1  /* Test that pthread_kill succeeds during thread exit.
       2     Copyright (C) 2021-2023 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  /* This test verifies that pthread_kill for a thread that is exiting
      20     succeeds (with or without actually delivering the signal).  */
      21  
      22  #include <array_length.h>
      23  #include <stdbool.h>
      24  #include <stddef.h>
      25  #include <support/xsignal.h>
      26  #include <support/xthread.h>
      27  #include <unistd.h>
      28  
      29  /* Set to true by timeout_thread_function when the test should
      30     terminate.  */
      31  static bool timeout;
      32  
      33  static void *
      34  timeout_thread_function (void *unused)
      35  {
      36    usleep (1000 * 1000);
      37    __atomic_store_n (&timeout, true, __ATOMIC_RELAXED);
      38    return NULL;
      39  }
      40  
      41  /* Used to synchronize the sending threads with the target thread and
      42     main thread.  */
      43  static pthread_barrier_t barrier_1;
      44  static pthread_barrier_t barrier_2;
      45  
      46  /* The target thread to which signals are to be sent.  */
      47  static pthread_t target_thread;
      48  
      49  /* Set by the main thread to true after timeout has been set to
      50     true.  */
      51  static bool exiting;
      52  
      53  static void *
      54  sender_thread_function (void *unused)
      55  {
      56    while (true)
      57      {
      58        /* Wait until target_thread has been initialized.  The target
      59           thread and main thread participate in this barrier.  */
      60        xpthread_barrier_wait (&barrier_1);
      61  
      62        if (exiting)
      63          break;
      64  
      65        xpthread_kill (target_thread, SIGUSR1);
      66  
      67        /* Communicate that the signal has been sent.  The main thread
      68           participates in this barrier.  */
      69        xpthread_barrier_wait (&barrier_2);
      70      }
      71    return NULL;
      72  }
      73  
      74  static void *
      75  target_thread_function (void *unused)
      76  {
      77    target_thread = pthread_self ();
      78    xpthread_barrier_wait (&barrier_1);
      79    return NULL;
      80  }
      81  
      82  static int
      83  do_test (void)
      84  {
      85    xsignal (SIGUSR1, SIG_IGN);
      86  
      87    pthread_t thr_timeout = xpthread_create (NULL, timeout_thread_function, NULL);
      88  
      89    pthread_t threads[4];
      90    xpthread_barrier_init (&barrier_1, NULL, array_length (threads) + 2);
      91    xpthread_barrier_init (&barrier_2, NULL, array_length (threads) + 1);
      92  
      93    for (int i = 0; i < array_length (threads); ++i)
      94      threads[i] = xpthread_create (NULL, sender_thread_function, NULL);
      95  
      96    while (!__atomic_load_n (&timeout, __ATOMIC_RELAXED))
      97      {
      98        xpthread_create (NULL, target_thread_function, NULL);
      99  
     100        /* Wait for the target thread to be set up and signal sending to
     101           start.  */
     102        xpthread_barrier_wait (&barrier_1);
     103  
     104        /* Wait for signal sending to complete.  */
     105        xpthread_barrier_wait (&barrier_2);
     106  
     107        xpthread_join (target_thread);
     108      }
     109  
     110    exiting = true;
     111  
     112    /* Signal the sending threads to exit.  */
     113    xpthread_create (NULL, target_thread_function, NULL);
     114    xpthread_barrier_wait (&barrier_1);
     115  
     116    for (int i = 0; i < array_length (threads); ++i)
     117      xpthread_join (threads[i]);
     118    xpthread_join (thr_timeout);
     119  
     120    return 0;
     121  }
     122  
     123  #include <support/test-driver.c>