glibc/nptl/pthread_create.c

/* Copyright (C) 2002-2015 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <http://www.gnu.org/licenses/>.  */

#include <ctype.h>
#include <errno.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include "pthreadP.h"
#include <hp-timing.h>
#include <ldsodefs.h>
#include <atomic.h>
#include <libc-internal.h>
#include <resolv.h>
#include <kernel-features.h>
#include <exit-thread.h>
#include <default-sched.h>
#include <futex-internal.h>

#include <shlib-compat.h>

#include <stap-probe.h>


/* Nozero if debugging mode is enabled.  */
int __pthread_debug;

/* Globally enabled events.  */
static td_thr_events_t __nptl_threads_events __attribute_used__;

/* Pointer to descriptor with the last event.  */
static struct pthread *__nptl_last_event __attribute_used__;

/* Number of threads running.  */
unsigned int __nptl_nthreads = 1;


/* Code to allocate and deallocate a stack.  */
#include "allocatestack.c"

/* createthread.c defines this function, and two macros:
   START_THREAD_DEFN and START_THREAD_SELF (see below).

   create_thread is obliged to initialize PD->stopped_start.  It
   should be true if the STOPPED_START parameter is true, or if
   create_thread needs the new thread to synchronize at startup for
   some other implementation reason.  If PD->stopped_start will be
   true, then create_thread is obliged to perform the operation
   "lll_lock (PD->lock, LLL_PRIVATE)" before starting the thread.

   The return value is zero for success or an errno code for failure.
   If the return value is ENOMEM, that will be translated to EAGAIN,
   so create_thread need not do that.  On failure, *THREAD_RAN should
   be set to true iff the thread actually started up and then got
   cancelled before calling user code (*PD->start_routine), in which
   case it is responsible for doing its own cleanup.  */

static int create_thread (struct pthread *pd, const struct pthread_attr *attr,
			  bool stopped_start, STACK_VARIABLES_PARMS,
			  bool *thread_ran);

#include <createthread.c>


struct pthread *
internal_function
__find_in_stack_list (pd)
     struct pthread *pd;
{
  list_t *entry;
  struct pthread *result = NULL;

  lll_lock (stack_cache_lock, LLL_PRIVATE);

  list_for_each (entry, &stack_used)
    {
      struct pthread *curp;

      curp = list_entry (entry, struct pthread, list);
      if (curp == pd)
	{
	  result = curp;
	  break;
	}
    }

  if (result == NULL)
    list_for_each (entry, &__stack_user)
      {
	struct pthread *curp;

	curp = list_entry (entry, struct pthread, list);
	if (curp == pd)
	  {
	    result = curp;
	    break;
	  }
      }

  lll_unlock (stack_cache_lock, LLL_PRIVATE);

  return result;
}


/* Deallocate POSIX thread-local-storage.  */
void
attribute_hidden
__nptl_deallocate_tsd (void)
{
  struct pthread *self = THREAD_SELF;

  /* Maybe no data was ever allocated.  This happens often so we have
     a flag for this.  */
  if (THREAD_GETMEM (self, specific_used))
    {
      size_t round;
      size_t cnt;

      round = 0;
      do
	{
	  size_t idx;

	  /* So far no new nonzero data entry.  */
	  THREAD_SETMEM (self, specific_used, false);

	  for (cnt = idx = 0; cnt < PTHREAD_KEY_1STLEVEL_SIZE; ++cnt)
	    {
	      struct pthread_key_data *level2;

	      level2 = THREAD_GETMEM_NC (self, specific, cnt);

	      if (level2 != NULL)
		{
		  size_t inner;

		  for (inner = 0; inner < PTHREAD_KEY_2NDLEVEL_SIZE;
		       ++inner, ++idx)
		    {
		      void *data = level2[inner].data;

		      if (data != NULL)
			{
			  /* Always clear the data.  */
			  level2[inner].data = NULL;

			  /* Make sure the data corresponds to a valid
			     key.  This test fails if the key was
			     deallocated and also if it was
			     re-allocated.  It is the user's
			     responsibility to free the memory in this
			     case.  */
			  if (level2[inner].seq
			      == __pthread_keys[idx].seq
			      /* It is not necessary to register a destructor
				 function.  */
			      && __pthread_keys[idx].destr != NULL)
			    /* Call the user-provided destructor.  */
			    __pthread_keys[idx].destr (data);
			}
		    }
		}
	      else
		idx += PTHREAD_KEY_1STLEVEL_SIZE;
	    }

	  if (THREAD_GETMEM (self, specific_used) == 0)
	    /* No data has been modified.  */
	    goto just_free;
	}
      /* We only repeat the process a fixed number of times.  */
      while (__builtin_expect (++round < PTHREAD_DESTRUCTOR_ITERATIONS, 0));

