Linux Ethernet Bridging - Jan 2021 - [Bridge] [PATCH net-next 3/4] 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, then 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 then 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 can 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. In
  case the driver returns 0 then the SW will continue to configure the
  node accordingly.

In this way is more clear when the SW needs to stop configuring the
node, or when the SW is used as a backup or the HW can implement the
functionality.

Signed-off-by: Horatiu Vultur <horatiu.vultur at microchip.com>
---
 net/bridge/br_mrp_switchdev.c | 189 +++++++++++++++++++++++++---------
 net/bridge/br_private_mrp.h   |  24 +++--
 2 files changed, 152 insertions(+), 61 deletions(-)

diff --git a/net/bridge/br_mrp_switchdev.c b/net/bridge/br_mrp_switchdev.c
index ed547e03ace1..e93a84532a4e 100644
--- a/net/bridge/br_mrp_switchdev.c
+++ b/net/bridge/br_mrp_switchdev.c
@@ -14,14 +14,12 @@ int br_mrp_switchdev_add(struct net_bridge *br, struct
br_mrp *mrp)
 		.ring_id = mrp->ring_id,
 		.prio = mrp->prio,
 	};
-	int err;
-
-	err = switchdev_port_obj_add(br->dev, &mrp_obj.obj, NULL);
 
-	if (err && err != -EOPNOTSUPP)
-		return err;
+	/* If switchdev is not enabled then just run in SW */
+	if (!IS_ENABLED(CONFIG_NET_SWITCHDEV))
+		return 0;
 
-	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)
@@ -33,40 +31,69 @@ 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 switchdev is not enabled then just run in SW */
+	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,
 	};
 	int err;
 
+	/* If switchdev is not enabled then just run in SW */
+	if (!IS_ENABLED(CONFIG_NET_SWITCHDEV))
+		return BR_MRP_SW;
+
+	/* First try to see if HW can implement comptletly the role in HW */
 	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;
+	/* In case of success then just return and notify the SW that doesn't
+	 * need to do anything
+	 */
+	if (!err)
+		return BR_MRP_HW;
+
+	/* There was some issue then is not possible at all to have this role so
+	 * just return failire
+	 */
+	if (err != -EOPNOTSUPP)
+		return BR_MRP_NONE;
+
+	/* In case the HW can't run complety in HW the protocol, we try again
+	 * and this time to allow the SW to help, but the HW needs to redirect
+	 * the frames to CPU.
+	 */
+	mrp_role.sw_backup = true;
+	err = switchdev_port_obj_add(br->dev, &mrp_role.obj, NULL);
+
+	/* In case of success then notify the SW that it needs to help with the
+	 * protocol
+	 */
+	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,
@@ -79,12 +106,29 @@ int br_mrp_switchdev_send_ring_test(struct net_bridge *br,
 	};
 	int err;
 
+	/* If switchdev is not enabled then just run in SW */
+	if (!IS_ENABLED(CONFIG_NET_SWITCHDEV))
+		return BR_MRP_SW;
+
 	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;
+	/* If everything succeed then the HW can send this frames, so the SW
+	 * doesn't need to generate them
+	 */
+	if (!err)
+		return BR_MRP_HW;
+
+	/* There was an error when the HW was configured so the SW return
+	 * failure
+	 */
+	if (err != -EOPNOTSUPP)
+		return BR_MRP_NONE;
+
+	/* So the HW can't generate these frames so allow the SW to do that */
+	return BR_MRP_SW;
 }
 
 int br_mrp_switchdev_set_ring_state(struct net_bridge *br,
@@ -97,19 +141,18 @@ 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 switchdev is not enabled then just run in SW */
+	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,
@@ -118,15 +161,46 @@ int br_mrp_switchdev_set_in_role(struct net_bridge *br,
struct br_mrp *mrp,
 		.in_id = mrp->in_id,
 		.ring_id = mrp->ring_id,
 		.i_port = rtnl_dereference(mrp->i_port)->dev,
+		.sw_backup = false,
 	};
 	int err;
 
+	/* If switchdev is not enabled then just run in SW */
+	if (!IS_ENABLED(CONFIG_NET_SWITCHDEV))
+		return BR_MRP_SW;
+
+	/* First try to see if HW can implement comptletly the role in HW */
 	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);
 
-	return err;
+	/* In case of success then just return and notify the SW that doesn't
+	 * need to do anything
+	 */
+	if (!err)
+		return BR_MRP_HW;
+
+	/* There was some issue then is not possible at all to have this role so
+	 * just return failire
+	 */
+	if (err != -EOPNOTSUPP)
+		return BR_MRP_NONE;
+
+	/* In case the HW can't run complety in HW the protocol, we try again
+	 * and this time to allow the SW to help, but the HW needs to redirect
+	 * the frames to CPU.
+	 */
+	mrp_role.sw_backup = true;
+	err = switchdev_port_obj_add(br->dev, &mrp_role.obj, NULL);
+
+	/* In case of success then notify the SW that it needs to help with the
+	 * protocol
+	 */
+	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,
@@ -138,18 +212,17 @@ 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 switchdev is not enabled then just run in SW */
+	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,
@@ -161,12 +234,29 @@ int br_mrp_switchdev_send_in_test(struct net_bridge *br,
struct br_mrp *mrp,
 	};
 	int err;
 
