net: Separate out SKB validation logic from transmit path.

dev_hard_start_xmit() does two things, it first validates and
canonicalizes the SKB, then it actually sends it.

Make a set of helper functions for doing the first part.

Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/core/dev.c b/net/core/dev.c
index 6d82194e414b9aa1e35a040656c6c2820b6507a1..704a5434f77d300fe266aa05ae563c861a698f86 100644 (file)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2644,80 +2644,97 @@ out:
        return skb;
 }
 
-int dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev,
-                       struct netdev_queue *txq)
+struct sk_buff *validate_xmit_vlan(struct sk_buff *skb, netdev_features_t features)
 {
-       int rc = NETDEV_TX_OK;
+       if (vlan_tx_tag_present(skb) &&
+           !vlan_hw_offload_capable(features, skb->vlan_proto)) {
+               skb = __vlan_put_tag(skb, skb->vlan_proto,
+                                    vlan_tx_tag_get(skb));
+               if (skb)
+                       skb->vlan_tci = 0;
+       }
+       return skb;
+}
 
-       if (likely(!skb->next)) {
-               netdev_features_t features;
+static struct sk_buff *validate_xmit_skb(struct sk_buff *skb, struct net_device *dev)
+{
+       netdev_features_t features;
 
-               /*
-                * If device doesn't need skb->dst, release it right now while
-                * its hot in this cpu cache
-                */
-               if (dev->priv_flags & IFF_XMIT_DST_RELEASE)
-                       skb_dst_drop(skb);
+       if (skb->next)
+               return skb;
 
-               features = netif_skb_features(skb);
+       /* If device doesn't need skb->dst, release it right now while
+        * its hot in this cpu cache
+        */
+       if (dev->priv_flags & IFF_XMIT_DST_RELEASE)
+               skb_dst_drop(skb);
 
-               if (vlan_tx_tag_present(skb) &&
-                   !vlan_hw_offload_capable(features, skb->vlan_proto)) {
-                       skb = __vlan_put_tag(skb, skb->vlan_proto,
-                                            vlan_tx_tag_get(skb));
-                       if (unlikely(!skb))
-                               goto out;
+       features = netif_skb_features(skb);
+       skb = validate_xmit_vlan(skb, features);
+       if (unlikely(!skb))
+               goto out_null;
 
-                       skb->vlan_tci = 0;
-               }
+       /* If encapsulation offload request, verify we are testing
+        * hardware encapsulation features instead of standard
+        * features for the netdev
+        */
+       if (skb->encapsulation)
+               features &= dev->hw_enc_features;
 
-               /* If encapsulation offload request, verify we are testing
-                * hardware encapsulation features instead of standard
-                * features for the netdev
-                */
-               if (skb->encapsulation)
-                       features &= dev->hw_enc_features;
+       if (netif_needs_gso(skb, features)) {
+               if (unlikely(dev_gso_segment(skb, features)))
+                       goto out_kfree_skb;
+       } else {
+               if (skb_needs_linearize(skb, features) &&
+                   __skb_linearize(skb))
+                       goto out_kfree_skb;
 
-               if (netif_needs_gso(skb, features)) {
-                       if (unlikely(dev_gso_segment(skb, features)))
-                               goto out_kfree_skb;
-                       if (skb->next)
-                               goto gso;
-               } else {
-                       if (skb_needs_linearize(skb, features) &&
-                           __skb_linearize(skb))
+               /* If packet is not checksummed and device does not
+                * support checksumming for this protocol, complete
+                * checksumming here.
+                */
+               if (skb->ip_summed == CHECKSUM_PARTIAL) {
+                       if (skb->encapsulation)
+                               skb_set_inner_transport_header(skb,
+                                                              skb_checksum_start_offset(skb));
+                       else
+                               skb_set_transport_header(skb,
+                                                        skb_checksum_start_offset(skb));
+                       if (!(features & NETIF_F_ALL_CSUM) &&
+                           skb_checksum_help(skb))
                                goto out_kfree_skb;
-
-                       /* If packet is not checksummed and device does not
-                        * support checksumming for this protocol, complete
-                        * checksumming here.
-                        */
-                       if (skb->ip_summed == CHECKSUM_PARTIAL) {
-                               if (skb->encapsulation)
-                                       skb_set_inner_transport_header(skb,
-                                               skb_checksum_start_offset(skb));
-                               else
-                                       skb_set_transport_header(skb,
-                                               skb_checksum_start_offset(skb));
-                               if (!(features & NETIF_F_ALL_CSUM) &&
-                                    skb_checksum_help(skb))
-                                       goto out_kfree_skb;
-                       }
                }
+       }
+
+       return skb;
+
+out_kfree_skb:
+       kfree_skb(skb);
+out_null:
+       return NULL;
+}
+
+int dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev,
+                       struct netdev_queue *txq)
+{
+       int rc = NETDEV_TX_OK;
+
+       skb = validate_xmit_skb(skb, dev);
+       if (!skb)
+               return rc;
 
+       if (likely(!skb->next))
                return xmit_one(skb, dev, txq, false);
-       }
 
-gso:
        skb->next = xmit_list(skb->next, dev, txq, &rc);
        if (likely(skb->next == NULL)) {
                skb->destructor = DEV_GSO_CB(skb)->destructor;
                consume_skb(skb);
                return rc;
        }
-out_kfree_skb:
+
        kfree_skb(skb);
-out:
+
        return rc;
 }
 EXPORT_SYMBOL_GPL(dev_hard_start_xmit);