1 /* sem_wait -- wait on a semaphore. Generic futex-using version.
2 Copyright (C) 2003, 2007 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Paul Mackerras <paulus@au.ibm.com>, 2003.
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, see
18 <http://www.gnu.org/licenses/>. */
22 #include <lowlevellock.h>
23 #include <internaltypes.h>
24 #include <semaphore.h>
31 __sem_wait_cleanup (void *arg)
33 struct new_sem *isem = (struct new_sem *) arg;
35 atomic_decrement (&isem->nwaiters);
42 struct new_sem *isem = (struct new_sem *) sem;
45 if (atomic_decrement_if_positive (&isem->value) > 0)
48 atomic_increment (&isem->nwaiters);
50 pthread_cleanup_push (__sem_wait_cleanup, isem);
54 /* Enable asynchronous cancellation. Required by the standard. */
55 int oldtype = __pthread_enable_asynccancel ();
57 err = lll_futex_wait (&isem->value, 0,
58 isem->private ^ FUTEX_PRIVATE_FLAG);
60 /* Disable asynchronous cancellation. */
61 __pthread_disable_asynccancel (oldtype);
63 if (err != 0 && err != -EWOULDBLOCK)
70 if (atomic_decrement_if_positive (&isem->value) > 0)
77 pthread_cleanup_pop (0);
79 atomic_decrement (&isem->nwaiters);