Beispiel #1
0
pthread_start_thread(void *arg)
{
  pthread_descr self = (pthread_descr) arg;
  struct pthread_request request;
  void * outcome;
#if HP_TIMING_AVAIL
  hp_timing_t tmpclock;
#endif
  /* Initialize special thread_self processing, if any.  */
#ifdef INIT_THREAD_SELF
  INIT_THREAD_SELF(self, self->p_nr);
#endif
#if HP_TIMING_AVAIL
  HP_TIMING_NOW (tmpclock);
  THREAD_SETMEM (self, p_cpuclock_offset, tmpclock);
#endif
  /* Make sure our pid field is initialized, just in case we get there
     before our father has initialized it. */
  THREAD_SETMEM(self, p_pid, __getpid());
  /* Initial signal mask is that of the creating thread. (Otherwise,
     we'd just inherit the mask of the thread manager.) */
  sigprocmask(SIG_SETMASK, &self->p_start_args.mask, NULL);
  /* Set the scheduling policy and priority for the new thread, if needed */
  if (THREAD_GETMEM(self, p_start_args.schedpolicy) >= 0)
    /* Explicit scheduling attributes were provided: apply them */
    __sched_setscheduler(THREAD_GETMEM(self, p_pid),
			 THREAD_GETMEM(self, p_start_args.schedpolicy),
                         &self->p_start_args.schedparam);
  else if (manager_thread->p_priority > 0)
    /* Default scheduling required, but thread manager runs in realtime
       scheduling: switch new thread to SCHED_OTHER policy */
    {
      struct sched_param default_params;
      default_params.sched_priority = 0;
      __sched_setscheduler(THREAD_GETMEM(self, p_pid),
                           SCHED_OTHER, &default_params);
    }
#if !(USE_TLS && HAVE___THREAD)
  /* Initialize thread-locale current locale to point to the global one.
     With __thread support, the variable's initializer takes care of this.  */
  __uselocale (LC_GLOBAL_LOCALE);
#else
  /* Initialize __resp.  */
  __resp = &self->p_res;
#endif
  /* Make gdb aware of new thread */
  if (__pthread_threads_debug && __pthread_sig_debug > 0) {
    request.req_thread = self;
    request.req_kind = REQ_DEBUG;
    TEMP_FAILURE_RETRY(write_not_cancel(__pthread_manager_request,
					(char *) &request, sizeof(request)));
    suspend(self);
  }
  /* Run the thread code */
  outcome = self->p_start_args.start_routine(THREAD_GETMEM(self,
							   p_start_args.arg));
  /* Exit with the given return value */
  __pthread_do_exit(outcome, CURRENT_STACK_FRAME);
}
 /* Do some minimal initialization which has to be done during the
    startup of the C library.  */
void __pthread_initialize_minimal(void)
{
    /* If we have special thread_self processing, initialize 
     * that for the main thread now.  */
#ifdef INIT_THREAD_SELF
    INIT_THREAD_SELF(&__pthread_initial_thread, 0);
#endif
}
Beispiel #3
0
 /* Do some minimal initialization which has to be done during the
    startup of the C library.  */
void __pthread_initialize_minimal(void)
{
    /* If we have special thread_self processing, initialize
     * that for the main thread now.  */
#ifdef INIT_THREAD_SELF
    INIT_THREAD_SELF(&__pthread_initial_thread, 0);
#endif

    __libc_multiple_threads_ptr = __libc_pthread_init (ptr_pthread_functions);
}
Beispiel #4
0
/* Do some minimal initialization which has to be done during the
   startup of the C library.  */
void
__pthread_initialize_minimal(void)
{
  /* If we have special thread_self processing, initialize that for the
     main thread now.  */
#ifdef INIT_THREAD_SELF
  INIT_THREAD_SELF(&__pthread_initial_thread, 0);
#endif
#if HP_TIMING_AVAIL
  __pthread_initial_thread.p_cpuclock_offset = _dl_cpuclock_offset;
#endif
}
static void pthread_handle_sigcancel(int sig)
{
  pthread_descr self = thread_self();
  sigjmp_buf * jmpbuf;
  

