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From: Larysa Zaremba <larysa.zaremba@intel.com>
To: Jesper Dangaard Brouer <jbrouer@redhat.com>
Cc: bpf@vger.kernel.org, brouer@redhat.com,
	Stanislav Fomichev <sdf@google.com>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>,
	Jakub Kicinski <kuba@kernel.org>,
	Martin KaFai Lau <martin.lau@linux.dev>,
	Song Liu <song@kernel.org>, Yonghong Song <yhs@fb.com>,
	John Fastabend <john.fastabend@gmail.com>,
	KP Singh <kpsingh@kernel.org>, Jiri Olsa <jolsa@kernel.org>,
	Jesse Brandeburg <jesse.brandeburg@intel.com>,
	Tony Nguyen <anthony.l.nguyen@intel.com>,
	Anatoly Burakov <anatoly.burakov@intel.com>,
	Alexander Lobakin <alexandr.lobakin@intel.com>,
	Magnus Karlsson <magnus.karlsson@gmail.com>,
	Maryam Tahhan <mtahhan@redhat.com>,
	xdp-hints@xdp-project.net, netdev@vger.kernel.org,
	intel-wired-lan@lists.osuosl.org, linux-kernel@vger.kernel.org
Subject: [xdp-hints] Re: [PATCH RESEND bpf-next 09/15] xdp: Add VLAN tag hint
Date: Mon, 15 May 2023 18:09:55 +0200	[thread overview]
Message-ID: <ZGJZU89AK/3mFZXW@lincoln> (raw)
In-Reply-To: <b0694577-e2b3-f6de-cf85-aed99fdf2496@redhat.com>

On Mon, May 15, 2023 at 05:36:12PM +0200, Jesper Dangaard Brouer wrote:
> 
> 
> On 12/05/2023 17.26, Larysa Zaremba wrote:
> > Implement functionality that enables drivers to expose VLAN tag
> > to XDP code.
> > 
> > Signed-off-by: Larysa Zaremba <larysa.zaremba@intel.com>
> > ---
> [...]
> 
> > diff --git a/net/core/xdp.c b/net/core/xdp.c
> > index 41e5ca8643ec..eff21501609f 100644
> > --- a/net/core/xdp.c
> > +++ b/net/core/xdp.c
> > @@ -738,6 +738,30 @@ __bpf_kfunc int bpf_xdp_metadata_rx_hash(const struct xdp_md *ctx, u32 *hash,
> >   	return -EOPNOTSUPP;
> >   }
> 
> Remember below becomes part of main documentation on HW metadata hints:
>  - https://kernel.org/doc/html/latest/networking/xdp-rx-metadata.html
> 
> Hint compiling locally I use:
>  make SPHINXDIRS="networking" htmldocs
> 
> > +/**
> > + * bpf_xdp_metadata_rx_ctag - Read XDP packet inner vlan tag.
> 
> Is bpf_xdp_metadata_rx_ctag a good function name for the inner vlan tag?
> Like wise below "stag".
> 
> I cannot remember if the C-tag or S-tag is the inner or outer vlan tag.
> 
> When reading BPF code that use these function names, then I would have
> to ask Google for help, or find-and-read this doc.
> 
> Can we come-up with a more intuitive name, that e.g. helps when reading
> the BPF-prog code?

Well, my reasoning for such naming is that if someone can configure s-tag 
stripping in ethtool with 'rx-vlan-stag-hw-parse', they shouldn't have any 
problem with understanding those function names.

One possible improvement that comes to mind is maybe (similarly ethtool) calling 
c-tag just 'tag' and letting s-tag stay 'stag'. Because c-tag is this default 
802.1q tag, which is supported by various hardware, while s-tag is significantly 
less widespread.

But there are many options, really.

What are your suggestions?

> 
> > + * @ctx: XDP context pointer.
> > + * @vlan_tag: Return value pointer.
> > + *
> 
> IMHO right here, there should be a description.
> 
> E.g. for what a VLAN "tag" means.  I assume a "tag" isn't the VLAN id,
> but the raw VLAN tag that also contains the prio numbers etc.
> 
> It this VLAN tag expected to be in network-byte-order ?
> IMHO this doc should define what is expected (and driver devel must
> follow this).

Will specify that.

> 
> > + * Returns 0 on success or ``-errno`` on error.
> > + */
> > +__bpf_kfunc int bpf_xdp_metadata_rx_ctag(const struct xdp_md *ctx, u16 *vlan_tag)
> > +{
> > +	return -EOPNOTSUPP;
> > +}
> > +
> > +/**
> > + * bpf_xdp_metadata_rx_stag - Read XDP packet outer vlan tag.
> > + * @ctx: XDP context pointer.
> > + * @vlan_tag: Return value pointer.
> > + *
> > + * Returns 0 on success or ``-errno`` on error.
> 
> IMHO we should provide more guidance to expected return codes, and what
> they mean.  IMHO driver developers must only return codes that are
> described here, and if they invent a new, add it as part of their patch.

That's a good suggestion, I will expand the comment to describe error codes used 
so far.

