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 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 37 static void co_sleep_cb(void *opaque) 38 { 39 QemuCoSleep *w = opaque; 40 qemu_co_sleep_wake(w); 41 } 42 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 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