htl/pt-exit.c

   1 /* Thread termination.
   2    Copyright (C) 2000-2023 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library;  if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <assert.h>
  20 #include <errno.h>
  21 #include <pthread.h>
  22 #include <stdlib.h>
  23
  24 #include <pt-internal.h>
  25 #include <pthreadP.h>
  26
  27 #include <atomic.h>
  28
  29
  30 /* Terminate the current thread and make STATUS available to any
  31    thread that might join it.  */
  32 void
  33 __pthread_exit (void *status)
  34 {
  35   struct __pthread *self = _pthread_self ();
  36   struct __pthread_cancelation_handler **handlers;
  37   int oldstate;
  38
  39   /* Run any cancelation handlers.  According to POSIX, the
  40      cancellation cleanup handlers should be called with cancellation
  41      disabled.  */
  42   __pthread_setcancelstate (PTHREAD_CANCEL_DISABLE, &oldstate);
  43
  44   for (handlers = __pthread_get_cleanup_stack ();
  45        *handlers != NULL;
  46        *handlers = (*handlers)->__next)
  47     (*handlers)->__handler ((*handlers)->__arg);
  48
  49   /* Call destructors for the thread_local TLS variables.  */
  50   call_function_static_weak (__call_tls_dtors);
  51
  52   __pthread_setcancelstate (oldstate, &oldstate);
  53
  54   /* Decrease the number of threads.  We use an atomic operation to
  55      make sure that only the last thread calls `exit'.  */
  56   if (atomic_fetch_add_relaxed (&__pthread_total, -1) == 1)
  57     /* We are the last thread.  */
  58     exit (0);
  59
  60   /* Destroy any thread specific data.  */
  61   __pthread_destroy_specific (self);
  62
  63   /* Note that after this point the process can be terminated at any
  64      point if another thread calls `pthread_exit' and happens to be
  65      the last thread.  */
  66
  67   __pthread_mutex_lock (&self->state_lock);
  68
  69   if (self->cancel_state == PTHREAD_CANCEL_ENABLE && self->cancel_pending)
  70     status = PTHREAD_CANCELED;
  71
  72   switch (self->state)
  73     {
  74     default:
  75       assert (!"Consistency error: unexpected self->state");
  76       abort ();
  77       break;
  78
  79     case PTHREAD_DETACHED:
  80       __pthread_mutex_unlock (&self->state_lock);
  81
  82       break;
  83
  84     case PTHREAD_JOINABLE:
  85       /* We need to stay around for a while since another thread
  86          might want to join us.  */
  87       self->state = PTHREAD_EXITED;
  88
  89       /* We need to remember the exit status.  A thread joining us
  90          might ask for it.  */
  91       self->status = status;
  92
  93       /* Broadcast the condition.  This will wake up threads that are
  94          waiting to join us.  */
  95       __pthread_cond_broadcast (&self->state_cond);
  96       __pthread_mutex_unlock (&self->state_lock);
  97
  98       break;
  99     }
 100
 101   /* Destroy any signal state.  */
 102   __pthread_sigstate_destroy (self);
 103
 104   /* Self terminating requires TLS, so defer the release of the TCB until
 105      the thread structure is reused.  */
 106
 107   /* Release kernel resources, including the kernel thread and the stack,
 108      and drop the self reference.  */
 109   __pthread_thread_terminate (self);
 110
 111   /* NOTREACHED */
 112   abort ();
 113 }
 114
 115 weak_alias (__pthread_exit, pthread_exit);