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SubjectRe: [PATCH RFC 1/2] net: macb: Check DMA mappings for error
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On Fri, 2014-02-21 at 11:30 -0800, Soren Brinkmann wrote:
[...]
> --- a/drivers/net/ethernet/cadence/macb.c
> +++ b/drivers/net/ethernet/cadence/macb.c
> @@ -632,11 +632,16 @@ static void gem_rx_refill(struct macb *bp)
> "Unable to allocate sk_buff\n");
> break;
> }
> - bp->rx_skbuff[entry] = skb;
>
> /* now fill corresponding descriptor entry */
> paddr = dma_map_single(&bp->pdev->dev, skb->data,
> bp->rx_buffer_size, DMA_FROM_DEVICE);
> + if (dma_mapping_error(&bp->pdev->dev, paddr)) {
> + dev_kfree_skb(skb);
> + break;
> + }
> +
> + bp->rx_skbuff[entry] = skb;

This bit looks good.

> if (entry == RX_RING_SIZE - 1)
> paddr |= MACB_BIT(RX_WRAP);
> @@ -1040,6 +1045,10 @@ static int macb_start_xmit(struct sk_buff *skb, struct net_device *dev)
> netdev_vdbg(bp->dev, "Allocated ring entry %u\n", entry);
> mapping = dma_map_single(&bp->pdev->dev, skb->data,
> len, DMA_TO_DEVICE);
> + if (dma_mapping_error(&bp->pdev->dev, mapping)) {
> + dev_kfree_skb(skb);

You need to unlock bp->lock before returning. Also, I think this should
be kfree_skb(), as that can be observed through dropwatch whereas
dev_kfree_skb() is completely silent.

Ben.

> + return NETDEV_TX_OK;
> + }
>
> tx_skb = &bp->tx_skb[entry];
> tx_skb->skb = skb;

--
Ben Hutchings
All the simple programs have been written, and all the good names taken.
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