hi , question function of net_rx(struct net_device *dev)
hi : the source code of net_rx(struct net_device *dev) is: http://lxr.oss.org.cn/source/drivers/net/ethernet/cirrus/cs89x0.c#L670 I can't understand codes about malloc buffer. ########################################## 684 /* Malloc up new buffer. */ 685 skb = netdev_alloc_skb(dev, length + 2); 686 if (skb == NULL) { 687 dev->stats.rx_dropped++; 688 return; 689 } 690 skb_reserve(skb, 2); /* longword align L3 header */ ########################################## How to explain 'length + 2' in line of 685? Why add 2 ? Thank you.
On 7/18/14, lx <lxlenovostar@gmail.com> wrote:
hi : the source code of net_rx(struct net_device *dev) is: http://lxr.oss.org.cn/source/drivers/net/ethernet/cirrus/cs89x0.c#L670
I can't understand codes about malloc buffer. ########################################## 684 /* Malloc up new buffer. */ 685 skb = netdev_alloc_skb(dev, length + 2); 686 if (skb == NULL) { 687 dev->stats.rx_dropped++; 688 return; 689 } 690 skb_reserve(skb, 2); /* longword align L3 header */ ##########################################
How to explain 'length + 2' in line of 685? Why add 2 ?
That's why it's explained on the line 690. http://lwn.net/Articles/89597/
Thank you.
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-- Regards, Denis
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