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coroutine-sleep: introduce qemu_co_sleep 

Allow using QemuCoSleep to sleep forever until woken by qemu_co_sleep_wake.
This makes the logic of qemu_co_sleep_ns_wakeable easy to understand.

In the future we will introduce an API that can work even if the
sleep and wake happen from different threads.  For now, initializing
w->to_wake after timer_mod is fine because the timer can only fire in
the same AioContext.

Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 20210517100548.28806-7-pbonzini@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Paolo Bonzini 2021-05-17 12:05:48 +02:00 committed by Stefan Hajnoczi
parent 29a6ea24eb
commit 0a6f0c76a0
2 changed files with 24 additions and 7 deletions
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5
include/qemu/coroutine.h
View File

@ -303,6 +303,11 @@ typedef struct QemuCoSleep {
void coroutine_fn qemu_co_sleep_ns_wakeable(QemuCoSleep *w,
QEMUClockType type, int64_t ns);
/**
* Yield the coroutine until the next call to qemu_co_sleep_wake.
*/
void coroutine_fn qemu_co_sleep(QemuCoSleep *w);
static inline void coroutine_fn qemu_co_sleep_ns(QEMUClockType type, int64_t ns)
{
QemuCoSleep w = { 0 };

26
util/qemu-coroutine-sleep.c
View File

@ -41,12 +41,9 @@ static void co_sleep_cb(void *opaque)
qemu_co_sleep_wake(w);
}
void coroutine_fn qemu_co_sleep_ns_wakeable(QemuCoSleep *w,
QEMUClockType type, int64_t ns)
void coroutine_fn qemu_co_sleep(QemuCoSleep *w)
{
Coroutine *co = qemu_coroutine_self();
AioContext *ctx = qemu_get_current_aio_context();
QEMUTimer ts;
const char *scheduled = qatomic_cmpxchg(&co->scheduled, NULL,
qemu_co_sleep_ns__scheduled);
@ -58,11 +55,26 @@ void coroutine_fn qemu_co_sleep_ns_wakeable(QemuCoSleep *w,
}
w->to_wake = co;
aio_timer_init(ctx, &ts, type, SCALE_NS, co_sleep_cb, w),
timer_mod(&ts, qemu_clock_get_ns(type) + ns);
qemu_coroutine_yield();
timer_del(&ts);
/* w->to_wake is cleared before resuming this coroutine. */
assert(w->to_wake == NULL);
}
void coroutine_fn qemu_co_sleep_ns_wakeable(QemuCoSleep *w,
QEMUClockType type, int64_t ns)
{
AioContext *ctx = qemu_get_current_aio_context();
QEMUTimer ts;
aio_timer_init(ctx, &ts, type, SCALE_NS, co_sleep_cb, w);
timer_mod(&ts, qemu_clock_get_ns(type) + ns);
/*
* The timer will fire in the current AiOContext, so the callback
* must happen after qemu_co_sleep yields and there is no race
* between timer_mod and qemu_co_sleep.
*/
qemu_co_sleep(w);
timer_del(&ts);
}