net: add skb functions to process remote checksum offload

This patch adds skb_remcsum_process and skb_gro_remcsum_process to
perform the appropriate adjustments to the skb when receiving
remote checksum offload.

Updated vxlan and gue to use these functions.

Tested: Ran TCP_RR and TCP_STREAM netperf for VXLAN and GUE, did
not see any change in performance.

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

4 files changed, 40 insertions, 32 deletions

diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index 31bac2a21ce3..c184717e8b28 100644
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -558,7 +558,6 @@ static struct vxlanhdr *vxlan_gro_remcsum(struct sk_buff *skb,
                                           u32 data)
 {
         size_t start, offset, plen;
-        __wsum delta;
 
         if (skb->remcsum_offload)
                 return vh;
@@ -580,12 +579,7 @@ static struct vxlanhdr *vxlan_gro_remcsum(struct sk_buff *skb,
                         return NULL;
         }
 
-        delta = remcsum_adjust((void *)vh + hdrlen,
-                               NAPI_GRO_CB(skb)->csum, start, offset);
-
-        /* Adjust skb->csum since we changed the packet */
-        skb->csum = csum_add(skb->csum, delta);
-        NAPI_GRO_CB(skb)->csum = csum_add(NAPI_GRO_CB(skb)->csum, delta);
+        skb_gro_remcsum_process(skb, (void *)vh + hdrlen, start, offset);
 
         skb->remcsum_offload = 1;
 
@@ -1159,7 +1153,6 @@ static struct vxlanhdr *vxlan_remcsum(struct sk_buff *skb, struct vxlanhdr *vh,
                                       size_t hdrlen, u32 data)
 {
         size_t start, offset, plen;
-        __wsum delta;
 
         if (skb->remcsum_offload) {
                 /* Already processed in GRO path */
@@ -1179,14 +1172,7 @@ static struct vxlanhdr *vxlan_remcsum(struct sk_buff *skb, struct vxlanhdr *vh,
 
         vh = (struct vxlanhdr *)(udp_hdr(skb) + 1);
 
-        if (unlikely(skb->ip_summed != CHECKSUM_COMPLETE))
-                __skb_checksum_complete(skb);
-
-        delta = remcsum_adjust((void *)vh + hdrlen,
-                               skb->csum, start, offset);
-
-        /* Adjust skb->csum since we changed the packet */
-        skb->csum = csum_add(skb->csum, delta);
+        skb_remcsum_process(skb, (void *)vh + hdrlen, start, offset);
 
         return vh;
 }
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 16251e96e6aa..1347ac50d2af 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -2318,6 +2318,21 @@ do {									\
                                            compute_pseudo(skb, proto)); \
 } while (0)
 
+static inline void skb_gro_remcsum_process(struct sk_buff *skb, void *ptr,
+                                           int start, int offset)
+{
+        __wsum delta;
+
+        BUG_ON(!NAPI_GRO_CB(skb)->csum_valid);
+
+        delta = remcsum_adjust(ptr, NAPI_GRO_CB(skb)->csum, start, offset);
+
+        /* Adjust skb->csum since we changed the packet */
+        skb->csum = csum_add(skb->csum, delta);
+        NAPI_GRO_CB(skb)->csum = csum_add(NAPI_GRO_CB(skb)->csum, delta);
+}
+
+
 static inline int dev_hard_header(struct sk_buff *skb, struct net_device *dev,
                                   unsigned short type,
                                   const void *daddr, const void *saddr,
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 2748ff639144..5405dfe02572 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -3099,6 +3099,27 @@ do {									\
                                        compute_pseudo(skb, proto));     \
 } while (0)
 
+/* 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)
+{
+        __wsum delta;
+
+         if (unlikely(skb->ip_summed != CHECKSUM_COMPLETE)) {
+                __skb_checksum_complete(skb);
+                skb_postpull_rcsum(skb, skb->data, ptr - (void *)skb->data);
+        }
+
+        delta = remcsum_adjust(ptr, skb->csum, start, offset);
+
+        /* Adjust skb->csum since we changed the packet */
+        skb->csum = csum_add(skb->csum, delta);
+}
+
 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
 void nf_conntrack_destroy(struct nf_conntrack *nfct);
 static inline void nf_conntrack_put(struct nf_conntrack *nfct)
diff --git a/net/ipv4/fou.c b/net/ipv4/fou.c
index 3bc0cf07661c..92ddea1e6457 100644
--- a/net/ipv4/fou.c
+++ b/net/ipv4/fou.c
@@ -70,7 +70,6 @@ static struct guehdr *gue_remcsum(struct sk_buff *skb, struct guehdr *guehdr,
         size_t start = ntohs(pd[0]);
         size_t offset = ntohs(pd[1]);
         size_t plen = hdrlen + max_t(size_t, offset + sizeof(u16), start);
-        __wsum delta;
 
         if (skb->remcsum_offload) {
                 /* Already processed in GRO path */
@@ -82,14 +81,7 @@ static struct guehdr *gue_remcsum(struct sk_buff *skb, struct guehdr *guehdr,
                 return NULL;
         guehdr = (struct guehdr *)&udp_hdr(skb)[1];
 
-        if (unlikely(skb->ip_summed != CHECKSUM_COMPLETE))
-                __skb_checksum_complete(skb);
-
-        delta = remcsum_adjust((void *)guehdr + hdrlen,
-                               skb->csum, start, offset);
-
-        /* Adjust skb->csum since we changed the packet */
-        skb->csum = csum_add(skb->csum, delta);
+        skb_remcsum_process(skb, (void *)guehdr + hdrlen, start, offset);
 
         return guehdr;
 }
@@ -228,7 +220,6 @@ static struct guehdr *gue_gro_remcsum(struct sk_buff *skb, unsigned int off,
         size_t start = ntohs(pd[0]);
         size_t offset = ntohs(pd[1]);
         size_t plen = hdrlen + max_t(size_t, offset + sizeof(u16), start);
-        __wsum delta;
 
         if (skb->remcsum_offload)
                 return guehdr;
@@ -243,12 +234,7 @@ static struct guehdr *gue_gro_remcsum(struct sk_buff *skb, unsigned int off,
                         return NULL;
         }
 
-        delta = remcsum_adjust((void *)guehdr + hdrlen,
-                               NAPI_GRO_CB(skb)->csum, start, offset);
-
-        /* Adjust skb->csum since we changed the packet */
-        skb->csum = csum_add(skb->csum, delta);
-        NAPI_GRO_CB(skb)->csum = csum_add(NAPI_GRO_CB(skb)->csum, delta);
+        skb_gro_remcsum_process(skb, (void *)guehdr + hdrlen, start, offset);
 
         skb->remcsum_offload = 1;