sysdeps/pthread/tst-pthread_cancel-select-loop.c

   1 /* Test that pthread_cancel succeeds during thread exit.
   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 /* This test tries to trigger an internal race condition in
  20    pthread_cancel, where the cancellation signal is sent after the
  21    thread has begun the cancellation process.  This can result in a
  22    spurious ESRCH error.  For the original bug 12889, the window is
  23    quite small, so the bug was not reproduced in every run.  */
  24
  25 #include <stdbool.h>
  26 #include <stddef.h>
  27 #include <support/check.h>
  28 #include <support/xthread.h>
  29 #include <support/xunistd.h>
  30 #include <sys/select.h>
  31 #include <unistd.h>
  32
  33 /* Set to true by timeout_thread_function when the test should
  34    terminate.  */
  35 static bool timeout;
  36
  37 static void *
  38 timeout_thread_function (void *unused)
  39 {
  40   usleep (5 * 1000 * 1000);
  41   __atomic_store_n (&timeout, true, __ATOMIC_RELAXED);
  42   return NULL;
  43 }
  44
  45 /* Used for blocking the select function below.  */
  46 static int pipe_fds[2];
  47
  48 static void *
  49 canceled_thread_function (void *unused)
  50 {
  51   while (true)
  52     {
  53       fd_set rfs;
  54       fd_set wfs;
  55       fd_set efs;
  56       FD_ZERO (&rfs);
  57       FD_ZERO (&wfs);
  58       FD_ZERO (&efs);
  59       FD_SET (pipe_fds[0], &rfs);
  60
  61       /* If the cancellation request is recognized early, the thread
  62          begins exiting while the cancellation signal arrives.  */
  63       select (FD_SETSIZE, &rfs, &wfs, &efs, NULL);
  64     }
  65   return NULL;
  66 }
  67
  68 static int
  69 do_test (void)
  70 {
  71   xpipe (pipe_fds);
  72   pthread_t thr_timeout = xpthread_create (NULL, timeout_thread_function, NULL);
  73
  74   while (!__atomic_load_n (&timeout, __ATOMIC_RELAXED))
  75     {
  76       pthread_t thr = xpthread_create (NULL, canceled_thread_function, NULL);
  77       xpthread_cancel (thr);
  78       TEST_VERIFY (xpthread_join (thr) == PTHREAD_CANCELED);
  79     }
  80
  81   xpthread_join (thr_timeout);
  82   xclose (pipe_fds[0]);
  83   xclose (pipe_fds[1]);
  84   return 0;
  85 }
  86
  87 #include <support/test-driver.c>