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- /* -*- mode:c; c-file-style:"k&r"; c-basic-offset: 4; tab-width:4; indent-tabs-mode:nil; mode:auto-fill; fill-column:78; -*- */
- /* vim: set ts=4 sw=4 et tw=78 fo=cqt wm=0: */
- /* 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 "pal_defs.h"
- #include "pal_linux_defs.h"
- #include "pal.h"
- #include "pal_internal.h"
- #include "pal_linux.h"
- #include "pal_error.h"
- #include "pal_debug.h"
- #include "api.h"
- #include <atomic.h>
- #include <linux/futex.h>
- #include <linux/time.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, NULL);
- if (ret < 0)
- atomic_set(event->event.signaled, 0);
- }
- }
- } else {
- // Only one thread wakes up, leave unsignaled
- ret = ocall_futex((int *) &event->event.signaled->counter,
- FUTEX_WAKE, 1, NULL);
- if (ret < 0)
- return ret;
- }
- return ret;
- }
- int _DkEventWaitTimeout (PAL_HANDLE event, uint64_t timeout)
- {
- int ret = 0;
- if (!event->event.isnotification || !atomic_read(event->event.signaled)) {
- unsigned long waittime = timeout;
- atomic_inc(&event->event.nwaiters);
- do {
- ret = ocall_futex((int *) &event->event.signaled->counter,
- FUTEX_WAIT, 0, timeout ? &waittime : NULL);
- if (ret < 0) {
- if (ret == -PAL_ERROR_TRYAGAIN)
- ret = 0;
- else
- 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, NULL);
- if (ret < 0) {
- if (ret == -PAL_ERROR_TRYAGAIN)
- ret = 0;
- else
- 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, uint64_t timeout)
- {
- return timeout == NO_TIMEOUT ? _DkEventWait(handle) :
- _DkEventWaitTimeout(handle, timeout);
- }
- struct handle_ops event_ops = {
- .close = &event_close,
- .wait = &event_wait,
- };
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