  if (self == &__pthread_manager_thread)
    {
#ifdef THREAD_SELF
      /* A new thread might get a cancel signal before it is fully
	 initialized, so that the thread register might still point to the
	 manager thread.  Double check that this is really the manager
	 thread.  */
      pthread_descr real_self = thread_self_stack();
      if (real_self == &__pthread_manager_thread)
	{
	  __pthread_manager_sighandler(sig);
	  return;
	}
      /* Oops, thread_self() isn't working yet..  */
      self = real_self;
# ifdef INIT_THREAD_SELF
      INIT_THREAD_SELF(self, self->p_nr);
# endif
#else
      __pthread_manager_sighandler(sig);
      return;
#endif
    }
  if (__builtin_expect (__pthread_exit_requested, 0)) {
    /* Main thread should accumulate times for thread manager and its
       children, so that timings for main thread account for all threads. */
    if (self == __pthread_main_thread) {
#ifdef USE_TLS
      waitpid(__pthread_manager_thread->p_pid, NULL, __WCLONE);
#else
      waitpid(__pthread_manager_thread.p_pid, NULL, __WCLONE);
#endif
    }
    _exit(__pthread_exit_code);
  }
  if (__builtin_expect (THREAD_GETMEM(self, p_canceled), 0)
      && THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE) {
    if (THREAD_GETMEM(self, p_canceltype) == PTHREAD_CANCEL_ASYNCHRONOUS)
      pthread_exit(PTHREAD_CANCELED);
    jmpbuf = THREAD_GETMEM(self, p_cancel_jmp);
    if (jmpbuf != NULL) {
      THREAD_SETMEM(self, p_cancel_jmp, NULL);
      siglongjmp(*jmpbuf, 1);
    }
  }
}
Beispiel #6
0
int attribute_noreturn __pthread_manager_event(void *arg)
{
  /* If we have special thread_self processing, initialize it.  */
#ifdef INIT_THREAD_SELF
  INIT_THREAD_SELF(&__pthread_manager_thread, 1);
#endif

  /* Get the lock the manager will free once all is correctly set up.  */
  __pthread_lock (THREAD_GETMEM((&__pthread_manager_thread), p_lock), NULL);
  /* Free it immediately.  */
  __pthread_unlock (THREAD_GETMEM((&__pthread_manager_thread), p_lock));

  __pthread_manager(arg);
}
Beispiel #7
0
/* Process creation */
static int
attribute_noreturn
pthread_start_thread(void *arg)
{
  pthread_descr self = (pthread_descr) arg;
  struct pthread_request request;
  void * outcome;
  /* Initialize special thread_self processing, if any.  */
#ifdef INIT_THREAD_SELF
  INIT_THREAD_SELF(self, self->p_nr);
#endif
  PDEBUG("\n");
  /* Make sure our pid field is initialized, just in case we get there
     before our father has initialized it. */
  THREAD_SETMEM(self, p_pid, getpid());
  /* Initial signal mask is that of the creating thread. (Otherwise,
     we'd just inherit the mask of the thread manager.) */
  sigprocmask(SIG_SETMASK, &self->p_start_args.mask, NULL);
  /* Set the scheduling policy and priority for the new thread, if needed */
  if (THREAD_GETMEM(self, p_start_args.schedpolicy) >= 0)
    /* Explicit scheduling attributes were provided: apply them */
    sched_setscheduler(THREAD_GETMEM(self, p_pid),
			 THREAD_GETMEM(self, p_start_args.schedpolicy),
                         &self->p_start_args.schedparam);
  else if (__pthread_manager_thread.p_priority > 0)
    /* Default scheduling required, but thread manager runs in realtime
       scheduling: switch new thread to SCHED_OTHER policy */
    {
      struct sched_param default_params;
      default_params.sched_priority = 0;
      sched_setscheduler(THREAD_GETMEM(self, p_pid),
                           SCHED_OTHER, &default_params);
    }
  /* Make gdb aware of new thread */
  if (__pthread_threads_debug && __pthread_sig_debug > 0) {
    request.req_thread = self;
    request.req_kind = REQ_DEBUG;
    TEMP_FAILURE_RETRY(write(__pthread_manager_request,
		(char *) &request, sizeof(request)));
    suspend(self);
  }
  /* Run the thread code */
  outcome = self->p_start_args.start_routine(THREAD_GETMEM(self,
							   p_start_args.arg));
  /* Exit with the given return value */
  __pthread_do_exit(outcome, CURRENT_STACK_FRAME);
}
Beispiel #8
0
pthread_start_thread_event(void *arg)
{
  pthread_descr self = (pthread_descr) arg;

