mptcp: pm: change to fullmesh only for 'subflow'

If an endpoint doesn't have the 'subflow' endpoint -- 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.

Signed-off-by: Matthieu Baerts (NGI0) <[email protected]>

Author: matttbe

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;
 }