mptcp: add mptcp_userspace_pm_lookup_addr helper

Like __lookup_addr() helper in pm_netlink.c, a new helper
mptcp_userspace_pm_lookup_addr() is also defined in pm_userspace.c.
It looks up the corresponding mptcp_pm_addr_entry address in
userspace_pm_local_addr_list through the passed "addr" parameter
and returns the found address entry.

This helper can be used in mptcp_userspace_pm_delete_local_addr(),
mptcp_userspace_pm_set_flags(), mptcp_userspace_pm_get_local_id()
and mptcp_userspace_pm_is_backup() to simplify the code.

Please note that with this change now list_for_each_entry() is used in
mptcp_userspace_pm_append_new_local_addr(), not list_for_each_entry_safe(),
but that's OK to do so because mptcp_userspace_pm_lookup_addr() only
returns an entry from the list, the list hasn't been modified here.

Signed-off-by: Geliang Tang <[email protected]>
Reviewed-by: Matthieu Baerts (NGI0) <[email protected]>
Signed-off-by: Matthieu Baerts (NGI0) <[email protected]>
Link: https://patch.msgid.link/20241213-net-next-mptcp-pm-misc-cleanup-v1-1-ddb6d00109a8@kernel.org
Signed-off-by: Jakub Kicinski <[email protected]>

Author: Geliang Tang

net/mptcp/pm_userspace.c

@@ -26,6 +26,19 @@ void mptcp_free_local_addr_list(struct mptcp_sock *msk)
 	}
 }
 
+static struct mptcp_pm_addr_entry *
+mptcp_userspace_pm_lookup_addr(struct mptcp_sock *msk,
+			       const struct mptcp_addr_info *addr)
+{
+	struct mptcp_pm_addr_entry *entry;
+
+	list_for_each_entry(entry, &msk->pm.userspace_pm_local_addr_list, list) {
+		if (mptcp_addresses_equal(&entry->addr, addr, false))
+			return entry;
+	}
+	return NULL;
+}
+
 static int mptcp_userspace_pm_append_new_local_addr(struct mptcp_sock *msk,
 						    struct mptcp_pm_addr_entry *entry,
 						    bool needs_id)
@@ -90,22 +103,20 @@ static int mptcp_userspace_pm_append_new_local_addr(struct mptcp_sock *msk,
 static int mptcp_userspace_pm_delete_local_addr(struct mptcp_sock *msk,
 						struct mptcp_pm_addr_entry *addr)
 {
-	struct mptcp_pm_addr_entry *entry, *tmp;
 	struct sock *sk = (struct sock *)msk;
+	struct mptcp_pm_addr_entry *entry;
 
-	list_for_each_entry_safe(entry, tmp, &msk->pm.userspace_pm_local_addr_list, list) {
-		if (mptcp_addresses_equal(&entry->addr, &addr->addr, false)) {
-			/* TODO: a refcount is needed because the entry can
-			 * be used multiple times (e.g. fullmesh mode).
-			 */
-			list_del_rcu(&entry->list);
-			sock_kfree_s(sk, entry, sizeof(*entry));
-			msk->pm.local_addr_used--;
-			return 0;
-		}
-	}
-
-	return -EINVAL;
+	entry = mptcp_userspace_pm_lookup_addr(msk, &addr->addr);
+	if (!entry)
+		return -EINVAL;
+
+	/* TODO: a refcount is needed because the entry can
+	 * be used multiple times (e.g. fullmesh mode).
+	 */
+	list_del_rcu(&entry->list);
+	sock_kfree_s(sk, entry, sizeof(*entry));
+	msk->pm.local_addr_used--;
+	return 0;
 }
 
 static struct mptcp_pm_addr_entry *
@@ -123,17 +134,12 @@ mptcp_userspace_pm_lookup_addr_by_id(struct mptcp_sock *msk, unsigned int id)
 int mptcp_userspace_pm_get_local_id(struct mptcp_sock *msk,
 				    struct mptcp_addr_info *skc)
 {
-	struct mptcp_pm_addr_entry *entry = NULL, *e, new_entry;
+	struct mptcp_pm_addr_entry *entry = NULL, new_entry;
 	__be16 msk_sport =  ((struct inet_sock *)
 			     inet_sk((struct sock *)msk))->inet_sport;
 
 	spin_lock_bh(&msk->pm.lock);
-	list_for_each_entry(e, &msk->pm.userspace_pm_local_addr_list, list) {
-		if (mptcp_addresses_equal(&e->addr, skc, false)) {
-			entry = e;
-			break;
-		}
-	}
+	entry = mptcp_userspace_pm_lookup_addr(msk, skc);
 	spin_unlock_bh(&msk->pm.lock);
 	if (entry)
 		return entry->addr.id;
@@ -153,15 +159,11 @@ bool mptcp_userspace_pm_is_backup(struct mptcp_sock *msk,
 				  struct mptcp_addr_info *skc)
 {
 	struct mptcp_pm_addr_entry *entry;
-	bool backup = false;
+	bool backup;
 
 	spin_lock_bh(&msk->pm.lock);
-	list_for_each_entry(entry, &msk->pm.userspace_pm_local_addr_list, list) {
-		if (mptcp_addresses_equal(&entry->addr, skc, false)) {
-			backup = !!(entry->flags & MPTCP_PM_ADDR_FLAG_BACKUP);
-			break;
-		}
-	}
+	entry = mptcp_userspace_pm_lookup_addr(msk, skc);
+	backup = entry && !!(entry->flags & MPTCP_PM_ADDR_FLAG_BACKUP);
 	spin_unlock_bh(&msk->pm.lock);
 
 	return backup;
@@ -606,13 +608,12 @@ int mptcp_userspace_pm_set_flags(struct sk_buff *skb, struct genl_info *info)
 		bkup = 1;
 
 	spin_lock_bh(&msk->pm.lock);
-	list_for_each_entry(entry, &msk->pm.userspace_pm_local_addr_list, list) {
-		if (mptcp_addresses_equal(&entry->addr, &loc.addr, false)) {
-			if (bkup)
-				entry->flags |= MPTCP_PM_ADDR_FLAG_BACKUP;
-			else
-				entry->flags &= ~MPTCP_PM_ADDR_FLAG_BACKUP;
-		}
+	entry = mptcp_userspace_pm_lookup_addr(msk, &loc.addr);
+	if (entry) {
+		if (bkup)
+			entry->flags |= MPTCP_PM_ADDR_FLAG_BACKUP;
+		else
+			entry->flags &= ~MPTCP_PM_ADDR_FLAG_BACKUP;
 	}
 	spin_unlock_bh(&msk->pm.lock);