[PATCH net-next 06/12] mptcp: pm: define struct mptcp_pm_ops

Matthieu Baerts (NGI0)
2025-03-13T10:22:33Z

From: Geliang Tang <tanggeliang@kylinos.cn>

In order to allow users to develop their own BPF-based path manager,
this patch defines a struct ops "mptcp_pm_ops" for an MPTCP path
manager, which contains a set of interfaces. Currently only init()
and release() interfaces are included, subsequent patches will add
others step by step.

Add a set of functions to register, unregister, find and validate a
given path manager struct ops.

"list" is used to add this path manager to mptcp_pm_list list when
it is registered. "name" is used to identify this path manager.
mptcp_pm_find() uses "name" to find a path manager on the list.

mptcp_pm_unregister is not used in this set, but will be invoked in
.unreg of struct bpf_struct_ops. mptcp_pm_validate() will be invoked
in .validate of struct bpf_struct_ops. That's why they are exported.

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>
---
include/net/mptcp.h | 12 ++++++++++++
net/mptcp/pm.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
net/mptcp/protocol.h | 5 +++++
3 files changed, 67 insertions(+)

diff --git a/include/net/mptcp.h b/include/net/mptcp.h
index 2c85ca92bb1c39989ae08a74ff4ef9b42099e60d..645d15695e3f5ec4b945bb543630f3dcc54453f2 100644
--- a/include/net/mptcp.h
+++ b/include/net/mptcp.h
@@ -14,6 +14,7 @@

struct mptcp_info;
struct mptcp_sock;
+struct mptcp_pm_addr_entry;
struct seq_file;

/* MPTCP sk_buff extension data */
@@ -121,6 +122,17 @@ struct mptcp_sched_ops {
void (*release)(struct mptcp_sock *msk);
} ____cacheline_aligned_in_smp;

+#define MPTCP_PM_NAME_MAX 16
+
+struct mptcp_pm_ops {
+ char name[MPTCP_PM_NAME_MAX];
+ struct module *owner;
+ struct list_head list;
+
+ void (*init)(struct mptcp_sock *msk);
+ void (*release)(struct mptcp_sock *msk);
+} ____cacheline_aligned_in_smp;
+
#ifdef CONFIG_MPTCP
void mptcp_init(void);

diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c
index 85ee999729a1c37f42bb21490d7f68d186e6734f..f4948a2cf9be078043bd237f56a57c27804ef4db 100644
--- a/net/mptcp/pm.c
+++ b/net/mptcp/pm.c
@@ -5,6 +5,8 @@
*/
#define pr_fmt(fmt) "MPTCP: " fmt

+#include <linux/rculist.h>
+#include <linux/spinlock.h>
#include "protocol.h"
#include "mib.h"

@@ -18,6 +20,9 @@ struct mptcp_pm_add_entry {
struct mptcp_sock *sock;
};

+static DEFINE_SPINLOCK(mptcp_pm_list_lock);
+static LIST_HEAD(mptcp_pm_list);
+
/* path manager helpers */

/* if sk is ipv4 or ipv6_only allows only same-family local and remote addresses,
@@ -1015,3 +1020,48 @@ void __init mptcp_pm_init(void)
mptcp_pm_kernel_register();
mptcp_pm_nl_init();
}
+
+/* Must be called with rcu read lock held */
+struct mptcp_pm_ops *mptcp_pm_find(const char *name)
+{
+ struct mptcp_pm_ops *pm_ops;
+
+ list_for_each_entry_rcu(pm_ops, &mptcp_pm_list, list) {
+ if (!strcmp(pm_ops->name, name))
+ return pm_ops;
+ }
+
+ return NULL;
+}
+
+int mptcp_pm_validate(struct mptcp_pm_ops *pm_ops)
+{
+ return 0;
+}
+
+int mptcp_pm_register(struct mptcp_pm_ops *pm_ops)
+{
+ int ret;
+
+ ret = mptcp_pm_validate(pm_ops);
+ if (ret)
+ return ret;
+
+ spin_lock(&mptcp_pm_list_lock);
+ if (mptcp_pm_find(pm_ops->name)) {
+ spin_unlock(&mptcp_pm_list_lock);
+ return -EEXIST;
+ }
+ list_add_tail_rcu(&pm_ops->list, &mptcp_pm_list);
+ spin_unlock(&mptcp_pm_list_lock);
+
+ pr_debug("%s registered\n", pm_ops->name);
+ return 0;
+}
+
+void mptcp_pm_unregister(struct mptcp_pm_ops *pm_ops)
+{
+ spin_lock(&mptcp_pm_list_lock);
+ list_del_rcu(&pm_ops->list);
+ spin_unlock(&mptcp_pm_list_lock);
+}
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 15e2a03025ecb4cae44ccb700fcbbdd06ab806d1..ac8a178426e4ef495d7c5b5b9bd4c8b8835d71e4 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -1050,6 +1050,11 @@ 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);

+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);
+int mptcp_pm_validate(struct mptcp_pm_ops *pm_ops);
+
void mptcp_userspace_pm_free_local_addr_list(struct mptcp_sock *msk);

void mptcp_event(enum mptcp_event_type type, const struct mptcp_sock *msk,

--
2.48.1