Stefan Hajnoczi <stefa...@redhat.com> writes:
> The HMP monitor runs in the main loop thread. Calling
Correct.
> AIO_WAIT_WHILE(qemu_get_aio_context(), ...) from the main loop thread is
> equivalent to AIO_WAIT_WHILE_UNLOCKED(NULL, ...) because neither unlocks
> the AioContext and the latter's assertion that we're in the main loop
> succeeds.
>
> Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com>
> ---
> monitor/hmp.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/monitor/hmp.c b/monitor/hmp.c
> index 2aa85d3982..5ecbdac802 100644
> --- a/monitor/hmp.c
> +++ b/monitor/hmp.c
> @@ -1167,7 +1167,7 @@ void handle_hmp_command(MonitorHMP *mon, const char
> *cmdline)
> Coroutine *co = qemu_coroutine_create(handle_hmp_command_co, &data);
> monitor_set_cur(co, &mon->common);
> aio_co_enter(qemu_get_aio_context(), co);
> - AIO_WAIT_WHILE(qemu_get_aio_context(), !data.done);
> + AIO_WAIT_WHILE_UNLOCKED(NULL, !data.done);
> }
>
> qobject_unref(qdict);
Acked-by: Markus Armbruster <arm...@redhat.com>
For an R-by, I need to understand this in more detail. I'm not familiar
with the innards of AIO_WAIT_WHILE() & friends, so I need to go real
slow.
We change
ctx from qemu_get_aio_context() to NULL
unlock from true to false
in
bool waited_ = false; \
AioWait *wait_ = &global_aio_wait; \
AioContext *ctx_ = (ctx); \
/* Increment wait_->num_waiters before evaluating cond. */ \
qatomic_inc(&wait_->num_waiters); \
/* Paired with smp_mb in aio_wait_kick(). */ \
smp_mb(); \
if (ctx_ && in_aio_context_home_thread(ctx_)) { \
while ((cond)) { \
aio_poll(ctx_, true); \
waited_ = true; \
} \
} else { \
assert(qemu_get_current_aio_context() == \
qemu_get_aio_context()); \
while ((cond)) { \
if (unlock && ctx_) { \
aio_context_release(ctx_); \
} \
aio_poll(qemu_get_aio_context(), true); \
if (unlock && ctx_) { \
aio_context_acquire(ctx_); \
} \
waited_ = true; \
} \
} \
qatomic_dec(&wait_->num_waiters); \
waited_; })
qemu_get_aio_context() is non-null here, correct?
What's the value of in_aio_context_home_thread(qemu_get_aio_context())?
