Re: [Qemu-devel] [RFC PATCH 2/3] sheepdog: pass NULL for io_flush

[Paolo Bonzini]

> > diff --git a/block/sheepdog.c b/block/sheepdog.c
> > index bb67c4c..2bccd9b 100644
> > --- a/block/sheepdog.c
> > +++ b/block/sheepdog.c
> > @@ -503,13 +503,6 @@ static void restart_co_req(void *opaque)
> >      qemu_coroutine_enter(co, NULL);
> >  }
> >  
> > -static int have_co_req(void *opaque)
> > -{
> > -    /* this handler is set only when there is a pending request, so
> > -     * always returns 1. */
> 
> Now you return 1 even when no request is pending (which is the case in
> which no io_flush handler would be set before). Why is this correct?
> (This is actually a question about PATCH 1/3, I just noticed it here.
> Are there more cases like this?)

In the dataplane code, the ioeventfd uses an io_flush callback that returns
true.

Paolo