From: David Miller <davem@davemloft.net>
To: jeff@garzik.org
Cc: yoshfuji@linux-ipv6.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org, herbert@gondor.apana.org.au
Subject: Re: [RFC/PATCH] SO_NO_CHECK for IPv6
Date: Thu, 22 Nov 2007 17:13:06 -0800 (PST) [thread overview]
Message-ID: <20071122.171306.166854987.davem@davemloft.net> (raw)
In-Reply-To: <4744CAA4.50102@garzik.org>
From: Jeff Garzik <jeff@garzik.org>
Date: Wed, 21 Nov 2007 19:17:40 -0500
> YOSHIFUJI Hideaki / 吉藤英明 wrote:
> > In article <20071121124532.GA17263@havoc.gtf.org> (at Wed, 21 Nov 2007 07:45:32 -0500), Jeff Garzik <jeff@garzik.org> says:
> >
> >> SO_NO_CHECK support for IPv6 appeared to be missing. This is presented,
> >> based on a reading of net/ipv4/udp.c.
> >
> > Disagree. UDP checksum is mandatory in IPv6.
>
> Ah, you mean that I need to turn off UDP checksum on receive end as well
> in IPv6... true.
>
> For those interested, I am dealing with a UDP app that already does very
> strong checksumming and encryption, so additional software checksumming
> at the lower layers is quite simply a waste of CPU cycles. Hardware
> checksumming is fine, as long as its "free."
Regardless of whatever verifications your application is doing
on the data, it is not checksumming the ports and that's what
the pseudo-header is helping with.
You cannot disable checksums in ipv6/UDP, they are not optional and
with %99.9999999 of cards doing the checksum in hardware, and even if
we do have to compute it it's free during the copy during recvmsg().
next prev parent reply other threads:[~2007-11-23 1:13 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-11-21 12:45 [RFC/PATCH] SO_NO_CHECK for IPv6 Jeff Garzik
2007-11-21 13:20 ` YOSHIFUJI Hideaki / 吉藤英明
2007-11-21 13:42 ` Herbert Xu
2007-11-22 0:17 ` Jeff Garzik
2007-11-22 2:34 ` Herbert Xu
2007-11-22 2:46 ` YOSHIFUJI Hideaki / 吉藤英明
2007-11-23 1:13 ` David Miller [this message]
2007-11-23 6:06 ` David Schwartz
2007-11-24 6:00 ` Herbert Xu
2007-11-25 15:41 ` David Schwartz
2007-11-26 2:47 ` Herbert Xu
2007-11-21 18:35 ` David Miller
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=20071122.171306.166854987.davem@davemloft.net \
--to=davem@davemloft.net \
--cc=herbert@gondor.apana.org.au \
--cc=jeff@garzik.org \
--cc=linux-kernel@vger.kernel.org \
--cc=netdev@vger.kernel.org \
--cc=yoshfuji@linux-ipv6.org \
/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;
as well as URLs for NNTP newsgroup(s).