      /* Just clear the memory of the first block for reuse.  */
      memset (&THREAD_SELF->specific_1stblock, '\0',
	      sizeof (self->specific_1stblock));

    just_free:
      /* Free the memory for the other blocks.  */
      for (cnt = 1; cnt < PTHREAD_KEY_1STLEVEL_SIZE; ++cnt)
	{
	  struct pthread_key_data *level2;

	  level2 = THREAD_GETMEM_NC (self, specific, cnt);
	  if (level2 != NULL)
	    {
	      /* The first block is allocated as part of the thread
		 descriptor.  */
	      free (level2);
	      THREAD_SETMEM_NC (self, specific, cnt, NULL);
	    }
	}

      THREAD_SETMEM (self, specific_used, false);
    }
}


/* Deallocate a thread's stack after optionally making sure the thread
   descriptor is still valid.  */
void
internal_function
__free_tcb (struct pthread *pd)
{
  /* The thread is exiting now.  */
  if (__builtin_expect (atomic_bit_test_set (&pd->cancelhandling,
					     TERMINATED_BIT) == 0, 1))
    {
      /* Remove the descriptor from the list.  */
      if (DEBUGGING_P && __find_in_stack_list (pd) == NULL)
	/* Something is really wrong.  The descriptor for a still
	   running thread is gone.  */
	abort ();

      /* Free TPP data.  */
      if (__glibc_unlikely (pd->tpp != NULL))
	{
	  struct priority_protection_data *tpp = pd->tpp;

	  pd->tpp = NULL;
	  free (tpp);
	}

      /* Queue the stack memory block for reuse and exit the process.  The
	 kernel will signal via writing to the address returned by
	 QUEUE-STACK when the stack is available.  */
      __deallocate_stack (pd);
    }
}


/* Local function to start thread and handle cleanup.
   createthread.c defines the macro START_THREAD_DEFN to the
   declaration that its create_thread function will refer to, and
   START_THREAD_SELF to the expression to optimally deliver the new
   thread's THREAD_SELF value.  */
START_THREAD_DEFN
{
  struct pthread *pd = START_THREAD_SELF;

#if HP_TIMING_AVAIL
  /* Remember the time when the thread was started.  */
  hp_timing_t now;
  HP_TIMING_NOW (now);
  THREAD_SETMEM (pd, cpuclock_offset, now);
#endif

  /* Initialize resolver state pointer.  */
  __resp = &pd->res;

  /* Initialize pointers to locale data.  */
  __ctype_init ();

  /* Allow setxid from now onwards.  */
  if (__glibc_unlikely (atomic_exchange_acq (&pd->setxid_futex, 0) == -2))
    futex_wake (&pd->setxid_futex, 1, FUTEX_PRIVATE);

#ifdef __NR_set_robust_list
# ifndef __ASSUME_SET_ROBUST_LIST
  if (__set_robust_list_avail >= 0)
# endif
    {
      INTERNAL_SYSCALL_DECL (err);
      /* This call should never fail because the initial call in init.c
	 succeeded.  */
      INTERNAL_SYSCALL (set_robust_list, err, 2, &pd->robust_head,
			sizeof (struct robust_list_head));
    }
#endif

#ifdef SIGCANCEL
  /* If the parent was running cancellation handlers while creating
     the thread the new thread inherited the signal mask.  Reset the
     cancellation signal mask.  */
  if (__glibc_unlikely (pd->parent_cancelhandling & CANCELING_BITMASK))
    {
      INTERNAL_SYSCALL_DECL (err);
      sigset_t mask;
      __sigemptyset (&mask);
      __sigaddset (&mask, SIGCANCEL);
      (void) INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_UNBLOCK, &mask,
			       NULL, _NSIG / 8);
    }
#endif

  /* This is where the try/finally block should be created.  For
     compilers without that support we do use setjmp.  */
  struct pthread_unwind_buf unwind_buf;

