Linux Ethernet Bridging - Apr 2020 - [Bridge] [PATCH net-next v3 01/11] bridge: uapi: mrp: Add mrp attributes.

Media Redundancy Protocol is a data network protocol standardized by
International Electrotechnical Commission as IEC 62439-2. It allows rings of
Ethernet switches to overcome any single failure with recovery time faster than
STP. It is primarily used in Industrial Ethernet applications.

Based on the previous RFC[1][2][3][4][5], and patches[6][7], the MRP state
machine and all the timers were moved to userspace, except for the timers used
to generate MRP Test frames.  In this way the userspace doesn't know and
should
not know if the HW or the kernel will generate the MRP Test frames. The
following changes were added to the bridge to support the MRP:
- the existing netlink interface was extended with MRP support,
- allow to detect when a MRP frame was received on a MRP ring port
- allow MRP instance to forward/terminate MRP frames
- generate MRP Test frames in case the HW doesn't have support for this

To be able to offload MRP support to HW, the switchdev API  was extend.

With these changes the userspace doesn't do the following because already
the
kernel/HW will do:
- doesn't need to forward/terminate MRP frames
- doesn't need to generate MRP Test frames
- doesn't need to detect when the ring is open/closed.

The userspace application that is using the new netlink can be found here[8].

The current implementation both in kernel and userspace supports only 2 roles:
  MRM - this one is responsible to send MRP_Test and MRP_Topo frames on both
  ring ports. It needs to process MRP_Test to know if the ring is open or
  closed. This operation is desired to be offloaded to the HW because it
  requires to generate and process up to 4000 frames per second. Whenever it
  detects that the ring is open it sends MRP_Topo frames to notify all MRC about
  changes in the topology. MRM needs also to process MRP_LinkChange frames,
  these frames are generated by the MRC. When the ring is open then the state
  of both ports is to forward frames and when the ring is closed then the
  secondary port is blocked.

  MRC - this one is responsible to forward MRP frames between the ring ports.
  In case one of the ring ports gets a link down or up, then MRC will generate
  a MRP_LinkChange frames. This node should also process MRP_Topo frames and to
  clear its FDB when it receives this frame.

 Userspace
               Deamon +----------+ Client
                +
                |
 +--------------|-----------------------------------------+
  Kernel        |
                + Netlink

                |                              + Interrupt
                |                              |
 +--------------|------------------------------|----------+
  HW            | Switchdev                    |
                +                              |

The user interacts using the client (called 'mrp'), the client talks to
the
deamon (called 'mrp_server'), which talks with the kernel using netlink.
The
kernel will try to offload the requests to the HW via switchdev API.

If this will be accepted then in the future the netlink interface can be
expended with multiple attributes which are required by different roles of the
MRP. Like Media Redundancy Automanager(MRA), Media Interconnect Manager(MIM) and
Media Interconnect Client(MIC).

[1] https://www.spinics.net/lists/netdev/msg623647.html
[2] https://www.spinics.net/lists/netdev/msg624378.html
[3] https://www.spinics.net/lists/netdev/msg627500.html
[4] https://www.spinics.net/lists/netdev/msg641005.html
[5] https://www.spinics.net/lists/netdev/msg643991.html
[6] https://www.spinics.net/lists/netdev/msg645378.html
[7] https://www.spinics.net/lists/kernel/msg3484685.html
[8] https://github.com/microchip-ung/mrp/tree/patch-v8

-v3:
  - fix unused variables

-v2:
  - drop patch 4
  - add port flag BR_MRP_LOST_CONT;
  - another fix for bisectability

-v1:
  - fix bisectability issues
  - in case of errors use extack

-RFC v5:
  - use nla_parse_nested
  - rework the usage of the rcu in br_mrp
  - reorder patches
  - few other small issues raised by Nikolay

-RFC v4:
  - extend existing netlink interface to add mrp support
  - use rcu locks

-RFC v3:
  - move MRP state machine in userspace
  - create generic netlink interface for configuring the HW using switchdev API

-RFC v2:
  - extend switchdev API to offload to HW

Horatiu Vultur (11):
  bridge: uapi: mrp: Add mrp attributes.
  bridge: mrp: Update Kconfig
  bridge: mrp: Extend bridge interface
  net: bridge: Add port attribute IFLA_BRPORT_MRP_RING_OPEN
  bridge: mrp: Add MRP interface.
  switchdev: mrp: Extend switchdev API to offload MRP
  bridge: switchdev: mrp: Implement MRP API for switchdev
  bridge: mrp: Connect MRP API with the switchdev API
  bridge: mrp: Implement netlink interface to configure MRP
  bridge: mrp: Integrate MRP into the bridge
  net: bridge: Add checks for enabling the STP.

 include/linux/if_bridge.h          |   2 +
 include/net/switchdev.h            |  62 ++++
 include/uapi/linux/if_bridge.h     |  42 +++
 include/uapi/linux/if_ether.h      |   1 +
 include/uapi/linux/if_link.h       |   1 +
 include/uapi/linux/mrp_bridge.h    |  84 +++++
 net/bridge/Kconfig                 |  12 +
 net/bridge/Makefile                |   2 +
 net/bridge/br_device.c             |   3 +
 net/bridge/br_if.c                 |   2 +
 net/bridge/br_input.c              |   3 +
 net/bridge/br_ioctl.c              |   3 +-
 net/bridge/br_mrp.c                | 556 +++++++++++++++++++++++++++++
 net/bridge/br_mrp_netlink.c        | 120 +++++++
 net/bridge/br_mrp_switchdev.c      | 140 ++++++++
 net/bridge/br_netlink.c            |  12 +-
 net/bridge/br_private.h            |  38 +-
 net/bridge/br_private_mrp.h        |  63 ++++
 net/bridge/br_stp.c                |   6 +
 net/bridge/br_stp_if.c             |  11 +-
 net/bridge/br_sysfs_br.c           |   4 +-
 tools/include/uapi/linux/if_link.h |   1 +
 22 files changed, 1160 insertions(+), 8 deletions(-)
 create mode 100644 include/uapi/linux/mrp_bridge.h
 create mode 100644 net/bridge/br_mrp.c
 create mode 100644 net/bridge/br_mrp_netlink.c
 create mode 100644 net/bridge/br_mrp_switchdev.c
 create mode 100644 net/bridge/br_private_mrp.h

-- 
2.17.1

Add new nested netlink attribute to configure the MRP. These attributes are used
by the userspace to add/delete/configure MRP instances and by the kernel to
notify the userspace when the MRP ring gets open/closed. MRP nested attribute
has the following attributes:

IFLA_BRIDGE_MRP_INSTANCE - the parameter type is br_mrp_instance which contains
  the instance id, and the ifindex of the two ports. The ports can't be part
of
  multiple instances. This is used to create/delete MRP instances.

IFLA_BRIDGE_MRP_PORT_STATE - the parameter type is u32. Which can be forwarding,
  blocking or disabled.

IFLA_BRIDGE_MRP_PORT_ROLE - the parameter type is br_mrp_port_role which
  contains the instance id and the role. The role can be primary or secondary.

IFLA_BRIDGE_MRP_RING_STATE - the parameter type is br_mrp_ring_state which
  contains the instance id and the state. The state can be open or closed.

IFLA_BRIDGE_MRP_RING_ROLE - the parameter type is br_mrp_ring_role which
  contains the instance id and the ring role. The role can be MRM or MRC.

IFLA_BRIDGE_MRP_START_TEST - the parameter type is br_mrp_start_test which
  contains the instance id, the interval at which to send the MRP_Test frames,
  how many test frames can be missed before declaring the ring open and the
  period which represent for how long to send the test frames.

Also add the file include/uapi/linux/mrp_bridge.h which defines all the types
used by MRP that are also needed by the userpace.

Signed-off-by: Horatiu Vultur <horatiu.vultur at microchip.com>
---
 include/uapi/linux/if_bridge.h  | 42 +++++++++++++++++
 include/uapi/linux/if_ether.h   |  1 +
 include/uapi/linux/mrp_bridge.h | 84 +++++++++++++++++++++++++++++++++
 3 files changed, 127 insertions(+)
 create mode 100644 include/uapi/linux/mrp_bridge.h

diff --git a/include/uapi/linux/if_bridge.h b/include/uapi/linux/if_bridge.h
index bfe621ea51b3..bd8c95488f16 100644
--- a/include/uapi/linux/if_bridge.h
+++ b/include/uapi/linux/if_bridge.h
@@ -120,6 +120,7 @@ enum {
 	IFLA_BRIDGE_MODE,
 	IFLA_BRIDGE_VLAN_INFO,
 	IFLA_BRIDGE_VLAN_TUNNEL_INFO,
+	IFLA_BRIDGE_MRP,
 	__IFLA_BRIDGE_MAX,
 };
 #define IFLA_BRIDGE_MAX (__IFLA_BRIDGE_MAX - 1)
@@ -157,6 +158,47 @@ struct bridge_vlan_xstats {
 	__u32 pad2;
 };
 
