[SKBUFF]: Merge common code between copy_skb_header and skb_clone

This patch creates a new function __copy_skb_header to merge the common
code between copy_skb_header and skb_clone.  Having two functions which
are largely the same is a source of wasted labour as well as confusion.

In fact the tc_verd stuff is almost certainly a bug since it's treated
differently in skb_clone compared to the callers of copy_skb_header
(skb_copy/pskb_copy/skb_copy_expand).

I've kept that difference in tact with a comment added asking for
clarification.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/skbuff.c

@@ -362,6 +362,44 @@ void kfree_skb(struct sk_buff *skb)
 	__kfree_skb(skb);
 }
 
+static void __copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
+{
+	new->tstamp		= old->tstamp;
+	new->dev		= old->dev;
+	new->transport_header	= old->transport_header;
+	new->network_header	= old->network_header;
+	new->mac_header		= old->mac_header;
+	new->dst		= dst_clone(old->dst);
+#ifdef CONFIG_INET
+	new->sp			= secpath_get(old->sp);
+#endif
+	memcpy(new->cb, old->cb, sizeof(old->cb));
+	new->csum_start		= old->csum_start;
+	new->csum_offset	= old->csum_offset;
+	new->local_df		= old->local_df;
+	new->pkt_type		= old->pkt_type;
+	new->ip_summed		= old->ip_summed;
+	skb_copy_queue_mapping(new, old);
+	new->priority		= old->priority;
+#if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)
+	new->ipvs_property	= old->ipvs_property;
+#endif
+	new->protocol		= old->protocol;
+	new->mark		= old->mark;
+	__nf_copy(new, old);
+#if defined(CONFIG_NETFILTER_XT_TARGET_TRACE) || \
+    defined(CONFIG_NETFILTER_XT_TARGET_TRACE_MODULE)
+	new->nf_trace		= old->nf_trace;
+#endif
+#ifdef CONFIG_NET_SCHED
+	new->tc_index		= old->tc_index;
+#ifdef CONFIG_NET_CLS_ACT
+	new->tc_verd		= old->tc_verd;
+#endif
+#endif
+	skb_copy_secmark(new, old);
+}
+
 /**
  *	skb_clone	-	duplicate an sk_buff
  *	@skb: buffer to clone
@@ -397,51 +435,22 @@ struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
 
 	n->next = n->prev = NULL;
 	n->sk = NULL;
-	C(tstamp);
-	C(dev);
-	C(transport_header);
-	C(network_header);
-	C(mac_header);
-	C(dst);
-	dst_clone(skb->dst);
-	C(sp);
-#ifdef CONFIG_INET
-	secpath_get(skb->sp);
-#endif
-	memcpy(n->cb, skb->cb, sizeof(skb->cb));
+	__copy_skb_header(n, skb);
+
 	C(len);
 	C(data_len);
 	C(mac_len);
-	C(csum);
-	C(local_df);
 	n->cloned = 1;
 	n->hdr_len = skb->nohdr ? skb_headroom(skb) : skb->hdr_len;
 	n->nohdr = 0;
-	C(pkt_type);
-	C(ip_summed);
-	skb_copy_queue_mapping(n, skb);
-	C(priority);
-#if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)
-	C(ipvs_property);
-#endif
-	C(protocol);
 	n->destructor = NULL;
-	C(mark);
-	__nf_copy(n, skb);
-#if defined(CONFIG_NETFILTER_XT_TARGET_TRACE) || \
-    defined(CONFIG_NETFILTER_XT_TARGET_TRACE_MODULE)
-	C(nf_trace);
-#endif
-#ifdef CONFIG_NET_SCHED
-	C(tc_index);
 #ifdef CONFIG_NET_CLS_ACT
-	n->tc_verd = SET_TC_VERD(skb->tc_verd,0);
+	/* FIXME What is this and why don't we do it in copy_skb_header? */
+	n->tc_verd = SET_TC_VERD(n->tc_verd,0);
 	n->tc_verd = CLR_TC_OK2MUNGE(n->tc_verd);
 	n->tc_verd = CLR_TC_MUNGED(n->tc_verd);
 	C(iif);
 #endif
-#endif
-	skb_copy_secmark(n, skb);
 	C(truesize);
 	atomic_set(&n->users, 1);
 	C(head);
@@ -463,50 +472,15 @@ static void copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
 	 */
 	unsigned long offset = new->data - old->data;
 #endif
-	new->sk		= NULL;
-	new->dev	= old->dev;
-	skb_copy_queue_mapping(new, old);
-	new->priority	= old->priority;
-	new->protocol	= old->protocol;
-	new->dst	= dst_clone(old->dst);
-#ifdef CONFIG_INET
-	new->sp		= secpath_get(old->sp);
-#endif
-	new->csum_start = old->csum_start;
-	new->csum_offset = old->csum_offset;
-	new->ip_summed = old->ip_summed;
-	new->transport_header = old->transport_header;
-	new->network_header   = old->network_header;
-	new->mac_header	      = old->mac_header;
+
+	__copy_skb_header(new, old);
+
 #ifndef NET_SKBUFF_DATA_USES_OFFSET
 	/* {transport,network,mac}_header are relative to skb->head */
 	new->transport_header += offset;
 	new->network_header   += offset;
 	new->mac_header	      += offset;
 #endif
-	memcpy(new->cb, old->cb, sizeof(old->cb));
-	new->local_df	= old->local_df;
-	new->fclone	= SKB_FCLONE_UNAVAILABLE;
-	new->pkt_type	= old->pkt_type;
-	new->tstamp	= old->tstamp;
-	new->destructor = NULL;
-	new->mark	= old->mark;
-	__nf_copy(new, old);
-#if defined(CONFIG_NETFILTER_XT_TARGET_TRACE) || \
-    defined(CONFIG_NETFILTER_XT_TARGET_TRACE_MODULE)
-	new->nf_trace	= old->nf_trace;
-#endif
-#if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)
-	new->ipvs_property = old->ipvs_property;
-#endif
-#ifdef CONFIG_NET_SCHED
-#ifdef CONFIG_NET_CLS_ACT
-	new->tc_verd = old->tc_verd;
-#endif
-	new->tc_index	= old->tc_index;
-#endif
-	skb_copy_secmark(new, old);
-	atomic_set(&new->users, 1);
 	skb_shinfo(new)->gso_size = skb_shinfo(old)->gso_size;
 	skb_shinfo(new)->gso_segs = skb_shinfo(old)->gso_segs;
 	skb_shinfo(new)->gso_type = skb_shinfo(old)->gso_type;