Re: [PATCH ref0] net: add Faraday FTMAC100 10/100 Ethernet driver

[Eric Dumazet]

Le jeudi 24 fÃvrier 2011 Ã 17:29 +0800, Po-Yu Chuang a Ãcrit :
> From: Po-Yu Chuang <ratbert@xxxxxxxxxxxxxxxx>
> 


> +
> +static bool ftmac100_rx_packet(struct ftmac100 *priv, int *processed)
> +{
> +	struct net_device *netdev = priv->netdev;
> +	struct ftmac100_rxdes *rxdes;
> +	struct sk_buff *skb;
> +	struct page *page;
> +	dma_addr_t map;
> +	int length;
> +
> +	rxdes = ftmac100_rx_locate_first_segment(priv);
> +	if (!rxdes)
> +		return false;
> +
> +	if (unlikely(ftmac100_rx_packet_error(priv, rxdes))) {
> +		ftmac100_rx_drop_packet(priv);
> +		return true;
> +	}
> +
> +	/*
> +	 * It is impossible to get multi-segment packets
> +	 * because we always provide big enough receive buffers.
> +	 */
> +	if (unlikely(!ftmac100_rxdes_last_segment(rxdes)))
> +		BUG();
> +
> +	/* start processing */
> +	skb = netdev_alloc_skb_ip_align(netdev, ETH_HLEN);

Oh I see... You should allocate a bigger head (say... 128 bytes)

And copy in it up to 128 bytes of first part... this to avoid upper
stack to reallocate skb head (because IP/TCP processing need to get
their headers in skb head)

> +	if (unlikely(!skb)) {
> +		if (net_ratelimit())
> +			netdev_err(netdev, "rx skb alloc failed\n");
> +
> +		ftmac100_rx_drop_packet(priv);
> +		return true;
> +	}
> +
> +	if (unlikely(ftmac100_rxdes_multicast(rxdes)))
> +		netdev->stats.multicast++;
> +
> +	map = ftmac100_rxdes_get_dma_addr(rxdes);
> +	dma_unmap_page(priv->dev, map, RX_BUF_SIZE, DMA_FROM_DEVICE);
> +
> +	length = ftmac100_rxdes_frame_length(rxdes);
> +	page = ftmac100_rxdes_get_page(rxdes);
> +	skb_fill_page_desc(skb, 0, page, 0, length);
> +	skb->len += length;
> +	skb->data_len += length;
> +	skb->truesize += length;
> +	__pskb_pull_tail(skb, ETH_HLEN);
> +
> +	ftmac100_alloc_rx_page(priv, rxdes);
> +
> +	ftmac100_rx_pointer_advance(priv);
> +
> +	skb->protocol = eth_type_trans(skb, netdev);
> +
> +	netdev->stats.rx_packets++;
> +	netdev->stats.rx_bytes += skb->len;
> +
> +	/* push packet to protocol stack */
> +	netif_receive_skb(skb);
> +
> +	(*processed)++;
> +	return true;
> +}
> +

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