netdev - Re: [PATCH net-next 1/8] net/flower: Introduce hardware offload support

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Message-ID: <20160301170128.GG2098@nanopsycho.orion>
Date:	Tue, 1 Mar 2016 18:01:28 +0100
From:	Jiri Pirko <jiri@...nulli.us>
To:	Amir Vadai <amir@...ai.me>
Cc:	"David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
	Or Gerlitz <ogerlitz@...lanox.com>,
	John Fastabend <john.r.fastabend@...el.com>,
	Saeed Mahameed <saeedm@...lanox.com>,
	Hadar Har-Zion <hadarh@...lanox.com>,
	Jiri Pirko <jiri@...lanox.com>
Subject: Re: [PATCH net-next 1/8] net/flower: Introduce hardware offload
 support

Tue, Mar 01, 2016 at 05:49:27PM CET, amir@...ai.me wrote:
>On Tue, Mar 01, 2016 at 03:47:19PM +0100, Jiri Pirko wrote:
>> Tue, Mar 01, 2016 at 03:24:43PM CET, amir@...ai.me wrote:
>> >This patch is based on a patch made by John Fastabend.
>> >It adds support for offloading cls_flower.
>> >A filter that is offloaded successfuly by hardware, will not be added to
>> >the hashtable and won't be processed by software.
>> 
>> That is wrong. User should explitly specify to not include rule into sw
>> by SKIP_KERNEL flag (does not exist now, with John's recent patch we'll
>> have only SKIP_HW). Please add that in this patchset.
>Why? If a rule is offloaded, why would the user want to reprocess it by
>software?
>If the user use SKIP_HW, it will be processed by SW. Else, the user
>would want it to be processed by HW or fallback to SW. I don't
>understand in which case the user would like to have it done twice.

For example if you turn on the offloading by unsetting NETIF_F_HW_TC.
Or if someone inserts skbs into rx path directly, for example pktgen.
We need SKIP_KERNEL to be set by user, not implicit.