From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754553AbZEZFru (ORCPT ); Tue, 26 May 2009 01:47:50 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753387AbZEZFrm (ORCPT ); Tue, 26 May 2009 01:47:42 -0400 Received: from fg-out-1718.google.com ([72.14.220.154]:32658 "EHLO fg-out-1718.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751659AbZEZFrm (ORCPT ); Tue, 26 May 2009 01:47:42 -0400 Message-ID: <4A1B827B.90302@monstr.eu> Date: Tue, 26 May 2009 07:47:39 +0200 From: Michal Simek Reply-To: monstr@monstr.eu User-Agent: Thunderbird 2.0.0.18 (X11/20081120) MIME-Version: 1.0 To: Arnd Bergmann CC: linux-arch@vger.kernel.org, John Williams , linux-kernel@vger.kernel.org Subject: Re: ipc64_perm - generic References: <4A1AE972.9010905@monstr.eu> <200905252221.44082.arnd@arndb.de> In-Reply-To: <200905252221.44082.arnd@arndb.de> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Arnd Bergmann wrote: > On Monday 25 May 2009 18:54:42 Michal Simek wrote: >> Hi Arnd, cc: John >> >> From asm-generic/posix_types.h >> >> 17 #ifndef __kernel_mode_t >> 18 typedef unsigned int __kernel_mode_t; >> 19 #endif >> >> This structure is not aligned properly because of pad2. >> >> 19 struct ipc64_perm { >> 20 __kernel_key_t key; >> 21 __kernel_uid32_t uid; >> 22 __kernel_gid32_t gid; >> 23 __kernel_uid32_t cuid; >> 24 __kernel_gid32_t cgid; >> 25 __kernel_mode_t mode; >> 26 unsigned short __pad1; >> 27 unsigned short seq; >> 28 unsigned short __pad2; >> 29 unsigned long __unused1; >> 30 unsigned long __unused2; >> 31 }; >> >> I think we should remove __pad1. >> What do you think? > > Right, well spotted. > > I'd like to keep the struct ipc64_perm compatible with most architectures, so > maybe we can play a little trick here: > >> Here is proposed struct. >> struct ipc64_perm { >> __kernel_key_t key; >> __kernel_uid32_t uid; >> __kernel_gid32_t gid; >> __kernel_uid32_t cuid; >> __kernel_gid32_t cgid; >> __kernel_mode_t mode; > > + unsigned char __pad1[4 - sizeof(__kernel_mode_t)]; > >> unsigned short seq; >> unsigned short __pad2; >> unsigned long __unused1; >> unsigned long __unused2; >> }; > > If that's too much of a hack, we could also change the default __kernel_mode_t > in asm-generic/posix_types.h to unsigned short, which it is on all 32-bit architectures > except mips and xtensa. For some reason, all 64 bit architechtures use unsigned > int for mode_t, but I couldn't find out why. Glibc uses unsigned int externally. Is it this final solution (that above) or we just change kernel_mode_t to short? Michal > > Arnd <>< -- Michal Simek, Ing. (M.Eng) w: www.monstr.eu p: +42-0-721842854