linux-kernel - Re: [PATCH net-next v9 7/9] libeth: add Rx buffer management

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Date: Tue, 9 Apr 2024 09:17:53 -0700
From: Kees Cook <keescook@...omium.org>
To: Alexander Lobakin <aleksander.lobakin@...el.com>
Cc: Jakub Kicinski <kuba@...nel.org>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>,
	Alexander Duyck <alexanderduyck@...com>,
	Yunsheng Lin <linyunsheng@...wei.com>,
	Jesper Dangaard Brouer <hawk@...nel.org>,
	Ilias Apalodimas <ilias.apalodimas@...aro.org>,
	Christoph Lameter <cl@...ux.com>, Vlastimil Babka <vbabka@...e.cz>,
	Andrew Morton <akpm@...ux-foundation.org>,
	nex.sw.ncis.osdt.itp.upstreaming@...el.com, netdev@...r.kernel.org,
	intel-wired-lan@...ts.osuosl.org, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next v9 7/9] libeth: add Rx buffer management

On Mon, Apr 08, 2024 at 11:45:32AM +0200, Alexander Lobakin wrote:
> From: Alexander Lobakin <aleksander.lobakin@...el.com>
> Date: Mon, 8 Apr 2024 11:11:12 +0200
> 
> > From: Jakub Kicinski <kuba@...nel.org>
> > Date: Fri, 5 Apr 2024 21:25:13 -0700
> > 
> >> On Thu,  4 Apr 2024 17:44:00 +0200 Alexander Lobakin wrote:
> >>> +/**
> >>> + * struct libeth_fq - structure representing a buffer queue
> >>> + * @fp: hotpath part of the structure
> >>
> >> Second time this happens this week, so maybe some tooling change in 6.9
> >> but apparently kdoc does not want to know about the tagged struct:
> >>
> >> include/net/libeth/rx.h:69: warning: Excess struct member 'fp' description in 'libeth_fq'
> > 
> > Oh no, maybe we should teach kdoc to parse struct_group*()?
> 
> scripts/kernel-doc apparently can handle them...
> 
> + Kees
> 

Ah, hm, scripts/kernel-doc throws away the early arguments of
struct_group_tagged, but I suspect it needs to create a synthetic member
for the tag. i.e. instead of:

	struct_group_tagged(tag, name, members...)

becoming

	members...

it needs to become

	struct tag name;
	members...

It seems this is the first place anyone has tried to document the tagged
struct name! :)

Does this work? I haven't tested it...

diff --git a/scripts/kernel-doc b/scripts/kernel-doc
index 967f1abb0edb..64a19228d5dd 100755
--- a/scripts/kernel-doc
+++ b/scripts/kernel-doc
@@ -1151,7 +1151,8 @@ sub dump_struct($$) {
         # - first eat non-declaration parameters and rewrite for final match
         # - then remove macro, outer parens, and trailing semicolon
         $members =~ s/\bstruct_group\s*\(([^,]*,)/STRUCT_GROUP(/gos;
-        $members =~ s/\bstruct_group_(attr|tagged)\s*\(([^,]*,){2}/STRUCT_GROUP(/gos;
+        $members =~ s/\bstruct_group_attr\s*\(([^,]*,){2}/STRUCT_GROUP(/gos;
+        $members =~ s/\bstruct_group_tagged\s*\(([^,]*,)([^,]*,)/struct $1 $2; STRUCT_GROUP(/gos;
         $members =~ s/\b__struct_group\s*\(([^,]*,){3}/STRUCT_GROUP(/gos;
         $members =~ s/\bSTRUCT_GROUP(\(((?:(?>[^)(]+)|(?1))*)\))[^;]*;/$2/gos;
 

> > 
> >>
> >>> + * @pp: &page_pool for buffer management
> >>> + * @fqes: array of Rx buffers
> >>> + * @truesize: size to allocate per buffer, w/overhead
> >>> + * @count: number of descriptors/buffers the queue has
> >>> + * @buf_len: HW-writeable length per each buffer
> >>> + * @nid: ID of the closest NUMA node with memory
> >>> + */
> >>> +struct libeth_fq {
> >>> +	struct_group_tagged(libeth_fq_fp, fp,
> >>> +		struct page_pool	*pp;
> >>> +		struct libeth_fqe	*fqes;
> >>> +
> >>> +		u32			truesize;
> >>> +		u32			count;
> >>> +	);
> >>> +
> >>> +	/* Cold fields */
> >>> +	u32			buf_len;
> >>> +	int			nid;
> >>> +};
> 
> Thanks,
> Olek

-- 
Kees Cook