[PATCH 3.16.y-ckt 035/180] net: add skb_checksum_complete_unset

[Luis Henriques]

3.16.7-ckt11 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Tom Herbert <tom at herbertland.com>

commit 4e18b9adf2f910ec4d30b811a74a5b626e6c6125 upstream.

This function changes ip_summed to CHECKSUM_NONE if CHECKSUM_COMPLETE
is set. This is called to discard checksum-complete when packet
is being modified and checksum is not pulled for headers in a layer.

Signed-off-by: Tom Herbert <tom at herbertland.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 include/linux/skbuff.h | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 6bb6bd86b0dc..e6c09cffb995 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -2798,6 +2798,18 @@ static inline bool __skb_checksum_validate_needed(struct sk_buff *skb,
  */
 #define CHECKSUM_BREAK 76
 
+/* Unset checksum-complete
+ *
+ * Unset checksum complete can be done when packet is being modified
+ * (uncompressed for instance) and checksum-complete value is
+ * invalidated.
+ */
+static inline void skb_checksum_complete_unset(struct sk_buff *skb)
+{
+	if (skb->ip_summed == CHECKSUM_COMPLETE)
+		skb->ip_summed = CHECKSUM_NONE;
+}
+
 /* Validate (init) checksum based on checksum complete.
  *
  * Return values: