bridge: mrp: Extend br_mrp_switchdev to detect better the errors

This patch extends the br_mrp_switchdev functions to be able to have a
better understanding what cause the issue and if the SW needs to be used
as a backup.

There are the following cases:
- when the code is compiled without CONFIG_NET_SWITCHDEV. In this case
return success so the SW can continue with the protocol. Depending
on the function, it returns 0 or BR_MRP_SW.
- when code is compiled with CONFIG_NET_SWITCHDEV and the driver doesn't
implement any MRP callbacks. In this case the HW can't run MRP so it
just returns -EOPNOTSUPP. So the SW will stop further to configure the
node.
- when code is compiled with CONFIG_NET_SWITCHDEV and the driver fully
supports any MRP functionality. In this case the SW doesn't need to do
anything. The functions will return 0 or BR_MRP_HW.
- when code is compiled with CONFIG_NET_SWITCHDEV and the HW can't run
completely the protocol but it can help the SW to run it. For
example, the HW can't support completely MRM role(can't detect when it
stops receiving MRP Test frames) but it can redirect these frames to
CPU. In this case it is possible to have a SW fallback. The SW will
try initially to call the driver with sw_backup set to false, meaning
that the HW should implement completely the role. If the driver returns
-EOPNOTSUPP, the SW will try again with sw_backup set to false,
meaning that the SW will detect when it stops receiving the frames but
it needs HW support to redirect the frames to CPU. In case the driver
returns 0 then the SW will continue to configure the node accordingly.

Signed-off-by: Horatiu Vultur <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/bridge/br_mrp_switchdev.c

···
 
 #include "br_private_mrp.h"
 
+static enum br_mrp_hw_support
+br_mrp_switchdev_port_obj(struct net_bridge *br,
+			  const struct switchdev_obj *obj, bool add)
+{
+	int err;
+
+	if (add)
+		err = switchdev_port_obj_add(br->dev, obj, NULL);
+	else
+		err = switchdev_port_obj_del(br->dev, obj);
+
+	/* In case of success just return and notify the SW that doesn't need
+	 * to do anything
+	 */
+	if (!err)
+		return BR_MRP_HW;
+
+	if (err != -EOPNOTSUPP)
+		return BR_MRP_NONE;
+
+	/* Continue with SW backup */
+	return BR_MRP_SW;
+}
+
 int br_mrp_switchdev_add(struct net_bridge *br, struct br_mrp *mrp)
 {
 	struct switchdev_obj_mrp mrp_obj = {
···
 		.ring_id = mrp->ring_id,
 		.prio = mrp->prio,
 	};
-	int err;
 
-	err = switchdev_port_obj_add(br->dev, &mrp_obj.obj, NULL);
+	if (!IS_ENABLED(CONFIG_NET_SWITCHDEV))
+		return 0;
 
-	if (err && err != -EOPNOTSUPP)
-		return err;
-
-	return 0;
+	return switchdev_port_obj_add(br->dev, &mrp_obj.obj, NULL);
 }
 
 int br_mrp_switchdev_del(struct net_bridge *br, struct br_mrp *mrp)
···
 		.s_port = NULL,
 		.ring_id = mrp->ring_id,
 	};
-	int err;
 
-	err = switchdev_port_obj_del(br->dev, &mrp_obj.obj);
+	if (!IS_ENABLED(CONFIG_NET_SWITCHDEV))
+		return 0;
 
-	if (err && err != -EOPNOTSUPP)
-		return err;
-
-	return 0;
+	return switchdev_port_obj_del(br->dev, &mrp_obj.obj);
 }
 
-int br_mrp_switchdev_set_ring_role(struct net_bridge *br,
-				   struct br_mrp *mrp,
-				   enum br_mrp_ring_role_type role)
+enum br_mrp_hw_support
+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,
+		.sw_backup = false,
 	};
+	enum br_mrp_hw_support support;
 	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);
+	if (!IS_ENABLED(CONFIG_NET_SWITCHDEV))
+		return BR_MRP_SW;
 
