Patch "tcp: remove redundant check on tskb" has been added to the 4.19-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    tcp: remove redundant check on tskb

to the 4.19-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     tcp-remove-redundant-check-on-tskb.patch
and it can be found in the queue-4.19 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit ca7efda8d271d45d41a4d997721a19de258545f7
Author: Colin Ian King <colin.i.king@xxxxxxxxx>
Date:   Thu Apr 4 15:46:03 2019 +0100

    tcp: remove redundant check on tskb
    
    [ Upstream commit d1edc085559744fbda7a55e97eeae8bd6135a11b ]
    
    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: Colin Ian King <colin.king@xxxxxxxxxxxxx>
    Reviewed-by: Mukesh Ojha <mojha@xxxxxxxxxxxxxx>
    Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
    Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
    Stable-dep-of: 94062790aedb ("tcp: defer shutdown(SEND_SHUTDOWN) for TCP_SYN_RECV sockets")
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 670804d4c1690..8b78cb96a8461 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -3132,7 +3132,6 @@ 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++;
@@ -3148,11 +3147,9 @@ 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);