> On Mon, 14 Oct 2019 12:49:55 +0200, Lorenzo Bianconi wrote:
> > Implement XDP_TX verdict and ndo_xdp_xmit net_device_ops function
> > pointer
> > 
> > Signed-off-by: Lorenzo Bianconi <[email protected]>
> 
> > @@ -1972,6 +1975,109 @@ int mvneta_rx_refill_queue(struct mvneta_port *pp, 
> > struct mvneta_rx_queue *rxq)
> >     return i;
> >  }
> >  
> > +static int
> > +mvneta_xdp_submit_frame(struct mvneta_port *pp, struct mvneta_tx_queue 
> > *txq,
> > +                   struct xdp_frame *xdpf, bool dma_map)
> > +{
> > +   struct mvneta_tx_desc *tx_desc;
> > +   struct mvneta_tx_buf *buf;
> > +   dma_addr_t dma_addr;
> > +
> > +   if (txq->count >= txq->tx_stop_threshold)
> > +           return MVNETA_XDP_CONSUMED;
> > +
> > +   tx_desc = mvneta_txq_next_desc_get(txq);
> > +
> > +   buf = &txq->buf[txq->txq_put_index];
> > +   if (dma_map) {
> > +           /* ndo_xdp_xmit */
> > +           dma_addr = dma_map_single(pp->dev->dev.parent, xdpf->data,
> > +                                     xdpf->len, DMA_TO_DEVICE);
> > +           if (dma_mapping_error(pp->dev->dev.parent, dma_addr)) {
> > +                   mvneta_txq_desc_put(txq);
> > +                   return MVNETA_XDP_CONSUMED;
> > +           }
> > +           buf->type = MVNETA_TYPE_XDP_NDO;
> > +   } else {
> > +           struct page *page = virt_to_page(xdpf->data);
> > +
> > +           dma_addr = page_pool_get_dma_addr(page) +
> > +                      pp->rx_offset_correction + MVNETA_MH_SIZE;
> > +           dma_sync_single_for_device(pp->dev->dev.parent, dma_addr,
> > +                                      xdpf->len, DMA_BIDIRECTIONAL);
> 
> This looks a little suspicious, XDP could have moved the start of frame
> with adjust_head, right? You should also use xdpf->data to find where
> the frame starts, no?

uhm, right..we need to update the dma_addr doing something like:

dma_addr = page_pool_get_dma_addr(page) + xdpf->data - xdpf;

and then use xdpf->len for dma-sync

> 
> > +           buf->type = MVNETA_TYPE_XDP_TX;
> > +   }
> > +   buf->xdpf = xdpf;
> > +
> > +   tx_desc->command = MVNETA_TXD_FLZ_DESC;
> > +   tx_desc->buf_phys_addr = dma_addr;
> > +   tx_desc->data_size = xdpf->len;
> > +
> > +   mvneta_update_stats(pp, 1, xdpf->len, true);
> > +   mvneta_txq_inc_put(txq);
> > +   txq->pending++;
> > +   txq->count++;
> > +
> > +   return MVNETA_XDP_TX;
> > +}
> > +
> > +static int
> > +mvneta_xdp_xmit_back(struct mvneta_port *pp, struct xdp_buff *xdp)
> > +{
> > +   struct xdp_frame *xdpf = convert_to_xdp_frame(xdp);
> > +   int cpu = smp_processor_id();
> > +   struct mvneta_tx_queue *txq;
> > +   struct netdev_queue *nq;
> > +   u32 ret;
> > +
> > +   if (unlikely(!xdpf))
> > +           return MVNETA_XDP_CONSUMED;
> 
> Personally I'd prefer you haven't called a function which return code
> has to be error checked in local variable init.

do you mean moving cpu = smp_processor_id(); after the if condition?

Regards,
Lorenzo

> 
> > +
> > +   txq = &pp->txqs[cpu % txq_number];
> > +   nq = netdev_get_tx_queue(pp->dev, txq->id);
> > +
> > +   __netif_tx_lock(nq, cpu);
> > +   ret = mvneta_xdp_submit_frame(pp, txq, xdpf, false);
> > +   if (ret == MVNETA_XDP_TX)
> > +           mvneta_txq_pend_desc_add(pp, txq, 0);
> > +   __netif_tx_unlock(nq);
> > +
> > +   return ret;
> > +}

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