+++ /dev/null
-/*
- * compat_futex.c
- *
- * Userspace RCU library - sys_futex compatibility code
- *
- * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- *
- * This 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.
- *
- * This 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 this library; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
- */
-
-#include <stdio.h>
-#include <pthread.h>
-#include <signal.h>
-#include <assert.h>
-#include <errno.h>
-#include <poll.h>
-#include <stdint.h>
-
-#include <urcu/arch.h>
-#include <urcu/futex.h>
-#include <urcu/system.h>
-
-/*
- * Using attribute "weak" for __urcu_compat_futex_lock and
- * __urcu_compat_futex_cond. Those are globally visible by the entire
- * program, even though many shared objects may have their own version.
- * The first version that gets loaded will be used by the entire program
- * (executable and all shared objects).
- */
-
-__attribute__((weak))
-pthread_mutex_t __urcu_compat_futex_lock = PTHREAD_MUTEX_INITIALIZER;
-__attribute__((weak))
-pthread_cond_t __urcu_compat_futex_cond = PTHREAD_COND_INITIALIZER;
-
-/*
- * _NOT SIGNAL-SAFE_. pthread_cond is not signal-safe anyway. Though.
- * For now, timeout, uaddr2 and val3 are unused.
- * Waiter will relinquish the CPU until woken up.
- */
-
-int compat_futex_noasync(int32_t *uaddr, int op, int32_t val,
- const struct timespec *timeout, int32_t *uaddr2, int32_t val3)
-{
- int ret = 0, lockret;
-
- /*
- * Check if NULL. Don't let users expect that they are taken into
- * account.
- */
- assert(!timeout);
- assert(!uaddr2);
- assert(!val3);
-
- /*
- * memory barriers to serialize with the previous uaddr modification.
- */
- cmm_smp_mb();
-
- lockret = pthread_mutex_lock(&__urcu_compat_futex_lock);
- if (lockret) {
- errno = lockret;
- ret = -1;
- goto end;
- }
- switch (op) {
- case FUTEX_WAIT:
- /*
- * Wait until *uaddr is changed to something else than "val".
- * Comparing *uaddr content against val figures out which
- * thread has been awakened.
- */
- while (CMM_LOAD_SHARED(*uaddr) == val)
- pthread_cond_wait(&__urcu_compat_futex_cond,
- &__urcu_compat_futex_lock);
- break;
- case FUTEX_WAKE:
- /*
- * Each wake is sending a broadcast, thus attempting wakeup of
- * all awaiting threads, independently of their respective
- * uaddr.
- */
- pthread_cond_broadcast(&__urcu_compat_futex_cond);
- break;
- default:
- errno = EINVAL;
- ret = -1;
- }
- lockret = pthread_mutex_unlock(&__urcu_compat_futex_lock);
- if (lockret) {
- errno = lockret;
- ret = -1;
- }
-end:
- return ret;
-}
-
-/*
- * _ASYNC SIGNAL-SAFE_.
- * For now, timeout, uaddr2 and val3 are unused.
- * Waiter will busy-loop trying to read the condition.
- * It is OK to use compat_futex_async() on a futex address on which
- * futex() WAKE operations are also performed.
- */
-
-int compat_futex_async(int32_t *uaddr, int op, int32_t val,
- const struct timespec *timeout, int32_t *uaddr2, int32_t val3)
-{
- int ret = 0;
-
- /*
- * Check if NULL. Don't let users expect that they are taken into
- * account.
- */
- assert(!timeout);
- assert(!uaddr2);
- assert(!val3);
-
- /*
- * Ensure previous memory operations on uaddr have completed.
- */
- cmm_smp_mb();
-
- switch (op) {
- case FUTEX_WAIT:
- while (CMM_LOAD_SHARED(*uaddr) == val) {
- if (poll(NULL, 0, 10) < 0) {
- ret = -1;
- /* Keep poll errno. Caller handles EINTR. */
- goto end;
- }
- }
- break;
- case FUTEX_WAKE:
- break;
- default:
- errno = EINVAL;
- ret = -1;
- }
-end:
- return ret;
-}
projects / urcu.git / blobdiff