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 14:39:15 +0200
From:   Pablo Neira Ayuso <pablo@...filter.org>
To:     Edward Cree <ecree@...arflare.com>
Cc:     Jiri Pirko <jiri@...nulli.us>, 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

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