Re: [PATCH net-next v8 0/6] move CAN skb headroom content to skb extensions

[Paolo Abeni]

On 2/1/26 3:33 PM, Oliver Hartkopp via B4 Relay wrote:
> CAN bus related skbuffs (ETH_P_CAN/ETH_P_CANFD/ETH_P_CANXL) simply contain
> CAN frame structs for CAN CC/FD/XL of skb->len length at skb->data. Those
> CAN skbs do not have network/mac/transport headers nor other such
> references for encapsulated protocols like ethernet/IP protocols.
> 
> To store data for CAN specific use-cases all CAN bus related skbuffs are
> created with a 16 byte private skb headroom (struct can_skb_priv). Using
> the skb headroom and accessing skb->head for this private data led to
> several problems in the past likely due to "The struct can_skb_priv
> business is highly unconventional for the networking stack." [1]
> 
> This patch set aims to remove the unconventional skb headroom usage for CAN
> bus related skbuffs and use the common skb extensions instead.
> 
> [1] https://lore.kernel.org/linux-can/20260104074222.29e660ac@xxxxxxxxxx/

Could you please share how skb_ext size change with this series?
(possibly breaking down the actual size to each separate extension).

Ideally/hopefully the  skbuff_ext_cache size is not going to change, and
that would ensure that this change will not cause any indirect regressions.

/P