On 16/10/2016 18:40, Stefan Hajnoczi wrote:
> > void bdrv_wakeup(BlockDriverState *bs)
> > {
> > + if (bs->wakeup) {
> > + aio_bh_schedule_oneshot(qemu_get_aio_context(), dummy_bh_cb, NULL);
> > + }
> > }
>
> Why use a dummy BH instead of aio_notify()?
Originally I used aio_bh_schedule_oneshot() because aio_notify() is not
enough for aio_poll() to return true. It's also true that I am not
using anymore the result of aio_poll, though.
Since this is not a fast path and it's not very much stressed by
qemu-iotests, I think it's better if we can move towards making
aio_notify() more or less an internal detail. If you prefer
aio_notify(), however, I can look into that as well.
Thanks,
Paolo
>> > void bdrv_dec_in_flight(BlockDriverState *bs)
>> > diff --git a/include/block/block.h b/include/block/block.h
>> > index ba4318b..72d5d8e 100644
>> > --- a/include/block/block.h
>> > +++ b/include/block/block.h
>> > @@ -343,9 +343,27 @@ void bdrv_drain_all(void);
>> > #define bdrv_poll_while(bs, cond) ({ \
>> > bool waited_ = false; \
>> > BlockDriverState *bs_ = (bs); \
>> > - while ((cond)) { \
>> > - aio_poll(bdrv_get_aio_context(bs_), true); \
>> > - waited_ = true; \
>> > + AioContext *ctx_ = bdrv_get_aio_context(bs_); \
>> > + if (aio_context_in_iothread(ctx_)) { \
>> > + while ((cond)) { \
>> > + aio_poll(ctx_, true); \
>> > + waited_ = true; \
>> > + } \
>> > + } else { \
>> > + assert(qemu_get_current_aio_context() == \
>> > + qemu_get_aio_context()); \
> The assumption is that IOThread #1 will never call bdrv_poll_while() on
> IOThread #2's AioContext. I believe that is true today. Is this what
> you had in mind?
>
> Please add a comment since it's not completely obvious from the assert
> expression.
>
