mptcp: pm: register in-kernel and userspace PM

This patch defines the original in-kernel netlink path manager as a
new struct mptcp_pm_ops named "mptcp_pm_kernel", and register it in
mptcp_pm_kernel_register(). And define the userspace path manager as
a new struct mptcp_pm_ops named "mptcp_pm_userspace", and register it
in mptcp_pm_init().

To ensure that there's always a valid path manager available, the default
path manager "mptcp_pm_kernel" will be skipped in mptcp_pm_unregister().

Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250313-net-next-mptcp-pm-ops-intro-v1-7-f4e4a88efc50@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

4 files changed, 26 insertions, 0 deletions

diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c
index f4948a2cf9be..3896f21a46bd 100644
--- a/net/mptcp/pm.c
+++ b/net/mptcp/pm.c
@@ -1018,6 +1018,7 @@ void mptcp_pm_data_init(struct mptcp_sock *msk)
 void __init mptcp_pm_init(void)
 {
 	mptcp_pm_kernel_register();
+	mptcp_pm_userspace_register();
 	mptcp_pm_nl_init();
 }
 
@@ -1061,6 +1062,10 @@ int mptcp_pm_register(struct mptcp_pm_ops *pm_ops)
 
 void mptcp_pm_unregister(struct mptcp_pm_ops *pm_ops)
 {
+	/* skip unregistering the default path manager */
+	if (WARN_ON_ONCE(pm_ops == &mptcp_pm_kernel))
+		return;
+
 	spin_lock(&mptcp_pm_list_lock);
 	list_del_rcu(&pm_ops->list);
 	spin_unlock(&mptcp_pm_list_lock);
diff --git a/net/mptcp/pm_kernel.c b/net/mptcp/pm_kernel.c
index 806a9b5b3c07..d39e7c178460 100644
--- a/net/mptcp/pm_kernel.c
+++ b/net/mptcp/pm_kernel.c
@@ -1398,8 +1398,15 @@ static struct pernet_operations mptcp_pm_pernet_ops = {
 	.size = sizeof(struct pm_nl_pernet),
 };
 
+struct mptcp_pm_ops mptcp_pm_kernel = {
+	.name			= "kernel",
+	.owner			= THIS_MODULE,
+};
+
 void __init mptcp_pm_kernel_register(void)
 {
 	if (register_pernet_subsys(&mptcp_pm_pernet_ops) < 0)
 		panic("Failed to register MPTCP PM pernet subsystem.\n");
+
+	mptcp_pm_register(&mptcp_pm_kernel);
 }
diff --git a/net/mptcp/pm_userspace.c b/net/mptcp/pm_userspace.c
index 13856df22673..2cb62f026b1f 100644
--- a/net/mptcp/pm_userspace.c
+++ b/net/mptcp/pm_userspace.c
@@ -682,3 +682,13 @@ int mptcp_userspace_pm_get_addr(u8 id, struct mptcp_pm_addr_entry *addr,
 	sock_put(sk);
 	return ret;
 }
+
+static struct mptcp_pm_ops mptcp_pm_userspace = {
+	.name			= "userspace",
+	.owner			= THIS_MODULE,
+};
+
+void __init mptcp_pm_userspace_register(void)
+{
+	mptcp_pm_register(&mptcp_pm_userspace);
+}
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index ac8a178426e4..c9e435a1fd7c 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -1050,6 +1050,9 @@ int mptcp_pm_remove_addr(struct mptcp_sock *msk, const struct mptcp_rm_list *rm_
 void mptcp_pm_remove_addr_entry(struct mptcp_sock *msk,
 				struct mptcp_pm_addr_entry *entry);
 
+/* the default path manager, used in mptcp_pm_unregister */
+extern struct mptcp_pm_ops mptcp_pm_kernel;
+
 struct mptcp_pm_ops *mptcp_pm_find(const char *name);
 int mptcp_pm_register(struct mptcp_pm_ops *pm_ops);
 void mptcp_pm_unregister(struct mptcp_pm_ops *pm_ops);
@@ -1158,6 +1161,7 @@ static inline u8 subflow_get_local_id(const struct mptcp_subflow_context *subflo
 }
 
 void __init mptcp_pm_kernel_register(void);
+void __init mptcp_pm_userspace_register(void);
 void __init mptcp_pm_nl_init(void);
 void mptcp_pm_worker(struct mptcp_sock *msk);
 void __mptcp_pm_kernel_worker(struct mptcp_sock *msk);