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ab355d9aa5
* sysdeps/unix/sysv/linux/structsem.sym: Add SEM_VALUE_MAX. * sysdeps/unix/sysv/linux/sem_post.c: Don't overflow value field. * sysdeps/unix/sysv/linux/i386/i486/sem_post.S: Likewise. * sysdeps/unix/sysv/linux/x86_64/sem_post.S: Likewise.
81 lines
2.2 KiB
C
81 lines
2.2 KiB
C
/* sem_post -- post to a POSIX semaphore. Generic futex-using version.
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Copyright (C) 2003, 2004, 2007, 2008 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Jakub Jelinek <jakub@redhat.com>, 2003.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, write to the Free
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Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA. */
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#include <errno.h>
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#include <sysdep.h>
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#include <lowlevellock.h>
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#include <internaltypes.h>
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#include <semaphore.h>
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#include <shlib-compat.h>
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int
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__new_sem_post (sem_t *sem)
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{
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struct new_sem *isem = (struct new_sem *) sem;
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__typeof (isem->value) cur;
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do
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{
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cur = isem->value;
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if (isem->value == SEM_VALUE_MAX)
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{
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__set_errno (EOVERFLOW);
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return -1;
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}
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}
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while (atomic_compare_and_exchange_bool_acq (&isem->value, cur + 1, cur));
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atomic_full_barrier ();
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if (isem->nwaiters > 0)
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{
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int err = lll_futex_wake (&isem->value, 1,
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isem->private ^ FUTEX_PRIVATE_FLAG);
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if (__builtin_expect (err, 0) < 0)
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{
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__set_errno (-err);
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return -1;
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}
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}
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return 0;
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}
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versioned_symbol (libpthread, __new_sem_post, sem_post, GLIBC_2_1);
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#if SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_1)
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int
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attribute_compat_text_section
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__old_sem_post (sem_t *sem)
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{
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int *futex = (int *) sem;
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int nr = atomic_increment_val (futex);
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/* We always have to assume it is a shared semaphore. */
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int err = lll_futex_wake (futex, 1, LLL_SHARED);
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if (__builtin_expect (err, 0) < 0)
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{
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__set_errno (-err);
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return -1;
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}
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return 0;
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}
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compat_symbol (libpthread, __old_sem_post, sem_post, GLIBC_2_0);
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#endif
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