mptcp: pm: avoid code duplication to lookup endp

The helper __lookup_addr() can be used in mptcp_pm_nl_get_local_id()
and mptcp_pm_nl_is_backup() to simplify the code, and avoid code
duplication.

Co-developed-by: Matthieu Baerts (NGI0) <[email protected]>
Signed-off-by: Matthieu Baerts (NGI0) <[email protected]>
Signed-off-by: Geliang Tang <[email protected]>
Signed-off-by: Matthieu Baerts (NGI0) <[email protected]>
Link: https://patch.msgid.link/20241115-net-next-mptcp-pm-lockless-dump-v1-2-f4a1bcb4ca2c@kernel.org
Signed-off-by: Jakub Kicinski <[email protected]>

Author: Geliang Tang

net/mptcp/pm_netlink.c

@@ -1143,17 +1143,13 @@ int mptcp_pm_nl_get_local_id(struct mptcp_sock *msk, struct mptcp_addr_info *skc
 {
 	struct mptcp_pm_addr_entry *entry;
 	struct pm_nl_pernet *pernet;
-	int ret = -1;
+	int ret;
 
 	pernet = pm_nl_get_pernet_from_msk(msk);
 
 	rcu_read_lock();
-	list_for_each_entry_rcu(entry, &pernet->local_addr_list, list) {
-		if (mptcp_addresses_equal(&entry->addr, skc, entry->addr.port)) {
-			ret = entry->addr.id;
-			break;
-		}
-	}
+	entry = __lookup_addr(pernet, skc);
+	ret = entry ? entry->addr.id : -1;
 	rcu_read_unlock();
 	if (ret >= 0)
 		return ret;
@@ -1180,15 +1176,11 @@ bool mptcp_pm_nl_is_backup(struct mptcp_sock *msk, struct mptcp_addr_info *skc)
 {
 	struct pm_nl_pernet *pernet = pm_nl_get_pernet_from_msk(msk);
 	struct mptcp_pm_addr_entry *entry;
-	bool backup = false;
+	bool backup;
 
 	rcu_read_lock();
-	list_for_each_entry_rcu(entry, &pernet->local_addr_list, list) {
-		if (mptcp_addresses_equal(&entry->addr, skc, entry->addr.port)) {
-			backup = !!(entry->flags & MPTCP_PM_ADDR_FLAG_BACKUP);
-			break;
-		}
-	}
+	entry = __lookup_addr(pernet, skc);
+	backup = entry && !!(entry->flags & MPTCP_PM_ADDR_FLAG_BACKUP);
 	rcu_read_unlock();
 
 	return backup;