1/*
2 * AioContext wait support
3 *
4 * Copyright (C) 2018 Red Hat, Inc.
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a copy
7 * of this software and associated documentation files (the "Software"), to deal
8 * in the Software without restriction, including without limitation the rights
9 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10 * copies of the Software, and to permit persons to whom the Software is
11 * furnished to do so, subject to the following conditions:
12 *
13 * The above copyright notice and this permission notice shall be included in
14 * all copies or substantial portions of the Software.
15 *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
19 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
22 * THE SOFTWARE.
23 */
24
25#include "qemu/osdep.h"
26#include "qemu/main-loop.h"
27#include "block/aio-wait.h"
28
29AioWait global_aio_wait;
30
31static void dummy_bh_cb(void *opaque)
32{
33 /* The point is to make AIO_WAIT_WHILE()'s aio_poll() return */
34}
35
36void aio_wait_kick(void)
37{
38 /* The barrier (or an atomic op) is in the caller. */
39 if (atomic_read(&global_aio_wait.num_waiters)) {
40 aio_bh_schedule_oneshot(qemu_get_aio_context(), dummy_bh_cb, NULL);
41 }
42}
43
44typedef struct {
45 bool done;
46 QEMUBHFunc *cb;
47 void *opaque;
48} AioWaitBHData;
49
50/* Context: BH in IOThread */
51static void aio_wait_bh(void *opaque)
52{
53 AioWaitBHData *data = opaque;
54
55 data->cb(data->opaque);
56
57 data->done = true;
58 aio_wait_kick();
59}
60
61void aio_wait_bh_oneshot(AioContext *ctx, QEMUBHFunc *cb, void *opaque)
62{
63 AioWaitBHData data = {
64 .cb = cb,
65 .opaque = opaque,
66 };
67
68 assert(qemu_get_current_aio_context() == qemu_get_aio_context());
69
70 aio_bh_schedule_oneshot(ctx, aio_wait_bh, &data);
71 AIO_WAIT_WHILE(ctx, !data.done);
72}
73