1  /* Test support for single-thread optimizations.  With threads, static version.
       2     Copyright (C) 2020-2023 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 is a stripped-down version of
      20     tst-single_threaded-pthread.c, without any loading of dynamic
      21     objects.  */
      22  
      23  #include <stdio.h>
      24  #include <support/check.h>
      25  #include <support/xthread.h>
      26  #include <sys/single_threaded.h>
      27  
      28  /* First barrier synchronizes main thread, thread 1, thread 2.  */
      29  static pthread_barrier_t barrier1;
      30  
      31  /* Second barrier synchronizes main thread, thread 2.  */
      32  static pthread_barrier_t barrier2;
      33  
      34  static void *
      35  threadfunc (void *closure)
      36  {
      37    TEST_VERIFY (!__libc_single_threaded);
      38  
      39    /* Wait for the main thread and the other thread.  */
      40    xpthread_barrier_wait (&barrier1);
      41    TEST_VERIFY (!__libc_single_threaded);
      42  
      43    /* Second thread waits on second barrier, too.  */
      44    if (closure != NULL)
      45      xpthread_barrier_wait (&barrier2);
      46    TEST_VERIFY (!__libc_single_threaded);
      47  
      48    return NULL;
      49  }
      50  
      51  static int
      52  do_test (void)
      53  {
      54    TEST_VERIFY (__libc_single_threaded);
      55  
      56    /* Two threads plus main thread.  */
      57    xpthread_barrier_init (&barrier1, NULL, 3);
      58  
      59    /* Main thread and second thread.  */
      60    xpthread_barrier_init (&barrier2, NULL, 2);
      61  
      62    pthread_t thr1 = xpthread_create (NULL, threadfunc, NULL);
      63    TEST_VERIFY (!__libc_single_threaded);
      64  
      65    pthread_t thr2 = xpthread_create (NULL, threadfunc, &thr2);
      66    TEST_VERIFY (!__libc_single_threaded);
      67  
      68    xpthread_barrier_wait (&barrier1);
      69    TEST_VERIFY (!__libc_single_threaded);
      70  
      71    /* Join first thread.  This should not bring us back into
      72       single-threaded mode.  */
      73    xpthread_join (thr1);
      74    TEST_VERIFY (!__libc_single_threaded);
      75  
      76    /* We may be back in single-threaded mode after joining both
      77       threads, but this is not guaranteed.  */
      78    xpthread_barrier_wait (&barrier2);
      79    xpthread_join (thr2);
      80    printf ("info: __libc_single_threaded after joining all threads: %d\n",
      81            __libc_single_threaded);
      82  
      83    return 0;
      84  }
      85  
      86  #include <support/test-driver.c>