1  /* Signal a condition.  Generic version.
       2     Copyright (C) 2000-2023 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 <pthread.h>
      20  
      21  #include <pt-internal.h>
      22  
      23  /* Unblock at least one of the threads that are blocked on condition
      24     variable COND.  */
      25  int
      26  __pthread_cond_signal (pthread_cond_t *cond)
      27  {
      28    struct __pthread *wakeup;
      29  
      30    __pthread_spin_wait (&cond->__lock);
      31    wakeup = cond->__queue;
      32    if (wakeup != NULL)
      33      __pthread_dequeue (wakeup);
      34    __pthread_spin_unlock (&cond->__lock);
      35  
      36    if (wakeup != NULL)
      37      __pthread_wakeup (wakeup);
      38  
      39    return 0;
      40  }
      41  
      42  weak_alias (__pthread_cond_signal, pthread_cond_signal);