  /* No previous handlers.  */
  unwind_buf.priv.data.prev = NULL;
  unwind_buf.priv.data.cleanup = NULL;

  int not_first_call;
  not_first_call = setjmp ((struct __jmp_buf_tag *) unwind_buf.cancel_jmp_buf);
  if (__glibc_likely (! not_first_call))
    {
      /* Store the new cleanup handler info.  */
      THREAD_SETMEM (pd, cleanup_jmp_buf, &unwind_buf);

      if (__glibc_unlikely (pd->stopped_start))
	{
	  int oldtype = CANCEL_ASYNC ();

	  /* Get the lock the parent locked to force synchronization.  */
	  lll_lock (pd->lock, LLL_PRIVATE);
	  /* And give it up right away.  */
	  lll_unlock (pd->lock, LLL_PRIVATE);

	  CANCEL_RESET (oldtype);
	}

      LIBC_PROBE (pthread_start, 3, (pthread_t) pd, pd->start_routine, pd->arg);

      /* Run the code the user provided.  */
#ifdef CALL_THREAD_FCT
      THREAD_SETMEM (pd, result, CALL_THREAD_FCT (pd));
#else
      THREAD_SETMEM (pd, result, pd->start_routine (pd->arg));
#endif
    }

  /* Call destructors for the thread_local TLS variables.  */
#ifndef SHARED
  if (&__call_tls_dtors != NULL)
#endif
    __call_tls_dtors ();

  /* Run the destructor for the thread-local data.  */
  __nptl_deallocate_tsd ();

  /* Clean up any state libc stored in thread-local variables.  */
  __libc_thread_freeres ();

  /* If this is the last thread we terminate the process now.  We
     do not notify the debugger, it might just irritate it if there
     is no thread left.  */
  if (__glibc_unlikely (atomic_decrement_and_test (&__nptl_nthreads)))
    /* This was the last thread.  */
    exit (0);

  /* Report the death of the thread if this is wanted.  */
  if (__glibc_unlikely (pd->report_events))
    {
      /* See whether TD_DEATH is in any of the mask.  */
      const int idx = __td_eventword (TD_DEATH);
      const uint32_t mask = __td_eventmask (TD_DEATH);

      if ((mask & (__nptl_threads_events.event_bits[idx]
		   | pd->eventbuf.eventmask.event_bits[idx])) != 0)
	{
	  /* Yep, we have to signal the death.  Add the descriptor to
	     the list but only if it is not already on it.  */
	  if (pd->nextevent == NULL)
	    {
	      pd->eventbuf.eventnum = TD_DEATH;
	      pd->eventbuf.eventdata = pd;

	      do
		pd->nextevent = __nptl_last_event;
	      while (atomic_compare_and_exchange_bool_acq (&__nptl_last_event,
							   pd, pd->nextevent));
	    }

	  /* Now call the function to signal the event.  */
	  __nptl_death_event ();
	}
    }

  /* The thread is exiting now.  Don't set this bit until after we've hit
     the event-reporting breakpoint, so that td_thr_get_info on us while at
     the breakpoint reports TD_THR_RUN state rather than TD_THR_ZOMBIE.  */
  atomic_bit_set (&pd->cancelhandling, EXITING_BIT);

#ifndef __ASSUME_SET_ROBUST_LIST
  /* If this thread has any robust mutexes locked, handle them now.  */
# ifdef __PTHREAD_MUTEX_HAVE_PREV
  void *robust = pd->robust_head.list;
# else
  __pthread_slist_t *robust = pd->robust_list.__next;
# endif
  /* We let the kernel do the notification if it is able to do so.
     If we have to do it here there for sure are no PI mutexes involved
     since the kernel support for them is even more recent.  */
  if (__set_robust_list_avail < 0
      && __builtin_expect (robust != (void *) &pd->robust_head, 0))
    {
      do
	{
	  struct __pthread_mutex_s *this = (struct __pthread_mutex_s *)
	    ((char *) robust - offsetof (struct __pthread_mutex_s,
					 __list.__next));
	  robust = *((void **) robust);

# ifdef __PTHREAD_MUTEX_HAVE_PREV
	  this->__list.__prev = NULL;
# endif
	  this->__list.__next = NULL;

	  atomic_or (&this->__lock, FUTEX_OWNER_DIED);
	  futex_wake ((unsigned int *) &this->__lock, 1,
		      /* XYZ */ FUTEX_SHARED);
	}
      while (robust != (void *) &pd->robust_head);
    }
#endif

