mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-23 13:30:06 +00:00
123 lines
3.0 KiB
C
123 lines
3.0 KiB
C
/* sem_wait -- wait on a semaphore. Generic futex-using version.
|
|
Copyright (C) 2003, 2007 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 <lowlevellock.h>
|
|
#include <internaltypes.h>
|
|
#include <semaphore.h>
|
|
|
|
#include <pthreadP.h>
|
|
#include <shlib-compat.h>
|
|
|
|
|
|
void
|
|
attribute_hidden
|
|
__sem_wait_cleanup (void *arg)
|
|
{
|
|
struct new_sem *isem = (struct new_sem *) arg;
|
|
|
|
atomic_decrement (&isem->nwaiters);
|
|
}
|
|
|
|
/* This is in a seperate function in order to make sure gcc
|
|
puts the call site into an exception region, and thus the
|
|
cleanups get properly run. */
|
|
static int
|
|
__attribute__ ((noinline))
|
|
do_futex_wait (struct new_sem *isem)
|
|
{
|
|
int err, oldtype = __pthread_enable_asynccancel ();
|
|
|
|
err = lll_futex_wait (&isem->value, 0, isem->private ^ FUTEX_PRIVATE_FLAG);
|
|
|
|
__pthread_disable_asynccancel (oldtype);
|
|
return err;
|
|
}
|
|
|
|
int
|
|
__new_sem_wait (sem_t *sem)
|
|
{
|
|
struct new_sem *isem = (struct new_sem *) sem;
|
|
int err;
|
|
|
|
if (atomic_decrement_if_positive (&isem->value) > 0)
|
|
return 0;
|
|
|
|
atomic_increment (&isem->nwaiters);
|
|
|
|
pthread_cleanup_push (__sem_wait_cleanup, isem);
|
|
|
|
while (1)
|
|
{
|
|
err = do_futex_wait(isem);
|
|
if (err != 0 && err != -EWOULDBLOCK)
|
|
{
|
|
__set_errno (-err);
|
|
err = -1;
|
|
break;
|
|
}
|
|
|
|
if (atomic_decrement_if_positive (&isem->value) > 0)
|
|
{
|
|
err = 0;
|
|
break;
|
|
}
|
|
}
|
|
|
|
pthread_cleanup_pop (0);
|
|
|
|
atomic_decrement (&isem->nwaiters);
|
|
|
|
return err;
|
|
}
|
|
versioned_symbol (libpthread, __new_sem_wait, sem_wait, GLIBC_2_1);
|
|
|
|
|
|
#if SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_1)
|
|
int
|
|
attribute_compat_text_section
|
|
__old_sem_wait (sem_t *sem)
|
|
{
|
|
int *futex = (int *) sem;
|
|
int err;
|
|
|
|
do
|
|
{
|
|
if (atomic_decrement_if_positive (futex) > 0)
|
|
return 0;
|
|
|
|
/* Enable asynchronous cancellation. Required by the standard. */
|
|
int oldtype = __pthread_enable_asynccancel ();
|
|
|
|
/* Always assume the semaphore is shared. */
|
|
err = lll_futex_wait (futex, 0, LLL_SHARED);
|
|
|
|
/* Disable asynchronous cancellation. */
|
|
__pthread_disable_asynccancel (oldtype);
|
|
}
|
|
while (err == 0 || err == -EWOULDBLOCK);
|
|
|
|
__set_errno (-err);
|
|
return -1;
|
|
}
|
|
|
|
compat_symbol (libpthread, __old_sem_wait, sem_wait, GLIBC_2_0);
|
|
#endif
|