#ifdef INIT_THREAD_SELF
  INIT_THREAD_SELF(self, self->p_nr);
#endif
  /* Make sure our pid field is initialized, just in case we get there
     before our father has initialized it. */
  THREAD_SETMEM(self, p_pid, __getpid());
  /* Get the lock the manager will free once all is correctly set up.  */
  __pthread_lock (THREAD_GETMEM(self, p_lock), NULL);
  /* Free it immediately.  */
  __pthread_unlock (THREAD_GETMEM(self, p_lock));

  /* Continue with the real function.  */
  pthread_start_thread (arg);
}
Beispiel #9
0
static int pthread_start_thread(void * arg)
{
  pthread_descr self = (pthread_descr) arg;
  void * outcome;
  /* Initialize special thread_self processing, if any.  */
#ifdef INIT_THREAD_SELF
  INIT_THREAD_SELF(self);
#endif
  /* Make sure our pid field is initialized, just in case we get there
     before our father has initialized it. */
  self->p_pid = __getpid();
  /* Initial signal mask is that of the creating thread. (Otherwise,
     we'd just inherit the mask of the thread manager.) */
  sigprocmask(SIG_SETMASK, &self->p_start_args.mask, NULL);
  /* Set the scheduling policy and priority for the new thread, if needed */
  if (self->p_start_args.schedpolicy != SCHED_OTHER)
    __sched_setscheduler(self->p_pid, self->p_start_args.schedpolicy,
                         &self->p_start_args.schedparam);
  /* Run the thread code */
  outcome = self->p_start_args.start_routine(self->p_start_args.arg);
  /* Exit with the given return value */
  pthread_exit(outcome);
  return 0;
}
Beispiel #10
0
int attribute_noreturn __pthread_manager(void *arg)
{
  int reqfd = (int) (long int) arg;
#ifdef USE_SELECT
  struct timeval tv;
  fd_set fd;
#else
  struct pollfd ufd;
#endif
  sigset_t manager_mask;
  int n;
  struct pthread_request request;

  /* If we have special thread_self processing, initialize it.  */
#ifdef INIT_THREAD_SELF
  INIT_THREAD_SELF(&__pthread_manager_thread, 1);
#endif
  /* Set the error variable.  */
  __pthread_manager_thread.p_errnop = &__pthread_manager_thread.p_errno;
  __pthread_manager_thread.p_h_errnop = &__pthread_manager_thread.p_h_errno;

#ifdef __UCLIBC_HAS_XLOCALE__
  /* Initialize thread's locale to the global locale. */
  __pthread_manager_thread.locale = __global_locale;
#endif /* __UCLIBC_HAS_XLOCALE__ */

