linux-kernel - Re: [PATCH net] net: ethtool: Allow matching on vlan CFI bit

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Date:   Wed, 12 Jun 2019 15:31:54 +0900
From:   Toshiaki Makita <toshiaki.makita1@...il.com>
To:     Maxime Chevallier <maxime.chevallier@...tlin.com>,
        davem@...emloft.net, Pablo Neira Ayuso <pablo@...filter.org>,
        Florian Fainelli <f.fainelli@...il.com>,
        Jiri Pirko <jiri@...lanox.com>,
        Jakub Kicinski <jakub.kicinski@...ronome.com>
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Antoine Tenart <antoine.tenart@...tlin.com>,
        thomas.petazzoni@...tlin.com,
        Michał Mirosław <mirq-linux@...e.qmqm.pl>
Subject: Re: [PATCH net] net: ethtool: Allow matching on vlan CFI bit

On 2019/06/12 0:54, Maxime Chevallier wrote:
> Using ethtool, users can specify a classification action matching on the
> full vlan tag, which includes the CFI bit.
> 
> However, when converting the ethool_flow_spec to a flow_rule, we use
> dissector keys to represent the matching patterns.
> 
> Since the vlan dissector key doesn't include the CFI bit, this
> information was silently discarded when translating the ethtool
> flow spec in to a flow_rule.
> 
> This commit adds the CFI bit into the vlan dissector key, and allows
> propagating the information to the driver when parsing the ethtool flow
> spec.
> 
> Fixes: eca4205f9ec3 ("ethtool: add ethtool_rx_flow_spec to flow_rule structure translator")
> Reported-by: Michał Mirosław <mirq-linux@...e.qmqm.pl>
> Signed-off-by: Maxime Chevallier <maxime.chevallier@...tlin.com>
> ---
> Hi all,
> 
> Although this prevents information to be silently discarded when parsing
> an ethtool_flow_spec, this information doesn't seem to be used by any
> driver that converts an ethtool_flow_spec to a flow_rule, hence I'm not
> sure this is suitable for -net.
> 
> Thanks,
> 
> Maxime
> 
>   include/net/flow_dissector.h | 1 +
>   net/core/ethtool.c           | 5 +++++
>   2 files changed, 6 insertions(+)
> 
> diff --git a/include/net/flow_dissector.h b/include/net/flow_dissector.h
> index 7c5a8d9a8d2a..9d2e395c6568 100644
> --- a/include/net/flow_dissector.h
> +++ b/include/net/flow_dissector.h
> @@ -46,6 +46,7 @@ struct flow_dissector_key_tags {
>   
>   struct flow_dissector_key_vlan {
>   	u16	vlan_id:12,
> +		vlan_cfi:1,

Current IEEE 802.1Q defines this bit as DEI not CFI, so IMO this should be
vlan_dei.

Toshiaki Makita