The new net.mptcp.pm_type sysctl determines which path manager will be
used by each newly-created MPTCP socket.

Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
---
 Documentation/networking/mptcp-sysctl.rst | 18 ++++++++++++++++++
 net/mptcp/ctrl.c                          | 18 ++++++++++++++++++
 net/mptcp/pm.c                            | 13 +++++++++----
 net/mptcp/protocol.h                      |  1 +
 4 files changed, 46 insertions(+), 4 deletions(-)

diff --git a/Documentation/networking/mptcp-sysctl.rst b/Documentation/networking/mptcp-sysctl.rst
index b0d4da71e68e..e263dfcc4b40 100644
--- a/Documentation/networking/mptcp-sysctl.rst
+++ b/Documentation/networking/mptcp-sysctl.rst
@@ -46,6 +46,24 @@ allow_join_initial_addr_port - BOOLEAN
 
 	Default: 1
 
+pm_type - INTEGER
+
+	Set the default path manager type to use for each new MPTCP
+	socket. In-kernel path management will control subflow
+	connections and address advertisements according to
+	per-namespace values configured over the MPTCP netlink
+	API. Userspace path management puts per-MPTCP-connection subflow
+	connection decisions and address advertisements under control of
+	a privileged userspace program, at the cost of more netlink
+	traffic to propagate all of the related events and commands.
+
+	This is a per-namespace sysctl.
+
+	* 0 - In-kernel path manager
+	* 1 - Userspace path manager
+
+	Default: 0
+
 stale_loss_cnt - INTEGER
 	The number of MPTCP-level retransmission intervals with no traffic and
 	pending outstanding data on a given subflow required to declare it stale.
diff --git a/net/mptcp/ctrl.c b/net/mptcp/ctrl.c
index 8b235468c88f..64f1366aec5e 100644
--- a/net/mptcp/ctrl.c
+++ b/net/mptcp/ctrl.c
@@ -16,6 +16,8 @@
 #define MPTCP_SYSCTL_PATH "net/mptcp"
 
 static int mptcp_pernet_id;
+static int mptcp_pm_type_max = __MPTCP_PM_TYPE_MAX;
+
 struct mptcp_pernet {
 #ifdef CONFIG_SYSCTL
 	struct ctl_table_header *ctl_table_hdr;
@@ -26,6 +28,7 @@ struct mptcp_pernet {
 	u8 mptcp_enabled;
 	u8 checksum_enabled;
 	u8 allow_join_initial_addr_port;
+	u8 pm_type;
 };
 
 static struct mptcp_pernet *mptcp_get_pernet(const struct net *net)
@@ -58,6 +61,11 @@ unsigned int mptcp_stale_loss_cnt(const struct net *net)
 	return mptcp_get_pernet(net)->stale_loss_cnt;
 }
 
+int mptcp_get_pm_type(const struct net *net)
+{
+	return mptcp_get_pernet(net)->pm_type;
+}
+
 static void mptcp_pernet_set_defaults(struct mptcp_pernet *pernet)
 {
 	pernet->mptcp_enabled = 1;
@@ -65,6 +73,7 @@ static void mptcp_pernet_set_defaults(struct mptcp_pernet *pernet)
 	pernet->checksum_enabled = 0;
 	pernet->allow_join_initial_addr_port = 1;
 	pernet->stale_loss_cnt = 4;
+	pernet->pm_type = MPTCP_PM_TYPE_KERNEL;
 }
 
 #ifdef CONFIG_SYSCTL
@@ -108,6 +117,14 @@ static struct ctl_table mptcp_sysctl_table[] = {
 		.mode = 0644,
 		.proc_handler = proc_douintvec_minmax,
 	},
+	{
+		.procname = "pm_type",
+		.maxlen = sizeof(u8),
+		.mode = 0644,
+		.proc_handler = proc_dou8vec_minmax,
+		.extra1       = SYSCTL_ZERO,
+		.extra2       = &mptcp_pm_type_max
+	},
 	{}
 };
 
@@ -128,6 +145,7 @@ static int mptcp_pernet_new_table(struct net *net, struct mptcp_pernet *pernet)
 	table[2].data = &pernet->checksum_enabled;
 	table[3].data = &pernet->allow_join_initial_addr_port;
 	table[4].data = &pernet->stale_loss_cnt;
+	table[5].data = &pernet->pm_type;
 
 	hdr = register_net_sysctl(net, MPTCP_SYSCTL_PATH, table);
 	if (!hdr)
diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c
index 7f96a888e2d5..7ef27d41ad56 100644
--- a/net/mptcp/pm.c
+++ b/net/mptcp/pm.c
@@ -368,8 +368,12 @@ void mptcp_pm_subflow_chk_stale(const struct mptcp_sock *msk, struct sock *ssk)
 
 void mptcp_pm_data_init(struct mptcp_sock *msk)
 {
-	bool subflows_allowed = !!mptcp_pm_get_subflows_max(msk);
+	u8 pm_type = mptcp_get_pm_type(sock_net((struct sock *)msk));
 	struct mptcp_pm_data *pm = &msk->pm;
+	bool subflows_allowed;
+
+	subflows_allowed = !!mptcp_pm_get_subflows_max(msk) &&
+		pm_type == MPTCP_PM_TYPE_KERNEL;
 
