/* Deallocate a thread structure.

   Copyright (C) 2000-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   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 <assert.h>

#include <pthread.h>

#include <stdlib.h>

#include <pt-internal.h>

#include <atomic.h>

/* List of thread structures corresponding to free thread IDs.  */

extern struct __pthread *__pthread_free_threads;

extern pthread_mutex_t __pthread_free_threads_lock;

/* Deallocate the thread structure for PTHREAD.  */

void

__pthread_dealloc (struct __pthread *pthread)

{

  assert (pthread->state != PTHREAD_TERMINATED);

  if (!atomic_decrement_and_test (&pthread->nr_refs))

    return;

  /* Withdraw this thread from the thread ID lookup table.  */

  __pthread_setid (pthread->thread, NULL);

  /* Mark the thread as terminated.  We broadcast the condition

     here to prevent pthread_join from waiting for this thread to

     exit where it was never really started.  Such a call to

     pthread_join is completely bogus, but unfortunately allowed

     by the standards.  */

  __pthread_mutex_lock (&pthread->state_lock);

  if (pthread->state != PTHREAD_EXITED)

    __pthread_cond_broadcast (&pthread->state_cond);

  __pthread_mutex_unlock (&pthread->state_lock);

  /* We do not actually deallocate the thread structure, but add it to

     a list of re-usable thread structures.  */

  __pthread_mutex_lock (&__pthread_free_threads_lock);

  __pthread_enqueue (&__pthread_free_threads, pthread);

  __pthread_mutex_unlock (&__pthread_free_threads_lock);

  /* Setting PTHREAD->STATE to PTHREAD_TERMINATED makes this TCB

     available for reuse.  After that point, we can no longer assume

     that PTHREAD is valid.

     Note that it is safe to not lock this update to PTHREAD->STATE:

     the only way that it can now be accessed is in __pthread_alloc,

     which reads this variable.  */

  pthread->state = PTHREAD_TERMINATED;

}