-	return err;
+	support = br_mrp_switchdev_port_obj(br, &mrp_role.obj,
+					    role != BR_MRP_RING_ROLE_DISABLED);
+	if (support != BR_MRP_SW)
+		return support;
+
+	/* If the driver can't configure to run completely the protocol in HW,
+	 * then try again to configure the HW so the SW can run the protocol.
+	 */
+	mrp_role.sw_backup = true;
+	if (role != BR_MRP_RING_ROLE_DISABLED)
+		err = switchdev_port_obj_add(br->dev, &mrp_role.obj, NULL);
+	else
+		err = switchdev_port_obj_del(br->dev, &mrp_role.obj);
+
+	if (!err)
+		return BR_MRP_SW;
+
+	return BR_MRP_NONE;
 }
 
-int br_mrp_switchdev_send_ring_test(struct net_bridge *br,
-				    struct br_mrp *mrp, u32 interval,
-				    u8 max_miss, u32 period,
-				    bool monitor)
+enum br_mrp_hw_support
+br_mrp_switchdev_send_ring_test(struct net_bridge *br, struct br_mrp *mrp,
+				u32 interval, u8 max_miss, u32 period,
+				bool monitor)
 {
 	struct switchdev_obj_ring_test_mrp test = {
 		.obj.orig_dev = br->dev,
···
 		.period = period,
 		.monitor = monitor,
 	};
-	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);
+	if (!IS_ENABLED(CONFIG_NET_SWITCHDEV))
+		return BR_MRP_SW;
 
-	return err;
+	return br_mrp_switchdev_port_obj(br, &test.obj, interval != 0);
 }
 
 int br_mrp_switchdev_set_ring_state(struct net_bridge *br,
···
 		.ring_state = state,
 		.ring_id = mrp->ring_id,
 	};
-	int err;
 
-	err = switchdev_port_obj_add(br->dev, &mrp_state.obj, NULL);
+	if (!IS_ENABLED(CONFIG_NET_SWITCHDEV))
+		return 0;
 
-	if (err && err != -EOPNOTSUPP)
-		return err;
-
-	return 0;
+	return switchdev_port_obj_add(br->dev, &mrp_state.obj, NULL);
 }
 
-int br_mrp_switchdev_set_in_role(struct net_bridge *br, struct br_mrp *mrp,
-				 u16 in_id, u32 ring_id,
-				 enum br_mrp_in_role_type role)
+enum br_mrp_hw_support
+br_mrp_switchdev_set_in_role(struct net_bridge *br, struct br_mrp *mrp,
+			     u16 in_id, u32 ring_id,
+			     enum br_mrp_in_role_type role)
 {
 	struct switchdev_obj_in_role_mrp mrp_role = {
 		.obj.orig_dev = br->dev,
···
 		.in_id = mrp->in_id,
 		.ring_id = mrp->ring_id,
 		.i_port = rtnl_dereference(mrp->i_port)->dev,
+		.sw_backup = false,
 	};
+	enum br_mrp_hw_support support;
 	int err;
 
-	if (role == BR_MRP_IN_ROLE_DISABLED)
-		err = switchdev_port_obj_del(br->dev, &mrp_role.obj);
-	else
-		err = switchdev_port_obj_add(br->dev, &mrp_role.obj, NULL);
+	if (!IS_ENABLED(CONFIG_NET_SWITCHDEV))
+		return BR_MRP_SW;
 
-	return err;
+	support = br_mrp_switchdev_port_obj(br, &mrp_role.obj,
+					    role != BR_MRP_IN_ROLE_DISABLED);
+	if (support != BR_MRP_NONE)
+		return support;
+
+	/* If the driver can't configure to run completely the protocol in HW,
+	 * then try again to configure the HW so the SW can run the protocol.
+	 */
+	mrp_role.sw_backup = true;
+	if (role != BR_MRP_IN_ROLE_DISABLED)
+		err = switchdev_port_obj_add(br->dev, &mrp_role.obj, NULL);
+	else
+		err = switchdev_port_obj_del(br->dev, &mrp_role.obj);
+
+	if (!err)
+		return BR_MRP_SW;
+
+	return BR_MRP_NONE;
 }
 
 int br_mrp_switchdev_set_in_state(struct net_bridge *br, struct br_mrp *mrp,
···
 		.in_state = state,
 		.in_id = mrp->in_id,
 	};
-	int err;
 
