net: correct off-by-one write allocations reports

commit 2b85a34e911bf483c27cfdd124aeb1605145dc80
(net: No more expensive sock_hold()/sock_put() on each tx)
changed initial sk_wmem_alloc value.

We need to take into account this offset when reporting
sk_wmem_alloc to user, in PROC_FS files or various
ioctls (SIOCOUTQ/TIOCOUTQ)

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 0f01e5d..35ba035 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -130,7 +130,7 @@
 	if (asoc->ep->sndbuf_policy)
 		amt = asoc->sndbuf_used;
 	else
-		amt = atomic_read(&asoc->base.sk->sk_wmem_alloc);
+		amt = sk_wmem_alloc_get(asoc->base.sk);
 
 	if (amt >= asoc->base.sk->sk_sndbuf) {
 		if (asoc->base.sk->sk_userlocks & SOCK_SNDBUF_LOCK)
@@ -6523,7 +6523,7 @@
 {
 	int amt = 0;
 
-	amt = sk->sk_sndbuf - atomic_read(&sk->sk_wmem_alloc);
+	amt = sk->sk_sndbuf - sk_wmem_alloc_get(sk);
 	if (amt < 0)
 		amt = 0;
 	return amt;