net: factor out skb_mac_gso_segment() from skb_gso_segment()

This function will be used in next GRE_GSO patch. This patch does
not change any functionality. It only exports skb_mac_gso_segment()
function.

[ Use skb_reset_mac_len() -DaveM ]

Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 50 insertions, 31 deletions

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 9deb672d999f..920361bc27e7 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -2671,6 +2671,8 @@ extern void netdev_upper_dev_unlink(struct net_device *dev,
 extern int skb_checksum_help(struct sk_buff *skb);
 extern struct sk_buff *__skb_gso_segment(struct sk_buff *skb,
         netdev_features_t features, bool tx_path);
+extern struct sk_buff *skb_mac_gso_segment(struct sk_buff *skb,
+                                          netdev_features_t features);
 
 static inline
 struct sk_buff *skb_gso_segment(struct sk_buff *skb, netdev_features_t features)
diff --git a/net/core/dev.c b/net/core/dev.c
index f44473696b8b..67deae60214c 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2327,37 +2327,20 @@ out:
 }
 EXPORT_SYMBOL(skb_checksum_help);
 
-/* openvswitch calls this on rx path, so we need a different check.
- */
-static inline bool skb_needs_check(struct sk_buff *skb, bool tx_path)
-{
-        if (tx_path)
-                return skb->ip_summed != CHECKSUM_PARTIAL;
-        else
-                return skb->ip_summed == CHECKSUM_NONE;
-}
-
 /**
- *      __skb_gso_segment - Perform segmentation on skb.
+ *      skb_mac_gso_segment - mac layer segmentation handler.
  *      @skb: buffer to segment
  *      @features: features for the output path (see dev->features)
- *      @tx_path: whether it is called in TX path
- *
- *      This function segments the given skb and returns a list of segments.
- *
- *      It may return NULL if the skb requires no segmentation.  This is
- *      only possible when GSO is used for verifying header integrity.
  */
-struct sk_buff *__skb_gso_segment(struct sk_buff *skb,
-                                  netdev_features_t features, bool tx_path)
+struct sk_buff *skb_mac_gso_segment(struct sk_buff *skb,
+                                    netdev_features_t features)
 {
         struct sk_buff *segs = ERR_PTR(-EPROTONOSUPPORT);
         struct packet_offload *ptype;
         __be16 type = skb->protocol;
-        int vlan_depth = ETH_HLEN;
-        int err;
 
         while (type == htons(ETH_P_8021Q)) {
+                int vlan_depth = ETH_HLEN;
                 struct vlan_hdr *vh;
 
                 if (unlikely(!pskb_may_pull(skb, vlan_depth + VLAN_HLEN)))
@@ -2368,22 +2351,14 @@ struct sk_buff *__skb_gso_segment(struct sk_buff *skb,
                 vlan_depth += VLAN_HLEN;
         }
 
-        skb_reset_mac_header(skb);
-        skb->mac_len = skb->network_header - skb->mac_header;
         __skb_pull(skb, skb->mac_len);
 
-        if (unlikely(skb_needs_check(skb, tx_path))) {
-                skb_warn_bad_offload(skb);
-
-                if (skb_header_cloned(skb) &&
-                    (err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
-                        return ERR_PTR(err);
-        }
-
         rcu_read_lock();
         list_for_each_entry_rcu(ptype, &offload_base, list) {
                 if (ptype->type == type && ptype->callbacks.gso_segment) {
                         if (unlikely(skb->ip_summed != CHECKSUM_PARTIAL)) {
+                                int err;
+
                                 err = ptype->callbacks.gso_send_check(skb);
                                 segs = ERR_PTR(err);
                                 if (err || skb_gso_ok(skb, features))
@@ -2401,6 +2376,48 @@ struct sk_buff *__skb_gso_segment(struct sk_buff *skb,
 
         return segs;
 }
+EXPORT_SYMBOL(skb_mac_gso_segment);
+
+
+/* openvswitch calls this on rx path, so we need a different check.
+ */
+static inline bool skb_needs_check(struct sk_buff *skb, bool tx_path)
+{
+        if (tx_path)
+                return skb->ip_summed != CHECKSUM_PARTIAL;
+        else
+                return skb->ip_summed == CHECKSUM_NONE;
+}
+
+/**
+ *      __skb_gso_segment - Perform segmentation on skb.
+ *      @skb: buffer to segment
+ *      @features: features for the output path (see dev->features)
+ *      @tx_path: whether it is called in TX path
+ *
+ *      This function segments the given skb and returns a list of segments.
+ *
+ *      It may return NULL if the skb requires no segmentation.  This is
+ *      only possible when GSO is used for verifying header integrity.
+ */
+struct sk_buff *__skb_gso_segment(struct sk_buff *skb,
+                                  netdev_features_t features, bool tx_path)
+{
+        if (unlikely(skb_needs_check(skb, tx_path))) {
+                int err;
+
+                skb_warn_bad_offload(skb);
+
+                if (skb_header_cloned(skb) &&
+                    (err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
+                        return ERR_PTR(err);
+        }
+
+        skb_reset_mac_header(skb);
+        skb_reset_mac_len(skb);
+
+        return skb_mac_gso_segment(skb, features);
+}
 EXPORT_SYMBOL(__skb_gso_segment);
 
 /* Take action when hardware reception checksum errors are detected. */