mptcp: add userspace_pm_lookup_addr_by_id helper

Corresponding __lookup_addr_by_id() helper in the in-kernel netlink PM,
this patch adds a new helper mptcp_userspace_pm_lookup_addr_by_id() to
lookup the address entry with the given id on the userspace pm local
address list.
Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/mptcp/pm_userspace.c

@@ -106,19 +106,26 @@ static int mptcp_userspace_pm_delete_local_addr(struct mptcp_sock *msk,
 	return -EINVAL;
 }
 
+static struct mptcp_pm_addr_entry *
+mptcp_userspace_pm_lookup_addr_by_id(struct mptcp_sock *msk, unsigned int id)
+{
+	struct mptcp_pm_addr_entry *entry;
+
+	list_for_each_entry(entry, &msk->pm.userspace_pm_local_addr_list, list) {
+		if (entry->addr.id == id)
+			return entry;
+	}
+	return NULL;
+}
+
 int mptcp_userspace_pm_get_flags_and_ifindex_by_id(struct mptcp_sock *msk,
 						   unsigned int id,
 						   u8 *flags, int *ifindex)
 {
-	struct mptcp_pm_addr_entry *entry, *match = NULL;
+	struct mptcp_pm_addr_entry *match;
 
 	spin_lock_bh(&msk->pm.lock);
-	list_for_each_entry(entry, &msk->pm.userspace_pm_local_addr_list, list) {
-		if (id == entry->addr.id) {
-			match = entry;
-			break;
-		}
-	}
+	match = mptcp_userspace_pm_lookup_addr_by_id(msk, id);
 	spin_unlock_bh(&msk->pm.lock);
 	if (match) {
 		*flags = match->flags;
@@ -261,7 +268,7 @@ int mptcp_pm_nl_remove_doit(struct sk_buff *skb, struct genl_info *info)
 {
 	struct nlattr *token = info->attrs[MPTCP_PM_ATTR_TOKEN];
 	struct nlattr *id = info->attrs[MPTCP_PM_ATTR_LOC_ID];
-	struct mptcp_pm_addr_entry *match = NULL;
+	struct mptcp_pm_addr_entry *match;
 	struct mptcp_pm_addr_entry *entry;
 	struct mptcp_sock *msk;
 	LIST_HEAD(free_list);
@@ -298,13 +305,7 @@ int mptcp_pm_nl_remove_doit(struct sk_buff *skb, struct genl_info *info)
 
 	lock_sock(sk);
 
-	list_for_each_entry(entry, &msk->pm.userspace_pm_local_addr_list, list) {
-		if (entry->addr.id == id_val) {
-			match = entry;
-			break;
-		}
-	}
-
+	match = mptcp_userspace_pm_lookup_addr_by_id(msk, id_val);
 	if (!match) {
 		GENL_SET_ERR_MSG(info, "address with specified id not found");
 		release_sock(sk);