From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Hutchings Subject: Re: [PATCH] net: update the usage of CHECKSUM_UNNECESSARY Date: Tue, 8 May 2012 19:20:58 +0100 Message-ID: <1336501258.2749.3.camel@bwh-desktop.uk.solarflarecom.com> References: <20120319211241.11291.53271.stgit@localhost6.localdomain6> <20120508174831.GA27406@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, jeffrey.t.kirsher-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org, devel-s9riP+hp16TNLxjTenLetw@public.gmane.org To: "Michael S. Tsirkin" Return-path: In-Reply-To: <20120508174831.GA27406-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: devel-bounces-s9riP+hp16TNLxjTenLetw@public.gmane.org Sender: devel-bounces-s9riP+hp16TNLxjTenLetw@public.gmane.org List-Id: netdev.vger.kernel.org On Tue, 2012-05-08 at 20:48 +0300, Michael S. Tsirkin wrote: > On Mon, Mar 19, 2012 at 02:12:41PM -0700, Yi Zou wrote: > > As suggested by Ben, this adds the clarification on the usage of > > CHECKSUM_UNNECESSARY on the outgoing patch. Also add the usage > > description of NETIF_F_FCOE_CRC and CHECKSUM_UNNECESSARY > > for the kernel FCoE protocol driver. > > > > This is a follow-up to the following: > > http://patchwork.ozlabs.org/patch/147315/ > > > > Signed-off-by: Yi Zou > > Cc: Ben Hutchings > > Cc: Jeff Kirsher > > Cc: www.Open-FCoE.org > > --- > > > > include/linux/skbuff.h | 7 +++++++ > > 1 files changed, 7 insertions(+), 0 deletions(-) > > > > diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h > > index 8dc8257..a2b9953 100644 > > --- a/include/linux/skbuff.h > > +++ b/include/linux/skbuff.h > > @@ -94,6 +94,13 @@ > > * about CHECKSUM_UNNECESSARY. 8) > > * NETIF_F_IPV6_CSUM about as dumb as the last one but does IPv6 instead. > > * > > + * UNNECESSARY: device will do per protocol specific csum. Protocol drivers > > + * that do not want net to perform the checksum calculation should use > > + * this flag in their outgoing skbs. > > + * NETIF_F_FCOE_CRC this indicates the device can do FCoE FC CRC > > + * offload. Correspondingly, the FCoE protocol driver > > + * stack should use CHECKSUM_UNNECESSARY. > > + * > > * Any questions? No questions, good. --ANK > > */ > > > > So just to make sure I understand, you never get > UNNECESSARY packets on tx unless you declared NETIF_F_FCOE_CRC? > > Maybe the comment says this somehow but could not figure it out. That's what should happen now. In future CHECKSUM_UNNECESSARY could be used on output by other protocols which don't use TCP/IP-style checksums, but always dependent on the output device supporting the relevant offload feature. Ben. -- Ben Hutchings, Staff Engineer, Solarflare Not speaking for my employer; that's the marketing department's job. They asked us to note that Solarflare product names are trademarked.