Merge branch 'mptcp-pm-prep-work-for-new-ops-and-sysctl-knobs'

Matthieu Baerts says:

====================
mptcp: pm: prep work for new ops and sysctl knobs

Here are a few cleanups, preparation work for the new PM ops, and sysctl
knobs.

- Patch 1: reorg: move generic NL code used by all PMs to pm_netlink.c.

- Patch 2: use kmemdup() instead of kmalloc + copy.

- Patch 3: small cleanup to use pm var instead of msk->pm.

- Patch 4: reorg: id_avail_bitmap is only used by the in-kernel PM.

- Patch 5: use struct_group to easily reset a subset of PM data vars.

- Patch 6: introduce the minimal skeleton for the new PM ops.

- Patch 7: register in-kernel and userspace PM ops.

- Patch 8: new net.mptcp.path_manager sysctl knob, deprecating pm_type.

- Patch 9: map the new path_manager sysctl knob with pm_type.

- Patch 10: map the old pm_type sysctl knob with path_manager.

- Patch 11: new net.mptcp.available_path_managers sysctl knob.

- Patch 12: new test to validate path_manager and pm_type mapping.

Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
====================

Link: https://patch.msgid.link/20250313-net-next-mptcp-pm-ops-intro-v1-0-f4e4a88efc50@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

1 files changed, 81 insertions, 16 deletions

diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c
index 833839d7286e..18b19dbccbba 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,
@@ -511,13 +516,13 @@ void mptcp_pm_fully_established(struct mptcp_sock *msk, const struct sock *ssk)
 	 * be sure to serve this event only once.
 	 */
 	if (READ_ONCE(pm->work_pending) &&
-	    !(msk->pm.status & BIT(MPTCP_PM_ALREADY_ESTABLISHED)))
+	    !(pm->status & BIT(MPTCP_PM_ALREADY_ESTABLISHED)))
 		mptcp_pm_schedule_work(msk, MPTCP_PM_ESTABLISHED);
 
-	if ((msk->pm.status & BIT(MPTCP_PM_ALREADY_ESTABLISHED)) == 0)
+	if ((pm->status & BIT(MPTCP_PM_ALREADY_ESTABLISHED)) == 0)
 		announce = true;
 
-	msk->pm.status |= BIT(MPTCP_PM_ALREADY_ESTABLISHED);
+	pm->status |= BIT(MPTCP_PM_ALREADY_ESTABLISHED);
 	spin_unlock_bh(&pm->lock);
 
 	if (announce)
@@ -978,10 +983,7 @@ void mptcp_pm_data_reset(struct mptcp_sock *msk)
 	u8 pm_type = mptcp_get_pm_type(sock_net((struct sock *)msk));
 	struct mptcp_pm_data *pm = &msk->pm;
 
-	pm->add_addr_signaled = 0;
-	pm->add_addr_accepted = 0;
-	pm->local_addr_used = 0;
-	pm->subflows = 0;
+	memset(&pm->reset, 0, sizeof(pm->reset));
 	pm->rm_list_tx.nr = 0;
 	pm->rm_list_rx.nr = 0;
 	WRITE_ONCE(pm->pm_type, pm_type);
@@ -1000,16 +1002,9 @@ void mptcp_pm_data_reset(struct mptcp_sock *msk)
 			   !!mptcp_pm_get_add_addr_accept_max(msk) &&
 			   subflows_allowed);
 		WRITE_ONCE(pm->accept_subflow, subflows_allowed);
-	} else {
-		WRITE_ONCE(pm->work_pending, 0);
-		WRITE_ONCE(pm->accept_addr, 0);
-		WRITE_ONCE(pm->accept_subflow, 0);
-	}
 
-	WRITE_ONCE(pm->addr_signal, 0);
-	WRITE_ONCE(pm->remote_deny_join_id0, false);
-	pm->status = 0;
-	bitmap_fill(msk->pm.id_avail_bitmap, MPTCP_PM_MAX_ADDR_ID + 1);
+		bitmap_fill(pm->id_avail_bitmap, MPTCP_PM_MAX_ADDR_ID + 1);
+	}
 }
 
 void mptcp_pm_data_init(struct mptcp_sock *msk)
@@ -1022,5 +1017,75 @@ 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();
 }
+
+/* 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)
+{
+	/* 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);
+}
+
+/* Build string with list of available path manager values.
+ * Similar to tcp_get_available_congestion_control()
+ */
+void mptcp_pm_get_available(char *buf, size_t maxlen)
+{
+	struct mptcp_pm_ops *pm_ops;
+	size_t offs = 0;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(pm_ops, &mptcp_pm_list, list) {
+		offs += snprintf(buf + offs, maxlen - offs, "%s%s",
+				 offs == 0 ? "" : " ", pm_ops->name);
+
+		if (WARN_ON_ONCE(offs >= maxlen))
+			break;
+	}
+	rcu_read_unlock();
+}