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_int.h"
16 #include "qemu/timer.h"
17 #include "block/aio.h"
18
19 static const char *qemu_co_sleep_ns__scheduled = "qemu_co_sleep_ns";
20
qemu_co_sleep_wake(QemuCoSleep * w)21 void qemu_co_sleep_wake(QemuCoSleep *w)
22 {
23 Coroutine *co;
24
25 co = w->to_wake;
26 w->to_wake = NULL;
27 if (co) {
28 /* Write of schedule protected by barrier write in aio_co_schedule */
29 const char *scheduled = qatomic_cmpxchg(&co->scheduled,
30 qemu_co_sleep_ns__scheduled, NULL);
31
32 assert(scheduled == qemu_co_sleep_ns__scheduled);
33 aio_co_wake(co);
34 }
35 }
36
co_sleep_cb(void * opaque)37 static void co_sleep_cb(void *opaque)
38 {
39 QemuCoSleep *w = opaque;
40 qemu_co_sleep_wake(w);
41 }
42
qemu_co_sleep(QemuCoSleep * w)43 void coroutine_fn qemu_co_sleep(QemuCoSleep *w)
44 {
45 Coroutine *co = qemu_coroutine_self();
46
47 const char *scheduled = qatomic_cmpxchg(&co->scheduled, NULL,
48 qemu_co_sleep_ns__scheduled);
49 if (scheduled) {
50 fprintf(stderr,
51 "%s: Co-routine was already scheduled in '%s'\n",
52 __func__, scheduled);
53 abort();
54 }
55
56 w->to_wake = co;
57 qemu_coroutine_yield();
58
59 /* w->to_wake is cleared before resuming this coroutine. */
60 assert(w->to_wake == NULL);
61 }
62
qemu_co_sleep_ns_wakeable(QemuCoSleep * w,QEMUClockType type,int64_t ns)63 void coroutine_fn qemu_co_sleep_ns_wakeable(QemuCoSleep *w,
64 QEMUClockType type, int64_t ns)
65 {
66 AioContext *ctx = qemu_get_current_aio_context();
67 QEMUTimer ts;
68
69 aio_timer_init(ctx, &ts, type, SCALE_NS, co_sleep_cb, w);
70 timer_mod(&ts, qemu_clock_get_ns(type) + ns);
71
72 /*
73 * The timer will fire in the current AiOContext, so the callback
74 * must happen after qemu_co_sleep yields and there is no race
75 * between timer_mod and qemu_co_sleep.
76 */
77 qemu_co_sleep(w);
78 timer_del(&ts);
79 }
80