+enum {
+	IFLA_BRIDGE_MRP_UNSPEC,
+	IFLA_BRIDGE_MRP_INSTANCE,
+	IFLA_BRIDGE_MRP_PORT_STATE,
+	IFLA_BRIDGE_MRP_PORT_ROLE,
+	IFLA_BRIDGE_MRP_RING_STATE,
+	IFLA_BRIDGE_MRP_RING_ROLE,
+	IFLA_BRIDGE_MRP_START_TEST,
+	__IFLA_BRIDGE_MRP_MAX,
+};
+
+struct br_mrp_instance {
+	__u32 ring_id;
+	__u32 p_ifindex;
+	__u32 s_ifindex;
+};
+
+struct br_mrp_port_role {
+	__u32 ring_id;
+	__u32 role;
+};
+
+struct br_mrp_ring_state {
+	__u32 ring_id;
+	__u32 ring_state;
+};
+
+struct br_mrp_ring_role {
+	__u32 ring_id;
+	__u32 ring_role;
+};
+
+struct br_mrp_start_test {
+	__u32 ring_id;
+	__u32 interval;
+	__u32 max_miss;
+	__u32 period;
+};
+
+#define IFLA_BRIDGE_MRP_MAX (__IFLA_BRIDGE_MRP_MAX - 1)
+
 struct bridge_stp_xstats {
 	__u64 transition_blk;
 	__u64 transition_fwd;
diff --git a/include/uapi/linux/if_ether.h b/include/uapi/linux/if_ether.h
index f6ceb2e63d1e..d6de2b167448 100644
--- a/include/uapi/linux/if_ether.h
+++ b/include/uapi/linux/if_ether.h
@@ -92,6 +92,7 @@
 #define ETH_P_PREAUTH	0x88C7		/* 802.11 Preauthentication */
 #define ETH_P_TIPC	0x88CA		/* TIPC 			*/
 #define ETH_P_LLDP	0x88CC		/* Link Layer Discovery Protocol */
+#define ETH_P_MRP	0x88E3		/* Media Redundancy Protocol	*/
 #define ETH_P_MACSEC	0x88E5		/* 802.1ae MACsec */
 #define ETH_P_8021AH	0x88E7          /* 802.1ah Backbone Service Tag */
 #define ETH_P_MVRP	0x88F5          /* 802.1Q MVRP                  */
diff --git a/include/uapi/linux/mrp_bridge.h b/include/uapi/linux/mrp_bridge.h
new file mode 100644
index 000000000000..2600cdf5a284
--- /dev/null
+++ b/include/uapi/linux/mrp_bridge.h
@@ -0,0 +1,84 @@
+/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
+
+#ifndef _UAPI_LINUX_MRP_BRIDGE_H_
+#define _UAPI_LINUX_MRP_BRIDGE_H_
+
+#include <linux/types.h>
+#include <linux/if_ether.h>
+
+#define MRP_MAX_FRAME_LENGTH		200
+#define MRP_DEFAULT_PRIO		0x8000
+#define MRP_DOMAIN_UUID_LENGTH		16
+#define MRP_VERSION			1
+#define MRP_FRAME_PRIO			7
+
+enum br_mrp_ring_role_type {
+	BR_MRP_RING_ROLE_DISABLED,
+	BR_MRP_RING_ROLE_MRC,
+	BR_MRP_RING_ROLE_MRM,
+};
+
+enum br_mrp_ring_state_type {
+	BR_MRP_RING_STATE_OPEN,
+	BR_MRP_RING_STATE_CLOSED,
+};
+
+enum br_mrp_port_state_type {
+	BR_MRP_PORT_STATE_DISABLED,
+	BR_MRP_PORT_STATE_BLOCKED,
+	BR_MRP_PORT_STATE_FORWARDING,
+	BR_MRP_PORT_STATE_NOT_CONNECTED,
+};
+
+enum br_mrp_port_role_type {
+	BR_MRP_PORT_ROLE_PRIMARY,
+	BR_MRP_PORT_ROLE_SECONDARY,
+	BR_MRP_PORT_ROLE_NONE,
+};
+
+enum br_mrp_tlv_header_type {
+	BR_MRP_TLV_HEADER_END = 0x0,
+	BR_MRP_TLV_HEADER_COMMON = 0x1,
+	BR_MRP_TLV_HEADER_RING_TEST = 0x2,
+	BR_MRP_TLV_HEADER_RING_TOPO = 0x3,
+	BR_MRP_TLV_HEADER_RING_LINK_DOWN = 0x4,
+	BR_MRP_TLV_HEADER_RING_LINK_UP = 0x5,
+};
+
+struct br_mrp_tlv_hdr {
+	__u8 type;
+	__u8 length;
+};
+
+struct br_mrp_end_hdr {
+	struct br_mrp_tlv_hdr hdr;
+};
+
+struct br_mrp_common_hdr {
+	__u16 seq_id;
+	__u8 domain[MRP_DOMAIN_UUID_LENGTH];
+};
+
+struct br_mrp_ring_test_hdr {
+	__u16 prio;
+	__u8 sa[ETH_ALEN];
+	__u16 port_role;
+	__u16 state;
+	__u16 transitions;
+	__u32 timestamp;
+};
+
+struct br_mrp_ring_topo_hdr {
+	__u16 prio;
+	__u8 sa[ETH_ALEN];
+	__u16 interval;
+};
+
+struct br_mrp_ring_link_hdr {
+	__u8 sa[ETH_ALEN];
+	__u16 port_role;
+	__u16 interval;
+	__u16 blocked;
+};
+
+#endif
-- 
2.17.1

Add the option BRIDGE_MRP to allow to build in or not MRP support.
The default value is N.

Signed-off-by: Horatiu Vultur <horatiu.vultur at microchip.com>
---
 net/bridge/Kconfig | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/net/bridge/Kconfig b/net/bridge/Kconfig
index e4fb050e2078..51a6414145d2 100644
--- a/net/bridge/Kconfig
+++ b/net/bridge/Kconfig
@@ -61,3 +61,15 @@ config BRIDGE_VLAN_FILTERING
 	  Say N to exclude this support and reduce the binary size.
 
 	  If unsure, say Y.
+
+config BRIDGE_MRP
+	bool "MRP protocol"
+	depends on BRIDGE
+	default n
+	help
+	  If you say Y here, then the Ethernet bridge will be able to run MRP
+	  protocol to detect loops
+
+	  Say N to exclude this support and reduce the binary size.
+
+	  If unsure, say N.
-- 
2.17.1

To integrate MRP into the bridge, first the bridge needs to be aware of ports
that are part of an MRP ring and which rings are on the bridge.
Therefore extend bridge interface with the following:
- add new flag(BR_MPP_AWARE) to the net bridge ports, this bit will be
  set when the port is added to an MRP instance. In this way it knows if
  the frame was received on MRP ring port
- add new flag(BR_MRP_LOST_CONT) to the net bridge ports, this bit will be set
  when the port lost the continuity of MRP Test frames.
- add a list of MRP instances

Signed-off-by: Horatiu Vultur <horatiu.vultur at microchip.com>
---
 include/linux/if_bridge.h | 2 ++
 net/bridge/br_private.h   | 4 ++++
 2 files changed, 6 insertions(+)

diff --git a/include/linux/if_bridge.h b/include/linux/if_bridge.h
index 9e57c4411734..b3a8d3054af0 100644
--- a/include/linux/if_bridge.h
+++ b/include/linux/if_bridge.h
@@ -47,6 +47,8 @@ struct br_ip_list {
 #define BR_BCAST_FLOOD		BIT(14)
 #define BR_NEIGH_SUPPRESS	BIT(15)
 #define BR_ISOLATED		BIT(16)
+#define BR_MRP_AWARE		BIT(17)
+#define BR_MRP_LOST_CONT	BIT(18)
 
 #define BR_DEFAULT_AGEING_TIME	(300 * HZ)
 
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index 1f97703a52ff..835a70f8d3ea 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -428,6 +428,10 @@ struct net_bridge {
 	int offload_fwd_mark;
 #endif
 	struct hlist_head		fdb_list;
+
+#if IS_ENABLED(CONFIG_BRIDGE_MRP)
+	struct list_head		__rcu mrp_list;
+#endif
 };
 
 struct br_input_skb_cb {
-- 
2.17.1

This patch adds a new port attribute, IFLA_BRPORT_MRP_RING_OPEN, which allows
to notify the userspace when the port lost the continuite of MRP frames.

This attribute is set by kernel whenever the SW or HW detects that the ring is
being open or closed.

Signed-off-by: Horatiu Vultur <horatiu.vultur at microchip.com>
---
 include/uapi/linux/if_link.h       | 1 +
 net/bridge/br_netlink.c            | 3 +++
 tools/include/uapi/linux/if_link.h | 1 +
 3 files changed, 5 insertions(+)

diff --git a/include/uapi/linux/if_link.h b/include/uapi/linux/if_link.h
index 61e0801c82df..4a295deb933b 100644
--- a/include/uapi/linux/if_link.h
+++ b/include/uapi/linux/if_link.h
@@ -343,6 +343,7 @@ enum {
 	IFLA_BRPORT_NEIGH_SUPPRESS,
 	IFLA_BRPORT_ISOLATED,
 	IFLA_BRPORT_BACKUP_PORT,
+	IFLA_BRPORT_MRP_RING_OPEN,
 	__IFLA_BRPORT_MAX
 };
 #define IFLA_BRPORT_MAX (__IFLA_BRPORT_MAX - 1)
diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
index 43dab4066f91..4084f1ef8641 100644
--- a/net/bridge/br_netlink.c
+++ b/net/bridge/br_netlink.c
@@ -151,6 +151,7 @@ static inline size_t br_port_info_size(void)
 		+ nla_total_size(sizeof(u8))	/* IFLA_BRPORT_MULTICAST_ROUTER */
 #endif
 		+ nla_total_size(sizeof(u16))	/* IFLA_BRPORT_GROUP_FWD_MASK */
+		+ nla_total_size(sizeof(u8))	/* IFLA_BRPORT_MRP_RING_OPEN */
 		+ 0;
 }
 
