net: ethtool: Track pause storm events

With TX pause enabled, if a device is unable to pass packets up to the
stack (e.g., CPU is hanged), the device can cause pause storm. Given
that devices can have native support to protect the neighbor from such
flooding, such events need some tracking. This support is to track TX
pause storm events for better observability.

Reviewed-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Mohsin Bashir <mohsin.bashr@gmail.com>
Link: https://patch.msgid.link/20260302230149.1580195-2-mohsin.bashr@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Documentation/netlink/specs/ethtool.yaml

@@ -879,6 +879,19 @@ attribute-sets:
       -
         name: rx-frames
         type: u64
+      -
+        name: tx-pause-storm-events
+        type: u64
+        doc: >-
+            TX pause storm event count. Increments each time device
+            detects that its pause assertion condition has been true
+            for too long for normal operation. As a result, the device
+            has temporarily disabled its own Pause TX function to
+            protect the network from itself.
+            This counter should never increment under normal overload
+            conditions; it indicates catastrophic failure like an OS
+            crash. The rate of incrementing is implementation specific.
+
   -
     name: pause
     attr-cnt-name: __ethtool-a-pause-cnt