linux-kernel - Re: [PATCH net] net: mvpp2: cls: Add missing NETIF_F

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Message-ID: <20190509104403.64c9c45b@cakuba.hsd1.ca.comcast.net>
Date:   Thu, 9 May 2019 10:44:03 -0700
From:   Jakub Kicinski <jakub.kicinski@...ronome.com>
To:     Maxime Chevallier <maxime.chevallier@...tlin.com>
Cc:     davem@...emloft.net, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Antoine Tenart <antoine.tenart@...tlin.com>,
        thomas.petazzoni@...tlin.com, gregory.clement@...tlin.com,
        miquel.raynal@...tlin.com, nadavh@...vell.com, stefanc@...vell.com,
        mw@...ihalf.com, Russell King <linux@...linux.org.uk>,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH net] net: mvpp2: cls: Add missing NETIF_F_NTUPLE flag

On Thu, 9 May 2019 07:14:08 +0200, Maxime Chevallier wrote:
> Hello Jakub, David,
> 
> On Tue, 7 May 2019 10:28:03 -0700
> Jakub Kicinski <jakub.kicinski@...ronome.com> wrote:
> 
> >> -	if (mvpp22_rss_is_supported())
> >> +	if (mvpp22_rss_is_supported()) {
> >>  		dev->hw_features |= NETIF_F_RXHASH;
> >> +		dev->features |= NETIF_F_NTUPLE;    
> >
> >Hm, why not in hw_features?  
> 
> Because as of today, there's nothing implemented to disable
> classification offload in the driver, so the feature can't be toggled.
> 
> Is this an issue ? Sorry if I'm doing this wrong, but I didn't see any
> indication that this feature has to be host-writeable.

No I don't think it's an issue, I was expecting you'd flush all the
filters when feature is disabled (remove them entirely), I didn't
expect that to be too hard.

> I can make so that it's toggle-able, but it's not as straightforward as
> we would think, since the classifier is also used for RSS (so, we can't
> just disable the classifier as a whole, we would have to invalidate
> each registered flow).

Ack, I don't think disabling the hardware components is required.
Just remove the existing filters, and don't allow new ones.  
But no strong feelings here, feel free to repost with:

Acked-by: Jakub Kicinski <jakub.kicinski@...ronome.com>

if flushing the filters is too much hassle.