@@ -213,6 +214,8 @@ static int br_port_fill_attrs(struct sk_buff *skb,
 	    nla_put_u16(skb, IFLA_BRPORT_GROUP_FWD_MASK, p->group_fwd_mask) ||
 	    nla_put_u8(skb, IFLA_BRPORT_NEIGH_SUPPRESS,
 		       !!(p->flags & BR_NEIGH_SUPPRESS)) ||
+	    nla_put_u8(skb, IFLA_BRPORT_MRP_RING_OPEN, !!(p->flags &
+							  BR_MRP_LOST_CONT)) ||
 	    nla_put_u8(skb, IFLA_BRPORT_ISOLATED, !!(p->flags & BR_ISOLATED)))
 		return -EMSGSIZE;
 
diff --git a/tools/include/uapi/linux/if_link.h
b/tools/include/uapi/linux/if_link.h
index 024af2d1d0af..70dae9ba16f4 100644
--- a/tools/include/uapi/linux/if_link.h
+++ b/tools/include/uapi/linux/if_link.h
@@ -343,6 +343,7 @@ enum {
 	IFLA_BRPORT_NEIGH_SUPPRESS,
 	IFLA_BRPORT_ISOLATED,
 	IFLA_BRPORT_BACKUP_PORT,
+	IFLA_BRPORT_MRP_RING_OPEN,
 	__IFLA_BRPORT_MAX
 };
 #define IFLA_BRPORT_MAX (__IFLA_BRPORT_MAX - 1)
-- 
2.17.1

Define the MRP interface.
This interface is used by the netlink to update the MRP instances and by the MRP
to make the calls to switchdev to offload it to HW.

It defines an MRP instance 'struct br_mrp' which is a list of MRP
instances.
Which will be part of the 'struct net_bridge'. Each instance has 2 ring
ports,
a bridge and an ID.

In case the HW can't generate MRP Test frames then the SW will generate
those.

br_mrp_add - adds a new MRP instance.

br_mrp_del - deletes an existing MRP instance. Each instance has an ID(ring_id).

br_mrp_set_port_state - changes the port state. The port can be in forwarding
  state, which means that the frames can pass through or in blocked state which
  means that the frames can't pass through except MRP frames. This will
  eventually call the switchdev API to notify the HW. This information is used
  also by the SW bridge to know how to forward frames in case the HW doesn't
  have this capability.

br_mrp_set_port_role - a port role can be primary or secondary. This
  information is required to be pushed to HW in case the HW can generate
  MRP_Test frames.  Because the MRP_Test frames contains a file with this
  information. Otherwise the HW will not be able to generate the frames
  correctly.

br_mrp_set_ring_state - a ring can be in state open or closed. State open means
  that the mrp port stopped receiving MRP_Test frames, while closed means that
  the mrp port received MRP_Test frames. Similar with br_mrp_port_role, this
  information is pushed in HW because the MRP_Test frames contain this
  information.

br_mrp_set_ring_role - a ring can have the following roles MRM or MRC. For the
  role MRM it is expected that the HW can terminate the MRP frames, notify the
  SW that it stopped receiving MRP_Test frames and trapp all the other MRP
  frames.  While for MRC mode it is expected that the HW can forward the MRP
  frames only between the MRP ports and copy MRP_Topology frames to CPU. In
  case the HW doesn't support a role it needs to return an error code
different
  than -EOPNOTSUPP.

br_mrp_start_test - this starts/stops the generation of MRP_Test frames. To stop
  the generation of frames the interval needs to have a value of 0. In this case
  the userspace needs to know if the HW supports this or not. Not to have
  duplicate frames(generated by HW and SW). Because if the HW supports this then
  the SW will not generate anymore frames and will expect that the HW will
  notify when it stopped receiving MRP frames using the function
  br_mrp_port_open.

br_mrp_port_open - this function is used by drivers to notify the userspace via
  a netlink callback that one of the ports stopped receiving MRP_Test frames.
  This function is called only when the node has the role MRM. It is not
  supposed to be called from userspace.

br_mrp_port_switchdev_add - this corresponds to the function br_mrp_add,
  and will notify the HW that a MRP instance is added. The function gets
  as parameter the MRP instance.

br_mrp_port_switchdev_del - this corresponds to the function br_mrp_del,
  and will notify the HW that a MRP instance is removed. The function
  gets as parameter the ID of the MRP instance that is removed.

br_mrp_port_switchdev_set_state - this corresponds to the function
  br_mrp_set_port_state. It would notify the HW if it should block or not
  non-MRP frames.

br_mrp_port_switchdev_set_port - this corresponds to the function
  br_mrp_set_port_role. It would set the port role, primary or secondary.

br_mrp_switchdev_set_role - this corresponds to the function
  br_mrp_set_ring_role and would set one of the role MRM or MRC.

br_mrp_switchdev_set_ring_state - this corresponds to the function
  br_mrp_set_ring_state and would set the ring to be open or closed.

br_mrp_switchdev_send_ring_test - this corresponds to the function
  br_mrp_start_test. This will notify the HW to start or stop generating
  MRP_Test frames. Value 0 for the interval parameter means to stop generating
  the frames.

br_mrp_port_open - this function is used to notify the userspace that the port
  lost the continuity of MRP Test frames.

Signed-off-by: Horatiu Vultur <horatiu.vultur at microchip.com>
---
 net/bridge/br_private_mrp.h | 63 +++++++++++++++++++++++++++++++++++++
 1 file changed, 63 insertions(+)
 create mode 100644 net/bridge/br_private_mrp.h

diff --git a/net/bridge/br_private_mrp.h b/net/bridge/br_private_mrp.h
new file mode 100644
index 000000000000..2921a4b59f8e
--- /dev/null
+++ b/net/bridge/br_private_mrp.h
@@ -0,0 +1,63 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#ifndef _BR_PRIVATE_MRP_H_
+#define _BR_PRIVATE_MRP_H_
+
+#include "br_private.h"
+#include <uapi/linux/mrp_bridge.h>
+
+struct br_mrp {
+	/* list of mrp instances */
+	struct list_head		__rcu list;
+
+	struct net_bridge_port __rcu	*p_port;
+	struct net_bridge_port __rcu	*s_port;
+
+	u32				ring_id;
+
+	enum br_mrp_ring_role_type	ring_role;
+	u8				ring_role_offloaded;
+	enum br_mrp_ring_state_type	ring_state;
+	u32				ring_transitions;
+
+	struct delayed_work		test_work;
+	u32				test_interval;
+	unsigned long			test_end;
+	u32				test_count_miss;
+	u32				test_max_miss;
+
+	u32				seq_id;
+
+	struct rcu_head			rcu;
+};
+
+/* br_mrp.c */
+int br_mrp_add(struct net_bridge *br, struct br_mrp_instance *instance);
+int br_mrp_del(struct net_bridge *br, struct br_mrp_instance *instance);
+int br_mrp_set_port_state(struct net_bridge_port *p,
+			  enum br_mrp_port_state_type state);
+int br_mrp_set_port_role(struct net_bridge_port *p,
+			 struct br_mrp_port_role *role);
+int br_mrp_set_ring_state(struct net_bridge *br,
+			  struct br_mrp_ring_state *state);
+int br_mrp_set_ring_role(struct net_bridge *br, struct br_mrp_ring_role *role);
+int br_mrp_start_test(struct net_bridge *br, struct br_mrp_start_test *test);
+
+/* br_mrp_switchdev.c */
+int br_mrp_switchdev_add(struct net_bridge *br, struct br_mrp *mrp);
+int br_mrp_switchdev_del(struct net_bridge *br, struct br_mrp *mrp);
+int br_mrp_switchdev_set_ring_role(struct net_bridge *br, struct br_mrp *mrp,
+				   enum br_mrp_ring_role_type role);
+int br_mrp_switchdev_set_ring_state(struct net_bridge *br, struct br_mrp *mrp,
+				    enum br_mrp_ring_state_type state);
+int br_mrp_switchdev_send_ring_test(struct net_bridge *br, struct br_mrp *mrp,
+				    u32 interval, u8 max_miss, u32 period);
+int br_mrp_port_switchdev_set_state(struct net_bridge_port *p,
+				    enum br_mrp_port_state_type state);
+int br_mrp_port_switchdev_set_role(struct net_bridge_port *p,
+				   enum br_mrp_port_role_type role);
+
+/* br_mrp_netlink.c  */
+int br_mrp_port_open(struct net_device *dev, u8 loc);
+
+#endif /* _BR_PRIVATE_MRP_H */
-- 
2.17.1

Extend switchdev API to add support for MRP. The HW is notified in
following cases:

SWITCHDEV_OBJ_ID_MRP: This is used when a MRP instance is added/removed
  from the MRP ring.

SWITCHDEV_OBJ_ID_RING_ROLE_MRP: This is used when the role of the node
  changes. The current supported roles are MRM and MRC.

SWITCHDEV_OBJ_ID_RING_TEST_MRP: This is used when to start/stop sending
  MRP_Test frames on the mrp ring ports. This is called only on nodes that have
  the role MRM. In case this fails then the SW will generate the frames.

SWITCHDEV_OBJ_ID_RING_STATE_STATE: This is used when the ring changes it states
  to open or closed. This is required to notify HW because the MRP_Test frame
  contains the field MRP_InState which contains this information.

