Merge branch 'csums-next'

Tom Herbert says:

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

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)
- Simplify code

What is in this sixth patch set:

- Clarify the specific requirements of devices returning
  CHECKSUM_UNNECESSARY (comments in skbuff.h).
- Add csum_level field to skbuff. This is used to express how
  many checksums are covered by CHECKSUM_UNNECESSARY (stores n - 1).
- Change __skb_checksum_validate_needed to "consume" each checksum
  as indicated by csum_level as layers of the the packet are parsed.
- Remove skb_pop_rcv_encapsulation, no longer needed in the new
  csum_level model.
- Allow GRO path to "consume" checksums provided in CHECKSUM_UNNECESSARY
  and to report new verfied checksums for use in normal path fallback.
- Add proper support to SCTP to accept CHECKSUM_UNNECESSARY to validate
  header CRC.
- Modify drivers to set skb->csum_level instead of setting
  skb->encapsulation to indicate validation of an encapsulated
  checksum on receive.

v2:

Allocate a new 16 bits for flags in skbuff.

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, 16 insertions, 8 deletions

diff --git a/net/core/dev.c b/net/core/dev.c
index 26d296c2447c..a6077ef56345 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3962,13 +3962,6 @@ static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff
 
         gro_list_prepare(napi, skb);
 
-        if (skb->ip_summed == CHECKSUM_COMPLETE) {
-                NAPI_GRO_CB(skb)->csum = skb->csum;
-                NAPI_GRO_CB(skb)->csum_valid = 1;
-        } else {
-                NAPI_GRO_CB(skb)->csum_valid = 0;
-        }
-
         rcu_read_lock();
         list_for_each_entry_rcu(ptype, head, list) {
                 if (ptype->type != type || !ptype->callbacks.gro_receive)
@@ -3980,7 +3973,22 @@ static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff
                 NAPI_GRO_CB(skb)->flush = 0;
                 NAPI_GRO_CB(skb)->free = 0;
                 NAPI_GRO_CB(skb)->udp_mark = 0;
-                NAPI_GRO_CB(skb)->encapsulation = 0;
+
+                /* Setup for GRO checksum validation */
+                switch (skb->ip_summed) {
+                case CHECKSUM_COMPLETE:
+                        NAPI_GRO_CB(skb)->csum = skb->csum;
+                        NAPI_GRO_CB(skb)->csum_valid = 1;
+                        NAPI_GRO_CB(skb)->csum_cnt = 0;
+                        break;
+                case CHECKSUM_UNNECESSARY:
+                        NAPI_GRO_CB(skb)->csum_cnt = skb->csum_level + 1;
+                        NAPI_GRO_CB(skb)->csum_valid = 0;
+                        break;
+                default:
+                        NAPI_GRO_CB(skb)->csum_cnt = 0;
+                        NAPI_GRO_CB(skb)->csum_valid = 0;
+                }
 
                 pp = ptype->callbacks.gro_receive(&napi->gro_list, skb);
                 break;