support/support_wait_for_thread_exit.c

   1 /* Wait until all threads except the current thread has exited.
   2    Copyright (C) 2021-2022 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 <string.h>
  22 #include <support/check.h>
  23 #include <support/support.h>
  24 #include <unistd.h>
  25
  26 void
  27 support_wait_for_thread_exit (void)
  28 {
  29 #ifdef __linux__
  30   DIR *proc_self_task = opendir ("/proc/self/task");
  31   TEST_VERIFY_EXIT (proc_self_task != NULL);
  32
  33   while (true)
  34     {
  35       errno = 0;
  36       struct dirent *e = readdir (proc_self_task);
  37       if (e == NULL && errno != 0)
  38         FAIL_EXIT1 ("readdir: %m");
  39       if (e == NULL)
  40         {
  41           /* Only the main thread remains.  Testing may continue.  */
  42           closedir (proc_self_task);
  43           return;
  44         }
  45
  46       /* In some kernels, "0" entries denote a thread that has just
  47          exited.  */
  48       if (strcmp (e->d_name, ".") == 0 || strcmp (e->d_name, "..") == 0
  49           || strcmp (e->d_name, "0") == 0)
  50         continue;
  51
  52       int task_tid = atoi (e->d_name);
  53       if (task_tid <= 0)
  54         FAIL_EXIT1 ("Invalid /proc/self/task entry: %s", e->d_name);
  55
  56       if (task_tid == gettid ())
  57         /* The current thread.  Keep scanning for other
  58            threads.  */
  59         continue;
  60
  61       /* task_tid does not refer to this thread here, i.e., there is
  62          another running thread.  */
  63
  64       /* Small timeout to give the thread a chance to exit.  */
  65       usleep (50 * 1000);
  66
  67       /* Start scanning the directory from the start.  */
  68       rewinddir (proc_self_task);
  69     }
  70 #else
  71   /* Use a large timeout because we cannot verify that the thread has
  72      exited.  */
  73   usleep (5 * 1000 * 1000);
  74 #endif
  75 }