill (pid, SIG_DEQUEUE);
}


/* stopping the world is a two-stage process.  From this thread we signal 
 * all the others with SIG_STOP_FOR_GC.  The handler for this signal does
 * the usual pseudo-atomic checks (we don't want to stop a thread while 
 * it's in the middle of allocation) then kills _itself_ with SIGSTOP.
 */

void gc_stop_the_world()
{
    /* stop all other threads by sending them SIG_STOP_FOR_GC */
    struct thread *p,*th=arch_os_get_current_thread();
    pid_t old_pid;
    int finished;
    do {
      finished=1;
      for(p=all_threads,old_pid=p->pid; p; p=p->next) {
          if(p==th) continue;
          if(p->state==STATE_RUNNING) {
            p->state=STATE_STOPPING;
            if(kill(p->pid,SIG_STOP_FOR_GC)==-1) {
                /* we can't kill the process; assume because it
                 * died already (and its parent is dead so never
                 * saw the SIGCHLD) */
                p->state=STATE_DEAD;
            }
          }
          if((p->state!=STATE_STOPPED) &&
             (p->state!=STATE_DEAD)) {
            finished=0;
          }
      }
      if(old_pid!=all_threads->pid) {
          finished=0;
      }
    } while(!finished);
}

void gc_start_the_world()
{
    struct thread *p,*th=arch_os_get_current_thread();
    /* if a resumed thread creates a new thread before we're done with
     * this loop, the new thread will get consed on the front of *
     * all_threads_lock, but it won't have been stopped so won't need
     * restarting */
    for(p=all_threads;p;p=p->next) {
      if((p==th) || (p->state==STATE_DEAD)) continue;
      p->state=STATE_RUNNING;
      kill(p->pid,SIG_STOP_FOR_GC);
    }
}
#endif

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