Many users of skb_checksum_help() are just using it to recalculate
outbound checksum, so why not expose the interface in a more useful
way. Suggested by Ingo Oeser.

Signed-off-by: Stephen Hemminger <[EMAIL PROTECTED]>

--- linux-2.6.orig/include/linux/skbuff.h       2006-04-27 11:12:53.000000000 
-0700
+++ linux-2.6/include/linux/skbuff.h    2006-05-11 11:17:39.000000000 -0700
@@ -1343,6 +1343,24 @@
                __skb_checksum_complete(skb);
 }
 
+extern int skb_checksum_recalc(struct sk_buff *skb);
+/**
+ *     skb_checksum_help - recalculate checksum of packet
+ *     @skb: packet to process
+ *     @inward: direction of flow, zero is receiving
+ *
+ * Invalidate hardware checksum when packet is to be mangled on
+ * receive and complete checksum manually on outgoing path.
+ */
+static inline int skb_checksum_help(struct sk_buff *skb, int inward)
+{
+       if (inward) {
+               skb->ip_summed = CHECKSUM_NONE;
+               return 0;
+       }
+       return skb_checksum_recalc(skb);
+}
+
 #ifdef CONFIG_NETFILTER
 static inline void nf_conntrack_put(struct nf_conntrack *nfct)
 {
--- sky2.orig/net/core/dev.c    2006-05-10 10:17:51.000000000 -0700
+++ sky2/net/core/dev.c 2006-05-11 11:22:27.000000000 -0700
@@ -1144,39 +1144,6 @@
 EXPORT_SYMBOL(netif_device_attach);
 
 
-/*
- * Invalidate hardware checksum when packet is to be mangled, and
- * complete checksum manually on outgoing path.
- */
-int skb_checksum_help(struct sk_buff *skb, int inward)
-{
-       unsigned int csum;
-       int ret = 0, offset = skb->h.raw - skb->data;
-
-       if (inward) {
-               skb->ip_summed = CHECKSUM_NONE;
-               goto out;
-       }
-
-       if (skb_cloned(skb)) {
-               ret = pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
-               if (ret)
-                       goto out;
-       }
-
-       BUG_ON(offset > (int)skb->len);
-       csum = skb_checksum(skb, offset, skb->len-offset, 0);
-
-       offset = skb->tail - skb->h.raw;
-       BUG_ON(offset <= 0);
-       BUG_ON(skb->csum + 2 > offset);
-
-       *(u16*)(skb->h.raw + skb->csum) = csum_fold(csum);
-       skb->ip_summed = CHECKSUM_NONE;
-out:   
-       return ret;
-}
-
 /* Take action when hardware reception checksum errors are detected. */
 #ifdef CONFIG_BUG
 void netdev_rx_csum_fault(struct net_device *dev)
@@ -3403,7 +3370,6 @@
 EXPORT_SYMBOL(register_gifconf);
 EXPORT_SYMBOL(register_netdevice);
 EXPORT_SYMBOL(register_netdevice_notifier);
-EXPORT_SYMBOL(skb_checksum_help);
 EXPORT_SYMBOL(synchronize_net);
 EXPORT_SYMBOL(unregister_netdevice);
 EXPORT_SYMBOL(unregister_netdevice_notifier);
--- sky2.orig/net/core/skbuff.c 2006-04-27 11:12:54.000000000 -0700
+++ sky2/net/core/skbuff.c      2006-05-11 11:23:13.000000000 -0700
@@ -1334,6 +1334,36 @@
 }
 
 /**
+ *     skb_checksum_recalc - force software checksum
+ *     @skb: skb to process
+ *     Force complete checksum, this is used to force a software checksum
+ *     on the outgoing path.
+ */
+int skb_checksum_recalc(struct sk_buff *skb)
+{
+       unsigned int csum;
+       int ret = 0, offset = skb->h.raw - skb->data;
+
+       if (skb_cloned(skb)) {
+               ret = pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
+               if (ret)
+                       goto out;
+       }
+
+       BUG_ON(offset > (int)skb->len);
+       csum = skb_checksum(skb, offset, skb->len-offset, 0);
+
+       offset = skb->tail - skb->h.raw;
+       BUG_ON(offset <= 0);
+       BUG_ON(skb->csum + 2 > offset);
+
+       *(u16*)(skb->h.raw + skb->csum) = csum_fold(csum);
+       skb->ip_summed = CHECKSUM_NONE;
+out:
+       return ret;
+}
+
+/**
  *     skb_dequeue - remove from the head of the queue
  *     @list: list to dequeue from
  *
@@ -1854,6 +1884,7 @@
 EXPORT_SYMBOL(pskb_copy);
 EXPORT_SYMBOL(pskb_expand_head);
 EXPORT_SYMBOL(skb_checksum);
+EXPORT_SYMBOL(skb_checksum_recalc);
 EXPORT_SYMBOL(skb_clone);
 EXPORT_SYMBOL(skb_clone_fraglist);
 EXPORT_SYMBOL(skb_copy);
-
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