mirror of
https://sourceware.org/git/glibc.git
synced 2024-12-29 05:51:10 +00:00
147 lines
3.6 KiB
C
147 lines
3.6 KiB
C
/* sem_waitcommon -- wait on a semaphore, shared code.
|
|
Copyright (C) 2003-2017 Free Software Foundation, Inc.
|
|
This file is part of the GNU C Library.
|
|
Contributed by Paul Mackerras <paulus@au.ibm.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 <errno.h>
|
|
#include <sysdep.h>
|
|
#include <futex-internal.h>
|
|
#include <internaltypes.h>
|
|
#include <semaphore.h>
|
|
#include <sys/time.h>
|
|
|
|
#include <pthreadP.h>
|
|
#include <shlib-compat.h>
|
|
#include <atomic.h>
|
|
|
|
|
|
static void
|
|
__sem_wait_32_finish (struct new_sem *sem);
|
|
|
|
static void
|
|
__sem_wait_cleanup (void *arg)
|
|
{
|
|
struct new_sem *sem = (struct new_sem *) arg;
|
|
|
|
__sem_wait_32_finish (sem);
|
|
}
|
|
|
|
/* Wait until at least one token is available, possibly with a timeout.
|
|
This is in a separate function in order to make sure gcc
|
|
puts the call site into an exception region, and thus the
|
|
cleanups get properly run. TODO still necessary? Other futex_wait
|
|
users don't seem to need it. */
|
|
static int
|
|
__attribute__ ((noinline))
|
|
do_futex_wait (struct new_sem *sem, const struct timespec *abstime)
|
|
{
|
|
int err;
|
|
|
|
err = futex_abstimed_wait_cancelable (&sem->value, SEM_NWAITERS_MASK,
|
|
abstime, sem->private);
|
|
|
|
return err;
|
|
}
|
|
|
|
/* Fast path: Try to grab a token without blocking. */
|
|
static int
|
|
__new_sem_wait_fast (struct new_sem *sem, int definitive_result)
|
|
{
|
|
unsigned int v;
|
|
int ret = 0;
|
|
|
|
__sparc32_atomic_do_lock24(&sem->pad);
|
|
|
|
v = sem->value;
|
|
if ((v >> SEM_VALUE_SHIFT) == 0)
|
|
ret = -1;
|
|
else
|
|
sem->value = v - (1 << SEM_VALUE_SHIFT);
|
|
|
|
__sparc32_atomic_do_unlock24(&sem->pad);
|
|
|
|
return ret;
|
|
}
|
|
|
|
/* Slow path that blocks. */
|
|
static int
|
|
__attribute__ ((noinline))
|
|
__new_sem_wait_slow (struct new_sem *sem, const struct timespec *abstime)
|
|
{
|
|
unsigned int v;
|
|
int err = 0;
|
|
|
|
__sparc32_atomic_do_lock24(&sem->pad);
|
|
|
|
sem->nwaiters++;
|
|
|
|
pthread_cleanup_push (__sem_wait_cleanup, sem);
|
|
|
|
/* Wait for a token to be available. Retry until we can grab one. */
|
|
v = sem->value;
|
|
do
|
|
{
|
|
if (!(v & SEM_NWAITERS_MASK))
|
|
sem->value = v | SEM_NWAITERS_MASK;
|
|
|
|
/* If there is no token, wait. */
|
|
if ((v >> SEM_VALUE_SHIFT) == 0)
|
|
{
|
|
__sparc32_atomic_do_unlock24(&sem->pad);
|
|
|
|
err = do_futex_wait(sem, abstime);
|
|
if (err == ETIMEDOUT || err == EINTR)
|
|
{
|
|
__set_errno (err);
|
|
err = -1;
|
|
goto error;
|
|
}
|
|
err = 0;
|
|
|
|
__sparc32_atomic_do_lock24(&sem->pad);
|
|
|
|
/* We blocked, so there might be a token now. */
|
|
v = sem->value;
|
|
}
|
|
}
|
|
/* If there is no token, we must not try to grab one. */
|
|
while ((v >> SEM_VALUE_SHIFT) == 0);
|
|
|
|
sem->value = v - (1 << SEM_VALUE_SHIFT);
|
|
|
|
__sparc32_atomic_do_unlock24(&sem->pad);
|
|
|
|
error:
|
|
pthread_cleanup_pop (0);
|
|
|
|
__sem_wait_32_finish (sem);
|
|
|
|
return err;
|
|
}
|
|
|
|
/* Stop being a registered waiter (non-64b-atomics code only). */
|
|
static void
|
|
__sem_wait_32_finish (struct new_sem *sem)
|
|
{
|
|
__sparc32_atomic_do_lock24(&sem->pad);
|
|
|
|
if (--sem->nwaiters == 0)
|
|
sem->value &= ~SEM_NWAITERS_MASK;
|
|
|
|
__sparc32_atomic_do_unlock24(&sem->pad);
|
|
}
|