SWITCHDEV_ATTR_ID_MRP_PORT_STATE: This is used when the port's state is
  changed. It can be in blocking/forwarding mode.

SWITCHDEV_ATTR_ID_MRP_PORT_ROLE: This is used when port's role changes. The
  roles of the port can be primary/secondary. This is required to notify HW
  because the MRP_Test frame contains the field MRP_PortRole that contains this
  information.

Signed-off-by: Horatiu Vultur <horatiu.vultur at microchip.com>
---
 include/net/switchdev.h | 62 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 62 insertions(+)

diff --git a/include/net/switchdev.h b/include/net/switchdev.h
index aee86a189432..ae7aeb0d1f9c 100644
--- a/include/net/switchdev.h
+++ b/include/net/switchdev.h
@@ -40,6 +40,10 @@ enum switchdev_attr_id {
 	SWITCHDEV_ATTR_ID_BRIDGE_VLAN_FILTERING,
 	SWITCHDEV_ATTR_ID_BRIDGE_MC_DISABLED,
 	SWITCHDEV_ATTR_ID_BRIDGE_MROUTER,
+#if IS_ENABLED(CONFIG_BRIDGE_MRP)
+	SWITCHDEV_ATTR_ID_MRP_PORT_STATE,
+	SWITCHDEV_ATTR_ID_MRP_PORT_ROLE,
+#endif
 };
 
 struct switchdev_attr {
@@ -55,6 +59,11 @@ struct switchdev_attr {
 		clock_t ageing_time;			/* BRIDGE_AGEING_TIME */
 		bool vlan_filtering;			/* BRIDGE_VLAN_FILTERING */
 		bool mc_disabled;			/* MC_DISABLED */
+#if IS_ENABLED(CONFIG_BRIDGE_MRP)
+		u8 mrp_port_state;			/* MRP_PORT_STATE */
+		u8 mrp_port_role;			/* MRP_PORT_ROLE */
+		u8 mrp_ring_state;			/* MRP_RING_STATE */
+#endif
 	} u;
 };
 
@@ -63,6 +72,12 @@ enum switchdev_obj_id {
 	SWITCHDEV_OBJ_ID_PORT_VLAN,
 	SWITCHDEV_OBJ_ID_PORT_MDB,
 	SWITCHDEV_OBJ_ID_HOST_MDB,
+#if IS_ENABLED(CONFIG_BRIDGE_MRP)
+	SWITCHDEV_OBJ_ID_MRP,
+	SWITCHDEV_OBJ_ID_RING_TEST_MRP,
+	SWITCHDEV_OBJ_ID_RING_ROLE_MRP,
+	SWITCHDEV_OBJ_ID_RING_STATE_MRP,
+#endif
 };
 
 struct switchdev_obj {
@@ -94,6 +109,53 @@ struct switchdev_obj_port_mdb {
 #define SWITCHDEV_OBJ_PORT_MDB(OBJ) \
 	container_of((OBJ), struct switchdev_obj_port_mdb, obj)
 
+
+#if IS_ENABLED(CONFIG_BRIDGE_MRP)
+/* SWITCHDEV_OBJ_ID_MRP */
+struct switchdev_obj_mrp {
+	struct switchdev_obj obj;
+	struct net_device *p_port;
+	struct net_device *s_port;
+	u32 ring_id;
+};
+
+#define SWITCHDEV_OBJ_MRP(OBJ) \
+	container_of((OBJ), struct switchdev_obj_mrp, obj)
+
+/* SWITCHDEV_OBJ_ID_RING_TEST_MRP */
+struct switchdev_obj_ring_test_mrp {
+	struct switchdev_obj obj;
+	/* The value is in us and a value of 0 represents to stop */
+	u32 interval;
+	u8 max_miss;
+	u32 ring_id;
+	u32 period;
+};
+
+#define SWITCHDEV_OBJ_RING_TEST_MRP(OBJ) \
+	container_of((OBJ), struct switchdev_obj_ring_test_mrp, obj)
+
+/* SWICHDEV_OBJ_ID_RING_ROLE_MRP */
+struct switchdev_obj_ring_role_mrp {
+	struct switchdev_obj obj;
+	u8 ring_role;
+	u32 ring_id;
+};
+
+#define SWITCHDEV_OBJ_RING_ROLE_MRP(OBJ) \
+	container_of((OBJ), struct switchdev_obj_ring_role_mrp, obj)
+
+struct switchdev_obj_ring_state_mrp {
+	struct switchdev_obj obj;
+	u8 ring_state;
+	u32 ring_id;
+};
+
+#define SWITCHDEV_OBJ_RING_STATE_MRP(OBJ) \
+	container_of((OBJ), struct switchdev_obj_ring_state_mrp, obj)
+
+#endif
+
 typedef int switchdev_obj_dump_cb_t(struct switchdev_obj *obj);
 
 enum switchdev_notifier_type {
-- 
2.17.1

Implement the MRP api for switchdev.
These functions will just eventually call the switchdev functions:
switchdev_port_obj_add/del and switchdev_port_attr_set.

Signed-off-by: Horatiu Vultur <horatiu.vultur at microchip.com>
---
 net/bridge/Makefile           |   2 +
 net/bridge/br_mrp_switchdev.c | 140 ++++++++++++++++++++++++++++++++++
 2 files changed, 142 insertions(+)
 create mode 100644 net/bridge/br_mrp_switchdev.c

diff --git a/net/bridge/Makefile b/net/bridge/Makefile
index 49da7ae6f077..3cacf9dd78d5 100644
--- a/net/bridge/Makefile
+++ b/net/bridge/Makefile
@@ -25,3 +25,5 @@ bridge-$(CONFIG_BRIDGE_VLAN_FILTERING) += br_vlan.o
br_vlan_tunnel.o br_vlan_opt
 bridge-$(CONFIG_NET_SWITCHDEV) += br_switchdev.o
 
 obj-$(CONFIG_NETFILTER) += netfilter/
+
+bridge-$(CONFIG_BRIDGE_MRP)	+= br_mrp_switchdev.o
diff --git a/net/bridge/br_mrp_switchdev.c b/net/bridge/br_mrp_switchdev.c
new file mode 100644
index 000000000000..51cb1d5a24b4
--- /dev/null
+++ b/net/bridge/br_mrp_switchdev.c
@@ -0,0 +1,140 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <net/switchdev.h>
+
+#include "br_private_mrp.h"
+
+int br_mrp_switchdev_add(struct net_bridge *br, struct br_mrp *mrp)
+{
+	struct switchdev_obj_mrp mrp_obj = {
+		.obj.orig_dev = br->dev,
+		.obj.id = SWITCHDEV_OBJ_ID_MRP,
+		.p_port = rtnl_dereference(mrp->p_port)->dev,
+		.s_port = rtnl_dereference(mrp->s_port)->dev,
+		.ring_id = mrp->ring_id,
+	};
+	int err;
+
+	err = switchdev_port_obj_add(br->dev, &mrp_obj.obj, NULL);
+
+	if (err && err != -EOPNOTSUPP)
+		return err;
+
+	return 0;
+}
+
+int br_mrp_switchdev_del(struct net_bridge *br, struct br_mrp *mrp)
+{
+	struct switchdev_obj_mrp mrp_obj = {
+		.obj.orig_dev = br->dev,
+		.obj.id = SWITCHDEV_OBJ_ID_MRP,
+		.p_port = NULL,
+		.s_port = NULL,
+		.ring_id = mrp->ring_id,
+	};
+	int err;
+
+	err = switchdev_port_obj_del(br->dev, &mrp_obj.obj);
+
+	if (err && err != -EOPNOTSUPP)
+		return err;
+
+	return 0;
+}
+
+int br_mrp_switchdev_set_ring_role(struct net_bridge *br,
+				   struct br_mrp *mrp,
+				   enum br_mrp_ring_role_type role)
+{
+	struct switchdev_obj_ring_role_mrp mrp_role = {
+		.obj.orig_dev = br->dev,
+		.obj.id = SWITCHDEV_OBJ_ID_RING_ROLE_MRP,
+		.ring_role = role,
+		.ring_id = mrp->ring_id,
+	};
+	int err;
+
+	if (role == BR_MRP_RING_ROLE_DISABLED)
+		err = switchdev_port_obj_del(br->dev, &mrp_role.obj);
+	else
+		err = switchdev_port_obj_add(br->dev, &mrp_role.obj, NULL);
+
+	return err;
+}
+
+int br_mrp_switchdev_send_ring_test(struct net_bridge *br,
+				    struct br_mrp *mrp, u32 interval,
+				    u8 max_miss, u32 period)
+{
+	struct switchdev_obj_ring_test_mrp test = {
+		.obj.orig_dev = br->dev,
+		.obj.id = SWITCHDEV_OBJ_ID_RING_TEST_MRP,
+		.interval = interval,
+		.max_miss = max_miss,
+		.ring_id = mrp->ring_id,
+		.period = period,
+	};
+	int err;
+
+	if (interval == 0)
+		err = switchdev_port_obj_del(br->dev, &test.obj);
+	else
+		err = switchdev_port_obj_add(br->dev, &test.obj, NULL);
+
+	return err;
+}
+
+int br_mrp_switchdev_set_ring_state(struct net_bridge *br,
+				    struct br_mrp *mrp,
+				    enum br_mrp_ring_state_type state)
+{
+	struct switchdev_obj_ring_state_mrp mrp_state = {
+		.obj.orig_dev = br->dev,
+		.obj.id = SWITCHDEV_OBJ_ID_RING_STATE_MRP,
+		.ring_state = state,
+		.ring_id = mrp->ring_id,
+	};
+	int err;
+
+	err = switchdev_port_obj_add(br->dev, &mrp_state.obj, NULL);
+
+	if (err && err != -EOPNOTSUPP)
+		return err;
+
+	return 0;
+}
+
+int br_mrp_port_switchdev_set_state(struct net_bridge_port *p,
+				    enum br_mrp_port_state_type state)
+{
+	struct switchdev_attr attr = {
+		.orig_dev = p->dev,
+		.id = SWITCHDEV_ATTR_ID_MRP_PORT_STATE,
+		.u.mrp_port_state = state,
+	};
+	int err;
+
+	err = switchdev_port_attr_set(p->dev, &attr);
+	if (err && err != -EOPNOTSUPP)
+		br_warn(p->br, "error setting offload MRP state on port
%u(%s)\n",
+			(unsigned int)p->port_no, p->dev->name);
+
+	return err;
+}
+
+int br_mrp_port_switchdev_set_role(struct net_bridge_port *p,
+				   enum br_mrp_port_role_type role)
+{
+	struct switchdev_attr attr = {
+		.orig_dev = p->dev,
+		.id = SWITCHDEV_ATTR_ID_MRP_PORT_ROLE,
+		.u.mrp_port_role = role,
+	};
+	int err;
+
+	err = switchdev_port_attr_set(p->dev, &attr);
+	if (err && err != -EOPNOTSUPP)
+		return err;
+
+	return 0;
+}
-- 
2.17.1

