[NET] move skb_can_coalesce to skbuff.h

This one also removes the duplicate can_coalesce in tcp.c and makes it
use skb_can_coalesce.
Signed-off-by: Arnaldo Carvalho de Melo <acme@conectiva.com.br>

include/linux/skbuff.h

@@ -993,6 +993,18 @@ static inline int skb_add_data(struct sk_buff *skb,
 	return -EFAULT;
 }
 
+static inline int skb_can_coalesce(struct sk_buff *skb, int i,
+				   struct page *page, int off)
+{
+	if (i) {
+		struct skb_frag_struct *frag = &skb_shinfo(skb)->frags[i - 1];
+
+		return page == frag->page &&
+		       off == frag->page_offset + frag->size;
+	}
+	return 0;
+}
+
 /**
  *	skb_linearize - convert paged skb to linear one
  *	@skb: buffer to linarize

net/ipv4/ip_output.c

@@ -702,17 +702,6 @@ ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk
 	return 0;
 }
 
-static inline int
-skb_can_coalesce(struct sk_buff *skb, int i, struct page *page, int off)
-{
-	if (i) {
-		skb_frag_t *frag = &skb_shinfo(skb)->frags[i-1];
-		return page == frag->page &&
-			off == frag->page_offset+frag->size;
-	}
-	return 0;
-}
-
 static inline unsigned int
 csum_page(struct page *page, int offset, int copy)
 {

net/ipv4/tcp.c

@@ -737,17 +737,6 @@ static int wait_for_tcp_memory(struct sock *sk, long *timeo)
 	goto out;
 }
 
-static inline int can_coalesce(struct sk_buff *skb, int i, struct page *page,
-			       int off)
-{
-	if (i) {
-		skb_frag_t *frag = &skb_shinfo(skb)->frags[i - 1];
-		return page == frag->page &&
-		       off == frag->page_offset + frag->size;
-	}
-	return 0;
-}
-
 static inline void fill_page_desc(struct sk_buff *skb, int i,
 				  struct page *page, int off, int size)
 {
@@ -865,7 +854,7 @@ static ssize_t do_tcp_sendpages(struct sock *sk, struct page **pages, int poffse
 			copy = size;
 
 		i = skb_shinfo(skb)->nr_frags;
-		if (can_coalesce(skb, i, page, offset)) {
+		if (skb_can_coalesce(skb, i, page, offset)) {
 			skb_shinfo(skb)->frags[i - 1].size += copy;
 		} else if (i < MAX_SKB_FRAGS) {
 			get_page(page);
@@ -1053,7 +1042,7 @@ int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 				struct page *page = TCP_PAGE(sk);
 				int off = TCP_OFF(sk);
 
-				if (can_coalesce(skb, i, page, off) &&
+				if (skb_can_coalesce(skb, i, page, off) &&
 				    off != PAGE_SIZE) {
 					/* We can extend the last page
 					 * fragment. */