From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Ravinandan Arakali" Subject: RE: [PATCH]NET: Add ECN support for TSO Date: Fri, 7 Jul 2006 11:56:35 -0700 Message-ID: <000f01c6a1f7$125ebaf0$4710100a@pc.s2io.com> References: <1151464007.5124.13.camel@rh4> Reply-To: Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Cc: Return-path: Received: from barracuda.s2io.com ([72.1.205.138]:23533 "EHLO barracuda.mail.s2io.com") by vger.kernel.org with ESMTP id S932224AbWGGS5F (ORCPT ); Fri, 7 Jul 2006 14:57:05 -0400 To: "'Michael Chan'" , , In-Reply-To: <1151464007.5124.13.camel@rh4> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Michael, Are network cards expected to be aware-of and implement RFC3540(ECN with nonces) ? Thanks, Ravi -----Original Message----- From: netdev-owner@vger.kernel.org [mailto:netdev-owner@vger.kernel.org]On Behalf Of Michael Chan Sent: Tuesday, June 27, 2006 8:07 PM To: davem@davemloft.net; herbert@gondor.apana.org.au Cc: netdev@vger.kernel.org Subject: [PATCH]NET: Add ECN support for TSO In the current TSO implementation, NETIF_F_TSO and ECN cannot be turned on together in a TCP connection. The problem is that most hardware that supports TSO does not handle CWR correctly if it is set in the TSO packet. Correct handling requires CWR to be set in the first packet only if it is set in the TSO header. This patch adds the ability to turn on NETIF_F_TSO and ECN using GSO if necessary to handle TSO packets with CWR set. Hardware that handles CWR correctly can turn on NETIF_F_TSO_ECN in the dev-> features flag. All TSO packets with CWR set will have the SKB_GSO_TCPV4_ECN set. If the output device does not have the NETIF_F_TSO_ECN feature set, GSO will split the packet up correctly with CWR only set in the first segment. It is further assumed that all hardware will handle ECE properly by replicating the ECE flag in all segments. If that is not the case, a simple extension of the logic will be required. Signed-off-by: Michael Chan