Re: [PATCH net-next v4 4/8] bridge: mrp: Extend br_mrp_switchdev to detect better the errors

The 02/17/2021 10:56, Vladimir Oltean wrote:

On Tue, Feb 16, 2021 at 10:42:01PM +0100, Horatiu Vultur wrote:

quoted

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 <horatiu.vultur@microchip.com>
---
 net/bridge/br_mrp_switchdev.c | 171 +++++++++++++++++++++-------------
 net/bridge/br_private_mrp.h   |  24 +++--
 2 files changed, 118 insertions(+), 77 deletions(-)

diff --git a/net/bridge/br_mrp_switchdev.c b/net/bridge/br_mrp_switchdev.c
index 3c9a4abcf4ee..cb54b324fa8c 100644
--- a/net/bridge/br_mrp_switchdev.c
+++ b/net/bridge/br_mrp_switchdev.c

@@ -4,6 +4,30 @@

 #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;
+

Looks like you could have added this check here and simplified all the
callers:

        if (!IS_ENABLED(CONFIG_NET_SWITCHDEV))
                return BR_MRP_SW;

Yes, good catch!

quoted

+     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;
+}
+

-- 
/Horatiu