From: michi1@michaelblizek.twilightparadox.com
To: kernelnewbies@kernelnewbies.org, netdev@vger.kernel.org,
kuznet@ms2.inr.ac.ru, yoshfuji@linux-ipv6.org,
jakub@cloudflare.com, pabeni@redhat.com
Subject: Re: UDP implementation and the MSG_MORE flag
Date: Wed, 3 Feb 2021 23:21:10 +0100 [thread overview]
Message-ID: <20210203222054.6zhq47o7rzjstpdq@grml> (raw)
In-Reply-To: <20210126141248.GA27281@optiplex>
Hi!
On 15:12 Tue 26 Jan , Oliver Graute wrote:
> Some UDP packets send via the loopback interface are dropped in the
> kernel on the receive side when using sendto with the MSG_MORE flag.
> Every drop increases the InCsumErrors in /proc/self/net/snmp. Some
> example code to reproduce it is appended below.
>
> In the code we tracked it down to this code section. ( Even a little
> further but its unclear to me wy the csum() is wrong in the bad case)
I think it is unlikely that the error is on the receiving side. I recommend to
capture the data that is being sent with a sniffer and see if there is
anything wrong. You may also want to try disabling hardware acceleration on
your network devices, because the checksum is sometimes done in hardware.
-Michi
--
programing a layer 3+4 network protocol for mesh networks
see http://michaelblizek.twilightparadox.com
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prev parent reply other threads:[~2021-02-03 22:21 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-26 14:12 UDP implementation and the MSG_MORE flag Oliver Graute
2021-02-03 22:21 ` michi1 [this message]
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