util/qemu-coroutine-sleep.c

   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 }