netdev - Re: [PATCH net] net: flow_offload: skip hw stats check for FLOW_ACTION_HW_STATS

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Date:   Mon, 20 Apr 2020 15:48:26 +0200
From:   Jiri Pirko <jiri@...nulli.us>
To:     Pablo Neira Ayuso <pablo@...filter.org>
Cc:     Edward Cree <ecree@...arflare.com>,
        netfilter-devel@...r.kernel.org, davem@...emloft.net,
        netdev@...r.kernel.org, kuba@...nel.org
Subject: Re: [PATCH net] net: flow_offload: skip hw stats check for
 FLOW_ACTION_HW_STATS_DISABLED

Mon, Apr 20, 2020 at 02:39:15PM CEST, pablo@...filter.org wrote:
>On Mon, Apr 20, 2020 at 01:28:22PM +0100, Edward Cree wrote:
>> On 20/04/2020 12:52, Jiri Pirko wrote:
>> > However for TC, when user specifies "HW_STATS_DISABLED", the driver
>> > should not do stats.
>>
>> What should a driver do if the user specifies DISABLED, but the stats
>>  are still needed for internal bookkeeping (e.g. to prod an ARP entry
>>  that's in use for encapsulation offload, so that it doesn't get
>>  expired out of the cache)?  Enable the stats on the HW anyway but
>>  not report them to FLOW_CLS_STATS?  Or return an error?
>
>My interpretation is that HW_STATS_DISABLED means that the front-end
>does not care / does not need counters. The driver can still allocate

That is wrong interpretation. If user does not care, he specifies "ANY".
That is the default.

When he says "DISABLED" he means disabled. Not "I don't care".


>them if needed. So the enum flow_action_hw_stats flags represent what
>the front-end requires.