> 
> See, formatting in bpf_xdp_metadata_rx_hash and check how this gets
> compiled into HTML.
> 
> 
> > + */
> > +__bpf_kfunc int bpf_xdp_metadata_rx_stag(const struct xdp_md *ctx, u16 *vlan_tag)
> > +{
> > +	return -EOPNOTSUPP;
> > +}
> > +
> 

  reply	other threads:[~2023-05-15 16:12 UTC|newest]

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-05-12 15:25 [xdp-hints] [PATCH RESEND bpf-next 00/15] new kfunc XDP hints and ice implementation Larysa Zaremba
2023-05-12 15:25 ` [xdp-hints] [PATCH RESEND bpf-next 01/15] ice: make RX hash reading code more reusable Larysa Zaremba
2023-05-19 16:46   ` [xdp-hints] " Alexander Lobakin
2023-05-22 15:03     ` Larysa Zaremba
2023-05-22 15:36       ` Alexander Lobakin
2023-05-12 15:25 ` [xdp-hints] [PATCH RESEND bpf-next 02/15] ice: make RX HW timestamp " Larysa Zaremba
2023-05-19 16:52   ` [xdp-hints] " Alexander Lobakin
2023-05-22 15:07     ` Larysa Zaremba
2023-05-12 15:25 ` [xdp-hints] [PATCH RESEND bpf-next 03/15] ice: make RX checksum checking " Larysa Zaremba
2023-05-22 15:51   ` [xdp-hints] " Alexander Lobakin
2023-05-22 16:05     ` Larysa Zaremba
2023-05-12 15:25 ` [xdp-hints] [PATCH RESEND bpf-next 04/15] ice: Make ptype internal to descriptor info processing Larysa Zaremba
2023-05-12 15:25 ` [xdp-hints] [PATCH RESEND bpf-next 05/15] ice: Introduce ice_xdp_buff Larysa Zaremba
2023-05-22 16:46   ` [xdp-hints] " Alexander Lobakin
2023-05-23  8:02     ` Larysa Zaremba
2023-05-25 11:02       ` Alexander Lobakin
2023-05-12 15:25 ` [xdp-hints] [PATCH RESEND bpf-next 06/15] ice: Support HW timestamp hint Larysa Zaremba
2023-05-12 18:19   ` [xdp-hints] " Stanislav Fomichev
2023-05-16 16:17     ` Jesper Dangaard Brouer
2023-05-12 15:25 ` [xdp-hints] [PATCH RESEND bpf-next 07/15] ice: Support RX hash XDP hint Larysa Zaremba
2023-05-12 18:22   ` [xdp-hints] " Stanislav Fomichev
2023-05-15 13:46     ` Larysa Zaremba
2023-05-12 15:26 ` [xdp-hints] [PATCH RESEND bpf-next 08/15] ice: Support XDP hints in AF_XDP ZC mode Larysa Zaremba
2023-05-12 15:26 ` [xdp-hints] [PATCH RESEND bpf-next 09/15] xdp: Add VLAN tag hint Larysa Zaremba
2023-05-12 18:28   ` [xdp-hints] " Stanislav Fomichev
2023-05-15 15:36   ` Jesper Dangaard Brouer
2023-05-15 16:09     ` Larysa Zaremba [this message]
2023-05-22  8:37       ` Jesper Dangaard Brouer
2023-05-22 15:48         ` Larysa Zaremba
2023-05-23 10:16           ` Jesper Dangaard Brouer
2023-05-23 17:35             ` Larysa Zaremba
2023-05-12 15:26 ` [xdp-hints] [PATCH RESEND bpf-next 10/15] ice: Implement " Larysa Zaremba
2023-05-12 18:31   ` [xdp-hints] " Stanislav Fomichev
2023-05-15 13:41     ` Larysa Zaremba
2023-05-15 15:07       ` Jesper Dangaard Brouer
2023-05-15 15:45         ` Larysa Zaremba
2023-05-12 15:26 ` [xdp-hints] [PATCH RESEND bpf-next 11/15] xdp: Add checksum level hint Larysa Zaremba
2023-05-12 18:34   ` [xdp-hints] " Stanislav Fomichev
2023-05-15 13:49     ` Larysa Zaremba
2023-05-12 15:26 ` [xdp-hints] [PATCH RESEND bpf-next 12/15] ice: Implement " Larysa Zaremba
2023-05-12 15:26 ` [xdp-hints] [PATCH RESEND bpf-next 13/15] selftests/bpf: Allow VLAN packets in xdp_hw_metadata Larysa Zaremba
2023-05-12 18:33   ` [xdp-hints] " Stanislav Fomichev
2023-05-15 14:05     ` Larysa Zaremba
2023-05-12 15:26 ` [xdp-hints] [PATCH RESEND bpf-next 14/15] net, xdp: allow metadata > 32 Larysa Zaremba
2023-05-15 16:17   ` [xdp-hints] " Jesper Dangaard Brouer
2023-05-15 17:08     ` Larysa Zaremba
2023-05-16 12:37       ` Alexander Lobakin
2023-05-16 15:35         ` Jesper Dangaard Brouer
2023-05-19 16:35           ` Alexander Lobakin
2023-05-22 11:41             ` Jesper Dangaard Brouer
2023-05-22 15:28               ` Alexander Lobakin
2023-05-22 15:55                 ` Daniel Borkmann
2023-05-12 15:26 ` [xdp-hints] [PATCH RESEND bpf-next 15/15] selftests/bpf: Add flags and new hints to xdp_hw_metadata Larysa Zaremba
2023-05-12 18:37   ` [xdp-hints] " Stanislav Fomichev

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