On Fri, 04/01 11:49, Paolo Bonzini wrote:
>
>
> On 01/04/2016 11:46, Fam Zheng wrote:
> > +
> > +static void bdrv_co_drain_bh_cb(void *opaque)
> > +{
> > + BdrvCoDrainData *data = opaque;
> > + Coroutine *co = data->co;
> > +
> > + bdrv_drain(data->bs);
> > + data->done = true;
> > + qemu_coroutine_enter(co, NULL);
> > +}
> > +
> > +static void coroutine_fn bdrv_co_drain(BlockDriverState *bs)
> > +{
> > + QEMUBH *bh;
> > + BdrvCoDrainData data;
> > +
> > + assert(qemu_in_coroutine());
> > + data = (BdrvCoDrainData) {
> > + .co = qemu_coroutine_self(),
> > + .bs = bs,
> > + .done = false,
> > + };
> > + bh = aio_bh_new(bdrv_get_aio_context(bs), bdrv_co_drain_bh_cb, &data),
> > + qemu_bh_schedule(bh);
> > +
> > + do {
> > + qemu_coroutine_yield();
> > + } while (!data.done);
>
> The loop and "done" is not necessary. Also,
I was trying to protect against the bugs similar to the one fixed in
e424aff5f30, but you're right we can make this an assertion and the loop is not
needed. If a calling coroutine is resumed unexpectedly, we will catch it and
fix it.
>
> > + qemu_bh_delete(bh);
>
> this can be moved to bdrv_co_drain_bh_cb before bdrv_drain, so that the
> bottom half doesn't slow down the event loop until bdrv_drain completes.
Good point! Will fix.
Thanks,
Fam