  /* Mark the memory of the stack as usable to the kernel.  We free
     everything except for the space used for the TCB itself.  */
  size_t pagesize_m1 = __getpagesize () - 1;
#ifdef _STACK_GROWS_DOWN
  char *sp = CURRENT_STACK_FRAME;
  size_t freesize = (sp - (char *) pd->stackblock) & ~pagesize_m1;
#else
# error "to do"
#endif
  assert (freesize < pd->stackblock_size);
  if (freesize > PTHREAD_STACK_MIN)
    __madvise (pd->stackblock, freesize - PTHREAD_STACK_MIN, MADV_DONTNEED);

  /* If the thread is detached free the TCB.  */
  if (IS_DETACHED (pd))
    /* Free the TCB.  */
    __free_tcb (pd);
  else if (__glibc_unlikely (pd->cancelhandling & SETXID_BITMASK))
    {
      /* Some other thread might call any of the setXid functions and expect
	 us to reply.  In this case wait until we did that.  */
      do
	/* XXX This differs from the typical futex_wait_simple pattern in that
	   the futex_wait condition (setxid_futex) is different from the
	   condition used in the surrounding loop (cancelhandling).  We need
	   to check and document why this is correct.  */
	futex_wait_simple (&pd->setxid_futex, 0, FUTEX_PRIVATE);
      while (pd->cancelhandling & SETXID_BITMASK);

      /* Reset the value so that the stack can be reused.  */
      pd->setxid_futex = 0;
    }

  /* We cannot call '_exit' here.  '_exit' will terminate the process.

     The 'exit' implementation in the kernel will signal when the
     process is really dead since 'clone' got passed the CLONE_CHILD_CLEARTID
     flag.  The 'tid' field in the TCB will be set to zero.

     The exit code is zero since in case all threads exit by calling
     'pthread_exit' the exit status must be 0 (zero).  */
  __exit_thread ();

  /* NOTREACHED */
}


/* Return true iff obliged to report TD_CREATE events.  */
static bool
report_thread_creation (struct pthread *pd)
{
  if (__glibc_unlikely (THREAD_GETMEM (THREAD_SELF, report_events)))
    {
      /* The parent thread is supposed to report events.
	 Check whether the TD_CREATE event is needed, too.  */
      const size_t idx = __td_eventword (TD_CREATE);
      const uint32_t mask = __td_eventmask (TD_CREATE);

      return ((mask & (__nptl_threads_events.event_bits[idx]
		       | pd->eventbuf.eventmask.event_bits[idx])) != 0);
    }
  return false;
}


int
__pthread_create_2_1 (newthread, attr, start_routine, arg)
     pthread_t *newthread;
     const pthread_attr_t *attr;
     void *(*start_routine) (void *);
     void *arg;
{
  STACK_VARIABLES;

  const struct pthread_attr *iattr = (struct pthread_attr *) attr;
  struct pthread_attr default_attr;
  bool free_cpuset = false;
  if (iattr == NULL)
    {
      lll_lock (__default_pthread_attr_lock, LLL_PRIVATE);
      default_attr = __default_pthread_attr;
      size_t cpusetsize = default_attr.cpusetsize;
      if (cpusetsize > 0)
	{
	  cpu_set_t *cpuset;
	  if (__glibc_likely (__libc_use_alloca (cpusetsize)))
	    cpuset = __alloca (cpusetsize);
	  else
	    {
	      cpuset = malloc (cpusetsize);
	      if (cpuset == NULL)
		{
		  lll_unlock (__default_pthread_attr_lock, LLL_PRIVATE);
		  return ENOMEM;
		}
	      free_cpuset = true;
	    }
	  memcpy (cpuset, default_attr.cpuset, cpusetsize);
	  default_attr.cpuset = cpuset;
	}
      lll_unlock (__default_pthread_attr_lock, LLL_PRIVATE);
      iattr = &default_attr;
    }

  struct pthread *pd = NULL;
  int err = ALLOCATE_STACK (iattr, &pd);
  int retval = 0;

  if (__glibc_unlikely (err != 0))
    /* Something went wrong.  Maybe a parameter of the attributes is
       invalid or we could not allocate memory.  Note we have to
       translate error codes.  */
    {
      retval = err == ENOMEM ? EAGAIN : err;
      goto out;
    }


  /* Initialize the TCB.  All initializations with zero should be
     performed in 'get_cached_stack'.  This way we avoid doing this if
     the stack freshly allocated with 'mmap'.  */

#if TLS_TCB_AT_TP
  /* Reference to the TCB itself.  */
  pd->header.self = pd;

