FAILED: patch "[PATCH] mptcp: pm: re-using ID of unused removed subflows" failed to apply to 5.15-stable tree

FAILED: patch "[PATCH] mptcp: pm: re-using ID of unused removed subflows" failed to apply to 5.15-stable tree

[gregkh]

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 edd8b5d868a4d459f3065493001e293901af758d
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2024082612-hydrated-overdress-ea6a@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

edd8b5d868a4 ("mptcp: pm: re-using ID of unused removed subflows")
d045b9eb95a9 ("mptcp: introduce implicit endpoints")
33397b83eee6 ("selftests: mptcp: add backup with port testcase")
09f12c3ab7a5 ("mptcp: allow to use port and non-signal in set_flags")
6a0653b96f5d ("selftests: mptcp: add fullmesh setting tests")
327b9a94e2a8 ("selftests: mptcp: more stable join tests-cases")

thanks,

greg k-h

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

From edd8b5d868a4d459f3065493001e293901af758d Mon Sep 17 00:00:00 2001
From: "Matthieu Baerts (NGI0)" <matttbe@kernel.org>
Date: Mon, 19 Aug 2024 21:45:21 +0200
Subject: [PATCH] mptcp: pm: re-using ID of unused removed subflows

If no subflow is attached to the 'subflow' endpoint that is being
removed, the addr ID will not be marked as available again.

Mark the linked ID as available when removing the 'subflow' endpoint if
no subflow is attached to it.

While at it, the local_addr_used counter is decremented if the ID was
marked as being used to reflect the reality, but also to allow adding
new endpoints after that.

Fixes: b6c08380860b ("mptcp: remove addr and subflow in PM netlink")
Cc: stable@vger.kernel.org
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20240819-net-mptcp-pm-reusing-id-v1-3-38035d40de5b@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
index 26f0329e16bb..8b232a210a06 100644
--- a/net/mptcp/pm_netlink.c
+++ b/net/mptcp/pm_netlink.c
@@ -1469,8 +1469,17 @@ static int mptcp_nl_remove_subflow_and_signal_addr(struct net *net,
 		remove_subflow = lookup_subflow_by_saddr(&msk->conn_list, addr);
 		mptcp_pm_remove_anno_addr(msk, addr, remove_subflow &&
 					  !(entry->flags & MPTCP_PM_ADDR_FLAG_IMPLICIT));
-		if (remove_subflow)
+
+		if (remove_subflow) {
 			mptcp_pm_remove_subflow(msk, &list);
+		} else if (entry->flags & MPTCP_PM_ADDR_FLAG_SUBFLOW) {
+			/* If the subflow has been used, but now closed */
+			spin_lock_bh(&msk->pm.lock);
+			if (!__test_and_set_bit(entry->addr.id, msk->pm.id_avail_bitmap))
+				msk->pm.local_addr_used--;
+			spin_unlock_bh(&msk->pm.lock);
+		}
+
 		release_sock(sk);
 
 next:

Re: FAILED: patch "[PATCH] mptcp: pm: re-using ID of unused removed subflows" failed to apply to 5.15-stable tree

[Matthieu Baerts]

Hi Greg,

On 26/08/2024 14:04, gregkh@linuxfoundation.org wrote:
> 
> 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>.

Thank you for the notification!

(...)

> ------------------ original commit in Linus's tree ------------------
> 
> From edd8b5d868a4d459f3065493001e293901af758d Mon Sep 17 00:00:00 2001
> From: "Matthieu Baerts (NGI0)" <matttbe@kernel.org>
> Date: Mon, 19 Aug 2024 21:45:21 +0200
> Subject: [PATCH] mptcp: pm: re-using ID of unused removed subflows
> 
> If no subflow is attached to the 'subflow' endpoint that is being
> removed, the addr ID will not be marked as available again.
> 
> Mark the linked ID as available when removing the 'subflow' endpoint if
> no subflow is attached to it.
> 
> While at it, the local_addr_used counter is decremented if the ID was
> marked as being used to reflect the reality, but also to allow adding
> new endpoints after that.
> 
> Fixes: b6c08380860b ("mptcp: remove addr and subflow in PM netlink")

Similar to my previous message linked to the backport of "mptcp: pm:
re-using ID of unused removed ADD_ADDR" where this patch depends on
86e39e04482b ("mptcp: keep track of local endpoint still available for
each msk"), I don't think we need to backport this patch to v5.15.

Cheers,
Matt
-- 
Sponsored by the NGI0 Core fund.