+	/* If switchdev is not enabled then just run in SW */
+	if (!IS_ENABLED(CONFIG_NET_SWITCHDEV))
+		return BR_MRP_SW;
+
 	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;
+	/* If everything succeed then the HW can send this frames, so the SW
+	 * doesn't need to generate them
+	 */
+	if (!err)
+		return BR_MRP_HW;
+
+	/* There was an error when the HW was configured so the SW return
+	 * failure
+	 */
+	if (err != -EOPNOTSUPP)
+		return BR_MRP_NONE;
+
+	/* So the HW can't generate these frames so allow the SW to do that */
+	return BR_MRP_SW;
 }
 
 int br_mrp_port_switchdev_set_state(struct net_bridge_port *p,
@@ -177,14 +267,12 @@ int br_mrp_port_switchdev_set_state(struct net_bridge_port
*p,
 		.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);
+	/* If switchdev is not enabled then just run in SW */
+	if (!IS_ENABLED(CONFIG_NET_SWITCHDEV))
+		return 0;
 
-	return err;
+	return switchdev_port_attr_set(p->dev, &attr);
 }
 
 int br_mrp_port_switchdev_set_role(struct net_bridge_port *p,
@@ -195,11 +283,10 @@ 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);
-	if (err && err != -EOPNOTSUPP)
-		return err;
+	/* If switchdev is not enabled then just run in SW */
+	if (!IS_ENABLED(CONFIG_NET_SWITCHDEV))
+		return 0;
 
-	return 0;
+	return switchdev_port_attr_set(p->dev, &attr);
 }
diff --git a/net/bridge/br_private_mrp.h b/net/bridge/br_private_mrp.h
index 31e666ae6955..e941dad398cf 100644
--- a/net/bridge/br_private_mrp.h
+++ b/net/bridge/br_private_mrp.h
@@ -79,24 +79,28 @@ int br_mrp_start_in_test(struct net_bridge *br,
 /* 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,
 				    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);
-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);
-- 
2.27.0

On Sat, Jan 23, 2021 at 11:23 AM Horatiu Vultur
<horatiu.vultur at microchip.com> wrote:
>
> 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, then 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 then 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 can 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. In
>   case the driver returns 0 then the SW will continue to configure the
>   node accordingly.
>
> In this way is more clear when the SW needs to stop configuring the
> node, or when the SW is used as a backup or the HW can implement the
> functionality.
>
> Signed-off-by: Horatiu Vultur <horatiu.vultur at microchip.com>
> -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,
>         };
>         int err;
>
> +       /* If switchdev is not enabled then just run in SW */
> +       if (!IS_ENABLED(CONFIG_NET_SWITCHDEV))
> +               return BR_MRP_SW;
> +
> +       /* First try to see if HW can implement comptletly the role in HW
*/
typo: completely
>         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;
> +       /* In case of success then just return and notify the SW that
doesn't
> +        * need to do anything
> +        */
> +       if (!err)
> +               return BR_MRP_HW;
> +
> +       /* There was some issue then is not possible at all to have this
role so
> +        * just return failire
typo: failure
> +        */
> +       if (err != -EOPNOTSUPP)
> +               return BR_MRP_NONE;
> +
> +       /* In case the HW can't run complety in HW the protocol, we try
again
typo: completely. Please proofread your comments closely. I saw at
least one typo in the commit messages too.

More in general comments that say what the code does can generally be eschewed.
> +        * and this time to allow the SW to help, but the HW needs to
redirect
> +        * the frames to CPU.
> +        */
> +       mrp_role.sw_backup = true;
> +       err = switchdev_port_obj_add(br->dev, &mrp_role.obj, NULL);
This calls the same function. I did not see code that changes behavior
based on sw_backup. Will this not give the same result?

Also, this lacks the role test (add or del). Is that because if
falling back onto SW mode during add, this code does not get called at
all on delete?
> +
> +       /* In case of success then notify the SW that it needs to help with
the
> +        * protocol
> +        */
> +       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,
> @@ -79,12 +106,29 @@ int br_mrp_switchdev_send_ring_test(struct net_bridge
*br,
>         };
>         int err;
>
> +       /* If switchdev is not enabled then just run in SW */
> +       if (!IS_ENABLED(CONFIG_NET_SWITCHDEV))
> +               return BR_MRP_SW;
> +
>         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;
> +       /* If everything succeed then the HW can send this frames, so the
SW
> +        * doesn't need to generate them
> +        */
> +       if (!err)
> +               return BR_MRP_HW;
> +
> +       /* There was an error when the HW was configured so the SW return
> +        * failure
> +        */
> +       if (err != -EOPNOTSUPP)
> +               return BR_MRP_NONE;
> +
> +       /* So the HW can't generate these frames so allow the SW to do
that */
> +       return BR_MRP_SW;
This is the same ternary test as above. It recurs a few times. Perhaps
it can use a helper.