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authorTom Herbert <therbert@google.com>2014-06-04 17:20:02 -0700
committerDavid S. Miller <davem@davemloft.net>2014-06-04 22:46:38 -0700
commit7e2b10c1e52ca37fb522be49f4be367f9311d0cd (patch)
tree67fd8a9e9b90f732c45f406df145c8a149d24a53 /net/core/skbuff.c
parent77157e1973cbdb8d60bdb0ec749d6014bedc5bd5 (diff)
downloadop-kernel-dev-7e2b10c1e52ca37fb522be49f4be367f9311d0cd.zip
op-kernel-dev-7e2b10c1e52ca37fb522be49f4be367f9311d0cd.tar.gz
net: Support for multiple checksums with gso
When creating a GSO packet segment we may need to set more than one checksum in the packet (for instance a TCP checksum and UDP checksum for VXLAN encapsulation). To be efficient, we want to do checksum calculation for any part of the packet at most once. This patch adds csum_start offset to skb_gso_cb. This tracks the starting offset for skb->csum which is initially set in skb_segment. When a protocol needs to compute a transport checksum it calls gso_make_checksum which computes the checksum value from the start of transport header to csum_start and then adds in skb->csum to get the full checksum. skb->csum and csum_start are then updated to reflect the checksum of the resultant packet starting from the transport header. This patch also adds a flag to skbuff, encap_hdr_csum, which is set in *gso_segment fucntions to indicate that a tunnel protocol needs checksum calculation Signed-off-by: Tom Herbert <therbert@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core/skbuff.c')
-rw-r--r--net/core/skbuff.c8
1 files changed, 7 insertions, 1 deletions
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 3f6c7e8..05f4bef 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -2885,7 +2885,9 @@ struct sk_buff *skb_segment(struct sk_buff *head_skb,
if (unlikely(!proto))
return ERR_PTR(-EINVAL);
- csum = !!can_checksum_protocol(features, proto);
+ csum = !head_skb->encap_hdr_csum &&
+ !!can_checksum_protocol(features, proto);
+
__skb_push(head_skb, doffset);
headroom = skb_headroom(head_skb);
pos = skb_headlen(head_skb);
@@ -2983,6 +2985,8 @@ struct sk_buff *skb_segment(struct sk_buff *head_skb,
nskb->csum = skb_copy_and_csum_bits(head_skb, offset,
skb_put(nskb, len),
len, 0);
+ SKB_GSO_CB(nskb)->csum_start =
+ skb_headroom(nskb) + offset;
continue;
}
@@ -3052,6 +3056,8 @@ perform_csum_check:
nskb->csum = skb_checksum(nskb, doffset,
nskb->len - doffset, 0);
nskb->ip_summed = CHECKSUM_NONE;
+ SKB_GSO_CB(nskb)->csum_start =
+ skb_headroom(nskb) + doffset;
}
} while ((offset += len) < head_skb->len);
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