tcp: remove redundant check on tskb

The non-null check on tskb is always false because it is in an else
path of a check on tskb and hence tskb is null in this code block.
This is check is therefore redundant and can be removed as well
as the label coalesc.

if (tsbk) {
        ...
} else {
        ...
        if (unlikely(!skb)) {
                if (tskb)       /* can never be true, redundant code */
                        goto coalesc;
                return;
        }
}

Addresses-Coverity: ("Logically dead code")
Signed-off-by: NColin Ian King <colin.king@canonical.com>
Reviewed-by: NMukesh Ojha <mojha@codeaurora.org>
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/tcp_output.c

@@ -3088,7 +3088,6 @@ void tcp_send_fin(struct sock *sk)
 		tskb = skb_rb_last(&sk->tcp_rtx_queue);
 
 	if (tskb) {
-coalesce:
 		TCP_SKB_CB(tskb)->tcp_flags |= TCPHDR_FIN;
 		TCP_SKB_CB(tskb)->end_seq++;
 		tp->write_seq++;
@@ -3104,11 +3103,9 @@ void tcp_send_fin(struct sock *sk)
 		}
 	} else {
 		skb = alloc_skb_fclone(MAX_TCP_HEADER, sk->sk_allocation);
-		if (unlikely(!skb)) {
-			if (tskb)
-				goto coalesce;
+		if (unlikely(!skb))
 			return;
-		}
+
 		INIT_LIST_HEAD(&skb->tcp_tsorted_anchor);
 		skb_reserve(skb, MAX_TCP_HEADER);
 		sk_forced_mem_schedule(sk, skb->truesize);