Implement the MRP API.

In case the HW can't generate MRP Test frames then the SW will try to
generate
the frames. In case that also the SW will fail in generating the frames then a
error is return to the userspace. The userspace is responsible to generate all
the other MRP frames regardless if the test frames are generated by HW or SW.

The forwarding/termination of MRP frames is happening in the kernel and is done
by the MRP instance. The userspace application doesn't do the forwarding.

Signed-off-by: Horatiu Vultur <horatiu.vultur at microchip.com>
---
 net/bridge/Makefile         |   2 +-
 net/bridge/br_mrp.c         | 556 ++++++++++++++++++++++++++++++++++++
 net/bridge/br_mrp_netlink.c |  29 ++
 3 files changed, 586 insertions(+), 1 deletion(-)
 create mode 100644 net/bridge/br_mrp.c
 create mode 100644 net/bridge/br_mrp_netlink.c

diff --git a/net/bridge/Makefile b/net/bridge/Makefile
index 3cacf9dd78d5..ccb394236fbd 100644
--- a/net/bridge/Makefile
+++ b/net/bridge/Makefile
@@ -26,4 +26,4 @@ bridge-$(CONFIG_NET_SWITCHDEV) += br_switchdev.o
 
 obj-$(CONFIG_NETFILTER) += netfilter/
 
-bridge-$(CONFIG_BRIDGE_MRP)	+= br_mrp_switchdev.o
+bridge-$(CONFIG_BRIDGE_MRP)	+= br_mrp_switchdev.o br_mrp.o br_mrp_netlink.o
diff --git a/net/bridge/br_mrp.c b/net/bridge/br_mrp.c
new file mode 100644
index 000000000000..8b1e85c11e3b
--- /dev/null
+++ b/net/bridge/br_mrp.c
@@ -0,0 +1,556 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <linux/mrp_bridge.h>
+#include "br_private_mrp.h"
+
+static const u8 mrp_test_dmac[ETH_ALEN] = { 0x1, 0x15, 0x4e, 0x0, 0x0, 0x1 };
+
+static struct net_bridge_port *br_mrp_get_port(struct net_bridge *br,
+					       u32 ifindex)
+{
+	struct net_bridge_port *res = NULL;
+	struct net_bridge_port *port;
+
+	list_for_each_entry(port, &br->port_list, list) {
+		if (port->dev->ifindex == ifindex) {
+			res = port;
+			break;
+		}
+	}
+
+	return res;
+}
+
+static struct br_mrp *br_mrp_find_id(struct net_bridge *br, u32 ring_id)
+{
+	struct br_mrp *res = NULL;
+	struct br_mrp *mrp;
+
+	list_for_each_entry_rcu(mrp, &br->mrp_list, list,
+				lockdep_rtnl_is_held()) {
+		if (mrp->ring_id == ring_id) {
+			res = mrp;
+			break;
+		}
+	}
+
+	return res;
+}
+
+static struct br_mrp *br_mrp_find_port(struct net_bridge *br,
+				       struct net_bridge_port *p)
+{
+	struct br_mrp *res = NULL;
+	struct br_mrp *mrp;
+
+	list_for_each_entry_rcu(mrp, &br->mrp_list, list,
+				lockdep_rtnl_is_held()) {
+		if (rcu_access_pointer(mrp->p_port) == p ||
+		    rcu_access_pointer(mrp->s_port) == p) {
+			res = mrp;
+			break;
+		}
+	}
+
+	return res;
+}
+
+static int br_mrp_next_seq(struct br_mrp *mrp)
+{
+	mrp->seq_id++;
+	return mrp->seq_id;
+}
+
+static struct sk_buff *br_mrp_skb_alloc(struct net_bridge_port *p,
+					const u8 *src, const u8 *dst)
+{
+	struct ethhdr *eth_hdr;
+	struct sk_buff *skb;
+	u16 *version;
+
+	skb = dev_alloc_skb(MRP_MAX_FRAME_LENGTH);
+	if (!skb)
+		return NULL;
+
+	skb->dev = p->dev;
+	skb->protocol = htons(ETH_P_MRP);
+	skb->priority = MRP_FRAME_PRIO;
+	skb_reserve(skb, sizeof(*eth_hdr));
+
+	eth_hdr = skb_push(skb, sizeof(*eth_hdr));
+	ether_addr_copy(eth_hdr->h_dest, dst);
+	ether_addr_copy(eth_hdr->h_source, src);
+	eth_hdr->h_proto = htons(ETH_P_MRP);
+
+	version = skb_put(skb, sizeof(*version));
+	*version = cpu_to_be16(MRP_VERSION);
+
+	return skb;
+}
+
+static void br_mrp_skb_tlv(struct sk_buff *skb,
+			   enum br_mrp_tlv_header_type type,
+			   u8 length)
+{
+	struct br_mrp_tlv_hdr *hdr;
+
+	hdr = skb_put(skb, sizeof(*hdr));
+	hdr->type = type;
+	hdr->length = length;
+}
+
+static void br_mrp_skb_common(struct sk_buff *skb, struct br_mrp *mrp)
+{
+	struct br_mrp_common_hdr *hdr;
+
+	br_mrp_skb_tlv(skb, BR_MRP_TLV_HEADER_COMMON, sizeof(*hdr));
+
+	hdr = skb_put(skb, sizeof(*hdr));
+	hdr->seq_id = cpu_to_be16(br_mrp_next_seq(mrp));
+	memset(hdr->domain, 0xff, MRP_DOMAIN_UUID_LENGTH);
+}
+
+static struct sk_buff *br_mrp_alloc_test_skb(struct br_mrp *mrp,
+					     struct net_bridge_port *p,
+					     enum br_mrp_port_role_type port_role)
+{
+	struct br_mrp_ring_test_hdr *hdr = NULL;
+	struct sk_buff *skb = NULL;
+
+	if (!p)
+		return NULL;
+
+	skb = br_mrp_skb_alloc(p, p->dev->dev_addr, mrp_test_dmac);
+	if (!skb)
+		return NULL;
+
+	br_mrp_skb_tlv(skb, BR_MRP_TLV_HEADER_RING_TEST, sizeof(*hdr));
+	hdr = skb_put(skb, sizeof(*hdr));
+
+	hdr->prio = cpu_to_be16(MRP_DEFAULT_PRIO);
+	ether_addr_copy(hdr->sa, p->br->dev->dev_addr);
+	hdr->port_role = cpu_to_be16(port_role);
+	hdr->state = cpu_to_be16(mrp->ring_state);
+	hdr->transitions = cpu_to_be16(mrp->ring_transitions);
+	hdr->timestamp = cpu_to_be32(jiffies_to_msecs(jiffies));
+
+	br_mrp_skb_common(skb, mrp);
+	br_mrp_skb_tlv(skb, BR_MRP_TLV_HEADER_END, 0x0);
+
+	return skb;
+}
+
+static void br_mrp_test_work_expired(struct work_struct *work)
+{
+	struct delayed_work *del_work = to_delayed_work(work);
+	struct br_mrp *mrp = container_of(del_work, struct br_mrp, test_work);
+	struct net_bridge_port *p;
+	bool notify_open = false;
+	struct sk_buff *skb;
+
+	if (time_before_eq(mrp->test_end, jiffies))
+		return;
+
+	if (mrp->test_count_miss < mrp->test_max_miss) {
+		mrp->test_count_miss++;
+	} else {
+		/* Notify that the ring is open only if the ring state is
+		 * closed, otherwise it would continue to notify at every
+		 * interval.
+		 */
+		if (mrp->ring_state == BR_MRP_RING_STATE_CLOSED)
+			notify_open = true;
+	}
+
+	rcu_read_lock();
+
+	p = rcu_dereference(mrp->p_port);
+	if (p) {
+		skb = br_mrp_alloc_test_skb(mrp, p, BR_MRP_PORT_ROLE_PRIMARY);
+		if (!skb)
+			goto out;
+
+		skb_reset_network_header(skb);
+		dev_queue_xmit(skb);
+
+		if (notify_open && !mrp->ring_role_offloaded)
+			br_mrp_port_open(p->dev, true);
+	}
+
+	p = rcu_dereference(mrp->s_port);
+	if (p) {
+		skb = br_mrp_alloc_test_skb(mrp, p, BR_MRP_PORT_ROLE_SECONDARY);
+		if (!skb)
+			goto out;
+
+		skb_reset_network_header(skb);
+		dev_queue_xmit(skb);
+
+		if (notify_open && !mrp->ring_role_offloaded)
+			br_mrp_port_open(p->dev, true);
+	}
+
+out:
+	rcu_read_unlock();
+
+	queue_delayed_work(system_wq, &mrp->test_work,
+			   usecs_to_jiffies(mrp->test_interval));
+}
+
+/* Deletes the MRP instance.
+ * note: called under rtnl_lock
+ */
+static void br_mrp_del_impl(struct net_bridge *br, struct br_mrp *mrp)
+{
+	struct net_bridge_port *p;
+
+	/* Stop sending MRP_Test frames */
+	cancel_delayed_work_sync(&mrp->test_work);
+	br_mrp_switchdev_send_ring_test(br, mrp, 0, 0, 0);
+
+	br_mrp_switchdev_del(br, mrp);
+
+	/* Reset the ports */
+	p = rtnl_dereference(mrp->p_port);
+	if (p) {
+		spin_lock_bh(&br->lock);
+		p->state = BR_STATE_FORWARDING;
+		p->flags &= ~BR_MRP_AWARE;
+		spin_unlock_bh(&br->lock);
+		br_mrp_port_switchdev_set_state(p, BR_STATE_FORWARDING);
+		rcu_assign_pointer(mrp->p_port, NULL);
+	}
+
+	p = rtnl_dereference(mrp->s_port);
+	if (p) {
+		spin_lock_bh(&br->lock);
+		p->state = BR_STATE_FORWARDING;
+		p->flags &= ~BR_MRP_AWARE;
+		spin_unlock_bh(&br->lock);
+		br_mrp_port_switchdev_set_state(p, BR_STATE_FORWARDING);
+		rcu_assign_pointer(mrp->s_port, NULL);
+	}
+
+	list_del_rcu(&mrp->list);
+	kfree_rcu(mrp, rcu);
+}
+
+/* Adds a new MRP instance.
+ * note: called under rtnl_lock
+ */
+int br_mrp_add(struct net_bridge *br, struct br_mrp_instance *instance)
+{
+	struct net_bridge_port *p;
+	struct br_mrp *mrp;
+	int err;
+
+	/* If the ring exists, it is not possible to create another one with the
+	 * same ring_id
+	 */
+	mrp = br_mrp_find_id(br, instance->ring_id);
+	if (mrp)
+		return -EINVAL;
+
+	if (!br_mrp_get_port(br, instance->p_ifindex) ||
+	    !br_mrp_get_port(br, instance->s_ifindex))
+		return -EINVAL;
+
+	mrp = kzalloc(sizeof(*mrp), GFP_KERNEL);
+	if (!mrp)
+		return -ENOMEM;
+
+	mrp->ring_id = instance->ring_id;
+
+	p = br_mrp_get_port(br, instance->p_ifindex);
+	spin_lock_bh(&br->lock);
+	p->state = BR_STATE_FORWARDING;
+	p->flags |= BR_MRP_AWARE;
