Re: [TCP]: Account skb overhead in tcp_fragment

[Herbert Xu <herbert@gondor.apana.org.au>]

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On Thu, Apr 20, 2006 at 11:01:11AM +1000, herbert wrote:
> Hi Dave:
> 
> Since sk_stream_alloc_pskb takes an extra argument that accounts for
> paged data all we need to do to account sk_buff overhead correctly
> is to use that instead of sk_stream_alloc_skb.

Here is a better version that does not double-count the paged bits
that get moved across.
 
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Cheers,
-- 
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Email: Herbert Xu ~{PmV>HI~} <herbert@gondor.apana.org.au>
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diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 44df1db..a28ae59 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -533,6 +533,7 @@
 	struct tcp_sock *tp = tcp_sk(sk);
 	struct sk_buff *buff;
 	int nsize, old_factor;
+	int nlen;
 	u16 flags;
 
 	BUG_ON(len > skb->len);
@@ -552,8 +553,10 @@
 	if (buff == NULL)
 		return -ENOMEM; /* We'll just try again later. */
 
-	buff->truesize = skb->len - len;
-	skb->truesize -= buff->truesize;
+	sk_charge_skb(sk, buff);
+	nlen = skb->len - len - nsize;
+	buff->truesize += nlen;
+	skb->truesize -= nlen;
 
 	/* Correct the sequence numbers. */
 	TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len;
@@ -1039,7 +1042,8 @@
 	if (unlikely(buff == NULL))
 		return -ENOMEM;
 
-	buff->truesize = nlen;
+	sk_charge_skb(sk, buff);
+	buff->truesize += nlen;
 	skb->truesize -= nlen;
 
 	/* Correct the sequence numbers. */