devlink: Create dedicated trap group for layer 3 exceptions

Packets that hit exceptions during layer 3 forwarding must be trapped to
the CPU for the control plane to function properly. Create a dedicated
group for them, so that user space could choose to assign a different
policer for them.

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/networking/devlink/devlink-trap.rst

@@ -277,8 +277,11 @@ narrow. The description of these groups must be added to the following table:
      - Contains packet traps for packets that were dropped by the device during
        layer 2 forwarding (i.e., bridge)
    * - ``l3_drops``
-     - Contains packet traps for packets that were dropped by the device or hit
-       an exception (e.g., TTL error) during layer 3 forwarding
+     - Contains packet traps for packets that were dropped by the device during
+       layer 3 forwarding
+   * - ``l3_exceptions``
+     - Contains packet traps for packets that hit an exception (e.g., TTL
+       error) during layer 3 forwarding
    * - ``buffer_drops``
      - Contains packet traps for packets that were dropped by the device due to
        an enqueue decision