 	pm->add_addr_signaled = 0;
 	pm->add_addr_accepted = 0;
@@ -377,13 +381,14 @@ void mptcp_pm_data_init(struct mptcp_sock *msk)
 	pm->subflows = 0;
 	pm->rm_list_tx.nr = 0;
 	pm->rm_list_rx.nr = 0;
-	WRITE_ONCE(pm->pm_type, MPTCP_PM_TYPE_KERNEL);
+	WRITE_ONCE(pm->pm_type, pm_type);
 	/* pm->work_pending must be only be set to 'true' when
 	 * pm->pm_type is set to MPTCP_PM_TYPE_KERNEL
 	 */
 	WRITE_ONCE(pm->work_pending,
-		   (!!mptcp_pm_get_local_addr_max(msk) && subflows_allowed) ||
-		   !!mptcp_pm_get_add_addr_signal_max(msk));
+		   pm_type == MPTCP_PM_TYPE_KERNEL &&
+		   ((!!mptcp_pm_get_local_addr_max(msk) && subflows_allowed) ||
+		    !!mptcp_pm_get_add_addr_signal_max(msk)));
 	WRITE_ONCE(pm->addr_signal, 0);
 	WRITE_ONCE(pm->accept_addr,
 		   !!mptcp_pm_get_add_addr_accept_max(msk) && subflows_allowed);
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index edaf0cc75474..b56ad45703dd 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -563,6 +563,7 @@ unsigned int mptcp_get_add_addr_timeout(const struct net *net);
 int mptcp_is_checksum_enabled(const struct net *net);
 int mptcp_allow_join_id0(const struct net *net);
 unsigned int mptcp_stale_loss_cnt(const struct net *net);
+int mptcp_get_pm_type(const struct net *net);
 void mptcp_subflow_fully_established(struct mptcp_subflow_context *subflow,
 				     struct mptcp_options_received *mp_opt);
 bool __mptcp_retransmit_pending_data(struct sock *sk);
-- 
2.34.0

On Wed, 17 Nov 2021, Mat Martineau wrote:

> The new net.mptcp.pm_type sysctl determines which path manager will be
> used by each newly-created MPTCP socket.
>
> Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
> ---
> Documentation/networking/mptcp-sysctl.rst | 18 ++++++++++++++++++
> net/mptcp/ctrl.c                          | 18 ++++++++++++++++++
> net/mptcp/pm.c                            | 13 +++++++++----
> net/mptcp/protocol.h                      |  1 +
> 4 files changed, 46 insertions(+), 4 deletions(-)
>
> diff --git a/Documentation/networking/mptcp-sysctl.rst b/Documentation/networking/mptcp-sysctl.rst
> index b0d4da71e68e..e263dfcc4b40 100644
> --- a/Documentation/networking/mptcp-sysctl.rst
> +++ b/Documentation/networking/mptcp-sysctl.rst
> @@ -46,6 +46,24 @@ allow_join_initial_addr_port - BOOLEAN
>
> 	Default: 1
>
> +pm_type - INTEGER
> +
> +	Set the default path manager type to use for each new MPTCP
> +	socket. In-kernel path management will control subflow
> +	connections and address advertisements according to
> +	per-namespace values configured over the MPTCP netlink
> +	API. Userspace path management puts per-MPTCP-connection subflow
> +	connection decisions and address advertisements under control of
> +	a privileged userspace program, at the cost of more netlink
> +	traffic to propagate all of the related events and commands.
> +
> +	This is a per-namespace sysctl.
> +
> +	* 0 - In-kernel path manager
> +	* 1 - Userspace path manager
> +
> +	Default: 0
> +
> stale_loss_cnt - INTEGER
> 	The number of MPTCP-level retransmission intervals with no traffic and
> 	pending outstanding data on a given subflow required to declare it stale.
> diff --git a/net/mptcp/ctrl.c b/net/mptcp/ctrl.c
> index 8b235468c88f..64f1366aec5e 100644
> --- a/net/mptcp/ctrl.c
> +++ b/net/mptcp/ctrl.c
> @@ -16,6 +16,8 @@
> #define MPTCP_SYSCTL_PATH "net/mptcp"
>
> static int mptcp_pernet_id;
> +static int mptcp_pm_type_max = __MPTCP_PM_TYPE_MAX;
> +

CI found an unused variable warning here - above line needs "#ifdef 
CONFIG_SYSCTL" around it.

