nptl/sysdeps/pthread/pthread_cond_broadcast.c

   1 /* Copyright (C) 2003, 2004, 2006 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Martin Schwidefsky <schwidefsky@de.ibm.com>, 2003.
   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, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <endian.h>
  21 #include <errno.h>
  22 #include <sysdep.h>
  23 #include <lowlevellock.h>
  24 #include <pthread.h>
  25 #include <pthreadP.h>
  26
  27 #include <shlib-compat.h>
  28 #include <kernel-features.h>
  29
  30
  31 int
  32 __pthread_cond_broadcast (cond)
  33      pthread_cond_t *cond;
  34 {
  35   /* Make sure we are alone.  */
  36   lll_mutex_lock (cond->__data.__lock);
  37
  38   /* Are there any waiters to be woken?  */
  39   if (cond->__data.__total_seq > cond->__data.__wakeup_seq)
  40     {
  41       /* Yes.  Mark them all as woken.  */
  42       cond->__data.__wakeup_seq = cond->__data.__total_seq;
  43       cond->__data.__woken_seq = cond->__data.__total_seq;
  44       cond->__data.__futex = (unsigned int) cond->__data.__total_seq * 2;
  45       int futex_val = cond->__data.__futex;
  46       /* Signal that a broadcast happened.  */
  47       ++cond->__data.__broadcast_seq;
  48
  49       /* We are done.  */
  50       lll_mutex_unlock (cond->__data.__lock);
  51
  52       /* Do not use requeue for pshared condvars.  */
  53       if (cond->__data.__mutex == (void *) ~0l)
  54         goto wake_all;
  55
  56       /* Wake everybody.  */
  57       pthread_mutex_t *mut = (pthread_mutex_t *) cond->__data.__mutex;
  58
  59       /* XXX: Kernel so far doesn't support requeue to PI futex.  */
  60       if (__builtin_expect (mut->__data.__kind & PTHREAD_MUTEX_PRIO_INHERIT_NP,
  61                             0))
  62         goto wake_all;
  63
  64       /* lll_futex_requeue returns 0 for success and non-zero
  65          for errors.  */
  66       if (__builtin_expect (lll_futex_requeue (&cond->__data.__futex, 1,
  67                                                INT_MAX, &mut->__data.__lock,
  68                                                futex_val), 0))
  69         {
  70           /* The requeue functionality is not available.  */
  71         wake_all:
  72           lll_futex_wake (&cond->__data.__futex, INT_MAX);
  73         }
  74
  75       /* That's all.  */
  76       return 0;
  77     }
  78
  79   /* We are done.  */
  80   lll_mutex_unlock (cond->__data.__lock);
  81
  82   return 0;
  83 }
  84
  85 versioned_symbol (libpthread, __pthread_cond_broadcast, pthread_cond_broadcast,
  86                   GLIBC_2_3_2);