[NET]: Add sk_stream_wmem_schedule

This patch introduces sk_stream_wmem_schedule as a short-hand for
the sk_forward_alloc checking on egress.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/sock.h

@@ -709,6 +709,12 @@ static inline int sk_stream_rmem_schedule(struct sock *sk, struct sk_buff *skb)
 		sk_stream_mem_schedule(sk, skb->truesize, 1);
 }
 
+static inline int sk_stream_wmem_schedule(struct sock *sk, int size)
+{
+	return size <= sk->sk_forward_alloc ||
+	       sk_stream_mem_schedule(sk, size, 0);
+}
+
 /* Used by processes to "lock" a socket state, so that
  * interrupts and bottom half handlers won't change it
  * from under us. It essentially blocks any incoming
@@ -1203,8 +1209,7 @@ static inline struct sk_buff *sk_stream_alloc_pskb(struct sock *sk,
 	skb = alloc_skb_fclone(size + hdr_len, gfp);
 	if (skb) {
 		skb->truesize += mem;
-		if (sk->sk_forward_alloc >= (int)skb->truesize ||
-		    sk_stream_mem_schedule(sk, skb->truesize, 0)) {
+		if (sk_stream_wmem_schedule(sk, skb->truesize)) {
 			skb_reserve(skb, hdr_len);
 			return skb;
 		}
@@ -1227,8 +1232,7 @@ static inline struct page *sk_stream_alloc_page(struct sock *sk)
 {
 	struct page *page = NULL;
 
-	if (sk->sk_forward_alloc >= (int)PAGE_SIZE ||
-	    sk_stream_mem_schedule(sk, PAGE_SIZE, 0))
+	if (sk_stream_wmem_schedule(sk, PAGE_SIZE))
 		page = alloc_pages(sk->sk_allocation, 0);
 	else {
 		sk->sk_prot->enter_memory_pressure();

net/ipv4/tcp.c

@@ -552,8 +552,7 @@ static ssize_t do_tcp_sendpages(struct sock *sk, struct page **pages, int poffse
 			tcp_mark_push(tp, skb);
 			goto new_segment;
 		}
-		if (sk->sk_forward_alloc < copy &&
-		    !sk_stream_mem_schedule(sk, copy, 0))
+		if (!sk_stream_wmem_schedule(sk, copy))
 			goto wait_for_memory;
 
 		if (can_coalesce) {