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>

4 files changed, 16 insertions, 8 deletions

diff --git a/net/core/datagram.c b/net/core/datagram.c
index a16ed7bbe376..6b1c04ca1d50 100644
--- a/net/core/datagram.c
+++ b/net/core/datagram.c
@@ -739,11 +739,15 @@ __sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len)
 	__sum16 sum;
 
 	sum = csum_fold(skb_checksum(skb, 0, len, skb->csum));
-	if (likely(!sum)) {
-		if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE))
-			netdev_rx_csum_fault(skb->dev);
-		skb->ip_summed = CHECKSUM_UNNECESSARY;
-	}
+	if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) && !sum &&
+	    !skb->csum_complete_sw)
+		netdev_rx_csum_fault(skb->dev);
+
+	/* Save checksum complete for later use */
+	skb->csum = sum;
+	skb->ip_summed = CHECKSUM_COMPLETE;
+	skb->csum_complete_sw = 1;
+
 	return sum;
 }
 EXPORT_SYMBOL(__skb_checksum_complete_head);
diff --git a/net/ipv4/gre_offload.c b/net/ipv4/gre_offload.c
index 24deb3928b9e..eb92deb12666 100644
--- a/net/ipv4/gre_offload.c
+++ b/net/ipv4/gre_offload.c
@@ -131,10 +131,12 @@ static __sum16 gro_skb_checksum(struct sk_buff *skb)
 		csum_partial(skb->data, skb_gro_offset(skb), 0));
 	sum = csum_fold(NAPI_GRO_CB(skb)->csum);
 	if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE)) {
-		if (unlikely(!sum))
+		if (unlikely(!sum) && !skb->csum_complete_sw)
 			netdev_rx_csum_fault(skb->dev);
-	} else
+	} else {
 		skb->ip_summed = CHECKSUM_COMPLETE;
+		skb->csum_complete_sw = 1;
+	}
 
 	return sum;
 }
diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c
index 7b1840110173..546d2d439dda 100644
--- a/net/ipv4/udp_offload.c
+++ b/net/ipv4/udp_offload.c
@@ -200,6 +200,7 @@ unflush:
 	}
 
 	skb_gro_pull(skb, sizeof(struct udphdr)); /* pull encapsulating udp header */
+	skb_gro_postpull_rcsum(skb, uh, sizeof(struct udphdr));
 	pp = uo_priv->offload->callbacks.gro_receive(head, skb);
 
 out_unlock:
diff --git a/net/sunrpc/socklib.c b/net/sunrpc/socklib.c
index 0a648c502fc3..2df87f78e518 100644
--- a/net/sunrpc/socklib.c
+++ b/net/sunrpc/socklib.c
@@ -173,7 +173,8 @@ int csum_partial_copy_to_xdr(struct xdr_buf *xdr, struct sk_buff *skb)
 		return -1;
 	if (csum_fold(desc.csum))
 		return -1;
-	if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE))
+	if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
+	    !skb->csum_complete_sw)
 		netdev_rx_csum_fault(skb->dev);
 	return 0;
 no_checksum: