net: Infrastructure for CHECKSUM_PARTIAL with remote checsum offload

This patch adds infrastructure so that remote checksum offload can
set CHECKSUM_PARTIAL instead of calling csum_partial and writing
the modfied checksum field.

Add skb_remcsum_adjust_partial function to set an skb for using
CHECKSUM_PARTIAL with remote checksum offload.  Changed
skb_remcsum_process and skb_gro_remcsum_process to take a boolean
argument to indicate if checksum partial can be set or the
checksum needs to be modified using the normal algorithm.

Signed-off-by: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 14 insertions, 1 deletions

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index da6028a50687..30007afe70b3 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -3104,16 +3104,29 @@ do {									\
 				       compute_pseudo(skb, proto));	\
 } while (0)
 
+static inline void skb_remcsum_adjust_partial(struct sk_buff *skb, void *ptr,
+					      u16 start, u16 offset)
+{
+	skb->ip_summed = CHECKSUM_PARTIAL;
+	skb->csum_start = ((unsigned char *)ptr + start) - skb->head;
+	skb->csum_offset = offset - start;
+}
+
 /* Update skbuf and packet to reflect the remote checksum offload operation.
  * When called, ptr indicates the starting point for skb->csum when
  * ip_summed is CHECKSUM_COMPLETE. If we need create checksum complete
  * here, skb_postpull_rcsum is done so skb->csum start is ptr.
  */
 static inline void skb_remcsum_process(struct sk_buff *skb, void *ptr,
-				       int start, int offset)
+				       int start, int offset, bool nopartial)
 {
 	__wsum delta;
 
+	if (!nopartial) {
+		skb_remcsum_adjust_partial(skb, ptr, start, offset);
+		return;
+	}
+
 	 if (unlikely(skb->ip_summed != CHECKSUM_COMPLETE)) {
 		__skb_checksum_complete(skb);
 		skb_postpull_rcsum(skb, skb->data, ptr - (void *)skb->data);