Re: [Intel-wired-lan] [PATCH iwl-next] ice: flower: validate control flags

[Asbjørn Sloth Tønnesen]

Hi Sujai,

On 5/3/24 5:57 AM, Buvaneswaran, Sujai wrote:
> > -----Original Message-----
> > From: Intel-wired-lan <intel-wired-lan-bounces@xxxxxxxxxx> On Behalf Of
> > Asbjørn Sloth Tønnesen
> > Sent: Tuesday, April 16, 2024 8:14 PM
> > To: intel-wired-lan@xxxxxxxxxxxxxxxx
> > Cc: netdev@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Eric Dumazet
> > <edumazet@xxxxxxxxxx>; Nguyen, Anthony L
> > <anthony.l.nguyen@xxxxxxxxx>; Asbjørn Sloth Tønnesen <ast@xxxxxxxxxxx>;
> > Jakub Kicinski <kuba@xxxxxxxxxx>; Paolo Abeni <pabeni@xxxxxxxxxx>;
> > David S. Miller <davem@xxxxxxxxxxxxx>
> > Subject: [Intel-wired-lan] [PATCH iwl-next] ice: flower: validate control flags
> >
> > This driver currently doesn't support any control flags.
> >
> > Use flow_rule_has_control_flags() to check for control flags, such as can be
> > set through `tc flower ... ip_flags frag`.
> >
> > In case any control flags are masked, flow_rule_has_control_flags() sets a NL
> > extended error message, and we return -EOPNOTSUPP.
> >
> > Only compile-tested.
> >
> > Signed-off-by: Asbjørn Sloth Tønnesen <ast@xxxxxxxxxxx>
> > ---
> >   drivers/net/ethernet/intel/ice/ice_tc_lib.c | 4 ++++
> >   1 file changed, 4 insertions(+)
>
> Hi,
>
> I have tested this patch in upstream kernel - 6.9.0-rc5+ and observing no effect while adding tc flow rule with control flags.
> 'Not supported' error is not shown while adding the below tc rule.
>
> [root@cbl-mariner ~]# tc qdisc add dev ens5f0np0 ingress
> [root@cbl-mariner ~]#
> [root@cbl-mariner ~]# tc filter add dev ens5f0np0 ingress protocol ip flower ip_flags frag/firstfrag action drop

Thank you for testing!

I think the issue you are observing, is because you are missing "skip_sw":
tc filter add dev ens5f0np0 ingress protocol ip flower skip_sw \
	ip_flags frag/firstfrag action drop

Without skip_sw, then the hardware offload is opportunistic,
and therefore the error in hardware offloading doesn't bubble
through to user space.

Without skip_sw, you should still be able to observe a change in
`tc filter show dev ens5f0np0 ingress`. Without the patch you
should see "in_hw", and with it you should see "not_in_hw".

With skip_sw, then the error in hardware offloading causes
the tc command to fail, with the -EOPNOTSUPP error and
associated extended Netlink error message.

Also see Ido's testing for mlxsw in this other thread:
https://lore.kernel.org/netdev/ZiABPNMbOOYGiHCq@shredder/#t

--
Best regards
Asbjørn Sloth Tønnesen
Network Engineer
Fiberby - AS42541