  /* Self-reference for TLS.  */
  pd->header.tcb = pd;
#endif

  /* Store the address of the start routine and the parameter.  Since
     we do not start the function directly the stillborn thread will
     get the information from its thread descriptor.  */
  pd->start_routine = start_routine;
  pd->arg = arg;

  /* Copy the thread attribute flags.  */
  struct pthread *self = THREAD_SELF;
  pd->flags = ((iattr->flags & ~(ATTR_FLAG_SCHED_SET | ATTR_FLAG_POLICY_SET))
	       | (self->flags & (ATTR_FLAG_SCHED_SET | ATTR_FLAG_POLICY_SET)));

  /* Initialize the field for the ID of the thread which is waiting
     for us.  This is a self-reference in case the thread is created
     detached.  */
  pd->joinid = iattr->flags & ATTR_FLAG_DETACHSTATE ? pd : NULL;

  /* The debug events are inherited from the parent.  */
  pd->eventbuf = self->eventbuf;


  /* Copy the parent's scheduling parameters.  The flags will say what
     is valid and what is not.  */
  pd->schedpolicy = self->schedpolicy;
  pd->schedparam = self->schedparam;

  /* Copy the stack guard canary.  */
#ifdef THREAD_COPY_STACK_GUARD
  THREAD_COPY_STACK_GUARD (pd);
#endif

  /* Copy the pointer guard value.  */
#ifdef THREAD_COPY_POINTER_GUARD
  THREAD_COPY_POINTER_GUARD (pd);
#endif

  /* Verify the sysinfo bits were copied in allocate_stack if needed.  */
#ifdef NEED_DL_SYSINFO
  CHECK_THREAD_SYSINFO (pd);
#endif

  /* Inform start_thread (above) about cancellation state that might
     translate into inherited signal state.  */
  pd->parent_cancelhandling = THREAD_GETMEM (THREAD_SELF, cancelhandling);

  /* Determine scheduling parameters for the thread.  */
  if (__builtin_expect ((iattr->flags & ATTR_FLAG_NOTINHERITSCHED) != 0, 0)
      && (iattr->flags & (ATTR_FLAG_SCHED_SET | ATTR_FLAG_POLICY_SET)) != 0)
    {
      /* Use the scheduling parameters the user provided.  */
      if (iattr->flags & ATTR_FLAG_POLICY_SET)
        {
          pd->schedpolicy = iattr->schedpolicy;
          pd->flags |= ATTR_FLAG_POLICY_SET;
        }
      if (iattr->flags & ATTR_FLAG_SCHED_SET)
        {
          /* The values were validated in pthread_attr_setschedparam.  */
          pd->schedparam = iattr->schedparam;
          pd->flags |= ATTR_FLAG_SCHED_SET;
        }

      if ((pd->flags & (ATTR_FLAG_SCHED_SET | ATTR_FLAG_POLICY_SET))
          != (ATTR_FLAG_SCHED_SET | ATTR_FLAG_POLICY_SET))
        collect_default_sched (pd);
    }

  /* Pass the descriptor to the caller.  */
  *newthread = (pthread_t) pd;

  LIBC_PROBE (pthread_create, 4, newthread, attr, start_routine, arg);

  /* One more thread.  We cannot have the thread do this itself, since it
     might exist but not have been scheduled yet by the time we've returned
     and need to check the value to behave correctly.  We must do it before
     creating the thread, in case it does get scheduled first and then
     might mistakenly think it was the only thread.  In the failure case,
     we momentarily store a false value; this doesn't matter because there
     is no kosher thing a signal handler interrupting us right here can do
     that cares whether the thread count is correct.  */
  atomic_increment (&__nptl_nthreads);

  bool thread_ran = false;

  /* Start the thread.  */
  if (__glibc_unlikely (report_thread_creation (pd)))
    {
      /* Create the thread.  We always create the thread stopped
	 so that it does not get far before we tell the debugger.  */
      retval = create_thread (pd, iattr, true, STACK_VARIABLES_ARGS,
			      &thread_ran);
      if (retval == 0)
	{
	  /* create_thread should have set this so that the logic below can
	     test it.  */
	  assert (pd->stopped_start);

	  /* Now fill in the information about the new thread in
	     the newly created thread's data structure.  We cannot let
	     the new thread do this since we don't know whether it was
	     already scheduled when we send the event.  */
	  pd->eventbuf.eventnum = TD_CREATE;
	  pd->eventbuf.eventdata = pd;

