From 030737bcc3c404e273e97dbe06fe9561699a411b Mon Sep 17 00:00:00 2001
From: Eric Dumazet <edumazet@google.com>
Date: Sat, 19 Oct 2013 11:42:54 -0700
Subject: [PATCH] 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: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
net/core/skbuff.c | 22 +++++-----------------
1 file changed, 5 insertions(+), 17 deletions(-)
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 8ead744fcc94..0ab32faa520f 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -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,
--
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