netdev - Re: [RFC] xdp: pass flags to xdp_update_skb_shared

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Message-ID: <20250812091737.651fc41c@kernel.org>
Date: Tue, 12 Aug 2025 09:17:37 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: netdev@...r.kernel.org, bpf@...r.kernel.org
Cc: ast@...nel.org, daniel@...earbox.net, hawk@...nel.org,
 lorenzo@...nel.org, toke@...hat.com, john.fastabend@...il.com,
 sdf@...ichev.me, michael.chan@...adcom.com, anthony.l.nguyen@...el.com,
 przemyslaw.kitszel@...el.com, marcin.s.wojtas@...il.com, tariqt@...dia.com,
 mbloch@...dia.com, eperezma@...hat.com, aleksander.lobakin@...el.com
Subject: Re: [RFC] xdp: pass flags to xdp_update_skb_shared_info() directly

On Tue, 12 Aug 2025 09:15:28 -0700 Jakub Kicinski wrote:
> xdp_update_skb_shared_info() needs to update skb state which
> was maintained in xdp_buff / frame. Pass full flags into it,
> instead of breaking it out bit by bit. We will need to add
> a bit for unreadable frags (even tho XDP doesn't support
> those the driver paths may be common), at which point almost
> all call sites would become:
> 
>     xdp_update_skb_shared_info(skb, num_frags,
>                                sinfo->xdp_frags_size,
>                                MY_PAGE_SIZE * num_frags,
>                                xdp_buff_is_frag_pfmemalloc(xdp),
>                                xdp_buff_is_frag_unreadable(xdp));
> 
> Keep a helper for accessing the flags, in case we need to
> transform them somehow in the future (e.g. to cover up xdp_buff
> vs xdp_frame differences).

CC Olek

https://lore.kernel.org/all/20250812161528.835855-1-kuba@kernel.org/