netdev - RE: [Intel-wired-lan] [PATCH net-next 01/10] net: Document skb_metadata

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Message-ID: <IA3PR11MB89869E31C1570E0212B8FA4AE581A@IA3PR11MB8986.namprd11.prod.outlook.com>
Date: Mon, 12 Jan 2026 11:28:51 +0000
From: "Loktionov, Aleksandr" <aleksandr.loktionov@...el.com>
To: Jakub Sitnicki <jakub@...udflare.com>, "netdev@...r.kernel.org"
	<netdev@...r.kernel.org>
CC: "David S. Miller" <davem@...emloft.net>, Eric Dumazet
	<edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
	<pabeni@...hat.com>, Simon Horman <horms@...nel.org>, Michael Chan
	<michael.chan@...adcom.com>, Pavan Chebbi <pavan.chebbi@...adcom.com>, Andrew
 Lunn <andrew+netdev@...n.ch>, "Nguyen, Anthony L"
	<anthony.l.nguyen@...el.com>, "Kitszel, Przemyslaw"
	<przemyslaw.kitszel@...el.com>, Saeed Mahameed <saeedm@...dia.com>, "Leon
 Romanovsky" <leon@...nel.org>, Tariq Toukan <tariqt@...dia.com>, Mark Bloch
	<mbloch@...dia.com>, Alexei Starovoitov <ast@...nel.org>, Daniel Borkmann
	<daniel@...earbox.net>, Jesper Dangaard Brouer <hawk@...nel.org>, "John
 Fastabend" <john.fastabend@...il.com>, Stanislav Fomichev <sdf@...ichev.me>,
	"intel-wired-lan@...ts.osuosl.org" <intel-wired-lan@...ts.osuosl.org>,
	"bpf@...r.kernel.org" <bpf@...r.kernel.org>, "kernel-team@...udflare.com"
	<kernel-team@...udflare.com>
Subject: RE: [Intel-wired-lan] [PATCH net-next 01/10] net: Document
 skb_metadata_set contract with the drivers



> -----Original Message-----
> From: Intel-wired-lan <intel-wired-lan-bounces@...osl.org> On Behalf
> Of Jakub Sitnicki via Intel-wired-lan
> Sent: Saturday, January 10, 2026 10:05 PM
> To: netdev@...r.kernel.org
> Cc: David S. Miller <davem@...emloft.net>; Eric Dumazet
> <edumazet@...gle.com>; Jakub Kicinski <kuba@...nel.org>; Paolo Abeni
> <pabeni@...hat.com>; Simon Horman <horms@...nel.org>; Michael Chan
> <michael.chan@...adcom.com>; Pavan Chebbi <pavan.chebbi@...adcom.com>;
> Andrew Lunn <andrew+netdev@...n.ch>; Nguyen, Anthony L
> <anthony.l.nguyen@...el.com>; Kitszel, Przemyslaw
> <przemyslaw.kitszel@...el.com>; Saeed Mahameed <saeedm@...dia.com>;
> Leon Romanovsky <leon@...nel.org>; Tariq Toukan <tariqt@...dia.com>;
> Mark Bloch <mbloch@...dia.com>; Alexei Starovoitov <ast@...nel.org>;
> Daniel Borkmann <daniel@...earbox.net>; Jesper Dangaard Brouer
> <hawk@...nel.org>; John Fastabend <john.fastabend@...il.com>;
> Stanislav Fomichev <sdf@...ichev.me>; intel-wired-
> lan@...ts.osuosl.org; bpf@...r.kernel.org; kernel-team@...udflare.com
> Subject: [Intel-wired-lan] [PATCH net-next 01/10] net: Document
> skb_metadata_set contract with the drivers
> 
> Prepare to copy XDP metadata into an skb extension chunk. To access
> the metadata contents, we need to know where it is located. Document
> the expectation - skb->data must point right past the metadata when
> skb_metadata_set gets called.
> 
> Signed-off-by: Jakub Sitnicki <jakub@...udflare.com>
> ---
>  include/linux/skbuff.h | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index
> 86737076101d..df001283076f 100644
> --- a/include/linux/skbuff.h
> +++ b/include/linux/skbuff.h
> @@ -4554,6 +4554,13 @@ static inline bool skb_metadata_differs(const
> struct sk_buff *skb_a,
>  	       true : __skb_metadata_differs(skb_a, skb_b, len_a);  }
> 
> +/**
> + * skb_metadata_set - Record packet metadata length.
> + * @skb: packet carrying the metadata
> + * @meta_len: number of bytes of metadata preceding skb->data
> + *
> + * Must be called when skb->data already points past the metadata
> area.
> + */
>  static inline void skb_metadata_set(struct sk_buff *skb, u8 meta_len)
> {
>  	skb_shinfo(skb)->meta_len = meta_len;
> 
> --
> 2.43.0

Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@...el.com>