  /* Block all signals except __pthread_sig_cancel and SIGTRAP */
  __sigfillset(&manager_mask);
  sigdelset(&manager_mask, __pthread_sig_cancel); /* for thread termination */
  sigdelset(&manager_mask, SIGTRAP);            /* for debugging purposes */
  if (__pthread_threads_debug && __pthread_sig_debug > 0)
      sigdelset(&manager_mask, __pthread_sig_debug);
  sigprocmask(SIG_SETMASK, &manager_mask, NULL);
  /* Raise our priority to match that of main thread */
  __pthread_manager_adjust_prio(__pthread_main_thread->p_priority);
  /* Synchronize debugging of the thread manager */
  n = TEMP_FAILURE_RETRY(read(reqfd, (char *)&request,
				     sizeof(request)));
#ifndef USE_SELECT
  ufd.fd = reqfd;
  ufd.events = POLLIN;
#endif
  /* Enter server loop */
  while(1) {
#ifdef USE_SELECT
    tv.tv_sec = 2;
    tv.tv_usec = 0;
    FD_ZERO (&fd);
    FD_SET (reqfd, &fd);
    n = select (reqfd + 1, &fd, NULL, NULL, &tv);
#else
    PDEBUG("before poll\n");
    n = poll(&ufd, 1, 2000);
    PDEBUG("after poll\n");
#endif
    /* Check for termination of the main thread */
    if (getppid() == 1) {
      pthread_kill_all_threads(SIGKILL, 0);
      _exit(0);
    }
    /* Check for dead children */
    if (terminated_children) {
      terminated_children = 0;
      pthread_reap_children();
    }
    /* Read and execute request */
#ifdef USE_SELECT
    if (n == 1)
#else
    if (n == 1 && (ufd.revents & POLLIN))
#endif
    {

      PDEBUG("before read\n");
      n = read(reqfd, (char *)&request, sizeof(request));
      PDEBUG("after read, n=%d\n", n);
      switch(request.req_kind) {
      case REQ_CREATE:
        PDEBUG("got REQ_CREATE\n");
        request.req_thread->p_retcode =
          pthread_handle_create((pthread_t *) &request.req_thread->p_retval,
                                request.req_args.create.attr,
                                request.req_args.create.fn,
                                request.req_args.create.arg,
                                &request.req_args.create.mask,
                                request.req_thread->p_pid,
                                request.req_thread->p_report_events,
                                &request.req_thread->p_eventbuf.eventmask);
        PDEBUG("restarting %p\n", request.req_thread);
        restart(request.req_thread);
        break;
      case REQ_FREE:
        PDEBUG("got REQ_FREE\n");
        pthread_handle_free(request.req_args.free.thread_id);
        break;
      case REQ_PROCESS_EXIT:
        PDEBUG("got REQ_PROCESS_EXIT from %p, exit code = %d\n",
        request.req_thread, request.req_args.exit.code);
        pthread_handle_exit(request.req_thread,
                            request.req_args.exit.code);
        break;
      case REQ_MAIN_THREAD_EXIT:
        PDEBUG("got REQ_MAIN_THREAD_EXIT\n");
        main_thread_exiting = 1;
	/* Reap children in case all other threads died and the signal handler
	   went off before we set main_thread_exiting to 1, and therefore did
	   not do REQ_KICK. */
	pthread_reap_children();

        if (__pthread_main_thread->p_nextlive == __pthread_main_thread) {
          restart(__pthread_main_thread);
	  /* The main thread will now call exit() which will trigger an
	     __on_exit handler, which in turn will send REQ_PROCESS_EXIT
	     to the thread manager. In case you are wondering how the
	     manager terminates from its loop here. */
	}
        break;
      case REQ_POST:
        PDEBUG("got REQ_POST\n");
        sem_post(request.req_args.post);
        break;
      case REQ_DEBUG:
        PDEBUG("got REQ_DEBUG\n");
	/* Make gdb aware of new thread and gdb will restart the
	   new thread when it is ready to handle the new thread. */
	if (__pthread_threads_debug && __pthread_sig_debug > 0) {
	  PDEBUG("about to call raise(__pthread_sig_debug)\n");
	  raise(__pthread_sig_debug);
	}
      case REQ_KICK:
	/* This is just a prod to get the manager to reap some
	   threads right away, avoiding a potential delay at shutdown. */
	break;
      }
    }
  }
}
Beispiel #11
0
__pthread_manager(void *arg)
{
  pthread_descr self = manager_thread = arg;
  int reqfd = __pthread_manager_reader;
  struct pollfd ufd;
  sigset_t manager_mask;
  int n;
  struct pthread_request request;

