tcp: cleanup tcp_remove_empty_skb() use

All tcp_remove_empty_skb() callers now use tcp_write_queue_tail()
for the skb argument, we can therefore factorize code.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/tcp.h

@@ -311,7 +311,7 @@ void tcp_shutdown(struct sock *sk, int how);
 int tcp_v4_early_demux(struct sk_buff *skb);
 int tcp_v4_rcv(struct sk_buff *skb);
 
-void tcp_remove_empty_skb(struct sock *sk, struct sk_buff *skb);
+void tcp_remove_empty_skb(struct sock *sk);
 int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
 int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size);
 int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size);

net/ipv4/tcp.c

@@ -933,8 +933,10 @@ int tcp_send_mss(struct sock *sk, int *size_goal, int flags)
  * importantly be able to generate EPOLLOUT for Edge Trigger epoll()
  * users.
  */
-void tcp_remove_empty_skb(struct sock *sk, struct sk_buff *skb)
+void tcp_remove_empty_skb(struct sock *sk)
 {
+	struct sk_buff *skb = tcp_write_queue_tail(sk);
+
 	if (skb && TCP_SKB_CB(skb)->seq == TCP_SKB_CB(skb)->end_seq) {
 		tcp_unlink_write_queue(skb, sk);
 		if (tcp_write_queue_empty(sk))
@@ -1087,7 +1089,7 @@ ssize_t do_tcp_sendpages(struct sock *sk, struct page *page, int offset,
 	return copied;
 
 do_error:
-	tcp_remove_empty_skb(sk, tcp_write_queue_tail(sk));
+	tcp_remove_empty_skb(sk);
 	if (copied)
 		goto out;
 out_err:
@@ -1408,8 +1410,7 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size)
 	return copied + copied_syn;
 
 do_error:
-	skb = tcp_write_queue_tail(sk);
-	tcp_remove_empty_skb(sk, skb);
+	tcp_remove_empty_skb(sk);
 
 	if (copied + copied_syn)
 		goto out;

net/mptcp/protocol.c

@@ -1291,7 +1291,7 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk,
 		u64 snd_una = READ_ONCE(msk->snd_una);
 
 		if (snd_una != msk->snd_nxt) {
-			tcp_remove_empty_skb(ssk, tcp_write_queue_tail(ssk));
+			tcp_remove_empty_skb(ssk);
 			return 0;
 		}
 
@@ -1307,7 +1307,7 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk,
 
 	copy = min_t(size_t, copy, info->limit - info->sent);
 	if (!sk_wmem_schedule(ssk, copy)) {
-		tcp_remove_empty_skb(ssk, tcp_write_queue_tail(ssk));
+		tcp_remove_empty_skb(ssk);
 		return -ENOMEM;
 	}