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Commit 030737bc authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
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net: generalize skb_segment() 



While implementing GSO/TSO support for IPIP, I found skb_segment()
was assuming network header was immediately following mac header.

Its not really true in the case inet_gso_segment() is stacked :
By the time tcp_gso_segment() is called, network header points
to the inner IP header.

Let's instead assume nothing and pick the current offsets found in
original skb, we have skb_headers_offset_update() helper for that.

Also move the csum_start update inside skb_headers_offset_update()

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent b917eb15

net/core/skbuff.c

+5 −17
Original line number Diff line number Diff line
@@ -903,6 +903,9 @@ EXPORT_SYMBOL(skb_clone); 


static void skb_headers_offset_update(struct sk_buff *skb, int off)

{

	/* Only adjust this if it actually is csum_start rather than csum */

	if (skb->ip_summed == CHECKSUM_PARTIAL)

		skb->csum_start += off;

	/* {transport,network,mac}_header and tail are relative to skb->head */

	skb->transport_header += off;

	skb->network_header   += off;
@@ -1109,9 +1112,6 @@ int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail, 
#endif

	skb->tail	      += 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;

	skb->cloned   = 0;

	skb->hdr_len  = 0;

	skb->nohdr    = 0;
@@ -1176,7 +1176,6 @@ struct sk_buff *skb_copy_expand(const struct sk_buff *skb, 
					NUMA_NO_NODE);

	int oldheadroom = skb_headroom(skb);

	int head_copy_len, head_copy_off;

	int off;



	if (!n)

		return NULL;
@@ -1200,11 +1199,7 @@ struct sk_buff *skb_copy_expand(const struct sk_buff *skb, 


	copy_skb_header(n, skb);



	off                  = newheadroom - oldheadroom;

	if (n->ip_summed == CHECKSUM_PARTIAL)

		n->csum_start += off;



	skb_headers_offset_update(n, off);

	skb_headers_offset_update(n, newheadroom - oldheadroom);



	return n;

}
@@ -2837,14 +2832,7 @@ struct sk_buff *skb_segment(struct sk_buff *skb, netdev_features_t features) 
		__copy_skb_header(nskb, skb);

		nskb->mac_len = skb->mac_len;



		/* nskb and skb might have different headroom */

		if (nskb->ip_summed == CHECKSUM_PARTIAL)

			nskb->csum_start += skb_headroom(nskb) - headroom;



		skb_reset_mac_header(nskb);

		skb_set_network_header(nskb, skb->mac_len);

		nskb->transport_header = (nskb->network_header +

					  skb_network_header_len(skb));

		skb_headers_offset_update(nskb, skb_headroom(nskb) - headroom);



		skb_copy_from_linear_data_offset(skb, -tnl_hlen,

						 nskb->data - tnl_hlen,