RE: [PATCH net-next v1 1/6] ethtool: add interface to read Tx hardware timestamping statistics

[Keller, Jacob E]

> -----Original Message-----
> From: Rahul Rameshbabu <rrameshbabu@xxxxxxxxxx>
> Sent: Tuesday, April 2, 2024 10:15 PM
> To: Jakub Kicinski <kuba@xxxxxxxxxx>
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> Drewek, Wojciech <wojciech.drewek@xxxxxxxxx>
> Subject: Re: [PATCH net-next v1 1/6] ethtool: add interface to read Tx hardware
> timestamping statistics
> 
> On Tue, 02 Apr, 2024 19:18:42 -0700 Jakub Kicinski <kuba@xxxxxxxxxx> wrote:
> > On Tue,  2 Apr 2024 13:52:01 -0700 Rahul Rameshbabu wrote:
> >> +/**
> >> + * struct ethtool_ts_stats - HW timestamping statistics
> >> + * @tx_stats: struct group for TX HW timestamping
> >> + *	@pkts: Number of packets successfully timestamped by the hardware.
> >> + *	@lost: Number of hardware timestamping requests where the
> timestamping
> >> + *		information from the hardware never arrived for submission with
> >> + *		the skb.
> >> + *	@err: Number of arbitrary timestamp generation error events that the
> >> + *		hardware encountered, exclusive of @lost statistics. Cases such
> >> + *		as resource exhaustion, unavailability, firmware errors, and
> >> + *		detected illogical timestamp values not submitted with the skb
> >> + *		are inclusive to this counter.
> >> + */
> >> +struct ethtool_ts_stats {
> >> +	struct_group(tx_stats,
> >
> > Doesn't seem like the group should be documented:
> >
> > include/linux/ethtool.h:503: warning: Excess struct member 'tx_stats'
> description in 'ethtool_ts_stats'
> 
> Was looking into why our internal verification did not catch this. We
> run W=1 with clang, but looks like the warning does not get triggered
> unless explicitly run with scripts/kernel-doc.
> 
>   https://www.kernel.org/doc/html/latest/doc-guide/kernel-doc.html#how-to-
> format-kernel-doc-comments
> 
> I have debugged using strace that the way the kernel doc checking works
> when W=1 is set is that the matching source file that is being compiled
> is passed to scripts/kernel-doc, so include files are missed from the
> doc check. I think this is worth adding to the kernel documentation.
> 

It would be great if the W=1 setup could figure out the include files and send those to kernel-doc too, but I'm not sure if this is possible and if so how difficult it would be to implement it. A lot of headers produce warnings because a lot fewer people manually run kernel-doc on the entire source.

> Anyway, I will send out a v2 with this fixed but wait for potentially
> more feedback on v1.
> 
> --
> Thanks,
> 
> Rahul Rameshbabu