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coroutine-sleep: allow qemu_co_sleep_wake that wakes nothing

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All callers of qemu_co_sleep_wake are checking whether they are passing
a NULL argument inside the pointer-to-pointer: do the check in
qemu_co_sleep_wake itself.

As a side effect, qemu_co_sleep_wake can be called more than once and
it will only wake the coroutine once; after the first time, the argument
will be set to NULL via *sleep_state->user_state_pointer.  However, this
would not be safe unless co_sleep_cb keeps using the QemuCoSleepState*
directly, so make it go through the pointer-to-pointer instead.

Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 20210517100548.28806-4-pbonzini@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Paolo Bonzini 2021-05-17 12:05:45 +02:00 • committed by Stefan Hajnoczi
parent fb74a286fe
commit eaee072085
3 changed files with 15 additions and 18 deletions
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21
util/qemu-coroutine-sleep.c
View file

@ -27,19 +27,22 @@ struct QemuCoSleepState {
void qemu_co_sleep_wake(QemuCoSleepState *sleep_state)
{
/* Write of schedule protected by barrier write in aio_co_schedule */
const char *scheduled = qatomic_cmpxchg(&sleep_state->co->scheduled,
qemu_co_sleep_ns__scheduled, NULL);
if (sleep_state) {
/* Write of schedule protected by barrier write in aio_co_schedule */
const char *scheduled = qatomic_cmpxchg(&sleep_state->co->scheduled,
qemu_co_sleep_ns__scheduled, NULL);
assert(scheduled == qemu_co_sleep_ns__scheduled);
*sleep_state->user_state_pointer = NULL;
timer_del(&sleep_state->ts);
aio_co_wake(sleep_state->co);
assert(scheduled == qemu_co_sleep_ns__scheduled);
*sleep_state->user_state_pointer = NULL;
timer_del(&sleep_state->ts);
aio_co_wake(sleep_state->co);
}
}
static void co_sleep_cb(void *opaque)
{
qemu_co_sleep_wake(opaque);
QemuCoSleepState **sleep_state = opaque;
qemu_co_sleep_wake(*sleep_state);
}
void coroutine_fn qemu_co_sleep_ns_wakeable(QEMUClockType type, int64_t ns,
@ -60,7 +63,7 @@ void coroutine_fn qemu_co_sleep_ns_wakeable(QEMUClockType type, int64_t ns,
abort();
}
aio_timer_init(ctx, &state.ts, type, SCALE_NS, co_sleep_cb, &state);
aio_timer_init(ctx, &state.ts, type, SCALE_NS, co_sleep_cb, sleep_state);
*sleep_state = &state;
timer_mod(&state.ts, qemu_clock_get_ns(type) + ns);
qemu_coroutine_yield();