/* 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 . */
/*
* db_event.c
*
* This file contains implementation of Drawbridge event synchronization APIs.
*/
#include
#include
#include
#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,
};