htl/pt-join.c

   1 /* Wait for thread termination.
   2    Copyright (C) 2000-2021 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 <errno.h>
  20 #include <pthread.h>
  21 #include <stddef.h>
  22
  23 #include <pt-internal.h>
  24
  25 /* Make calling thread wait for termination of thread THREAD.  Return
  26    the exit status of the thread in *STATUS.  */
  27 static int
  28 __pthread_join_common (pthread_t thread, void **status, int try,
  29                        clockid_t clockid,
  30                        const struct timespec *abstime)
  31 {
  32   struct __pthread *pthread;
  33   int err = 0;
  34
  35   /* Lookup the thread structure for THREAD.  */
  36   pthread = __pthread_getid (thread);
  37   if (pthread == NULL)
  38     return ESRCH;
  39
  40   if (pthread == _pthread_self ())
  41     return EDEADLK;
  42
  43   __pthread_mutex_lock (&pthread->state_lock);
  44
  45   if (try == 0)
  46     {
  47       pthread_cleanup_push ((void (*)(void *)) __pthread_mutex_unlock,
  48                             &pthread->state_lock);
  49
  50       /* Rely on pthread_cond_wait being a cancellation point to make
  51          pthread_join one too.  */
  52       while (pthread->state == PTHREAD_JOINABLE && err != ETIMEDOUT)
  53         err = __pthread_cond_clockwait (&pthread->state_cond,
  54                                         &pthread->state_lock,
  55                                         clockid, abstime);
  56
  57       pthread_cleanup_pop (0);
  58     }
  59
  60   switch (pthread->state)
  61     {
  62     case PTHREAD_JOINABLE:
  63       __pthread_mutex_unlock (&pthread->state_lock);
  64       if (err != ETIMEDOUT)
  65         err = EBUSY;
  66       break;
  67
  68     case PTHREAD_EXITED:
  69       /* THREAD has already exited.  Salvage its exit status.  */
  70       if (status != NULL)
  71         *status = pthread->status;
  72
  73       __pthread_mutex_unlock (&pthread->state_lock);
  74
  75       __pthread_dealloc (pthread);
  76       break;
  77
  78     case PTHREAD_TERMINATED:
  79       /* Pretend THREAD wasn't there in the first place.  */
  80       __pthread_mutex_unlock (&pthread->state_lock);
  81       err = ESRCH;
  82       break;
  83
  84     default:
  85       /* Thou shalt not join non-joinable threads!  */
  86       __pthread_mutex_unlock (&pthread->state_lock);
  87       err = EINVAL;
  88       break;
  89     }
  90
  91   return err;
  92 }
  93
  94 int
  95 __pthread_join (pthread_t thread, void **status)
  96 {
  97   return __pthread_join_common (thread, status, 0, CLOCK_REALTIME, NULL);
  98 }
  99 weak_alias (__pthread_join, pthread_join);
 100
 101 int
 102 __pthread_tryjoin_np (pthread_t thread, void **status)
 103 {
 104   return __pthread_join_common (thread, status, 1, CLOCK_REALTIME, NULL);
 105 }
 106 weak_alias (__pthread_tryjoin_np, pthread_tryjoin_np);
 107
 108 int
 109 __pthread_timedjoin_np (pthread_t thread, void **status,
 110                         const struct timespec *abstime)
 111 {
 112   return __pthread_join_common (thread, status, 0, CLOCK_REALTIME, abstime);
 113 }
 114 weak_alias (__pthread_timedjoin_np, pthread_timedjoin_np);
 115
 116 int
 117 __pthread_clockjoin_np (pthread_t thread, void **status,
 118                         clockid_t clockid,
 119                         const struct timespec *abstime)
 120 {
 121   return __pthread_join_common (thread, status, 0, clockid, abstime);
 122 }
 123 weak_alias (__pthread_clockjoin_np, pthread_clockjoin_np);