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Message-ID: <cc41ccf443b1f2c7a4cb5e247dabfa53a6674226.camel@microchip.com>
Subject: Re: [PATCH net 0/8] Add support for two classes of VCAP rules
From:   Steen Hegelund <steen.hegelund@microchip.com>
To:     Paolo Abeni <pabeni@redhat.com>,
        "David S . Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>
CC:     <UNGLinuxDriver@microchip.com>,
        Randy Dunlap <rdunlap@infradead.org>,
        Casper Andersson <casper.casan@gmail.com>,
        Russell King <rmk+kernel@armlinux.org.uk>,
        Wan Jiabing <wanjiabing@vivo.com>,
        "Nathan Huckleberry" <nhuck@google.com>,
        <linux-kernel@vger.kernel.org>, <netdev@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>,
        "Daniel Machon" <daniel.machon@microchip.com>,
        Horatiu Vultur <horatiu.vultur@microchip.com>,
        Lars Povlsen <lars.povlsen@microchip.com>,
        Dan Carpenter <error27@gmail.com>
Date:   Thu, 22 Dec 2022 16:02:47 +0100
In-Reply-To: <0efd4a7072fb90cc9bc9992b00d9ade233a38de1.camel@redhat.com>
References: <20221221132517.2699698-1-steen.hegelund@microchip.com>
         <0efd4a7072fb90cc9bc9992b00d9ade233a38de1.camel@redhat.com>
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Hi Paolo,

On Thu, 2022-12-22 at 15:22 +0100, Paolo Abeni wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know th=
e
> content is safe
>=20
> Hello,
> On Wed, 2022-12-21 at 14:25 +0100, Steen Hegelund wrote:
> > This adds support for two classes of VCAP rules:
> >=20
> > - Permanent rules (added e.g. for PTP support)
> > - TC user rules (added by the TC userspace tool)
> >=20
> > For this to work the VCAP Loopups must be enabled from boot, so that th=
e
> > "internal" clients like PTP can add rules that are always active.
> >=20
> > When the TC tool add a flower filter the VCAP rule corresponding to thi=
s
> > filter will be disabled (kept in memory) until a TC matchall filter cre=
ates
> > a link from chain 0 to the chain (lookup) where the flower filter was
> > added.
> >=20
> > When the flower filter is enabled it will be written to the appropriate
> > VCAP lookup and become active in HW.
> >=20
> > Likewise the flower filter will be disabled if there is no link from ch=
ain
> > 0 to the chain of the filter (lookup), and when that happens the
> > corresponding VCAP rule will be read from the VCAP instance and stored =
in
> > memory until it is deleted or enabled again.
>=20
> Despite the 'net' target, this looks really like net-next material as
> most patches look like large refactor. I see there are a bunch of fixes
> in patches 3-8, but quite frankly it's not obvious at all what the
> refactors/new features described into the commit messages themself
> really fix.

Yes the patches 3-8 is the response to Michael Walles observations on LAN96=
6x
and Jakubs Kicinski comment (see link), but the description in the commits =
may
not be that clear, in the sense that they do not state one-to-one what the
mitigation is.

See https://lore.kernel.org/netdev/20221209150332.79a921fd@kernel.org/

So essentially this makes it possible to have rules that are always in the =
VCAP
HW (to make the PTP feature work), even before the TC chains have been
established (which was the problem that Michael encountered).

I still think this a net submission, since it fixes the problem that was
observed in the previous netnext window.

But I will rephrase the reasoning in a V2 to hopefully make that more
understandable.

If you still think it is better to post this in the upcoming net-next windo=
w, I
am also OK with that.

>=20
> I suggest to move this series to net-next (and thus repost after Jan
> 2), unless you come-up with some good reasons to keep it in net.
>=20
> Thanks,
>=20
> Paolo
>=20

BR
Steen