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- /* Copyright (C) 2014 Stony Brook University
- This file is part of Graphene Library OS.
- Graphene Library OS 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 3 of the
- License, or (at your option) any later version.
- Graphene Library OS 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 program. If not, see <http://www.gnu.org/licenses/>. */
- /*
- * db_event.c
- *
- * This file contains implementation of Drawbridge event synchronization APIs.
- */
- #include <atomic.h>
- #include <linux/futex.h>
- #include <linux/time.h>
- #include "api.h"
- #include "pal.h"
- #include "pal_debug.h"
- #include "pal_defs.h"
- #include "pal_error.h"
- #include "pal_internal.h"
- #include "pal_linux.h"
- #include "pal_linux_defs.h"
- #include "pal_linux_error.h"
- int _DkEventCreate(PAL_HANDLE* event, bool initialState, bool isnotification) {
- PAL_HANDLE ev = malloc(HANDLE_SIZE(event));
- SET_HANDLE_TYPE(ev, event);
- ev->event.isnotification = isnotification;
- ev->event.signaled = malloc_untrusted(sizeof(struct atomic_int));
- if (!ev->event.signaled) {
- free(ev);
- return -PAL_ERROR_NOMEM;
- }
- atomic_set(ev->event.signaled, initialState ? 1 : 0);
- atomic_set(&ev->event.nwaiters, 0);
- *event = ev;
- return 0;
- }
- int _DkEventSet(PAL_HANDLE event, int wakeup) {
- int ret = 0;
- if (event->event.isnotification) {
- // Leave it signaled, wake all
- if (atomic_cmpxchg(event->event.signaled, 0, 1) == 0) {
- int nwaiters = atomic_read(&event->event.nwaiters);
- if (nwaiters) {
- if (wakeup != -1 && nwaiters > wakeup)
- nwaiters = wakeup;
- ret = ocall_futex((int*)&event->event.signaled->counter, FUTEX_WAKE, nwaiters, -1);
- if (IS_ERR(ret)) {
- atomic_set(event->event.signaled, 0);
- ret = unix_to_pal_error(ERRNO(ret));
- }
- }
- }
- } else {
- // Only one thread wakes up, leave unsignaled
- ret = ocall_futex((int*)&event->event.signaled->counter, FUTEX_WAKE, 1, -1);
- if (IS_ERR(ret))
- return unix_to_pal_error(ERRNO(ret));
- }
- return ret;
- }
- int _DkEventWaitTimeout(PAL_HANDLE event, int64_t timeout_us) {
- int ret = 0;
- if (timeout_us < 0)
- return _DkEventWait(event);
- if (!event->event.isnotification || !atomic_read(event->event.signaled)) {
- atomic_inc(&event->event.nwaiters);
- do {
- ret = ocall_futex((int*)&event->event.signaled->counter, FUTEX_WAIT, 0, timeout_us);
- if (IS_ERR(ret)) {
- if (ERRNO(ret) == EWOULDBLOCK) {
- ret = 0;
- } else {
- ret = unix_to_pal_error(ERRNO(ret));
- break;
- }
- }
- } while (event->event.isnotification && !atomic_read(event->event.signaled));
- atomic_dec(&event->event.nwaiters);
- }
- return ret;
- }
- int _DkEventWait(PAL_HANDLE event) {
- int ret = 0;
- if (!event->event.isnotification || !atomic_read(event->event.signaled)) {
- atomic_inc(&event->event.nwaiters);
- do {
- ret = ocall_futex((int*)&event->event.signaled->counter, FUTEX_WAIT, 0, -1);
- if (IS_ERR(ret)) {
- if (ERRNO(ret) == EWOULDBLOCK) {
- ret = 0;
- } else {
- ret = unix_to_pal_error(ERRNO(ret));
- break;
- }
- }
- } while (event->event.isnotification && !atomic_read(event->event.signaled));
- atomic_dec(&event->event.nwaiters);
- }
- return ret;
- }
- int _DkEventClear(PAL_HANDLE event) {
- atomic_set(event->event.signaled, 0);
- return 0;
- }
- static int event_close(PAL_HANDLE handle) {
- _DkEventSet(handle, -1);
- free_untrusted(handle->event.signaled);
- return 0;
- }
- static int event_wait(PAL_HANDLE handle, int64_t timeout_us) {
- return _DkEventWaitTimeout(handle, timeout_us);
- }
- struct handle_ops event_ops = {
- .close = &event_close,
- .wait = &event_wait,
- };
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