netdev - [PATCH net-next 02/10] mptcp: pm: change to fullmesh only for 'subflow'

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Message-Id: <20250221-net-next-mptcp-pm-misc-cleanup-3-v1-2-2b70ab1cee79@kernel.org>
Date: Fri, 21 Feb 2025 16:43:55 +0100
From: "Matthieu Baerts (NGI0)" <matttbe@...nel.org>
To: mptcp@...ts.linux.dev, Mat Martineau <martineau@...nel.org>, 
 Geliang Tang <geliang@...nel.org>, "David S. Miller" <davem@...emloft.net>, 
 Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, 
 Paolo Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org, 
 "Matthieu Baerts (NGI0)" <matttbe@...nel.org>
Subject: [PATCH net-next 02/10] mptcp: pm: change to fullmesh only for
 'subflow'

If an endpoint doesn't have the 'subflow' flag -- in fact, has no type,
so not 'subflow', 'signal', nor 'implicit' -- there are then no subflows
created from this local endpoint to at least the initial destination
address. In this case, no need to call mptcp_pm_nl_fullmesh() which is
there to recreate the subflows to reflect the new value of the fullmesh
attribute.

Similarly, there is then no need to iterate over all connections to do
nothing, if only the 'fullmesh' flag has been changed, and the endpoint
doesn't have the 'subflow' one. So stop early when dealing with this
specific case.

Reviewed-by: Mat Martineau <martineau@...nel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@...nel.org>
---
 net/mptcp/pm_netlink.c | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
index ff1e5695dc1db5e32d5f45bef7cf22e43aea0ef1..1a0695e087af02347678b9b6914d303554bcf1f3 100644
--- a/net/mptcp/pm_netlink.c
+++ b/net/mptcp/pm_netlink.c
@@ -1923,11 +1923,16 @@ static void mptcp_pm_nl_fullmesh(struct mptcp_sock *msk,
 }

 static void mptcp_nl_set_flags(struct net *net, struct mptcp_addr_info *addr,
-			       u8 bkup, u8 changed)
+			       u8 flags, u8 changed)
 {
+	u8 is_subflow = !!(flags & MPTCP_PM_ADDR_FLAG_SUBFLOW);
+	u8 bkup = !!(flags & MPTCP_PM_ADDR_FLAG_BACKUP);
 	long s_slot = 0, s_num = 0;
 	struct mptcp_sock *msk;

+	if (changed == MPTCP_PM_ADDR_FLAG_FULLMESH && !is_subflow)
+		return;
+
 	while ((msk = mptcp_token_iter_next(net, &s_slot, &s_num)) != NULL) {
 		struct sock *sk = (struct sock *)msk;

@@ -1937,7 +1942,8 @@ static void mptcp_nl_set_flags(struct net *net, struct mptcp_addr_info *addr,
 		lock_sock(sk);
 		if (changed & MPTCP_PM_ADDR_FLAG_BACKUP)
 			mptcp_pm_nl_mp_prio_send_ack(msk, addr, NULL, bkup);
-		if (changed & MPTCP_PM_ADDR_FLAG_FULLMESH)
+		/* Subflows will only be recreated if the SUBFLOW flag is set */
+		if (is_subflow && (changed & MPTCP_PM_ADDR_FLAG_FULLMESH))
 			mptcp_pm_nl_fullmesh(msk, addr);
 		release_sock(sk);

@@ -1959,7 +1965,6 @@ int mptcp_pm_nl_set_flags(struct mptcp_pm_addr_entry *local,
 	struct mptcp_pm_addr_entry *entry;
 	struct pm_nl_pernet *pernet;
 	u8 lookup_by_id = 0;
-	u8 bkup = 0;

 	pernet = pm_nl_get_pernet(net);

@@ -1972,9 +1977,6 @@ int mptcp_pm_nl_set_flags(struct mptcp_pm_addr_entry *local,
 		}
 	}

-	if (local->flags & MPTCP_PM_ADDR_FLAG_BACKUP)
-		bkup = 1;
-
 	spin_lock_bh(&pernet->lock);
 	entry = lookup_by_id ? __lookup_addr_by_id(pernet, local->addr.id) :
 			       __lookup_addr(pernet, &local->addr);
@@ -1996,7 +1998,7 @@ int mptcp_pm_nl_set_flags(struct mptcp_pm_addr_entry *local,
 	*local = *entry;
 	spin_unlock_bh(&pernet->lock);

-	mptcp_nl_set_flags(net, &local->addr, bkup, changed);
+	mptcp_nl_set_flags(net, &local->addr, entry->flags, changed);
 	return 0;
 }

-- 
2.47.1