Subject: Re: [PATCH]: fix lro_gen_skb() alignment

From: Andrew Gallatin <[email-masked]>
Date: Fri, 30 Nov 2007 13:35:16 -0500

Herbert Xu wrote:
> Andrew Gallatin <[email-masked]> wrote:
>> diff --git a/net/ipv4/inet_lro.c b/net/ipv4/inet_lro.c
>> index ac3b1d3..91e9371 100644
>> --- a/net/ipv4/inet_lro.c
>> +++ b/net/ipv4/inet_lro.c
>> @@ -401,10 +401,11 @@ static struct sk_buff *lro_gen_skb(struc
>>        int data_len = len;
>>        int hdr_len = min(len, hlen);
>>
>> -       skb = netdev_alloc_skb(lro_mgr->dev, hlen);
>> +       skb = netdev_alloc_skb(lro_mgr->dev, hlen + NET_IP_ALIGN);
> 
> NET_IP_ALIGN should only be used if you're DMAing into the skb head.
> Otherwise you should say 2.  It would be nice to have another macro
> for that I suppose.

It is certainly simple enough to say 2.  Thank you for pointing
this out.  I have attached a patch to do that..

Signed off by: Andrew Gallatin <[email-masked]>

Drew
diff --git a/net/ipv4/inet_lro.c b/net/ipv4/inet_lro.c
index ac3b1d3..35b816e 100644
--- a/net/ipv4/inet_lro.c
+++ b/net/ipv4/inet_lro.c
@@ -401,10 +401,11 @@ static struct sk_buff *lro_gen_skb(struc
 	int data_len = len;
 	int hdr_len = min(len, hlen);
 
-	skb = netdev_alloc_skb(lro_mgr->dev, hlen);
+	skb = netdev_alloc_skb(lro_mgr->dev, hlen + 2);
 	if (!skb)
 		return NULL;
 
+	skb_reserve(skb, 2);
 	skb->len = len;
 	skb->data_len = len - hdr_len;
 	skb->truesize += true_size;