FAILED: patch "[PATCH] mptcp: push at DSS boundaries" failed to apply to 5.4-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 5.4-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.4.y
git checkout FETCH_HEAD
git cherry-pick -x b9cd26f640a308ea314ad23532de9a8592cd09d2
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2024030448-walrus-tribunal-7b38@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^..

Possible dependencies:

b9cd26f640a3 ("mptcp: push at DSS boundaries")
1094c6fe7280 ("mptcp: fix possible divide by zero")
8ce568ed06ce ("mptcp: drop tx skb cache")
4e14867d5e91 ("mptcp: tune re-injections for csum enabled mode")
2948d0a1e5ae ("mptcp: factor out __mptcp_retrans helper()")
eaeef1ce55ec ("mptcp: fix memory accounting on allocation error")
d489ded1a369 ("Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From b9cd26f640a308ea314ad23532de9a8592cd09d2 Mon Sep 17 00:00:00 2001
From: Paolo Abeni <pabeni@redhat.com>
Date: Fri, 23 Feb 2024 17:14:14 +0100
Subject: [PATCH] mptcp: push at DSS boundaries

when inserting not contiguous data in the subflow write queue,
the protocol creates a new skb and prevent the TCP stack from
merging it later with already queued skbs by setting the EOR marker.

Still no push flag is explicitly set at the end of previous GSO
packet, making the aggregation on the receiver side sub-optimal -
and packetdrill self-tests less predictable.

Explicitly mark the end of not contiguous DSS with the push flag.

Fixes: 6d0060f600ad ("mptcp: Write MPTCP DSS headers to outgoing data packets")
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://lore.kernel.org/r/20240223-upstream-net-20240223-misc-fixes-v1-4-162e87e48497@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 948606a537da..442fa7d9b57a 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -1260,6 +1260,7 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk,
 		mpext = mptcp_get_ext(skb);
 		if (!mptcp_skb_can_collapse_to(data_seq, skb, mpext)) {
 			TCP_SKB_CB(skb)->eor = 1;
+			tcp_mark_push(tcp_sk(ssk), skb);
 			goto alloc_skb;
 		}