From: Andrew Lunn <andrew@lunn.ch>
To: Vladimir Oltean <olteanv@gmail.com>
Cc: Lino Sanfilippo <LinoSanfilippo@gmx.de>,
woojung.huh@microchip.com, UNGLinuxDriver@microchip.com,
vivien.didelot@gmail.com, f.fainelli@gmail.com,
davem@davemloft.net, kuba@kernel.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] net: dsa: tag_ksz: dont let the hardware process the layer 4 checksum
Date: Wed, 14 Jul 2021 22:15:20 +0200 [thread overview]
Message-ID: <YO9F2LhTizvr1l11@lunn.ch> (raw)
In-Reply-To: <20210714194812.stay3oqyw3ogshhj@skbuf>
On Wed, Jul 14, 2021 at 10:48:12PM +0300, Vladimir Oltean wrote:
> Hi Lino,
>
> On Wed, Jul 14, 2021 at 09:17:23PM +0200, Lino Sanfilippo wrote:
> > If the checksum calculation is offloaded to the network device (e.g due to
> > NETIF_F_HW_CSUM inherited from the DSA master device), the calculated
> > layer 4 checksum is incorrect. This is since the DSA tag which is placed
> > after the layer 4 data is seen as a part of the data portion and thus
> > errorneously included into the checksum calculation.
> > To avoid this, always calculate the layer 4 checksum in software.
> >
> > Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
> > ---
>
> This needs to be solved more generically for all tail taggers. Let me
> try out a few things tomorrow and come with a proposal.
Maybe the skb_linearize() is also a generic problem, since many of the
tag drivers are using skb_put()? It looks like skb_linearize() is
cheap because checking if the skb is already linear is cheap. So maybe
we want to do it unconditionally?
Andrew
next prev parent reply other threads:[~2021-07-14 20:15 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-14 19:17 [PATCH 0/2] Fixes for KSZ DSA switch Lino Sanfilippo
2021-07-14 19:17 ` [PATCH 1/2] net: dsa: tag_ksz: linearize SKB before adding DSA tag Lino Sanfilippo
2021-07-14 19:17 ` [PATCH 2/2] net: dsa: tag_ksz: dont let the hardware process the layer 4 checksum Lino Sanfilippo
2021-07-14 19:48 ` Vladimir Oltean
2021-07-14 20:15 ` Andrew Lunn [this message]
2021-07-15 6:54 ` Vladimir Oltean
2021-07-15 11:16 ` Aw: " Lino Sanfilippo
2021-07-15 11:49 ` Vladimir Oltean
2021-07-15 13:04 ` Aw: " Lino Sanfilippo
2021-07-15 13:12 ` Vladimir Oltean
2021-07-15 13:34 ` Aw: " Lino Sanfilippo
2021-07-15 13:08 ` Andrew Lunn
2021-07-15 14:36 ` Vladimir Oltean
2021-07-15 15:50 ` Andrew Lunn
2021-07-19 8:20 ` Aw: " Lino Sanfilippo
2021-07-19 8:24 ` Vladimir Oltean
2021-07-15 16:24 ` Florian Fainelli
2021-07-15 23:23 ` [PATCH 0/2] Fixes for KSZ DSA switch Florian Fainelli
2021-07-16 8:49 ` Aw: " Lino Sanfilippo
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