- Mat

> struct mptcp_pernet {
> #ifdef CONFIG_SYSCTL
> 	struct ctl_table_header *ctl_table_hdr;
> @@ -26,6 +28,7 @@ struct mptcp_pernet {
> 	u8 mptcp_enabled;
> 	u8 checksum_enabled;
> 	u8 allow_join_initial_addr_port;
> +	u8 pm_type;
> };
>
> static struct mptcp_pernet *mptcp_get_pernet(const struct net *net)
> @@ -58,6 +61,11 @@ unsigned int mptcp_stale_loss_cnt(const struct net *net)
> 	return mptcp_get_pernet(net)->stale_loss_cnt;
> }
>
> +int mptcp_get_pm_type(const struct net *net)
> +{
> +	return mptcp_get_pernet(net)->pm_type;
> +}
> +
> static void mptcp_pernet_set_defaults(struct mptcp_pernet *pernet)
> {
> 	pernet->mptcp_enabled = 1;
> @@ -65,6 +73,7 @@ static void mptcp_pernet_set_defaults(struct mptcp_pernet *pernet)
> 	pernet->checksum_enabled = 0;
> 	pernet->allow_join_initial_addr_port = 1;
> 	pernet->stale_loss_cnt = 4;
> +	pernet->pm_type = MPTCP_PM_TYPE_KERNEL;
> }
>
> #ifdef CONFIG_SYSCTL
> @@ -108,6 +117,14 @@ static struct ctl_table mptcp_sysctl_table[] = {
> 		.mode = 0644,
> 		.proc_handler = proc_douintvec_minmax,
> 	},
> +	{
> +		.procname = "pm_type",
> +		.maxlen = sizeof(u8),
> +		.mode = 0644,
> +		.proc_handler = proc_dou8vec_minmax,
> +		.extra1       = SYSCTL_ZERO,
> +		.extra2       = &mptcp_pm_type_max
> +	},
> 	{}
> };
>
> @@ -128,6 +145,7 @@ static int mptcp_pernet_new_table(struct net *net, struct mptcp_pernet *pernet)
> 	table[2].data = &pernet->checksum_enabled;
> 	table[3].data = &pernet->allow_join_initial_addr_port;
> 	table[4].data = &pernet->stale_loss_cnt;
> +	table[5].data = &pernet->pm_type;
>
> 	hdr = register_net_sysctl(net, MPTCP_SYSCTL_PATH, table);
> 	if (!hdr)
> diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c
> index 7f96a888e2d5..7ef27d41ad56 100644
> --- a/net/mptcp/pm.c
> +++ b/net/mptcp/pm.c
> @@ -368,8 +368,12 @@ void mptcp_pm_subflow_chk_stale(const struct mptcp_sock *msk, struct sock *ssk)
>
> void mptcp_pm_data_init(struct mptcp_sock *msk)
> {
> -	bool subflows_allowed = !!mptcp_pm_get_subflows_max(msk);
> +	u8 pm_type = mptcp_get_pm_type(sock_net((struct sock *)msk));
> 	struct mptcp_pm_data *pm = &msk->pm;
> +	bool subflows_allowed;
> +
> +	subflows_allowed = !!mptcp_pm_get_subflows_max(msk) &&
> +		pm_type == MPTCP_PM_TYPE_KERNEL;
>
> 	pm->add_addr_signaled = 0;
> 	pm->add_addr_accepted = 0;
> @@ -377,13 +381,14 @@ void mptcp_pm_data_init(struct mptcp_sock *msk)
> 	pm->subflows = 0;
> 	pm->rm_list_tx.nr = 0;
> 	pm->rm_list_rx.nr = 0;
> -	WRITE_ONCE(pm->pm_type, MPTCP_PM_TYPE_KERNEL);
> +	WRITE_ONCE(pm->pm_type, pm_type);
> 	/* pm->work_pending must be only be set to 'true' when
> 	 * pm->pm_type is set to MPTCP_PM_TYPE_KERNEL
> 	 */
> 	WRITE_ONCE(pm->work_pending,
> -		   (!!mptcp_pm_get_local_addr_max(msk) && subflows_allowed) ||
> -		   !!mptcp_pm_get_add_addr_signal_max(msk));
> +		   pm_type == MPTCP_PM_TYPE_KERNEL &&
> +		   ((!!mptcp_pm_get_local_addr_max(msk) && subflows_allowed) ||
> +		    !!mptcp_pm_get_add_addr_signal_max(msk)));
> 	WRITE_ONCE(pm->addr_signal, 0);
> 	WRITE_ONCE(pm->accept_addr,
> 		   !!mptcp_pm_get_add_addr_accept_max(msk) && subflows_allowed);
> diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
> index edaf0cc75474..b56ad45703dd 100644
> --- a/net/mptcp/protocol.h
> +++ b/net/mptcp/protocol.h
> @@ -563,6 +563,7 @@ unsigned int mptcp_get_add_addr_timeout(const struct net *net);
> int mptcp_is_checksum_enabled(const struct net *net);
> int mptcp_allow_join_id0(const struct net *net);
> unsigned int mptcp_stale_loss_cnt(const struct net *net);
> +int mptcp_get_pm_type(const struct net *net);
> void mptcp_subflow_fully_established(struct mptcp_subflow_context *subflow,
> 				     struct mptcp_options_received *mp_opt);
> bool __mptcp_retransmit_pending_data(struct sock *sk);
> -- 
> 2.34.0
>
>

--
Mat Martineau
Intel