  /* If we have special thread_self processing, initialize it.  */
#ifdef INIT_THREAD_SELF
  INIT_THREAD_SELF(self, 1);
#endif
#if !(USE_TLS && HAVE___THREAD)
  /* Set the error variable.  */
  self->p_errnop = &self->p_errno;
  self->p_h_errnop = &self->p_h_errno;
#endif
  /* Block all signals except __pthread_sig_cancel and SIGTRAP */
  sigfillset(&manager_mask);
  sigdelset(&manager_mask, __pthread_sig_cancel); /* for thread termination */
  sigdelset(&manager_mask, SIGTRAP);            /* for debugging purposes */
  if (__pthread_threads_debug && __pthread_sig_debug > 0)
    sigdelset(&manager_mask, __pthread_sig_debug);
  sigprocmask(SIG_SETMASK, &manager_mask, NULL);
  /* Raise our priority to match that of main thread */
  __pthread_manager_adjust_prio(__pthread_main_thread->p_priority);
  /* Synchronize debugging of the thread manager */
  n = TEMP_FAILURE_RETRY(read_not_cancel(reqfd, (char *)&request,
					 sizeof(request)));
  ASSERT(n == sizeof(request) && request.req_kind == REQ_DEBUG);
  ufd.fd = reqfd;
  ufd.events = POLLIN;
  /* Enter server loop */
  while(1) {
    n = __poll(&ufd, 1, 2000);

    /* Check for termination of the main thread */
    if (getppid() == 1) {
      pthread_kill_all_threads(SIGKILL, 0);
      _exit(0);
    }
    /* Check for dead children */
    if (terminated_children) {
      terminated_children = 0;
      pthread_reap_children();
    }
    /* Read and execute request */
    if (n == 1 && (ufd.revents & POLLIN)) {
      n = TEMP_FAILURE_RETRY(read_not_cancel(reqfd, (char *)&request,
					     sizeof(request)));
#ifdef DEBUG
      if (n < 0) {
	char d[64];
	write(STDERR_FILENO, d, snprintf(d, sizeof(d), "*** read err %m\n"));
      } else if (n != sizeof(request)) {
	write(STDERR_FILENO, "*** short read in manager\n", 26);
      }
#endif

      switch(request.req_kind) {
      case REQ_CREATE:
        request.req_thread->p_retcode =
          pthread_handle_create((pthread_t *) &request.req_thread->p_retval,
                                request.req_args.create.attr,
                                request.req_args.create.fn,
                                request.req_args.create.arg,
                                &request.req_args.create.mask,
                                request.req_thread->p_pid,
				request.req_thread->p_report_events,
				&request.req_thread->p_eventbuf.eventmask);
        restart(request.req_thread);
        break;
      case REQ_FREE:
	pthread_handle_free(request.req_args.free.thread_id);
        break;
      case REQ_PROCESS_EXIT:
        pthread_handle_exit(request.req_thread,
                            request.req_args.exit.code);
	/* NOTREACHED */
        break;
      case REQ_MAIN_THREAD_EXIT:
        main_thread_exiting = 1;
	/* Reap children in case all other threads died and the signal handler
	   went off before we set main_thread_exiting to 1, and therefore did
	   not do REQ_KICK. */
	pthread_reap_children();

