netdev - Re: [PATCH net-next v2 3/8] net/sched: flower: Allow matching on layer 2 miss

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Message-ID: <753ea732-2016-36b7-bcc3-4536fa5cd6a4@blackwall.org>
Date: Mon, 29 May 2023 16:18:55 +0300
From: Nikolay Aleksandrov <razor@...ckwall.org>
To: Ido Schimmel <idosch@...dia.com>, netdev@...r.kernel.org,
 bridge@...ts.linux-foundation.org
Cc: davem@...emloft.net, kuba@...nel.org, pabeni@...hat.com,
 edumazet@...gle.com, taras.chornyi@...ision.eu, saeedm@...dia.com,
 leon@...nel.org, petrm@...dia.com, vladimir.oltean@....com,
 claudiu.manoil@....com, alexandre.belloni@...tlin.com,
 UNGLinuxDriver@...rochip.com, jhs@...atatu.com, xiyou.wangcong@...il.com,
 jiri@...nulli.us, roopa@...dia.com, simon.horman@...igine.com
Subject: Re: [PATCH net-next v2 3/8] net/sched: flower: Allow matching on
 layer 2 miss

On 29/05/2023 14:48, Ido Schimmel wrote:
> Add the 'TCA_FLOWER_L2_MISS' netlink attribute that allows user space to
> match on packets that encountered a layer 2 miss. The miss indication is
> set as metadata in the tc skb extension by the bridge driver upon FDB or
> MDB lookup miss and dissected by the flow dissector to the
> 'FLOW_DISSECTOR_KEY_META' key.
> 
> The use of this skb extension is guarded by the 'tc_skb_ext_tc' static
> key. As such, enable / disable this key when filters that match on layer
> 2 miss are added / deleted.
> 
> Tested:
> 
>  # cat tc_skb_ext_tc.py
>  #!/usr/bin/env -S drgn -s vmlinux
> 
>  refcount = prog["tc_skb_ext_tc"].key.enabled.counter.value_()
>  print(f"tc_skb_ext_tc reference count is {refcount}")
> 
>  # ./tc_skb_ext_tc.py
>  tc_skb_ext_tc reference count is 0
> 
>  # tc filter add dev swp1 egress proto all handle 101 pref 1 flower src_mac 00:11:22:33:44:55 action drop
>  # tc filter add dev swp1 egress proto all handle 102 pref 2 flower src_mac 00:11:22:33:44:55 l2_miss true action drop
>  # tc filter add dev swp1 egress proto all handle 103 pref 3 flower src_mac 00:11:22:33:44:55 l2_miss false action drop
> 
>  # ./tc_skb_ext_tc.py
>  tc_skb_ext_tc reference count is 2
> 
>  # tc filter replace dev swp1 egress proto all handle 102 pref 2 flower src_mac 00:01:02:03:04:05 l2_miss false action drop
> 
>  # ./tc_skb_ext_tc.py
>  tc_skb_ext_tc reference count is 2
> 
>  # tc filter del dev swp1 egress proto all handle 103 pref 3 flower
>  # tc filter del dev swp1 egress proto all handle 102 pref 2 flower
>  # tc filter del dev swp1 egress proto all handle 101 pref 1 flower
> 
>  # ./tc_skb_ext_tc.py
>  tc_skb_ext_tc reference count is 0
> 
> Signed-off-by: Ido Schimmel <idosch@...dia.com>
> ---
> 
> Notes:
>     v2:
>     * Split flow_dissector changes to a previous patch.
>     * Use tc skb extension instead of 'skb->l2_miss'.
> 
>  include/uapi/linux/pkt_cls.h |  2 ++
>  net/sched/cls_flower.c       | 30 ++++++++++++++++++++++++++++--
>  2 files changed, 30 insertions(+), 2 deletions(-)

Reviewed-by: Nikolay Aleksandrov <razor@...ckwall.org>