net: Introduce skb_checksum_start_offset()

Introduce skb_checksum_start_offset() to replace repetitive calculation.

Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 4c4bec6316d9e17fa3802611ca410eb10fd9c6a5..20ec0a64cb9ff0f8708a66ddaeb2ffd1d3ed72c9 100644 (file)
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -1355,6 +1355,11 @@ static inline void skb_set_mac_header(struct sk_buff *skb, const int offset)
 }
 #endif /* NET_SKBUFF_DATA_USES_OFFSET */
 
+static inline int skb_checksum_start_offset(const struct sk_buff *skb)
+{
+       return skb->csum_start - skb_headroom(skb);
+}
+
 static inline int skb_transport_offset(const struct sk_buff *skb)
 {
        return skb_transport_header(skb) - skb->data;