	  /* Enqueue the descriptor.  */
	  do
	    pd->nextevent = __nptl_last_event;
	  while (atomic_compare_and_exchange_bool_acq (&__nptl_last_event,
						       pd, pd->nextevent)
		 != 0);

	  /* Now call the function which signals the event.  */
	  __nptl_create_event ();
	}
    }
  else
    retval = create_thread (pd, iattr, false, STACK_VARIABLES_ARGS,
			    &thread_ran);

  if (__glibc_unlikely (retval != 0))
    {
      /* If thread creation "failed", that might mean that the thread got
	 created and ran a little--short of running user code--but then
	 create_thread cancelled it.  In that case, the thread will do all
	 its own cleanup just like a normal thread exit after a successful
	 creation would do.  */

      if (thread_ran)
	assert (pd->stopped_start);
      else
	{
	  /* Oops, we lied for a second.  */
	  atomic_decrement (&__nptl_nthreads);

	  /* Perhaps a thread wants to change the IDs and is waiting for this
	     stillborn thread.  */
	  if (__glibc_unlikely (atomic_exchange_acq (&pd->setxid_futex, 0)
				== -2))
	    futex_wake (&pd->setxid_futex, 1, FUTEX_PRIVATE);

	  /* Free the resources.  */
	  __deallocate_stack (pd);
	}

      /* We have to translate error codes.  */
      if (retval == ENOMEM)
	retval = EAGAIN;
    }
  else
    {
      if (pd->stopped_start)
	/* The thread blocked on this lock either because we're doing TD_CREATE
	   event reporting, or for some other reason that create_thread chose.
	   Now let it run free.  */
	lll_unlock (pd->lock, LLL_PRIVATE);

      /* We now have for sure more than one thread.  The main thread might
	 not yet have the flag set.  No need to set the global variable
	 again if this is what we use.  */
      THREAD_SETMEM (THREAD_SELF, header.multiple_threads, 1);
    }

 out:
  if (__glibc_unlikely (free_cpuset))
    free (default_attr.cpuset);

  return retval;
}
versioned_symbol (libpthread, __pthread_create_2_1, pthread_create, GLIBC_2_1);


#if SHLIB_COMPAT(libpthread, GLIBC_2_0, GLIBC_2_1)
int
__pthread_create_2_0 (newthread, attr, start_routine, arg)
     pthread_t *newthread;
     const pthread_attr_t *attr;
     void *(*start_routine) (void *);
     void *arg;
{
  /* The ATTR attribute is not really of type `pthread_attr_t *'.  It has
     the old size and access to the new members might crash the program.
     We convert the struct now.  */
  struct pthread_attr new_attr;

  if (attr != NULL)
    {
      struct pthread_attr *iattr = (struct pthread_attr *) attr;
      size_t ps = __getpagesize ();

      /* Copy values from the user-provided attributes.  */
      new_attr.schedparam = iattr->schedparam;
      new_attr.schedpolicy = iattr->schedpolicy;
      new_attr.flags = iattr->flags;

      /* Fill in default values for the fields not present in the old
	 implementation.  */
      new_attr.guardsize = ps;
      new_attr.stackaddr = NULL;
      new_attr.stacksize = 0;
      new_attr.cpuset = NULL;

      /* We will pass this value on to the real implementation.  */
      attr = (pthread_attr_t *) &new_attr;
    }

  return __pthread_create_2_1 (newthread, attr, start_routine, arg);
}
compat_symbol (libpthread, __pthread_create_2_0, pthread_create,
	       GLIBC_2_0);
#endif

/* Information for libthread_db.  */

#include "../nptl_db/db_info.c"

/* If pthread_create is present, libgcc_eh.a and libsupc++.a expects some other POSIX thread
   functions to be present as well.  */
PTHREAD_STATIC_FN_REQUIRE (pthread_mutex_lock)
PTHREAD_STATIC_FN_REQUIRE (pthread_mutex_trylock)
PTHREAD_STATIC_FN_REQUIRE (pthread_mutex_unlock)

PTHREAD_STATIC_FN_REQUIRE (pthread_once)
PTHREAD_STATIC_FN_REQUIRE (pthread_cancel)

PTHREAD_STATIC_FN_REQUIRE (pthread_key_create)
PTHREAD_STATIC_FN_REQUIRE (pthread_key_delete)
PTHREAD_STATIC_FN_REQUIRE (pthread_setspecific)
PTHREAD_STATIC_FN_REQUIRE (pthread_getspecific)