On Thu, Oct 29, 2020 at 03:02:16PM +0100, Lorenzo Bianconi wrote:
> > On Tue, 27 Oct 2020 20:04:07 +0100
> > Lorenzo Bianconi <lorenzo@xxxxxxxxxx> wrote:
> >
> > > diff --git a/net/core/xdp.c b/net/core/xdp.c
> > > index 48aba933a5a8..93eabd789246 100644
> > > --- a/net/core/xdp.c
> > > +++ b/net/core/xdp.c
> > > @@ -380,6 +380,57 @@ void xdp_return_frame_rx_napi(struct xdp_frame *xdpf)
> > > }
> > > EXPORT_SYMBOL_GPL(xdp_return_frame_rx_napi);
> > >
> > > +void xdp_flush_frame_bulk(struct xdp_frame_bulk *bq)
> > > +{
> > > + struct xdp_mem_allocator *xa = bq->xa;
> > > + int i;
> > > +
> > > + if (unlikely(!xa))
> > > + return;
> > > +
> > > + for (i = 0; i < bq->count; i++) {
> > > + struct page *page = virt_to_head_page(bq->q[i]);
> > > +
> > > + page_pool_put_full_page(xa->page_pool, page, false);
> > > + }
> > > + bq->count = 0;
> > > +}
> > > +EXPORT_SYMBOL_GPL(xdp_flush_frame_bulk);
> > > +
> > > +void xdp_return_frame_bulk(struct xdp_frame *xdpf,
> > > + struct xdp_frame_bulk *bq)
> > > +{
> > > + struct xdp_mem_info *mem = &xdpf->mem;
> > > + struct xdp_mem_allocator *xa, *nxa;
> > > +
> > > + if (mem->type != MEM_TYPE_PAGE_POOL) {
> > > + __xdp_return(xdpf->data, &xdpf->mem, false);
> > > + return;
> > > + }
> > > +
> > > + rcu_read_lock();
> > > +
> > > + xa = bq->xa;
> > > + if (unlikely(!xa || mem->id != xa->mem.id)) {
> > > + nxa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
> > > + if (unlikely(!xa)) {
> > > + bq->count = 0;
> > > + bq->xa = nxa;
> > > + xa = nxa;
> > > + }
> > > + }
> > > +
> > > + if (mem->id != xa->mem.id || bq->count == XDP_BULK_QUEUE_SIZE)
> > > + xdp_flush_frame_bulk(bq);
> > > +
> > > + bq->q[bq->count++] = xdpf->data;
> > > + if (mem->id != xa->mem.id)
> > > + bq->xa = nxa;
> > > +
> > > + rcu_read_unlock();
> > > +}
> > > +EXPORT_SYMBOL_GPL(xdp_return_frame_bulk);
> >
> > We (Ilias my co-maintainer and I) think above code is hard to read and
> > understand (as a reader you need to keep too many cases in your head).
> >
> > I think we both have proposals to improve this, here is mine:
> >
> > /* Defers return when frame belongs to same mem.id as previous frame */
> > void xdp_return_frame_bulk(struct xdp_frame *xdpf,
> > struct xdp_frame_bulk *bq)
> > {
> > struct xdp_mem_info *mem = &xdpf->mem;
> > struct xdp_mem_allocator *xa;
> >
> > if (mem->type != MEM_TYPE_PAGE_POOL) {
> > __xdp_return(xdpf->data, &xdpf->mem, false);
> > return;
> > }
> >
> > rcu_read_lock();
> >
> > xa = bq->xa;
> > if (unlikely(!xa)) {
> > xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
> > bq->count = 0;
> > bq->xa = xa;
> > }
> >
> > if (bq->count == XDP_BULK_QUEUE_SIZE)
> > xdp_flush_frame_bulk(bq);
> >
> > if (mem->id != xa->mem.id) {
> > xdp_flush_frame_bulk(bq);
> > bq->xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
> > }
> >
> > bq->q[bq->count++] = xdpf->data;
> >
> > rcu_read_unlock();
> > }
> >
> > Please review for correctness, and also for readability.
>
> the code seems fine to me (and even easier to read :)).
> I will update v2 using this approach. Thx.
+1 this is close to what we discussed this morning and it detangles 1 more 'weird'
if case
Thanks
/Ilias
>
> Regards,
> Lorenzo
>
> >
> > --
> > Best regards,
> > Jesper Dangaard Brouer
> > MSc.CS, Principal Kernel Engineer at Red Hat
> > LinkedIn: http://www.linkedin.com/in/brouer
> >
