From mboxrd@z Thu Jan 1 00:00:00 1970 From: Phoebe Buckheister Subject: Re: [PATCH net-next v4 1/4] ieee802154: add generic header handling routines Date: Thu, 6 Mar 2014 11:11:39 +0100 Message-ID: <20140306111139.2b7b6b8b@zoidberg> References: <1393943688-24221-2-git-send-email-phoebe.buckheister@itwm.fraunhofer.de> <20140304.170050.2058599034902221847.davem@davemloft.net> <7c9810ea21990e7e239b101f548818f7.squirrel@webmail.itwm.fhg.de> <20140305.193913.470467212827707623.davem@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, linux-zigbee-devel@lists.sourceforge.net To: David Miller Return-path: Received: from mailgw1.uni-kl.de ([131.246.120.220]:36808 "EHLO mailgw1.uni-kl.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751276AbaCFKLz (ORCPT ); Thu, 6 Mar 2014 05:11:55 -0500 Received: from itwm2.itwm.fhg.de (itwm2.itwm.fhg.de [131.246.191.3]) by mailgw1.uni-kl.de (8.14.3/8.14.3/Debian-9.4) with ESMTP id s26ABqhn025800 (version=TLSv1/SSLv3 cipher=EDH-RSA-DES-CBC3-SHA bits=168 verify=NOT) for ; Thu, 6 Mar 2014 11:11:53 +0100 In-Reply-To: <20140305.193913.470467212827707623.davem@redhat.com> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, 05 Mar 2014 19:39:13 -0500 (EST) David Miller wrote: > This is how we handle some fields of struct iphdr, and it's fine with > me. Wonderful, this will unclutter everything that concerns itself with some degree of header handling. > Be sure to use __LITTLE_ENDIAN_BITFIELD and __BIG_ENDIAN_BITFIELD for > your CPP checks. I looked at struct iphdr now that you mentioned it, and i was a little surprised to see that this header is often pointer-cast from an skb_network_header. As far as I can see, declaring all subfields (say) u16 in the bitfield endianness order when the entire bitfield is a u16 in the header will result in correct behaviour for cast/memcpy. Is this correct? If not, I'll write out explicit operations for each bitfield member.