Re: [Qemu-devel] [PATCH] net/net: Add ReadState for reuse codes

[Jason Wang]

On 2016年05月12日 14:33, Zhang Chen wrote:
> > > > > +    ret = net_fill_rstate(&s->rs, buf, size);
> > > > > +
> > > > > +    if (ret == -1) {
> > > > > +        goto eoc;
> > > > > +    } else if (ret == 1) {
> > > > > +        if (qemu_send_packet_async(&s->nc, s->rs.buf,
> > > > > +                                   s->rs.packet_len,
> > > > > + net_socket_send_completed) == 0) {
> > > > > +            net_socket_read_poll(s, false);
> > > >
> > > > This looks not elegant, maybe we could use callback (which was 
> > > > initialized by the helper I mention above) to do this. Any thoughts 
> > > > on this?
> > >
> > > Do you mean:
> > >
> > > remove
> > > +        if (qemu_send_packet_async(&s->nc, s->rs.buf,
> > > +                                   s->rs.packet_len,
> > > +                                   net_socket_send_completed) == 0) {
> > > +            net_socket_read_poll(s, false);
> > >
> > > add
> > >
> > > s->rs->done
> > >
> > > void socket_fill_rsstate_done_cb(SocketReadState *srs, void *opaque)
> > > {
> > >     NetSocketState *s = opaque;
> > >
> > >     if (qemu_send_packet_async(&s->nc, srs->buf,
> > >                                srs->packet_len,
> > >                                net_socket_send_completed) == 0) {
> > >         net_socket_read_poll(s, false);
> > >     }
> > > }
> >
> > Yes, but there's no need for opaque, we can infer the container by 
> > container_of().
>
> But in filter-mirror.c we need do this:
>
>
> void  redirector_fill_rsstate_done_cb(SocketReadState *srs, void *opaque)
> {
>     NetFilterState *nf = opaque;
>
>     redirector_to_filter(nf, srs->buf, srs->packet_len);
> }
>
> so,I think we have to use void *opaque.

You mean you need to get nf? Since SocketReadState were embedded in 
MirrorState, so you could get the address of MirrorState, then it's not 
hard to get nf address?