From: David Laight <David.Laight@ACULAB.COM>
To: 'Simon Horman' <horms@kernel.org>,
Herve Codina <herve.codina@bootlin.com>
Cc: "David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
Christophe Leroy <christophe.leroy@csgroup.eu>,
"Andy Shevchenko" <andriy.shevchenko@linux.intel.com>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
"stable@vger.kernel.org" <stable@vger.kernel.org>
Subject: RE: [PATCH net v1] net: wan: fsl_qmc_hdlc: Discard received CRC
Date: Fri, 2 Aug 2024 08:10:02 +0000 [thread overview]
Message-ID: <7659191688194f099cba22cc367c4eda@AcuMS.aculab.com> (raw)
In-Reply-To: <20240731084443.GL1967603@kernel.org>
From: Simon Horman
> Sent: 31 July 2024 09:45
>
> On Tue, Jul 30, 2024 at 08:31:33AM +0200, Herve Codina wrote:
> > Received frame from QMC contains the CRC.
> > Upper layers don't need this CRC and tcpdump mentioned trailing junk
> > data due to this CRC presence.
> >
> > As some other HDLC driver, simply discard this CRC.
>
> It might be nice to specifically site an example.
> But yes, I see this pattern in hdlc_rx_done().
Pretty much the only reason you'd want the received CRC is to do
error recovery assuming a single short error burst.
Not that I've ever seen a driver contain the required code.
'Back of envelope' calculation: 32bit crc, 2kbyte frame, so 18bits
of crc per data bit, sqrt for 'birthday paradox' - I bet you can
recover 8-bit error bursts.
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next prev parent reply other threads:[~2024-08-02 8:10 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-07-30 6:31 [PATCH net v1] net: wan: fsl_qmc_hdlc: Discard received CRC Herve Codina
2024-07-31 8:44 ` Simon Horman
2024-08-02 8:10 ` David Laight [this message]
2024-08-01 1:20 ` patchwork-bot+netdevbpf
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=7659191688194f099cba22cc367c4eda@AcuMS.aculab.com \
--to=david.laight@aculab.com \
--cc=andriy.shevchenko@linux.intel.com \
--cc=christophe.leroy@csgroup.eu \
--cc=davem@davemloft.net \
--cc=edumazet@google.com \
--cc=herve.codina@bootlin.com \
--cc=horms@kernel.org \
--cc=kuba@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=netdev@vger.kernel.org \
--cc=pabeni@redhat.com \
--cc=stable@vger.kernel.org \
--cc=thomas.petazzoni@bootlin.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox