RE: [EXT] Re: [PATCH net-next] net: mvpp2: Add parsing support for different IPv4 IHL values

[Stefan Chulski]

> > -----Original Message-----
> > From: Russell King - ARM Linux admin <linux@xxxxxxxxxxxxxxx>
> > Sent: Tuesday, April 13, 2021 12:18 PM
> > To: Stefan Chulski <stefanc@xxxxxxxxxxx>
> > Cc: netdev@xxxxxxxxxxxxxxx; thomas.petazzoni@xxxxxxxxxxx;
> > davem@xxxxxxxxxxxxx; Nadav Haklai <nadavh@xxxxxxxxxxx>; Yan
> Markman
> > <ymarkman@xxxxxxxxxxx>; linux-kernel@xxxxxxxxxxxxxxx;
> kuba@xxxxxxxxxx;
> > mw@xxxxxxxxxxxx; andrew@xxxxxxx; atenart@xxxxxxxxxx; Liron Himi
> > <lironh@xxxxxxxxxxx>; Dana Vardi <danat@xxxxxxxxxxx>
> > Subject: [EXT] Re: [PATCH net-next] net: mvpp2: Add parsing support
> > for different IPv4 IHL values
> >
> > External Email
> >
> > ----------------------------------------------------------------------
> > On Tue, Apr 13, 2021 at 11:45:31AM +0300, stefanc@xxxxxxxxxxx wrote:
> > > From: Stefan Chulski <stefanc@xxxxxxxxxxx>
> > >
> > > Add parser entries for different IPv4 IHL values.
> > > Each entry will set the L4 header offset according to the IPv4 IHL field.
> > > L3 header offset will set during the parsing of the IPv4 protocol.
> >
> > What is the impact of this commit? Is something broken at the moment,
> > if so what? Does this need to be backported to stable kernels?
> >
> > These are key questions, of which the former two should be covered in
> > every commit message so that the reason for the change can be known.
> > It's no good just describing what is being changed in the commit
> > without also describing why the change is being made.
> >
> > Thanks.
> 
> Due to missed parser support for IP header length > 20, RX IPv4 checksum
> offload fail.
> 
> Regards.

Currently driver set skb->ip_summed = CHECKSUM_NONE and checksum done by software.
So this just improve performance for packets with IP header length > 20. 
IMO we can keep it in net-next.

Stefan.