| /* sem_post -- post to a POSIX semaphore. Generic futex-using version. |
| Copyright (C) 2003-2014 Free Software Foundation, Inc. |
| This file is part of the GNU C Library. |
| Contributed by Jakub Jelinek <jakub@redhat.com>, 2003. |
| |
| The GNU C Library is free software; you can redistribute it and/or |
| modify it under the terms of the GNU Lesser General Public |
| License as published by the Free Software Foundation; either |
| version 2.1 of the License, or (at your option) any later version. |
| |
| The GNU C Library is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public |
| License along with the GNU C Library; if not, see |
| <http://www.gnu.org/licenses/>. */ |
| |
| #include <atomic.h> |
| #include <errno.h> |
| #include <sysdep.h> |
| #include <lowlevellock.h> |
| #include <internaltypes.h> |
| #include <semaphore.h> |
| |
| #include <shlib-compat.h> |
| |
| int |
| __new_sem_post (sem_t *sem) |
| { |
| struct new_sem *isem = (struct new_sem *) sem; |
| |
| __typeof (isem->value) cur; |
| do |
| { |
| cur = isem->value; |
| if (isem->value == SEM_VALUE_MAX) |
| { |
| __set_errno (EOVERFLOW); |
| return -1; |
| } |
| } |
| while (atomic_compare_and_exchange_bool_rel (&isem->value, cur + 1, cur)); |
| |
| atomic_full_barrier (); |
| if (isem->nwaiters > 0) |
| { |
| int err = lll_futex_wake (&isem->value, 1, |
| isem->private ^ FUTEX_PRIVATE_FLAG); |
| if (__builtin_expect (err, 0) < 0) |
| { |
| __set_errno (-err); |
| return -1; |
| } |
| } |
| return 0; |
| } |
| versioned_symbol (libpthread, __new_sem_post, sem_post, GLIBC_2_1); |
| |
| |
| #if SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_1) |
| int |
| attribute_compat_text_section |
| __old_sem_post (sem_t *sem) |
| { |
| int *futex = (int *) sem; |
| |
| (void) atomic_increment_val (futex); |
| /* We always have to assume it is a shared semaphore. */ |
| int err = lll_futex_wake (futex, 1, LLL_SHARED); |
| if (__builtin_expect (err, 0) < 0) |
| { |
| __set_errno (-err); |
| return -1; |
| } |
| return 0; |
| } |
| compat_symbol (libpthread, __old_sem_post, sem_post, GLIBC_2_0); |
| #endif |