+	spin_unlock_bh(&br->lock);
+	rcu_assign_pointer(mrp->p_port, p);
+
+	p = br_mrp_get_port(br, instance->s_ifindex);
+	spin_lock_bh(&br->lock);
+	p->state = BR_STATE_FORWARDING;
+	p->flags |= BR_MRP_AWARE;
+	spin_unlock_bh(&br->lock);
+	rcu_assign_pointer(mrp->s_port, p);
+
+	INIT_DELAYED_WORK(&mrp->test_work, br_mrp_test_work_expired);
+	list_add_tail_rcu(&mrp->list, &br->mrp_list);
+
+	err = br_mrp_switchdev_add(br, mrp);
+	if (err)
+		goto delete_mrp;
+
+	return 0;
+
+delete_mrp:
+	br_mrp_del_impl(br, mrp);
+
+	return err;
+}
+
+/* Deletes the MRP instance from which the port is part of
+ * note: called under rtnl_lock
+ */
+void br_mrp_port_del(struct net_bridge *br, struct net_bridge_port *p)
+{
+	struct br_mrp *mrp = br_mrp_find_port(br, p);
+
+	/* If the port is not part of a MRP instance just bail out */
+	if (!mrp)
+		return;
+
+	br_mrp_del_impl(br, mrp);
+}
+
+/* Deletes existing MRP instance based on ring_id
+ * note: called under rtnl_lock
+ */
+int br_mrp_del(struct net_bridge *br, struct br_mrp_instance *instance)
+{
+	struct br_mrp *mrp = br_mrp_find_id(br, instance->ring_id);
+
+	if (!mrp)
+		return -EINVAL;
+
+	br_mrp_del_impl(br, mrp);
+
+	return 0;
+}
+
+/* Set port state, port state can be forwarding, blocked or disabled
+ * note: already called with rcu_read_lock
+ */
+int br_mrp_set_port_state(struct net_bridge_port *p,
+			  enum br_mrp_port_state_type state)
+{
+	if (!p || !(p->flags & BR_MRP_AWARE))
+		return -EINVAL;
+
+	spin_lock_bh(&p->br->lock);
+
+	if (state == BR_MRP_PORT_STATE_FORWARDING)
+		p->state = BR_STATE_FORWARDING;
+	else
+		p->state = BR_STATE_BLOCKING;
+
+	spin_unlock_bh(&p->br->lock);
+
+	br_mrp_port_switchdev_set_state(p, state);
+
+	return 0;
+}
+
+/* Set port role, port role can be primary or secondary
+ * note: already called with rcu_read_lock
+ */
+int br_mrp_set_port_role(struct net_bridge_port *p,
+			 struct br_mrp_port_role *role)
+{
+	struct br_mrp *mrp;
+
+	if (!p || !(p->flags & BR_MRP_AWARE))
+		return -EINVAL;
+
+	mrp = br_mrp_find_id(p->br, role->ring_id);
+
+	if (!mrp)
+		return -EINVAL;
+
+	if (role->role == BR_MRP_PORT_ROLE_PRIMARY)
+		rcu_assign_pointer(mrp->p_port, p);
+	else
+		rcu_assign_pointer(mrp->s_port, p);
+
+	br_mrp_port_switchdev_set_role(p, role->role);
+
+	return 0;
+}
+
+/* Set ring state, ring state can be only Open or Closed
+ * note: already called with rcu_read_lock
+ */
+int br_mrp_set_ring_state(struct net_bridge *br,
+			  struct br_mrp_ring_state *state)
+{
+	struct br_mrp *mrp = br_mrp_find_id(br, state->ring_id);
+
+	if (!mrp)
+		return -EINVAL;
+
+	if (mrp->ring_state == BR_MRP_RING_STATE_CLOSED &&
+	    state->ring_state != BR_MRP_RING_STATE_CLOSED)
+		mrp->ring_transitions++;
+
+	mrp->ring_state = state->ring_state;
+
+	br_mrp_switchdev_set_ring_state(br, mrp, state->ring_state);
+
+	return 0;
+}
+
+/* Set ring role, ring role can be only MRM(Media Redundancy Manager) or
+ * MRC(Media Redundancy Client).
+ * note: already called with rcu_read_lock
+ */
+int br_mrp_set_ring_role(struct net_bridge *br,
+			 struct br_mrp_ring_role *role)
+{
+	struct br_mrp *mrp = br_mrp_find_id(br, role->ring_id);
+	int err;
+
+	if (!mrp)
+		return -EINVAL;
+
+	mrp->ring_role = role->ring_role;
+
+	/* If there is an error just bailed out */
+	err = br_mrp_switchdev_set_ring_role(br, mrp, role->ring_role);
+	if (err && err != -EOPNOTSUPP)
+		return err;
+
+	/* Now detect if the HW actually applied the role or not. If the HW
+	 * applied the role it means that the SW will not to do those operations
+	 * anymore. For example if the role ir MRM then the HW will notify the
+	 * SW when ring is open, but if the is not pushed to the HW the SW will
+	 * need to detect when the ring is open
+	 */
+	mrp->ring_role_offloaded = err == -EOPNOTSUPP ? 0 : 1;
+
+	return 0;
+}
+
+/* Start to generate MRP test frames, the frames are generated by HW and if it
+ * fails, they are generated by the SW.
+ * note: already called with rcu_read_lock
+ */
+int br_mrp_start_test(struct net_bridge *br,
+		      struct br_mrp_start_test *test)
+{
+	struct br_mrp *mrp = br_mrp_find_id(br, test->ring_id);
+
+	if (!mrp)
+		return -EINVAL;
+
+	/* Try to push is to the HW and if it fails then continue to generate in
+	 * SW and if that also fails then return error
+	 */
+	if (!br_mrp_switchdev_send_ring_test(br, mrp, test->interval,
+					     test->max_miss, test->period))
+		return 0;
+
+	mrp->test_interval = test->interval;
+	mrp->test_end = jiffies + usecs_to_jiffies(test->period);
+	mrp->test_max_miss = test->max_miss;
+	mrp->test_count_miss = 0;
+	queue_delayed_work(system_wq, &mrp->test_work,
+			   usecs_to_jiffies(test->interval));
+
+	return 0;
+}
+
+/* Process only MRP Test frame. All the other MRP frames are processed by
+ * userspace application
+ * note: already called with rcu_read_lock
+ */
+static void br_mrp_mrm_process(struct br_mrp *mrp, struct net_bridge_port
*port,
+			       struct sk_buff *skb)
+{
+	struct br_mrp_tlv_hdr *hdr;
+
+	hdr = (struct br_mrp_tlv_hdr *)(skb->data + sizeof(uint16_t));
+
+	if (!hdr)
+		return;
+
+	if (hdr->type != BR_MRP_TLV_HEADER_RING_TEST)
+		return;
+
+	mrp->test_count_miss = 0;
+
+	/* Notify the userspace that the ring is closed only when the ring is
+	 * not closed
+	 */
+	if (mrp->ring_state != BR_MRP_RING_STATE_CLOSED)
+		br_mrp_port_open(port->dev, false);
+}
+
+/* This will just forward the frame to the other mrp ring port(MRC role) or
will
+ * not do anything.
+ * note: already called with rcu_read_lock
+ */
+static int br_mrp_rcv(struct net_bridge_port *p,
+		      struct sk_buff *skb, struct net_device *dev)
+{
+	struct net_device *s_dev, *p_dev, *d_dev;
+	struct net_bridge_port *p_port, *s_port;
+	struct net_bridge *br;
+	struct sk_buff *nskb;
+	struct br_mrp *mrp;
+
+	/* If port is disabled don't accept any frames */
+	if (p->state == BR_STATE_DISABLED)
+		return 0;
+
+	br = p->br;
+	mrp =  br_mrp_find_port(br, p);
+	if (unlikely(!mrp))
+		return 0;
+
+	p_port = rcu_dereference(mrp->p_port);
+	if (!p_port)
+		return 0;
+
+	s_port = rcu_dereference(mrp->s_port);
+	if (!s_port)
+		return 0;
+
+	/* If the role is MRM then don't forward the frames */
+	if (mrp->ring_role == BR_MRP_RING_ROLE_MRM) {
+		br_mrp_mrm_process(mrp, p, skb);
+		return 1;
+	}
+
+	/* Clone the frame and forward it on the other MRP port */
+	nskb = skb_clone(skb, GFP_ATOMIC);
+	if (!nskb)
+		return 0;
+
+	p_dev = p_port->dev;
+	s_dev = s_port->dev;
+
+	if (p_dev == dev)
+		d_dev = s_dev;
+	else
+		d_dev = p_dev;
+
+	nskb->dev = d_dev;
+	skb_push(nskb, ETH_HLEN);
+	dev_queue_xmit(nskb);
+
+	return 1;
+}
+
+/* Check if the frame was received on a port that is part of MRP ring
+ * and if the frame has MRP eth. In that case process the frame otherwise do
+ * normal forwarding.
+ * note: already called with rcu_read_lock
+ */
+int br_mrp_process(struct net_bridge_port *p, struct sk_buff *skb)
+{
+	/* If there is no MRP instance do normal forwarding */
+	if (likely(!(p->flags & BR_MRP_AWARE)))
+		goto out;
+
+	if (unlikely(skb->protocol == htons(ETH_P_MRP)))
+		return br_mrp_rcv(p, skb, p->dev);
+
+out:
+	return 0;
+}
+
+bool br_mrp_enabled(struct net_bridge *br)
+{
+	return !list_empty(&br->mrp_list);
+}
diff --git a/net/bridge/br_mrp_netlink.c b/net/bridge/br_mrp_netlink.c
new file mode 100644
index 000000000000..b982db14bbf4
--- /dev/null
+++ b/net/bridge/br_mrp_netlink.c
@@ -0,0 +1,29 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <net/genetlink.h>
+
+#include <uapi/linux/mrp_bridge.h>
+#include "br_private.h"
+#include "br_private_mrp.h"
+
+int br_mrp_port_open(struct net_device *dev, u8 loc)
+{
+	struct net_bridge_port *p;
+	int err = 0;
+
+	p = br_port_get_rcu(dev);
+	if (!p) {
+		err = -EINVAL;
+		goto out;
+	}
+
+	if (loc)
+		p->flags |= BR_MRP_LOST_CONT;
+	else
+		p->flags &= ~BR_MRP_LOST_CONT;
+
+	br_ifinfo_notify(RTM_NEWLINK, NULL, p);
+
+out:
+	return err;
+}
-- 
2.17.1

