xref: /openbmc/qemu/util/qemu-coroutine-sleep.c (revision dc5bd18f)
1 /*
2  * QEMU coroutine sleep
3  *
4  * Copyright IBM, Corp. 2011
5  *
6  * Authors:
7  *  Stefan Hajnoczi    <stefanha@linux.vnet.ibm.com>
8  *
9  * This work is licensed under the terms of the GNU LGPL, version 2 or later.
10  * See the COPYING.LIB file in the top-level directory.
11  *
12  */
13 
14 #include "qemu/osdep.h"
15 #include "qemu/coroutine.h"
16 #include "qemu/coroutine_int.h"
17 #include "qemu/timer.h"
18 #include "block/aio.h"
19 
20 typedef struct CoSleepCB {
21     QEMUTimer *ts;
22     Coroutine *co;
23 } CoSleepCB;
24 
25 static void co_sleep_cb(void *opaque)
26 {
27     CoSleepCB *sleep_cb = opaque;
28 
29     /* Write of schedule protected by barrier write in aio_co_schedule */
30     atomic_set(&sleep_cb->co->scheduled, NULL);
31     aio_co_wake(sleep_cb->co);
32 }
33 
34 void coroutine_fn qemu_co_sleep_ns(QEMUClockType type, int64_t ns)
35 {
36     AioContext *ctx = qemu_get_current_aio_context();
37     CoSleepCB sleep_cb = {
38         .co = qemu_coroutine_self(),
39     };
40 
41     const char *scheduled = atomic_cmpxchg(&sleep_cb.co->scheduled, NULL,
42                                            __func__);
43     if (scheduled) {
44         fprintf(stderr,
45                 "%s: Co-routine was already scheduled in '%s'\n",
46                 __func__, scheduled);
47         abort();
48     }
49     sleep_cb.ts = aio_timer_new(ctx, type, SCALE_NS, co_sleep_cb, &sleep_cb);
50     timer_mod(sleep_cb.ts, qemu_clock_get_ns(type) + ns);
51     qemu_coroutine_yield();
52     timer_del(sleep_cb.ts);
53     timer_free(sleep_cb.ts);
54 }
55