On 2013年12月13日 18:36, David Laight wrote:
From: fre...@asix.com.tw
...
-       skb = __netdev_alloc_skb_ip_align(dev->net, size, flags);
+       if (dev->driver_info->flags & FLAG_HW_IPALIGN)
+               skb = __netdev_alloc_skb(dev->net, size, flags);
+       else
+               skb = __netdev_alloc_skb_ip_align(dev->net, size, flags);
Given the definition:
static inline struct sk_buff *__netdev_alloc_skb_ip_align(struct net_device 
*dev,
                 unsigned int length, gfp_t gfp)
{
         struct sk_buff *skb = __netdev_alloc_skb(dev, length + NET_IP_ALIGN, 
gfp);

         if (NET_IP_ALIGN && skb)
                 skb_reserve(skb, NET_IP_ALIGN);
         return skb;
}

It really ought to be possible to code that without an extra conditional.

        David




The AX88179_178A driver do need to know the value of NET_IP_ALIGN
to determine whether enabling the feature that makes IP header align
on a dword-aligned address, but according to the comments from David
Miller, I need to consider all situations, not just for the case that
NET_IP_ALIGN is zero, so the condition added in rx_submit is just used to
determine whether reserving NET_IP_ALIGN bytes for each SKB.

Freddy
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