mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-09 23:00:07 +00:00
581c785bf3
I used these shell commands: ../glibc/scripts/update-copyrights $PWD/../gnulib/build-aux/update-copyright (cd ../glibc && git commit -am"[this commit message]") and then ignored the output, which consisted lines saying "FOO: warning: copyright statement not found" for each of 7061 files FOO. I then removed trailing white space from math/tgmath.h, support/tst-support-open-dev-null-range.c, and sysdeps/x86_64/multiarch/strlen-vec.S, to work around the following obscure pre-commit check failure diagnostics from Savannah. I don't know why I run into these diagnostics whereas others evidently do not. remote: *** 912-#endif remote: *** 913: remote: *** 914- remote: *** error: lines with trailing whitespace found ... remote: *** error: sysdeps/unix/sysv/linux/statx_cp.c: trailing lines
101 lines
3.2 KiB
C
101 lines
3.2 KiB
C
/* sem_post -- post to a POSIX semaphore. Generic futex-using version.
|
|
Copyright (C) 2003-2022 Free Software Foundation, Inc.
|
|
This file is part of the GNU C Library.
|
|
|
|
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
|
|
<https://www.gnu.org/licenses/>. */
|
|
|
|
#include <atomic.h>
|
|
#include <errno.h>
|
|
#include <sysdep.h>
|
|
#include <lowlevellock.h> /* lll_futex* used by the old code. */
|
|
#include <futex-internal.h>
|
|
#include <internaltypes.h>
|
|
#include <semaphore.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;
|
|
|
|
#if __HAVE_64B_ATOMICS
|
|
/* Add a token to the semaphore. We use release MO to make sure that a
|
|
thread acquiring this token synchronizes with us and other threads that
|
|
added tokens before (the release sequence includes atomic RMW operations
|
|
by other threads). */
|
|
/* TODO Use atomic_fetch_add to make it scale better than a CAS loop? */
|
|
uint64_t d = atomic_load_relaxed (&isem->data);
|
|
do
|
|
{
|
|
if ((d & SEM_VALUE_MASK) == SEM_VALUE_MAX)
|
|
{
|
|
__set_errno (EOVERFLOW);
|
|
return -1;
|
|
}
|
|
}
|
|
while (!atomic_compare_exchange_weak_release (&isem->data, &d, d + 1));
|
|
|
|
/* If there is any potentially blocked waiter, wake one of them. */
|
|
if ((d >> SEM_NWAITERS_SHIFT) > 0)
|
|
futex_wake (((unsigned int *) &isem->data) + SEM_VALUE_OFFSET, 1, private);
|
|
#else
|
|
/* Add a token to the semaphore. Similar to 64b version. */
|
|
unsigned int v = atomic_load_relaxed (&isem->value);
|
|
do
|
|
{
|
|
if ((v >> SEM_VALUE_SHIFT) == SEM_VALUE_MAX)
|
|
{
|
|
__set_errno (EOVERFLOW);
|
|
return -1;
|
|
}
|
|
}
|
|
while (!atomic_compare_exchange_weak_release
|
|
(&isem->value, &v, v + (1 << SEM_VALUE_SHIFT)));
|
|
|
|
/* If there is any potentially blocked waiter, wake one of them. */
|
|
if ((v & SEM_NWAITERS_MASK) != 0)
|
|
futex_wake (&isem->value, 1, private);
|
|
#endif
|
|
|
|
return 0;
|
|
}
|
|
versioned_symbol (libpthread, __new_sem_post, sem_post, GLIBC_2_34);
|
|
|
|
#if OTHER_SHLIB_COMPAT (libpthread, GLIBC_2_1, GLIBC_2_34)
|
|
compat_symbol (libpthread, __new_sem_post, sem_post, GLIBC_2_1);
|
|
#endif
|
|
|
|
#if OTHER_SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_1)
|
|
int
|
|
attribute_compat_text_section
|
|
__old_sem_post (sem_t *sem)
|
|
{
|
|
unsigned int *futex = (unsigned 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. */
|
|
futex_wake (futex, 1, LLL_SHARED);
|
|
return 0;
|
|
}
|
|
compat_symbol (libpthread, __old_sem_post, sem_post, GLIBC_2_0);
|
|
#endif
|