Aw: Re: [PATCH 2/2] net: dsa: tag_ksz: dont let the hardware process the layer 4 checksum

[Lino Sanfilippo]

> Gesendet: Donnerstag, 15. Juli 2021 um 15:12 Uhr
> Von: "Vladimir Oltean" <olteanv@xxxxxxxxx>
> An: "Lino Sanfilippo" <LinoSanfilippo@xxxxxx>
> Cc: "Andrew Lunn" <andrew@xxxxxxx>, woojung.huh@xxxxxxxxxxxxx, UNGLinuxDriver@xxxxxxxxxxxxx, vivien.didelot@xxxxxxxxx, f.fainelli@xxxxxxxxx, davem@xxxxxxxxxxxxx, kuba@xxxxxxxxxx, netdev@xxxxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx
> Betreff: Re: [PATCH 2/2] net: dsa: tag_ksz: dont let the hardware process the layer 4 checksum
>
> On Thu, Jul 15, 2021 at 03:04:31PM +0200, Lino Sanfilippo wrote:
> > Please note that skb_put() asserts that the SKB is linearized. So I think we
> > should rather clear both NETIF_F_FRAGLIST and NETIF_F_SG unconditionally since also
> > header taggers use some form of skb_put() dont they?
>
> The tail taggers use skb_put() as part of the routine to make room for
> the tail tag.
>
> Some of the header taggers use __skb_put_padto() when the packets are
> too small (under ETH_ZLEN). When they are so small they are definitely
> linear already.
>
> We don't have a third form/use of skb_put().
>

Ah ok, I see. Then it should be fine do clear both flags only in case of
tail taggers.

Regards,
Lino