support/support_wait_for_thread_exit.c

   1 /* Wait until all threads except the current thread has exited.
   2    Copyright (C) 2021-2024 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 <dirent.h>
  20 #include <errno.h>
  21 #include <stdlib.h>
  22 #include <string.h>
  23 #include <support/check.h>
  24 #include <support/support.h>
  25 #include <unistd.h>
  26
  27 void
  28 support_wait_for_thread_exit (void)
  29 {
  30 #ifdef __linux__
  31   DIR *proc_self_task = opendir ("/proc/self/task");
  32   TEST_VERIFY_EXIT (proc_self_task != NULL);
  33
  34   while (true)
  35     {
  36       errno = 0;
  37       struct dirent *e = readdir (proc_self_task);
  38       if (e == NULL && errno != 0)
  39         FAIL_EXIT1 ("readdir: %m");
  40       if (e == NULL)
  41         {
  42           /* Only the main thread remains.  Testing may continue.  */
  43           closedir (proc_self_task);
  44           return;
  45         }
  46
  47       /* In some kernels, "0" entries denote a thread that has just
  48          exited.  */
  49       if (strcmp (e->d_name, ".") == 0 || strcmp (e->d_name, "..") == 0
  50           || strcmp (e->d_name, "0") == 0)
  51         continue;
  52
  53       int task_tid = atoi (e->d_name);
  54       if (task_tid <= 0)
  55         FAIL_EXIT1 ("Invalid /proc/self/task entry: %s", e->d_name);
  56
  57       if (task_tid == gettid ())
  58         /* The current thread.  Keep scanning for other
  59            threads.  */
  60         continue;
  61
  62       /* task_tid does not refer to this thread here, i.e., there is
  63          another running thread.  */
  64
  65       /* Small timeout to give the thread a chance to exit.  */
  66       usleep (50 * 1000);
  67
  68       /* Start scanning the directory from the start.  */
  69       rewinddir (proc_self_task);
  70     }
  71 #else
  72   /* Use a large timeout because we cannot verify that the thread has
  73      exited.  */
  74   usleep (5 * 1000 * 1000);
  75 #endif
  76 }