diff options
Diffstat (limited to 'libs/utils/futex_synchro.c')
| -rw-r--r-- | libs/utils/futex_synchro.c | 176 |
1 files changed, 0 insertions, 176 deletions
diff --git a/libs/utils/futex_synchro.c b/libs/utils/futex_synchro.c deleted file mode 100644 index ab48c69..0000000 --- a/libs/utils/futex_synchro.c +++ /dev/null @@ -1,176 +0,0 @@ -/* - * Copyright (C) 2008 The Android Open Source Project - * - * Licensed under the Apache License, Version 2.0 (the "License"); - * you may not use this file except in compliance with the License. - * You may obtain a copy of the License at - * - * http://www.apache.org/licenses/LICENSE-2.0 - * - * Unless required by applicable law or agreed to in writing, software - * distributed under the License is distributed on an "AS IS" BASIS, - * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. - * See the License for the specific language governing permissions and - * limitations under the License. - */ - -#include <stdio.h> -#include <limits.h> - -#include <sys/time.h> -#include <sched.h> - -#include <errno.h> - -#include <private/utils/futex_synchro.h> - - -// This futex glue code is need on desktop linux, but is already part of bionic. -#if !defined(HAVE_FUTEX_WRAPPERS) - -#include <unistd.h> -#include <sys/syscall.h> -typedef unsigned int u32; -#define asmlinkage -#define __user -#include <linux/futex.h> -#include <utils/Atomic.h> - - -int futex (int *uaddr, int op, int val, const struct timespec *timeout, int *uaddr2, int val3) -{ - int err = syscall(SYS_futex, uaddr, op, val, timeout, uaddr2, val3); - return err == 0 ? 0 : -errno; -} - -int __futex_wait(volatile void *ftx, int val, const struct timespec *timeout) -{ - return futex((int*)ftx, FUTEX_WAIT, val, timeout, NULL, 0); -} - -int __futex_wake(volatile void *ftx, int count) -{ - return futex((int*)ftx, FUTEX_WAKE, count, NULL, NULL, 0); -} - -int __atomic_cmpxchg(int old, int _new, volatile int *ptr) -{ - return android_atomic_cmpxchg(old, _new, ptr); -} - -int __atomic_swap(int _new, volatile int *ptr) -{ - return android_atomic_swap(_new, ptr); -} - -int __atomic_dec(volatile int *ptr) -{ - return android_atomic_dec(ptr); -} - -#else // !defined(__arm__) - -int __futex_wait(volatile void *ftx, int val, const struct timespec *timeout); -int __futex_wake(volatile void *ftx, int count); - -int __atomic_cmpxchg(int old, int _new, volatile int *ptr); -int __atomic_swap(int _new, volatile int *ptr); -int __atomic_dec(volatile int *ptr); - -#endif // !defined(HAVE_FUTEX_WRAPPERS) - - -// lock states -// -// 0: unlocked -// 1: locked, no waiters -// 2: locked, maybe waiters - -void futex_mutex_init(futex_mutex_t *m) -{ - m->value = 0; -} - -int futex_mutex_lock(futex_mutex_t *m, unsigned msec) -{ - if(__atomic_cmpxchg(0, 1, &m->value) == 0) { - return 0; - } - if(msec == FUTEX_WAIT_INFINITE) { - while(__atomic_swap(2, &m->value) != 0) { - __futex_wait(&m->value, 2, 0); - } - } else { - struct timespec ts; - ts.tv_sec = msec / 1000; - ts.tv_nsec = (msec % 1000) * 1000000; - while(__atomic_swap(2, &m->value) != 0) { - if(__futex_wait(&m->value, 2, &ts) == -ETIMEDOUT) { - return -1; - } - } - } - return 0; -} - -int futex_mutex_trylock(futex_mutex_t *m) -{ - if(__atomic_cmpxchg(0, 1, &m->value) == 0) { - return 0; - } - return -1; -} - -void futex_mutex_unlock(futex_mutex_t *m) -{ - if(__atomic_dec(&m->value) != 1) { - m->value = 0; - __futex_wake(&m->value, 1); - } -} - -/* XXX *technically* there is a race condition that could allow - * XXX a signal to be missed. If thread A is preempted in _wait() - * XXX after unlocking the mutex and before waiting, and if other - * XXX threads call signal or broadcast UINT_MAX times (exactly), - * XXX before thread A is scheduled again and calls futex_wait(), - * XXX then the signal will be lost. - */ - -void futex_cond_init(futex_cond_t *c) -{ - c->value = 0; -} - -int futex_cond_wait(futex_cond_t *c, futex_mutex_t *m, unsigned msec) -{ - if(msec == FUTEX_WAIT_INFINITE){ - int oldvalue = c->value; - futex_mutex_unlock(m); - __futex_wait(&c->value, oldvalue, 0); - futex_mutex_lock(m, FUTEX_WAIT_INFINITE); - return 0; - } else { - int oldvalue = c->value; - struct timespec ts; - ts.tv_sec = msec / 1000; - ts.tv_nsec = (msec % 1000) * 1000000; - futex_mutex_unlock(m); - const int err = __futex_wait(&c->value, oldvalue, &ts); - futex_mutex_lock(m, FUTEX_WAIT_INFINITE); - return err; - } -} - -void futex_cond_signal(futex_cond_t *c) -{ - __atomic_dec(&c->value); - __futex_wake(&c->value, 1); -} - -void futex_cond_broadcast(futex_cond_t *c) -{ - __atomic_dec(&c->value); - __futex_wake(&c->value, INT_MAX); -} - |