        if (__pthread_main_thread->p_nextlive == __pthread_main_thread) {
          restart(__pthread_main_thread);
	  /* The main thread will now call exit() which will trigger an
	     __on_exit handler, which in turn will send REQ_PROCESS_EXIT
	     to the thread manager. In case you are wondering how the
	     manager terminates from its loop here. */
	}
        break;
      case REQ_POST:
        sem_post(request.req_args.post);
        break;
      case REQ_DEBUG:
	/* Make gdb aware of new thread and gdb will restart the
	   new thread when it is ready to handle the new thread. */
	if (__pthread_threads_debug && __pthread_sig_debug > 0)
	  raise(__pthread_sig_debug);
        break;
      case REQ_KICK:
	/* This is just a prod to get the manager to reap some
	   threads right away, avoiding a potential delay at shutdown. */
	break;
      case REQ_FOR_EACH_THREAD:
	pthread_for_each_thread(request.req_args.for_each.arg,
	                        request.req_args.for_each.fn);
	restart(request.req_thread);
	break;
      }
    }
  }
}
Beispiel #12
0
int __pthread_manager(void * arg)
{
  int reqfd = (int) arg;
  sigset_t mask;
  fd_set readfds;
  struct timeval timeout;
  int n;
  struct pthread_request request;

  /* If we have special thread_self processing, initialize it.  */
#ifdef INIT_THREAD_SELF
  INIT_THREAD_SELF(&__pthread_manager_thread);
#endif
  /* Block all signals except PTHREAD_SIG_RESTART */
  sigfillset(&mask);
  sigdelset(&mask, PTHREAD_SIG_RESTART);
  sigprocmask(SIG_SETMASK, &mask, NULL);
  /* Enter server loop */
  while(1) {
    FD_ZERO(&readfds);
    FD_SET(reqfd, &readfds);
    timeout.tv_sec = 2;
    timeout.tv_usec = 0;
    n = select(FD_SETSIZE, &readfds, NULL, NULL, &timeout);
    /* Check for termination of the main thread */
    if (getppid() == 1) {
      pthread_kill_all_threads(SIGKILL, 0);
      _exit(0);
    }
    /* Check for dead children */
    if (terminated_children) {
      terminated_children = 0;
      pthread_reap_children();
    }
    /* Read and execute request */
    if (n == 1 && FD_ISSET(reqfd, &readfds)) {
      n = read(reqfd, (char *)&request, sizeof(request));
      ASSERT(n == sizeof(request));
      switch(request.req_kind) {
      case REQ_CREATE:
        request.req_thread->p_retcode =
          pthread_handle_create((pthread_t *) &request.req_thread->p_retval,
                                request.req_args.create.attr,
                                request.req_args.create.fn,
                                request.req_args.create.arg,
                                &request.req_args.create.mask,
                                request.req_thread->p_pid);
        restart(request.req_thread);
        break;
      case REQ_FREE:
        pthread_handle_free(request.req_args.free.thread);
        break;
      case REQ_PROCESS_EXIT:
        pthread_handle_exit(request.req_thread,
                            request.req_args.exit.code);
        break;
      case REQ_MAIN_THREAD_EXIT:
        main_thread_exiting = 1;
        if (__pthread_main_thread->p_nextlive == __pthread_main_thread) {
          restart(__pthread_main_thread);
          return 0;
        }
        break;
      }
    }
  }
}
Beispiel #13
0
static void pthread_initialize(void)
{
  struct sigaction sa;
  sigset_t mask;
#ifdef __ARCH_USE_MMU__
  struct rlimit limit;
  rlim_t max_stack;
#endif

  /* If already done (e.g. by a constructor called earlier!), bail out */
  if (__pthread_initial_thread_bos != NULL) return;
#ifdef TEST_FOR_COMPARE_AND_SWAP
  /* Test if compare-and-swap is available */
  __pthread_has_cas = compare_and_swap_is_available();
#endif
  /* For the initial stack, reserve at least STACK_SIZE bytes of stack
     below the current stack address, and align that on a
     STACK_SIZE boundary. */
  __pthread_initial_thread_bos =
    (char *)(((long)CURRENT_STACK_FRAME - 2 * STACK_SIZE) & ~(STACK_SIZE - 1));
  /* Update the descriptor for the initial thread. */
  __pthread_initial_thread.p_pid = getpid();
  /* If we have special thread_self processing, initialize that for the
     main thread now.  */
#ifdef INIT_THREAD_SELF
  INIT_THREAD_SELF(&__pthread_initial_thread, 0);
#endif
  /* The errno/h_errno variable of the main thread are the global ones.  */
  __pthread_initial_thread.p_errnop = &_errno;
  __pthread_initial_thread.p_h_errnop = &_h_errno;

