From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexander Duyck Subject: Re: [PATCH v4 1/5] net: Add support for hardware-offloaded encapsulation Date: Mon, 10 Dec 2012 08:22:31 -0800 Message-ID: <50C60C47.70102@gmail.com> References: <1354925658-24115-1-git-send-email-joseph.gasparakis@intel.com> <1354925658-24115-2-git-send-email-joseph.gasparakis@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: Joseph Gasparakis , davem@davemloft.net, shemminger@vyatta.com, chrisw@sous-sol.org, gospo@redhat.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, dmitry@broadcom.com, bhutchings@solarflare.com, Peter P Waskiewicz Jr , Alexander Duyck To: saeed bishara Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On 12/10/2012 02:04 AM, saeed bishara wrote: >> +static inline struct iphdr *inner_ip_hdr(const struct sk_buff *skb) >> +{ >> + return (struct iphdr *)skb_inner_network_header(skb); >> +} > Hi, > I'm a little bit bothered because of those inner_ functions, what > about the following approach: > 1. the skb will have a new state, that state can be outer (normal > mode) and inner. > 2. when you change the state to inner, all the helper functions such > as ip_hdr will return the innter header. > > that's ofcourse the API side. the implementation may still use the > fields you added to the skb. > > what you think? > saeed What you describe isn't too far off from what we are doing. However we need to store both the inner and the outer headers. All these inner_ functions are meant to do is assist drivers to access the inner headers in the case that skb->encapsulation is set. We wanted to avoid abstracting it too much since it is possible in the future that both inner and outer network headers may be needed if for instance you were to place a tunnelled frame inside of a VLAN with hardware tag insertion. Thanks, Alex