Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755518Ab0AFHS1 (ORCPT ); Wed, 6 Jan 2010 02:18:27 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754672Ab0AFHSY (ORCPT ); Wed, 6 Jan 2010 02:18:24 -0500 Received: from mga03.intel.com ([143.182.124.21]:10179 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754684Ab0AFHSX (ORCPT ); Wed, 6 Jan 2010 02:18:23 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.47,316,1257148800"; d="scan'208";a="229695811" Date: Wed, 6 Jan 2010 15:18:17 +0800 From: Wu Fengguang To: Roland Dreier Cc: Andrew Morton , David Miller , Stephen Rothwell , Al Viro , Christoph Hellwig , Eric Paris , LKML , "linux-fsdevel@vger.kernel.org" Subject: [PATCH v2] fs: O_* bit numbers uniqueness check Message-ID: <20100106071817.GA24428@localhost> References: <20100106065526.GB11368@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3048 Lines: 87 On Wed, Jan 06, 2010 at 03:08:08PM +0800, Roland Dreier wrote: > > > + /* please add new bits here to ensure allocation uniqueness */ > > + BUG_ON(20 != hweight32( > > + O_RDONLY | O_WRONLY | O_RDWR | > > I wonder if there's a way to make this BUILD_BUG_ON(), so the problem is > caught at compile time (a change like adding an O_ flag is often compile > tested only for obscure archs). One could create a compile-time > macro-ized version of hweight32() and use that, I guess, although I'm > not sure it's worth the ugliness. Yeah, I chose the boot time check because of hweight32().. > Failing that maybe this should be WARN_ON()? I'd be annoyed if my arch > wouldn't boot because some strange new O_ flag happened to collide. Good suggestion! Here is the updated patch. Andrew, this patch relies on the newly introduced O_RANDOM and Eric's FMODE_NONOTIFY. Thanks, Fengguang --- fs: O_* bit numbers uniqueness check The O_* bit numbers are defined in 20+ arch/*, and hence can silently overlap. Add a boot time check to ensure the uniqueness as suggested by David Miller. v2: change to WARN_ON() as suggested by Roland CC: David Miller CC: Stephen Rothwell CC: Al Viro CC: Christoph Hellwig CC: Eric Paris CC: Roland Dreier Signed-off-by: Wu Fengguang --- fs/fcntl.c | 14 ++++++++++++-- include/asm-generic/fcntl.h | 2 ++ 2 files changed, 14 insertions(+), 2 deletions(-) --- linux.orig/fs/fcntl.c 2010-01-06 14:41:26.000000000 +0800 +++ linux/fs/fcntl.c 2010-01-06 15:15:11.000000000 +0800 @@ -709,11 +709,21 @@ void kill_fasync(struct fasync_struct ** } EXPORT_SYMBOL(kill_fasync); -static int __init fasync_init(void) +static int __init fcntl_init(void) { + /* please add new bits here to ensure allocation uniqueness */ + WARN_ON(20 != hweight32( + O_RDONLY | O_WRONLY | O_RDWR | + O_CREAT | O_EXCL | O_NOCTTY | + O_TRUNC | O_APPEND | O_NONBLOCK | + O_SYNC | FASYNC | O_DIRECT | + O_LARGEFILE | O_DIRECTORY | O_NOFOLLOW | + O_NOATIME | O_CLOEXEC | O_RANDOM | + FMODE_EXEC | FMODE_NONOTIFY)); + fasync_cache = kmem_cache_create("fasync_cache", sizeof(struct fasync_struct), 0, SLAB_PANIC, NULL); return 0; } -module_init(fasync_init) +module_init(fcntl_init) --- linux.orig/include/asm-generic/fcntl.h 2010-01-06 14:45:34.000000000 +0800 +++ linux/include/asm-generic/fcntl.h 2010-01-06 14:50:57.000000000 +0800 @@ -4,6 +4,8 @@ #include /* + * When introducing new O_* bits, please check its uniqueness in fcntl_init(). + * * FMODE_EXEC is 0x20 * FMODE_NONOTIFY is 0x1000000 * These cannot be used by userspace O_* until internal and external open -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/