Merge branch 'inet_csums'

Tom Herbert says:

====================
net: Checksum offload changes - Part IV

I am working on overhauling RX checksum offload. Goals of this effort
are:

- Specify what exactly it means when driver returns CHECKSUM_UNNECESSARY
- Preserve CHECKSUM_COMPLETE through encapsulation layers
- Don't do skb_checksum more than once per packet
- Unify GRO and non-GRO csum verification as much as possible
- Unify the checksum functions (checksum_init)
- Simply code

What is in this fourth patch set:

- Preserve CHECKSUM_COMPLETE instead of changing it to
  CHECKSUM_UNNECESSARY. This allows correct reuse in validating multiple
  csums in a packet.
- When SW needs to compute the packet checksum, save it as
  CHECKSUM_COMPLETE. Also mark that checksum was compute by SW.
- Add skb_gro_postpull_rcsum to udp and vxlan to make GRO work with
  CHECKSUM_COMPLETE.

v2: Removed patch setting skb_encapsulation when validating checksum
    in tcp_gro_receive

Please review carefully and test if possible, mucking with basic
checksum functions is always a little precarious :-)
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 15 insertions, 9 deletions

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 1f50bfe2243d..5b5cd3189c98 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -572,7 +572,9 @@ struct sk_buff {
 	 */
 	__u8			encapsulation:1;
 	__u8			encap_hdr_csum:1;
-	/* 5/7 bit hole (depending on ndisc_nodetype presence) */
+	__u8			csum_valid:1;
+	__u8			csum_complete_sw:1;
+	/* 3/5 bit hole (depending on ndisc_nodetype presence) */
 	kmemcheck_bitfield_end(flags2);
 
 #if defined CONFIG_NET_DMA || defined CONFIG_NET_RX_BUSY_POLL
@@ -2735,7 +2737,7 @@ __sum16 __skb_checksum_complete(struct sk_buff *skb);
 
 static inline int skb_csum_unnecessary(const struct sk_buff *skb)
 {
-	return skb->ip_summed & CHECKSUM_UNNECESSARY;
+	return ((skb->ip_summed & CHECKSUM_UNNECESSARY) || skb->csum_valid);
 }
 
 /**
@@ -2769,10 +2771,8 @@ static inline bool __skb_checksum_validate_needed(struct sk_buff *skb,
 						  bool zero_okay,
 						  __sum16 check)
 {
-	if (skb_csum_unnecessary(skb)) {
-		return false;
-	} else if (zero_okay && !check) {
-		skb->ip_summed = CHECKSUM_UNNECESSARY;
+	if (skb_csum_unnecessary(skb) || (zero_okay && !check)) {
+		skb->csum_valid = 1;
 		return false;
 	}
 
@@ -2799,15 +2799,20 @@ static inline __sum16 __skb_checksum_validate_complete(struct sk_buff *skb,
 {
 	if (skb->ip_summed == CHECKSUM_COMPLETE) {
 		if (!csum_fold(csum_add(psum, skb->csum))) {
-			skb->ip_summed = CHECKSUM_UNNECESSARY;
+			skb->csum_valid = 1;
 			return 0;
 		}
 	}
 
 	skb->csum = psum;
 
-	if (complete || skb->len <= CHECKSUM_BREAK)
-		return __skb_checksum_complete(skb);
+	if (complete || skb->len <= CHECKSUM_BREAK) {
+		__sum16 csum;
+
+		csum = __skb_checksum_complete(skb);
+		skb->csum_valid = !csum;
+		return csum;
+	}
 
 	return 0;
 }
@@ -2831,6 +2836,7 @@ static inline __wsum null_compute_pseudo(struct sk_buff *skb, int proto)
 				zero_okay, check, compute_pseudo)	\
 ({									\
 	__sum16 __ret = 0;						\
+	skb->csum_valid = 0;						\
 	if (__skb_checksum_validate_needed(skb, zero_okay, check))	\
 		__ret = __skb_checksum_validate_complete(skb,		\
 				complete, compute_pseudo(skb, proto));	\