Implement netlink interface to configure MRP. The implementation
will do sanity checks over the attributes and then eventually call the MRP
interface.

Signed-off-by: Horatiu Vultur <horatiu.vultur at microchip.com>
---
 net/bridge/br_mrp_netlink.c | 91 +++++++++++++++++++++++++++++++++++++
 1 file changed, 91 insertions(+)

diff --git a/net/bridge/br_mrp_netlink.c b/net/bridge/br_mrp_netlink.c
index b982db14bbf4..7b4b8b0dcea0 100644
--- a/net/bridge/br_mrp_netlink.c
+++ b/net/bridge/br_mrp_netlink.c
@@ -6,6 +6,97 @@
 #include "br_private.h"
 #include "br_private_mrp.h"
 
+static const struct nla_policy br_mrp_policy[IFLA_BRIDGE_MRP_MAX + 1] = {
+	[IFLA_BRIDGE_MRP_UNSPEC]	= { .type = NLA_REJECT },
+	[IFLA_BRIDGE_MRP_INSTANCE]	= { .type = NLA_EXACT_LEN,
+					    .len = sizeof(struct br_mrp_instance)},
+	[IFLA_BRIDGE_MRP_PORT_STATE]	= { .type = NLA_U32 },
+	[IFLA_BRIDGE_MRP_PORT_ROLE]	= { .type = NLA_EXACT_LEN,
+					    .len = sizeof(struct br_mrp_port_role)},
+	[IFLA_BRIDGE_MRP_RING_STATE]	= { .type = NLA_EXACT_LEN,
+					    .len = sizeof(struct br_mrp_ring_state)},
+	[IFLA_BRIDGE_MRP_RING_ROLE]	= { .type = NLA_EXACT_LEN,
+					    .len = sizeof(struct br_mrp_ring_role)},
+	[IFLA_BRIDGE_MRP_START_TEST]	= { .type = NLA_EXACT_LEN,
+					    .len = sizeof(struct br_mrp_start_test)},
+};
+
+int br_mrp_parse(struct net_bridge *br, struct net_bridge_port *p,
+		 struct nlattr *attr, int cmd, struct netlink_ext_ack *extack)
+{
+	struct nlattr *tb[IFLA_BRIDGE_MRP_MAX + 1];
+	int err;
+
+	if (br->stp_enabled != BR_NO_STP) {
+		NL_SET_ERR_MSG_MOD(extack, "MRP can't be enabled if STP is already
enabled\n");
+		return -EINVAL;
+	}
+
+	err = nla_parse_nested(tb, IFLA_BRIDGE_MRP_MAX, attr,
+			       br_mrp_policy, extack);
+	if (err)
+		return err;
+
+	if (tb[IFLA_BRIDGE_MRP_INSTANCE]) {
+		struct br_mrp_instance *instance +			nla_data(tb[IFLA_BRIDGE_MRP_INSTANCE]);
+
+		if (cmd == RTM_SETLINK)
+			err = br_mrp_add(br, instance);
+		else
+			err = br_mrp_del(br, instance);
+		if (err)
+			return err;
+	}
+
+	if (tb[IFLA_BRIDGE_MRP_PORT_STATE]) {
+		enum br_mrp_port_state_type state +		
nla_get_u32(tb[IFLA_BRIDGE_MRP_PORT_STATE]);
+
+		err = br_mrp_set_port_state(p, state);
+		if (err)
+			return err;
+	}
+
+	if (tb[IFLA_BRIDGE_MRP_PORT_ROLE]) {
+		struct br_mrp_port_role *role +			nla_data(tb[IFLA_BRIDGE_MRP_PORT_ROLE]);
+
+		err = br_mrp_set_port_role(p, role);
+		if (err)
+			return err;
+	}
+
+	if (tb[IFLA_BRIDGE_MRP_RING_STATE]) {
+		struct br_mrp_ring_state *state +			nla_data(tb[IFLA_BRIDGE_MRP_RING_STATE]);
+
+		err = br_mrp_set_ring_state(br, state);
+		if (err)
+			return err;
+	}
+
+	if (tb[IFLA_BRIDGE_MRP_RING_ROLE]) {
+		struct br_mrp_ring_role *role +			nla_data(tb[IFLA_BRIDGE_MRP_RING_ROLE]);
+
+		err = br_mrp_set_ring_role(br, role);
+		if (err)
+			return err;
+	}
+
+	if (tb[IFLA_BRIDGE_MRP_START_TEST]) {
+		struct br_mrp_start_test *test +			nla_data(tb[IFLA_BRIDGE_MRP_START_TEST]);
+
+		err = br_mrp_start_test(br, test);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
 int br_mrp_port_open(struct net_device *dev, u8 loc)
 {
 	struct net_bridge_port *p;
-- 
2.17.1

To integrate MRP into the bridge, the bridge needs to do the following:
- detect if the MRP frame was received on MRP ring port in that case it would be
  processed otherwise just forward it as usual.
- enable parsing of MRP
- before whenever the bridge was set up, it would set all the ports in
  forwarding state. Add an extra check to not set ports in forwarding state if
  the port is an MRP ring port. The reason of this change is that if the MRP
  instance initially sets the port in blocked state by setting the bridge up it
  would overwrite this setting.

