Increase pm subflows counter on both server side and client side when
userspace pm creates a new subflow, and decrease the counter when it
closes a subflow.

Increase add_addr_signaled counter in mptcp_nl_cmd_announce() when the
address is announced by userspace PM.

This modification is similar to how the in-kernel PM is updating the
counter: when additional subflows are created/removed.

Fixes: 9ab4807c84a4 ("mptcp: netlink: Add MPTCP_PM_CMD_ANNOUNCE")
Fixes: 702c2f646d42 ("mptcp: netlink: allow userspace-driven subflow establishment")
Link: https://github.com/multipath-tcp/mptcp_net-next/issues/329
Signed-off-by: Geliang Tang <geliang.tang@suse.com>
---
 net/mptcp/pm.c           | 23 +++++++++++++++++++----
 net/mptcp/pm_userspace.c |  9 ++++++++-
 2 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c
index 7539137719ef..e7f944d09fcd 100644
--- a/net/mptcp/pm.c
+++ b/net/mptcp/pm.c
@@ -89,8 +89,15 @@ bool mptcp_pm_allow_new_subflow(struct mptcp_sock *msk)
 	unsigned int subflows_max;
 	int ret = 0;
 
-	if (mptcp_pm_is_userspace(msk))
-		return mptcp_userspace_pm_active(msk);
+	if (mptcp_pm_is_userspace(msk)) {
+		if (mptcp_userspace_pm_active(msk)) {
+			spin_lock_bh(&pm->lock);
+			pm->subflows++;
+			spin_unlock_bh(&pm->lock);
+			return true;
+		}
+		return false;
+	}
 
 	subflows_max = mptcp_pm_get_subflows_max(msk);
 
@@ -183,8 +190,16 @@ void mptcp_pm_subflow_check_next(struct mptcp_sock *msk, const struct sock *ssk,
 	struct mptcp_pm_data *pm = &msk->pm;
 	bool update_subflows;
 
-	update_subflows = (subflow->request_join || subflow->mp_join) &&
-			  mptcp_pm_is_kernel(msk);
+	update_subflows = subflow->request_join || subflow->mp_join;
+	if (mptcp_pm_is_userspace(msk)) {
+		if (update_subflows) {
+			spin_lock_bh(&pm->lock);
+			pm->subflows--;
+			spin_unlock_bh(&pm->lock);
+		}
+		return;
+	}
+
 	if (!READ_ONCE(pm->work_pending) && !update_subflows)
 		return;
 
diff --git a/net/mptcp/pm_userspace.c b/net/mptcp/pm_userspace.c
index ec26a3f0bc64..df09ebcc7a35 100644
--- a/net/mptcp/pm_userspace.c
+++ b/net/mptcp/pm_userspace.c
@@ -69,6 +69,7 @@ static int mptcp_userspace_pm_append_new_local_addr(struct mptcp_sock *msk,
 							MPTCP_PM_MAX_ADDR_ID + 1,
 							1);
 		list_add_tail_rcu(&e->list, &msk->pm.userspace_pm_local_addr_list);
+		msk->pm.local_addr_used++;
 		ret = e->addr.id;
 	} else if (match) {
 		ret = entry->addr.id;
@@ -89,6 +90,7 @@ static int mptcp_userspace_pm_delete_local_addr(struct mptcp_sock *msk,
 			/* TODO: a refcount is needed because the entry can
 			 * be used multiple times (e.g. fullmesh mode).
 			 */
+			msk->pm.local_addr_used--;
 			list_del_rcu(&entry->list);
 			kfree(entry);
 			return 0;
@@ -190,6 +192,7 @@ int mptcp_nl_cmd_announce(struct sk_buff *skb, struct genl_info *info)
 	spin_lock_bh(&msk->pm.lock);
 
 	if (mptcp_pm_alloc_anno_list(msk, &addr_val)) {
+		msk->pm.add_addr_signaled++;
 		mptcp_pm_announce_addr(msk, &addr_val.addr, false);
 		mptcp_pm_nl_addr_send_ack(msk);
 	}
@@ -348,7 +351,11 @@ int mptcp_nl_cmd_sf_create(struct sk_buff *skb, struct genl_info *info)
 
 	release_sock(sk);
 
-	if (err) {
+	if (!err) {
+		spin_lock_bh(&msk->pm.lock);
+		msk->pm.subflows++;
+		spin_unlock_bh(&msk->pm.lock);
+	} else {
 		spin_lock_bh(&msk->pm.lock);
 		mptcp_pm_remove_anno_list_by_saddr(msk, &addr_l);
 anno_list_err:
-- 
2.35.3