-	err = switchdev_port_obj_add(br->dev, &mrp_state.obj, NULL);
+	if (!IS_ENABLED(CONFIG_NET_SWITCHDEV))
+		return 0;
 
-	if (err && err != -EOPNOTSUPP)
-		return err;
-
-	return 0;
+	return switchdev_port_obj_add(br->dev, &mrp_state.obj, NULL);
 }
 
-int br_mrp_switchdev_send_in_test(struct net_bridge *br, struct br_mrp *mrp,
-				  u32 interval, u8 max_miss, u32 period)
+enum br_mrp_hw_support
+br_mrp_switchdev_send_in_test(struct net_bridge *br, struct br_mrp *mrp,
+			      u32 interval, u8 max_miss, u32 period)
 {
 	struct switchdev_obj_in_test_mrp test = {
 		.obj.orig_dev = br->dev,
···
 		.in_id = mrp->in_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);
+	if (!IS_ENABLED(CONFIG_NET_SWITCHDEV))
+		return BR_MRP_SW;
 
-	return err;
+	return br_mrp_switchdev_port_obj(br, &test.obj, interval != 0);
 }
 
 int br_mrp_port_switchdev_set_state(struct net_bridge_port *p, u32 state)
···
 		.id = SWITCHDEV_ATTR_ID_PORT_STP_STATE,
 		.u.stp_state = state,
 	};
-	int err;
 
-	err = switchdev_port_attr_set(p->dev, &attr, NULL);
-	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);
+	if (!IS_ENABLED(CONFIG_NET_SWITCHDEV))
+		return 0;
 
-	return err;
+	return switchdev_port_attr_set(p->dev, &attr, NULL);
 }
 
 int br_mrp_port_switchdev_set_role(struct net_bridge_port *p,
···
 		.id = SWITCHDEV_ATTR_ID_MRP_PORT_ROLE,
 		.u.mrp_port_role = role,
 	};
-	int err;
 
-	err = switchdev_port_attr_set(p->dev, &attr, NULL);
-	if (err && err != -EOPNOTSUPP)
-		return err;
+	if (!IS_ENABLED(CONFIG_NET_SWITCHDEV))
+		return 0;
 
-	return 0;
+	return switchdev_port_attr_set(p->dev, &attr, NULL);
 }

net/bridge/br_private_mrp.h

···
 /* 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);
+enum br_mrp_hw_support
+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,
-				    bool monitor);
+enum br_mrp_hw_support
+br_mrp_switchdev_send_ring_test(struct net_bridge *br, struct br_mrp *mrp,
+				u32 interval, u8 max_miss, u32 period,
+				bool monitor);
 int br_mrp_port_switchdev_set_state(struct net_bridge_port *p, u32 state);
 int br_mrp_port_switchdev_set_role(struct net_bridge_port *p,
 				   enum br_mrp_port_role_type role);
-int br_mrp_switchdev_set_in_role(struct net_bridge *br, struct br_mrp *mrp,
-				 u16 in_id, u32 ring_id,
-				 enum br_mrp_in_role_type role);
+enum br_mrp_hw_support
+br_mrp_switchdev_set_in_role(struct net_bridge *br, struct br_mrp *mrp,
+			     u16 in_id, u32 ring_id,
+			     enum br_mrp_in_role_type role);
 int br_mrp_switchdev_set_in_state(struct net_bridge *br, struct br_mrp *mrp,
 				  enum br_mrp_in_state_type state);
-int br_mrp_switchdev_send_in_test(struct net_bridge *br, struct br_mrp *mrp,
-				  u32 interval, u8 max_miss, u32 period);
+enum br_mrp_hw_support
+br_mrp_switchdev_send_in_test(struct net_bridge *br, struct br_mrp *mrp,
+			      u32 interval, u8 max_miss, u32 period);
 
 /* br_mrp_netlink.c  */
 int br_mrp_ring_port_open(struct net_device *dev, u8 loc);