1  /* Out-of-line notification function for the GSCOPE locking mechanism.
       2     Copyright (C) 2007-2023 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  #include <ldsodefs.h>
      20  #include <pthread.h>
      21  #include <htl/pt-internal.h>
      22  
      23  void
      24  __thread_gscope_wait (void)
      25  {
      26    size_t i;
      27    struct __pthread *t;
      28    int *gscope_flagp;
      29  
      30    __libc_rwlock_rdlock (GL (dl_pthread_threads_lock));
      31  
      32    /* Iterate over the list of threads.  */
      33    for (i = 0; i < GL (dl_pthread_num_threads); ++i)
      34      {
      35        t = GL (dl_pthread_threads[i]);
      36        if (t == NULL || t->tcb->gscope_flag == THREAD_GSCOPE_FLAG_UNUSED)
      37          continue;
      38  
      39        gscope_flagp = &t->tcb->gscope_flag;
      40  
      41        /* We have to wait until this thread is done with the global
      42           scope.  First tell the thread that we are waiting and
      43           possibly have to be woken.  */
      44        if (atomic_compare_and_exchange_bool_acq (gscope_flagp,
      45                                                  THREAD_GSCOPE_FLAG_WAIT,
      46                                                  THREAD_GSCOPE_FLAG_USED))
      47          continue;
      48  
      49        do
      50          lll_wait (gscope_flagp, THREAD_GSCOPE_FLAG_WAIT, LLL_PRIVATE);
      51        while (*gscope_flagp == THREAD_GSCOPE_FLAG_WAIT);
      52      }
      53  
      54    __libc_rwlock_unlock (GL (dl_pthread_threads_lock));
      55  }