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glibc  2.9
pthread_cond_broadcast.c
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00001 /* Copyright (C) 2003, 2004, 2006, 2007 Free Software Foundation, Inc.
00002    This file is part of the GNU C Library.
00003    Contributed by Martin Schwidefsky <schwidefsky@de.ibm.com>, 2003.
00004 
00005    The GNU C Library is free software; you can redistribute it and/or
00006    modify it under the terms of the GNU Lesser General Public
00007    License as published by the Free Software Foundation; either
00008    version 2.1 of the License, or (at your option) any later version.
00009 
00010    The GNU C Library is distributed in the hope that it will be useful,
00011    but WITHOUT ANY WARRANTY; without even the implied warranty of
00012    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00013    Lesser General Public License for more details.
00014 
00015    You should have received a copy of the GNU Lesser General Public
00016    License along with the GNU C Library; if not, write to the Free
00017    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00018    02111-1307 USA.  */
00019 
00020 #include <endian.h>
00021 #include <errno.h>
00022 #include <sysdep.h>
00023 #include <lowlevellock.h>
00024 #include <pthread.h>
00025 #include <pthreadP.h>
00026 
00027 #include <shlib-compat.h>
00028 #include <kernel-features.h>
00029 
00030 
00031 int
00032 __pthread_cond_broadcast (cond)
00033      pthread_cond_t *cond;
00034 {
00035   int pshared = (cond->__data.__mutex == (void *) ~0l)
00036               ? LLL_SHARED : LLL_PRIVATE;
00037   /* Make sure we are alone.  */
00038   lll_lock (cond->__data.__lock, pshared);
00039 
00040   /* Are there any waiters to be woken?  */
00041   if (cond->__data.__total_seq > cond->__data.__wakeup_seq)
00042     {
00043       /* Yes.  Mark them all as woken.  */
00044       cond->__data.__wakeup_seq = cond->__data.__total_seq;
00045       cond->__data.__woken_seq = cond->__data.__total_seq;
00046       cond->__data.__futex = (unsigned int) cond->__data.__total_seq * 2;
00047       int futex_val = cond->__data.__futex;
00048       /* Signal that a broadcast happened.  */
00049       ++cond->__data.__broadcast_seq;
00050 
00051       /* We are done.  */
00052       lll_unlock (cond->__data.__lock, pshared);
00053 
00054       /* Do not use requeue for pshared condvars.  */
00055       if (cond->__data.__mutex == (void *) ~0l)
00056        goto wake_all;
00057 
00058       /* Wake everybody.  */
00059       pthread_mutex_t *mut = (pthread_mutex_t *) cond->__data.__mutex;
00060 
00061       /* XXX: Kernel so far doesn't support requeue to PI futex.  */
00062       /* XXX: Kernel so far can only requeue to the same type of futex,
00063         in this case private (we don't requeue for pshared condvars).  */
00064       if (__builtin_expect (mut->__data.__kind
00065                          & (PTHREAD_MUTEX_PRIO_INHERIT_NP
00066                             | PTHREAD_MUTEX_PSHARED_BIT), 0))
00067        goto wake_all;
00068 
00069       /* lll_futex_requeue returns 0 for success and non-zero
00070         for errors.  */
00071       if (__builtin_expect (lll_futex_requeue (&cond->__data.__futex, 1,
00072                                           INT_MAX, &mut->__data.__lock,
00073                                           futex_val, LLL_PRIVATE), 0))
00074        {
00075          /* The requeue functionality is not available.  */
00076        wake_all:
00077          lll_futex_wake (&cond->__data.__futex, INT_MAX, pshared);
00078        }
00079 
00080       /* That's all.  */
00081       return 0;
00082     }
00083 
00084   /* We are done.  */
00085   lll_unlock (cond->__data.__lock, pshared);
00086 
00087   return 0;
00088 }
00089 
00090 versioned_symbol (libpthread, __pthread_cond_broadcast, pthread_cond_broadcast,
00091                 GLIBC_2_3_2);