gue: Call remcsum_adjust

Change remote checksum offload to call remcsum_adjust. This also
eliminates the optimization to skip an IP header as part of the
adjustment (really does not seem to be much of a win).

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

1 files changed, 17 insertions, 67 deletions

diff --git a/net/ipv4/fou.c b/net/ipv4/fou.c
index 3dfe9828e7ef..b986298a7ba3 100644
--- a/net/ipv4/fou.c
+++ b/net/ipv4/fou.c
@@ -64,15 +64,13 @@ static int fou_udp_recv(struct sock *sk, struct sk_buff *skb)
 }
 
 static struct guehdr *gue_remcsum(struct sk_buff *skb, struct guehdr *guehdr,
-                                  void *data, int hdrlen, u8 ipproto)
+                                  void *data, size_t hdrlen, u8 ipproto)
 {
         __be16 *pd = data;
-        u16 start = ntohs(pd[0]);
-        u16 offset = ntohs(pd[1]);
-        u16 poffset = 0;
-        u16 plen;
-        __wsum csum, delta;
-        __sum16 *psum;
+        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 */
@@ -80,35 +78,15 @@ static struct guehdr *gue_remcsum(struct sk_buff *skb, struct guehdr *guehdr,
                 return guehdr;
         }
 
-        if (start > skb->len - hdrlen ||
-            offset > skb->len - hdrlen - sizeof(u16))
-                return NULL;
-
-        if (unlikely(skb->ip_summed != CHECKSUM_COMPLETE))
-                __skb_checksum_complete(skb);
-
-        plen = hdrlen + offset + sizeof(u16);
         if (!pskb_may_pull(skb, plen))
                 return NULL;
         guehdr = (struct guehdr *)&udp_hdr(skb)[1];
 
-        if (ipproto == IPPROTO_IP && sizeof(struct iphdr) < plen) {
-                struct iphdr *ip = (struct iphdr *)(skb->data + hdrlen);
-
-                /* If next header happens to be IP we can skip that for the
-                 * checksum calculation since the IP header checksum is zero
-                 * if correct.
-                 */
-                poffset = ip->ihl * 4;
-        }
-
-        csum = csum_sub(skb->csum, skb_checksum(skb, poffset + hdrlen,
-                                                start - poffset - hdrlen, 0));
+        if (unlikely(skb->ip_summed != CHECKSUM_COMPLETE))
+                __skb_checksum_complete(skb);
 
-        /* Set derived checksum in packet */
-        psum = (__sum16 *)(skb->data + hdrlen + offset);
-        delta = csum_sub(csum_fold(csum), *psum);
-        *psum = csum_fold(csum);
+        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);
@@ -158,9 +136,6 @@ static int gue_udp_recv(struct sock *sk, struct sk_buff *skb)
 
         ip_hdr(skb)->tot_len = htons(ntohs(ip_hdr(skb)->tot_len) - len);
 
-        /* Pull UDP header now, skb->data points to guehdr */
-        __skb_pull(skb, sizeof(struct udphdr));
-
         /* Pull csum through the guehdr now . This can be used if
          * there is a remote checksum offload.
          */
@@ -188,7 +163,7 @@ static int gue_udp_recv(struct sock *sk, struct sk_buff *skb)
         if (unlikely(guehdr->control))
                 return gue_control_message(skb, guehdr);
 
-        __skb_pull(skb, hdrlen);
+        __skb_pull(skb, sizeof(struct udphdr) + hdrlen);
         skb_reset_transport_header(skb);
 
         return -guehdr->proto_ctype;
@@ -248,24 +223,17 @@ static struct guehdr *gue_gro_remcsum(struct sk_buff *skb, unsigned int off,
                                       size_t hdrlen, u8 ipproto)
 {
         __be16 *pd = data;
-        u16 start = ntohs(pd[0]);
-        u16 offset = ntohs(pd[1]);
-        u16 poffset = 0;
-        u16 plen;
-        void *ptr;
-        __wsum csum, delta;
-        __sum16 *psum;
+        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;
 
-        if (start > skb_gro_len(skb) - hdrlen ||
-            offset > skb_gro_len(skb) - hdrlen - sizeof(u16) ||
-            !NAPI_GRO_CB(skb)->csum_valid || skb->remcsum_offload)
+        if (!NAPI_GRO_CB(skb)->csum_valid)
                 return NULL;
 
-        plen = hdrlen + offset + sizeof(u16);
-
         /* Pull checksum that will be written */
         if (skb_gro_header_hard(skb, off + plen)) {
                 guehdr = skb_gro_header_slow(skb, off + plen, off);
@@ -273,26 +241,8 @@ static struct guehdr *gue_gro_remcsum(struct sk_buff *skb, unsigned int off,
                         return NULL;
         }
 
-        ptr = (void *)guehdr + hdrlen;
-
-        if (ipproto == IPPROTO_IP &&
-            (hdrlen + sizeof(struct iphdr) < plen)) {
-                struct iphdr *ip = (struct iphdr *)(ptr + hdrlen);
-
-                /* If next header happens to be IP we can skip
-                 * that for the checksum calculation since the
-                 * IP header checksum is zero if correct.
-                 */
-                poffset = ip->ihl * 4;
-        }
-
-        csum = csum_sub(NAPI_GRO_CB(skb)->csum,
-                        csum_partial(ptr + poffset, start - poffset, 0));
-
-        /* Set derived checksum in packet */
-        psum = (__sum16 *)(ptr + offset);
-        delta = csum_sub(csum_fold(csum), *psum);
-        *psum = csum_fold(csum);
+        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);