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glibc  2.9
pthread_cond_signal.c
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00001 /* Copyright (C) 2003, 2004, 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_signal (cond)
00033      pthread_cond_t *cond;
00034 {
00035   int pshared = (cond->__data.__mutex == (void *) ~0l)
00036               ? LLL_SHARED : LLL_PRIVATE;
00037 
00038   /* Make sure we are alone.  */
00039   lll_lock (cond->__data.__lock, pshared);
00040 
00041   /* Are there any waiters to be woken?  */
00042   if (cond->__data.__total_seq > cond->__data.__wakeup_seq)
00043     {
00044       /* Yes.  Mark one of them as woken.  */
00045       ++cond->__data.__wakeup_seq;
00046       ++cond->__data.__futex;
00047 
00048       /* Wake one.  */
00049       if (! __builtin_expect (lll_futex_wake_unlock (&cond->__data.__futex, 1,
00050                                                1, &cond->__data.__lock,
00051                                                pshared), 0))
00052        return 0;
00053 
00054       lll_futex_wake (&cond->__data.__futex, 1, pshared);
00055     }
00056 
00057   /* We are done.  */
00058   lll_unlock (cond->__data.__lock, pshared);
00059 
00060   return 0;
00061 }
00062 
00063 versioned_symbol (libpthread, __pthread_cond_signal, pthread_cond_signal,
00064                 GLIBC_2_3_2);