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Subject: Re: [PATCH v2 1/2] net: dsa: ensure linearized SKBs in case of tail
 taggers
To:     Vladimir Oltean <olteanv@gmail.com>
Cc:     Andrew Lunn <andrew@lunn.ch>,
        Florian Fainelli <f.fainelli@gmail.com>,
        woojung.huh@microchip.com, UNGLinuxDriver@microchip.com,
        vivien.didelot@gmail.com, davem@davemloft.net, kuba@kernel.org,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20210721215642.19866-1-LinoSanfilippo@gmx.de>
 <20210721215642.19866-2-LinoSanfilippo@gmx.de>
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 <8460fa10-6db7-273c-a2c2-9b54cc660d9a@gmail.com> <YPl9UX52nfvLzIFy@lunn.ch>
 <7b99c47a-1a3e-662d-edcd-8c91ccb3911e@gmx.de>
 <20210723122213.fvhudwyk36u7pw52@skbuf>
From:   Lino Sanfilippo <LinoSanfilippo@gmx.de>
Message-ID: <e5438617-8dc5-b9c8-7176-91075ca1fc36@gmx.de>
Date:   Fri, 23 Jul 2021 15:41:21 +0200
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Hi Vladimir,

On 23.07.21 at 14:22, Vladimir Oltean wrote:
> On Fri, Jul 23, 2021 at 09:47:39AM +0200, Lino Sanfilippo wrote:
>> since I got a message that the patches have already been applied to net=
dev/net.git.
>> How should I proceed if I want to send a new version of the series? Jus=
t ignore the
>> merge to netdev and send the patches nevertheless?
>
> Since the git history is immutable you need to work with what is already
> in the current net/master branch. What do you want to change, just
> address the feedback I gave? If that is all, just don't bother, I intend
> to look at adding a framework through which the DSA master can declare
> what features it supports in conjunction with specific DSA tagging proto=
cols.
> That is material for net-next, and Dave took your patch at the last
> minute for the "net" pull request towards Linus' tree. If you send
> another patch on "net" in that area now, we'd have to wait for another
> week or two until "net" will be merged again into "net-next". Not sure
> if it's worth it. The only thing that was of concern to me is that you
> assign the DSA interface's slave->vlan_features =3D master->vlan_feature=
s.
> So even though you clear the NETIF_F_SG feature for the DSA slave
> interface, VLAN uppers on top of DSA interfaces will still have NETIF_F_=
SG.
> However, those skbs will be linearized during the dev_queue_xmit call
> done by the 8021q driver towards DSA, so in the end, the way in which
> you restructured the code may not be cosmetically ideal, but also
> appears to not be functionally problematic.
> Anyway, your patch will probably conflict with the stable trees (the
> tag_ops->needed_tailroom was introduced very recently), so we will have
> another chance to fix it up when Greg sends the email that the patch
> failed to apply.
>

Yes, I just wanted to address your feedback concerning the feature assignm=
ent
in a new patch version. But as you explained this is not needed and would =
make
things just unnecessary complicated. So lets wait and see if there are any
conflicts with Gregs stable tree. Thanks for the explanation.

Best Regards,
Lino