From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753032AbbKXIzl (ORCPT ); Tue, 24 Nov 2015 03:55:41 -0500 Received: from Chamillionaire.breakpoint.cc ([80.244.247.6]:58164 "EHLO Chamillionaire.breakpoint.cc" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751990AbbKXIzk (ORCPT ); Tue, 24 Nov 2015 03:55:40 -0500 Date: Tue, 24 Nov 2015 09:55:32 +0100 From: Florian Westphal To: "K. Y. Srinivasan" Cc: davem@davemloft.net, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, devel@linuxdriverproject.org, olaf@aepfle.de, apw@canonical.com, jasowang@redhat.com Subject: Re: [PATCH net-next 08/10] hv_netvsc: Don't ask for additional head room in the skb Message-ID: <20151124085532.GA1740@breakpoint.cc> References: <1448321324-21318-1-git-send-email-kys@microsoft.com> <1448321346-21357-1-git-send-email-kys@microsoft.com> <1448321346-21357-8-git-send-email-kys@microsoft.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1448321346-21357-8-git-send-email-kys@microsoft.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org K. Y. Srinivasan wrote: > The rndis header is 116 bytes big and can be placed in the default > head room that will be available in the skb. Since the netvsc packet > is less than 48 bytes, we can use the skb control buffer > for the netvsc packet. With these changes we don't need to > ask for additional head room. Minor nit: could you add a BUILD_BUG_ON test for this? Something like BUILD_BUG_ON(sizeof(struct hv_netvsc_packet) > FIELD_SIZEOF(struct sk_buff, cb));