#ifdef __UCLIBC_HAS_XLOCALE__
  /* The locale of the main thread is the current locale in use. */
  __pthread_initial_thread.locale = __curlocale_var;
#endif /* __UCLIBC_HAS_XLOCALE__ */

 {			   /* uClibc-specific stdio initialization for threads. */
	 FILE *fp;

	 _stdio_user_locking = 0;	/* 2 if threading not initialized */
	 for (fp = _stdio_openlist; fp != NULL; fp = fp->__nextopen) {
		 if (fp->__user_locking != 1) {
			 fp->__user_locking = 0;
		 }
	 }
 }

  /* Play with the stack size limit to make sure that no stack ever grows
     beyond STACK_SIZE minus two pages (one page for the thread descriptor
     immediately beyond, and one page to act as a guard page). */

#ifdef __ARCH_USE_MMU__
  /* We cannot allocate a huge chunk of memory to mmap all thread stacks later
   * on a non-MMU system. Thus, we don't need the rlimit either. -StS */
  getrlimit(RLIMIT_STACK, &limit);
  max_stack = STACK_SIZE - 2 * getpagesize();
  if (limit.rlim_cur > max_stack) {
    limit.rlim_cur = max_stack;
    setrlimit(RLIMIT_STACK, &limit);
  }
#else
  /* For non-MMU, the initial thread stack can reside anywhere in memory.
   * We don't have a way of knowing where the kernel started things -- top
   * or bottom (well, that isn't exactly true, but the solution is fairly
   * complex and error prone).  All we can determine here is an address
   * that lies within that stack.  Save that address as a reference so that
   * as other thread stacks are created, we can adjust the estimated bounds
   * of the initial thread's stack appropriately.
   *
   * This checking is handled in NOMMU_INITIAL_THREAD_BOUNDS(), so see that
   * for a few more details.
   */
  __pthread_initial_thread_mid = CURRENT_STACK_FRAME;
  __pthread_initial_thread_tos = (char *) -1;
  __pthread_initial_thread_bos = (char *) 1; /* set it non-zero so we know we have been here */
  PDEBUG("initial thread stack bounds: bos=%p, tos=%p\n",
	 __pthread_initial_thread_bos, __pthread_initial_thread_tos);
#endif /* __ARCH_USE_MMU__ */

  /* Setup signal handlers for the initial thread.
     Since signal handlers are shared between threads, these settings
     will be inherited by all other threads. */
  memset(&sa, 0, sizeof(sa));
  sa.sa_handler = pthread_handle_sigrestart;
  __libc_sigaction(__pthread_sig_restart, &sa, NULL);
  sa.sa_handler = pthread_handle_sigcancel;
  sigaddset(&sa.sa_mask, __pthread_sig_restart);
  __libc_sigaction(__pthread_sig_cancel, &sa, NULL);
  if (__pthread_sig_debug > 0) {
      sa.sa_handler = pthread_handle_sigdebug;
      __sigemptyset(&sa.sa_mask);
      __libc_sigaction(__pthread_sig_debug, &sa, NULL);
  }
  /* Initially, block __pthread_sig_restart. Will be unblocked on demand. */
  __sigemptyset(&mask);
  sigaddset(&mask, __pthread_sig_restart);
  sigprocmask(SIG_BLOCK, &mask, NULL);
  /* And unblock __pthread_sig_cancel if it has been blocked. */
  sigdelset(&mask, __pthread_sig_restart);
  sigaddset(&mask, __pthread_sig_cancel);
  sigprocmask(SIG_UNBLOCK, &mask, NULL);
  /* Register an exit function to kill all other threads. */
  /* Do it early so that user-registered atexit functions are called
     before pthread_onexit_process. */
  on_exit(pthread_onexit_process, NULL);
}
static void pthread_initialize(void)
{
  struct sigaction sa;
  sigset_t mask;
  struct rlimit limit;
  int max_stack;

