mirror of
https://sourceware.org/git/glibc.git
synced 2024-12-29 05:51:10 +00:00
83 lines
2.3 KiB
C
83 lines
2.3 KiB
C
/* sem_post -- post to a POSIX semaphore. Generic futex-using version.
|
|
Copyright (C) 2003-2017 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 <futex-internal.h>
|
|
|
|
#include <shlib-compat.h>
|
|
|
|
|
|
/* See sem_wait for an explanation of the algorithm. */
|
|
int
|
|
__new_sem_post (sem_t *sem)
|
|
{
|
|
struct new_sem *isem = (struct new_sem *) sem;
|
|
int private = isem->private;
|
|
unsigned int v;
|
|
|
|
__sparc32_atomic_do_lock24 (&isem->pad);
|
|
|
|
v = isem->value;
|
|
if ((v >> SEM_VALUE_SHIFT) == SEM_VALUE_MAX)
|
|
{
|
|
__sparc32_atomic_do_unlock24 (&isem->pad);
|
|
|
|
__set_errno (EOVERFLOW);
|
|
return -1;
|
|
}
|
|
isem->value = v + (1 << SEM_VALUE_SHIFT);
|
|
|
|
__sparc32_atomic_do_unlock24 (&isem->pad);
|
|
|
|
if ((v & SEM_NWAITERS_MASK) != 0)
|
|
futex_wake (&isem->value, 1, private);
|
|
|
|
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;
|
|
|
|
/* We must need to synchronize with consumers of this token, so the atomic
|
|
increment must have release MO semantics. */
|
|
atomic_write_barrier ();
|
|
(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
|