net: pass correct parameter to skb_headers_offset_update()

Since commit 1a37e412a022(net: Use 16bits for *_headers fields of struct
skbuff), skb->*_header are relative to skb->head,
so copy_skb_header() should not call skb_headers_offset_update() now,
and we should pass correct parameter to skb_headers_offset_update() in
pskb_expand_head() and skb_copy_expand().

Signed-off-by: Weiping Pan <panweiping3@gmail.com>
Reviewed-by: Simon Horman <horms@verge.net.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/skbuff.c

@@ -909,18 +909,8 @@ static void skb_headers_offset_update(struct sk_buff *skb, int off)
 
 static void copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
 {
-#ifndef NET_SKBUFF_DATA_USES_OFFSET
-	/*
-	 *	Shift between the two data areas in bytes
-	 */
-	unsigned long offset = new->data - old->data;
-#endif
-
 	__copy_skb_header(new, old);
 
-#ifndef NET_SKBUFF_DATA_USES_OFFSET
-	skb_headers_offset_update(new, offset);
-#endif
 	skb_shinfo(new)->gso_size = skb_shinfo(old)->gso_size;
 	skb_shinfo(new)->gso_segs = skb_shinfo(old)->gso_segs;
 	skb_shinfo(new)->gso_type = skb_shinfo(old)->gso_type;
@@ -1112,7 +1102,7 @@ int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
 	skb->end      = skb->head + size;
 #endif
 	skb->tail	      += off;
-	skb_headers_offset_update(skb, off);
+	skb_headers_offset_update(skb, nhead);
 	/* Only adjust this if it actually is csum_start rather than csum */
 	if (skb->ip_summed == CHECKSUM_PARTIAL)
 		skb->csum_start += nhead;
@@ -1207,9 +1197,8 @@ struct sk_buff *skb_copy_expand(const struct sk_buff *skb,
 	off                  = newheadroom - oldheadroom;
 	if (n->ip_summed == CHECKSUM_PARTIAL)
 		n->csum_start += off;
-#ifdef NET_SKBUFF_DATA_USES_OFFSET
+
 	skb_headers_offset_update(n, off);
-#endif
 
 	return n;
 }