Signed-off-by: Horatiu Vultur <horatiu.vultur at microchip.com>
---
 net/bridge/br_device.c  |  3 +++
 net/bridge/br_if.c      |  2 ++
 net/bridge/br_input.c   |  3 +++
 net/bridge/br_netlink.c |  5 +++++
 net/bridge/br_private.h | 31 +++++++++++++++++++++++++++++++
 5 files changed, 44 insertions(+)

diff --git a/net/bridge/br_device.c b/net/bridge/br_device.c
index 0e3dbc5f3c34..8ec1362588af 100644
--- a/net/bridge/br_device.c
+++ b/net/bridge/br_device.c
@@ -463,6 +463,9 @@ void br_dev_setup(struct net_device *dev)
 	spin_lock_init(&br->lock);
 	INIT_LIST_HEAD(&br->port_list);
 	INIT_HLIST_HEAD(&br->fdb_list);
+#if IS_ENABLED(CONFIG_BRIDGE_MRP)
+	INIT_LIST_HEAD(&br->mrp_list);
+#endif
 	spin_lock_init(&br->hash_lock);
 
 	br->bridge_id.prio[0] = 0x80;
diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
index 4fe30b182ee7..ca685c0cdf95 100644
--- a/net/bridge/br_if.c
+++ b/net/bridge/br_if.c
@@ -333,6 +333,8 @@ static void del_nbp(struct net_bridge_port *p)
 	br_stp_disable_port(p);
 	spin_unlock_bh(&br->lock);
 
+	br_mrp_port_del(br, p);
+
 	br_ifinfo_notify(RTM_DELLINK, NULL, p);
 
 	list_del_rcu(&p->list);
diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
index fcc260840028..d5c34f36f0f4 100644
--- a/net/bridge/br_input.c
+++ b/net/bridge/br_input.c
@@ -342,6 +342,9 @@ rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
 		}
 	}
 
+	if (unlikely(br_mrp_process(p, skb)))
+		return RX_HANDLER_PASS;
+
 forward:
 	switch (p->state) {
 	case BR_STATE_FORWARDING:
diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
index 4084f1ef8641..1a5e681a626a 100644
--- a/net/bridge/br_netlink.c
+++ b/net/bridge/br_netlink.c
@@ -672,6 +672,11 @@ static int br_afspec(struct net_bridge *br,
 			if (err)
 				return err;
 			break;
+		case IFLA_BRIDGE_MRP:
+			err = br_mrp_parse(br, p, attr, cmd, extack);
+			if (err)
+				return err;
+			break;
 		}
 	}
 
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index 835a70f8d3ea..5835828320b6 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -1308,6 +1308,37 @@ unsigned long br_timer_value(const struct timer_list
*timer);
 extern int (*br_fdb_test_addr_hook)(struct net_device *dev, unsigned char
*addr);
 #endif
 
+/* br_mrp.c */
+#if IS_ENABLED(CONFIG_BRIDGE_MRP)
+int br_mrp_parse(struct net_bridge *br, struct net_bridge_port *p,
+		 struct nlattr *attr, int cmd, struct netlink_ext_ack *extack);
+int br_mrp_process(struct net_bridge_port *p, struct sk_buff *skb);
+bool br_mrp_enabled(struct net_bridge *br);
+void br_mrp_port_del(struct net_bridge *br, struct net_bridge_port *p);
+#else
+static inline int br_mrp_parse(struct net_bridge *br, struct net_bridge_port
*p,
+			       struct nlattr *attr, int cmd,
+			       struct netlink_ext_ack *extack)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int br_mrp_process(struct net_bridge_port *p, struct sk_buff
*skb)
+{
+	return 0;
+}
+
+static inline bool br_mrp_enabled(struct net_bridge *br)
+{
+	return 0;
+}
+
+static inline void br_mrp_port_del(struct net_bridge *br,
+				   struct net_bridge_port *p)
+{
+}
+#endif
+
 /* br_netlink.c */
 extern struct rtnl_link_ops br_link_ops;
 int br_netlink_init(void);
-- 
2.17.1

It is not possible to have the MRP and STP running at the same time on the
bridge, therefore add check when enabling the STP to check if MRP is already
enabled. In that case return error.

Signed-off-by: Horatiu Vultur <horatiu.vultur at microchip.com>
---
 net/bridge/br_ioctl.c    |  3 +--
 net/bridge/br_netlink.c  |  4 +++-
 net/bridge/br_private.h  |  3 ++-
 net/bridge/br_stp.c      |  6 ++++++
 net/bridge/br_stp_if.c   | 11 ++++++++++-
 net/bridge/br_sysfs_br.c |  4 +---
 6 files changed, 23 insertions(+), 8 deletions(-)

diff --git a/net/bridge/br_ioctl.c b/net/bridge/br_ioctl.c
index ae22d784b88a..5e71fc8b826f 100644
--- a/net/bridge/br_ioctl.c
+++ b/net/bridge/br_ioctl.c
@@ -242,8 +242,7 @@ static int old_dev_ioctl(struct net_device *dev, struct
ifreq *rq, int cmd)
 		if (!ns_capable(dev_net(dev)->user_ns, CAP_NET_ADMIN))
 			return -EPERM;
 
-		br_stp_set_enabled(br, args[1]);
-		ret = 0;
+		ret = br_stp_set_enabled(br, args[1], NULL);
 		break;
 
 	case BRCTL_SET_BRIDGE_PRIORITY:
diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
index 1a5e681a626a..a774e19c41bb 100644
--- a/net/bridge/br_netlink.c
+++ b/net/bridge/br_netlink.c
@@ -1109,7 +1109,9 @@ static int br_changelink(struct net_device *brdev, struct
nlattr *tb[],
 	if (data[IFLA_BR_STP_STATE]) {
 		u32 stp_enabled = nla_get_u32(data[IFLA_BR_STP_STATE]);
 
-		br_stp_set_enabled(br, stp_enabled);
+		err = br_stp_set_enabled(br, stp_enabled, extack);
+		if (err)
+			return err;
 	}
 
 	if (data[IFLA_BR_PRIORITY]) {
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index 5835828320b6..c35647cb138a 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -1283,7 +1283,8 @@ int br_set_ageing_time(struct net_bridge *br, clock_t
ageing_time);
 /* br_stp_if.c */
 void br_stp_enable_bridge(struct net_bridge *br);
 void br_stp_disable_bridge(struct net_bridge *br);
-void br_stp_set_enabled(struct net_bridge *br, unsigned long val);
+int br_stp_set_enabled(struct net_bridge *br, unsigned long val,
+		       struct netlink_ext_ack *extack);
 void br_stp_enable_port(struct net_bridge_port *p);
 void br_stp_disable_port(struct net_bridge_port *p);
 bool br_stp_recalculate_bridge_id(struct net_bridge *br);
diff --git a/net/bridge/br_stp.c b/net/bridge/br_stp.c
index 1f14b8455345..3e88be7aa269 100644
--- a/net/bridge/br_stp.c
+++ b/net/bridge/br_stp.c
@@ -36,6 +36,12 @@ void br_set_state(struct net_bridge_port *p, unsigned int
state)
 	};
 	int err;
 
+	/* Don't change the state of the ports if they are driven by a different
+	 * protocol.
+	 */
+	if (p->flags & BR_MRP_AWARE)
+		return;
+
 	p->state = state;
 	err = switchdev_port_attr_set(p->dev, &attr);
 	if (err && err != -EOPNOTSUPP)
diff --git a/net/bridge/br_stp_if.c b/net/bridge/br_stp_if.c
index d174d3a566aa..a42850b7eb9a 100644
--- a/net/bridge/br_stp_if.c
+++ b/net/bridge/br_stp_if.c
@@ -196,10 +196,17 @@ static void br_stp_stop(struct net_bridge *br)
 	br->stp_enabled = BR_NO_STP;
 }
 
-void br_stp_set_enabled(struct net_bridge *br, unsigned long val)
+int br_stp_set_enabled(struct net_bridge *br, unsigned long val,
+		       struct netlink_ext_ack *extack)
 {
 	ASSERT_RTNL();
 
+	if (br_mrp_enabled(br)) {
+		NL_SET_ERR_MSG_MOD(extack,
+				   "STP can't be enabled if MRP is already enabled\n");
+		return -EINVAL;
+	}
+
 	if (val) {
 		if (br->stp_enabled == BR_NO_STP)
 			br_stp_start(br);
@@ -207,6 +214,8 @@ void br_stp_set_enabled(struct net_bridge *br, unsigned long
val)
 		if (br->stp_enabled != BR_NO_STP)
 			br_stp_stop(br);
 	}
+
+	return 0;
 }
 
 /* called under bridge lock */
diff --git a/net/bridge/br_sysfs_br.c b/net/bridge/br_sysfs_br.c
index 9ab0f00b1081..7db06e3f642a 100644
--- a/net/bridge/br_sysfs_br.c
+++ b/net/bridge/br_sysfs_br.c
@@ -126,9 +126,7 @@ static ssize_t stp_state_show(struct device *d,
 
 static int set_stp_state(struct net_bridge *br, unsigned long val)
 {
-	br_stp_set_enabled(br, val);
-
-	return 0;
+	return br_stp_set_enabled(br, val, NULL);
 }
 
 static ssize_t stp_state_store(struct device *d,
-- 
2.17.1