Subject: Re: [PATCH RFC v2 1/6] ethtool: add interface to read Tx hardware timestamping statistics

From: Rahul Rameshbabu <[email-masked]>
Date: Thu, 14 Mar 2024 10:01:49 -0700

On Tue, 12 Mar, 2024 16:53:46 -0700 Jakub Kicinski <[email-masked]> wrote:
> On Sat,  9 Mar 2024 00:44:35 -0800 Rahul Rameshbabu wrote:
>> Multiple network devices that support hardware timestamping appear to have
>> common behavior with regards to timestamp handling. Implement common Tx
>> hardware timestamping statistics in a tx_stats struct_group. Common Rx
>> hardware timestamping statistics can subsequently be implemented in a
>> rx_stats struct_group for ethtool_ts_stats.
>
>>  Documentation/netlink/specs/ethtool.yaml | 20 +++++++++
>>  include/linux/ethtool.h                  | 21 ++++++++++
>>  include/uapi/linux/ethtool_netlink.h     | 15 +++++++
>>  net/ethtool/tsinfo.c                     | 52 +++++++++++++++++++++++-
>>  4 files changed, 107 insertions(+), 1 deletion(-)
>
> Feels like we should mention the new stats somehow in 
> Documentation/networking/ethtool-netlink.rst
>
>> diff --git a/Documentation/netlink/specs/ethtool.yaml b/Documentation/netlink/specs/ethtool.yaml
>> index 197208f419dc..f99b003c78c0 100644
>> --- a/Documentation/netlink/specs/ethtool.yaml
>> +++ b/Documentation/netlink/specs/ethtool.yaml
>> @@ -559,6 +559,21 @@ attribute-sets:
>>        -
>>          name: tx-lpi-timer
>>          type: u32
>> +  -
>> +    name: ts-stat
>> +    attributes:
>> +      -
>> +        name: pad
>> +        type: pad
>
> You can remove the pad entry, and...
>

You need the pad to match with ETHTOOL_A_TS_STAT_PAD (which similar to
other ethtool stats currently defined). Otherwise, you run into the
following.... mm-stat and fec-stat are good examples.

  [root@binary-eater-vm-01 linux-ethtool-ts]# ./tools/net/ynl/ethtool.py --show-time-stamping mlx5_1
  Traceback (most recent call last):
    File "/root/linux-ethtool-ts/tools/net/ynl/lib/ynl.py", line 598, in _decode
      attr_spec = attr_space.attrs_by_val[attr.type]
                  ~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^
  KeyError: 4

  During handling of the above exception, another exception occurred:

  Traceback (most recent call last):
    File "/root/linux-ethtool-ts/./tools/net/ynl/ethtool.py", line 437, in <module>
      main()
    File "/root/linux-ethtool-ts/./tools/net/ynl/ethtool.py", line 333, in main
      tsinfo = dumpit(ynl, args, 'tsinfo-get', req)
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    File "/root/linux-ethtool-ts/./tools/net/ynl/ethtool.py", line 91, in dumpit
      reply = ynl.dump(op_name, { 'header': {} } | extra)
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    File "/root/linux-ethtool-ts/tools/net/ynl/lib/ynl.py", line 873, in dump
      return self._op(method, vals, [], dump=True)
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    File "/root/linux-ethtool-ts/tools/net/ynl/lib/ynl.py", line 858, in _op
      rsp_msg = self._decode(decoded.raw_attrs, op.attr_set.name)
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    File "/root/linux-ethtool-ts/tools/net/ynl/lib/ynl.py", line 607, in _decode
      subdict = self._decode(NlAttrs(attr.raw), attr_spec['nested-attributes'], search_attrs)
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    File "/root/linux-ethtool-ts/tools/net/ynl/lib/ynl.py", line 601, in _decode
      raise Exception(f"Space '{space}' has no attribute with value '{attr.type}'")
  Exception: Space 'ts-stat' has no attribute with value '4'

>> +enum {
>> +	ETHTOOL_A_TS_STAT_UNSPEC,
>> +	ETHTOOL_A_TS_STAT_PAD,
>> +
>> +	ETHTOOL_A_TS_STAT_TX_PKT,			/* array, u64 */
>> +	ETHTOOL_A_TS_STAT_TX_LOST,			/* array, u64 */
>> +	ETHTOOL_A_TS_STAT_TX_ERR,			/* array, u64 */
>
> I don't think these are arrays.
>
>> +
>> +	/* add new constants above here */
>> +	__ETHTOOL_A_TS_STAT_CNT,
>> +	ETHTOOL_A_TS_STAT_MAX = (__ETHTOOL_A_TS_STAT_CNT - 1)
>> +
>> +};

--
Thanks,

Rahul Rameshbabu