FAILED: patch "[PATCH] mptcp: fix bad RCVPRUNED mib accounting" failed to apply to 5.15-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 5.15-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-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x 0a567c2a10033bf04ed618368d179bce6977984b
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2024080738-providing-expiring-91d1@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

0a567c2a1003 ("mptcp: fix bad RCVPRUNED mib accounting")
6511882cdd82 ("mptcp: allocate fwd memory separately on the rx and tx path")
765ff425528f ("mptcp: use lockdep_assert_held_once() instead of open-coding it")

thanks,

greg k-h

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

From 0a567c2a10033bf04ed618368d179bce6977984b Mon Sep 17 00:00:00 2001
From: Paolo Abeni <pabeni@redhat.com>
Date: Wed, 31 Jul 2024 12:10:14 +0200
Subject: [PATCH] mptcp: fix bad RCVPRUNED mib accounting

Since its introduction, the mentioned MIB accounted for the wrong
event: wake-up being skipped as not-needed on some edge condition
instead of incoming skb being dropped after landing in the (subflow)
receive queue.

Move the increment in the correct location.

Fixes: ce599c516386 ("mptcp: properly account bulk freed memory")
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>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index a2fc54ed68c0..0d536b183a6c 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -350,8 +350,10 @@ static bool __mptcp_move_skb(struct mptcp_sock *msk, struct sock *ssk,
 	skb_orphan(skb);
 
 	/* try to fetch required memory from subflow */
-	if (!mptcp_rmem_schedule(sk, ssk, skb->truesize))
+	if (!mptcp_rmem_schedule(sk, ssk, skb->truesize)) {
+		MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_RCVPRUNED);
 		goto drop;
+	}
 
 	has_rxtstamp = TCP_SKB_CB(skb)->has_rxtstamp;
 
@@ -844,10 +846,8 @@ void mptcp_data_ready(struct sock *sk, struct sock *ssk)
 		sk_rbuf = ssk_rbuf;
 
 	/* over limit? can't append more skbs to msk, Also, no need to wake-up*/
-	if (__mptcp_rmem(sk) > sk_rbuf) {
-		MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_RCVPRUNED);
+	if (__mptcp_rmem(sk) > sk_rbuf)
 		return;
-	}
 
 	/* Wake-up the reader only for in-sequence data */
 	mptcp_data_lock(sk);