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    SubjectRe: [PATCH v4 2/2] net: moxa: replace build_skb() with netdev_alloc_skb_ip_align() / memcpy()
    2014-08-19 16:49 GMT+02:00 Jonas Jensen <jonas.jensen@gmail.com>:
    [...]
    > diff --git a/drivers/net/ethernet/moxa/moxart_ether.c b/drivers/net/ethernet/moxa/moxart_ether.c
    > index aa45607..17c9f0e 100644
    > --- a/drivers/net/ethernet/moxa/moxart_ether.c
    > +++ b/drivers/net/ethernet/moxa/moxart_ether.c
    > @@ -226,14 +226,21 @@ static int moxart_rx_poll(struct napi_struct *napi, int budget)
    > if (len > RX_BUF_SIZE)
    > len = RX_BUF_SIZE;
    >
    > - skb = build_skb(priv->rx_buf[rx_head], priv->rx_buf_size);
    > + dma_sync_single_for_cpu(&ndev->dev,
    > + priv->rx_mapping[rx_head],
    > + priv->rx_buf_size, DMA_FROM_DEVICE);
    > + skb = netdev_alloc_skb_ip_align(ndev, len);
    > if (unlikely(!skb)) {
    > - net_dbg_ratelimited("build_skb failed\n");
    > + net_dbg_ratelimited("netdev_alloc_skb_ip_align failed\n");
    > priv->stats.rx_dropped++;
    > priv->stats.rx_errors++;
    > }
    > -
    > + memcpy(skb->data, priv->rx_buf[rx_head], len);

    This has implicit: if (!skb) BUG(); There should probably be a return
    or continue inside the if (!skb).

    > skb_put(skb, len);
    > + dma_sync_single_for_device(&ndev->dev,
    > + priv->rx_mapping[rx_head],
    > + priv->rx_buf_size, DMA_FROM_DEVICE);
    > +

    dma_sync_single_for_device() is not needed here as CPU does not and
    should not write to the DMA_FROM_DEVICE mapping.


    > skb->protocol = eth_type_trans(skb, ndev);
    > napi_gro_receive(&priv->napi, skb);
    > rx++;

    Best Regards,
    Michał Mirosław
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