  /* If already done (e.g. by a constructor called earlier!), bail out */
  if (__pthread_initial_thread_bos != NULL) return;
#ifdef TEST_FOR_COMPARE_AND_SWAP
  /* Test if compare-and-swap is available */
  __pthread_has_cas = compare_and_swap_is_available();
#endif
  /* For the initial stack, reserve at least STACK_SIZE bytes of stack
     below the current stack address, and align that on a
     STACK_SIZE boundary. */
  __pthread_initial_thread_bos =
    (char *)(((long)CURRENT_STACK_FRAME - 2 * STACK_SIZE) & ~(STACK_SIZE - 1));
  /* Update the descriptor for the initial thread. */
  __pthread_initial_thread.p_pid = __getpid();
  /* If we have special thread_self processing, initialize that for the
     main thread now.  */
#ifdef INIT_THREAD_SELF
  INIT_THREAD_SELF(&__pthread_initial_thread, 0);
#endif
  /* The errno/h_errno variable of the main thread are the global ones.  */
  __pthread_initial_thread.p_errnop = &_errno;
  __pthread_initial_thread.p_h_errnop = &_h_errno;
  /* Play with the stack size limit to make sure that no stack ever grows
     beyond STACK_SIZE minus two pages (one page for the thread descriptor
     immediately beyond, and one page to act as a guard page). */

#ifdef __UCLIBC_HAS_MMU__
  /* We cannot allocate a huge chunk of memory to mmap all thread stacks later
   * on a non-MMU system. Thus, we don't need the rlimit either. -StS */
  getrlimit(RLIMIT_STACK, &limit);
  max_stack = STACK_SIZE - 2 * __getpagesize();
  if (limit.rlim_cur > max_stack) {
    limit.rlim_cur = max_stack;
    setrlimit(RLIMIT_STACK, &limit);
  }
#else
  /* For non-MMU assume __pthread_initial_thread_tos at upper page boundary, and
   * __pthread_initial_thread_bos at address 0. These bounds are refined as we 
   * malloc other stack frames such that they don't overlap. -StS
   */
  __pthread_initial_thread_tos =
    (char *)(((long)CURRENT_STACK_FRAME + __getpagesize()) & ~(__getpagesize() - 1));
  __pthread_initial_thread_bos = (char *) 1; /* set it non-zero so we know we have been here */
  PDEBUG("initial thread stack bounds: bos=%p, tos=%p\n",
	 __pthread_initial_thread_bos, __pthread_initial_thread_tos);
#endif /* __UCLIBC_HAS_MMU__ */

  /* Setup signal handlers for the initial thread.
     Since signal handlers are shared between threads, these settings
     will be inherited by all other threads. */
  sa.sa_handler = pthread_handle_sigrestart;
  sigemptyset(&sa.sa_mask);
  sa.sa_flags = 0;
  __libc_sigaction(__pthread_sig_restart, &sa, NULL);
  sa.sa_handler = pthread_handle_sigcancel;
  // sa.sa_flags = 0;
  __libc_sigaction(__pthread_sig_cancel, &sa, NULL);
  if (__pthread_sig_debug > 0) {
      sa.sa_handler = pthread_handle_sigdebug;
      sigemptyset(&sa.sa_mask);
      // sa.sa_flags = 0;
      __libc_sigaction(__pthread_sig_debug, &sa, NULL);
  }
  /* Initially, block __pthread_sig_restart. Will be unblocked on demand. */
  sigemptyset(&mask);
  sigaddset(&mask, __pthread_sig_restart);
  sigprocmask(SIG_BLOCK, &mask, NULL);
  /* Register an exit function to kill all other threads. */
  /* Do it early so that user-registered atexit functions are called
     before pthread_onexit_process. */
  on_exit(pthread_onexit_process, NULL);
}