Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754857Ab0AFHmO (ORCPT ); Wed, 6 Jan 2010 02:42:14 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751656Ab0AFHmN (ORCPT ); Wed, 6 Jan 2010 02:42:13 -0500 Received: from mga11.intel.com ([192.55.52.93]:31828 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754520Ab0AFHmN (ORCPT ); Wed, 6 Jan 2010 02:42:13 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.49,225,1262592000"; d="scan'208";a="528861909" Date: Wed, 6 Jan 2010 15:42:06 +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: Re: [PATCH v2] fs: O_* bit numbers uniqueness check Message-ID: <20100106074206.GA25668@localhost> References: <20100106065526.GB11368@localhost> <20100106071817.GA24428@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: 4565 Lines: 124 On Wed, Jan 06, 2010 at 03:30:31PM +0800, Roland Dreier wrote: > > > Yeah, I chose the boot time check because of hweight32().. > > One could do something like > > #define HWEIGHT32(x) (!!((x) & (1u << 0)) + > !!((x) & (1u << 1)) + > //... > !!((x) & (1u << 31))); > > that would probably work with BUILD_BUG_ON(). > > But as I said maybe it's too ugly. Yes, it'll feel like this. Then you'll have to fix the possible error in order to compile ;) --- 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. v3: change to BUILD_BUG_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 ++ include/linux/bitops.h | 33 +++++++++++++++++++++++++++++++++ 3 files changed, 47 insertions(+), 2 deletions(-) --- linux.orig/fs/fcntl.c 2010-01-06 14:41:26.000000000 +0800 +++ linux/fs/fcntl.c 2010-01-06 15:37:14.000000000 +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 */ + BUILD_BUG_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 --- linux.orig/include/linux/bitops.h 2010-01-06 15:33:39.000000000 +0800 +++ linux/include/linux/bitops.h 2010-01-06 15:38:57.000000000 +0800 @@ -8,6 +8,39 @@ #define BIT_WORD(nr) ((nr) / BITS_PER_LONG) #define BITS_PER_BYTE 8 #define BITS_TO_LONGS(nr) DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(long)) + +#define HWEIGHT32(x) (!!((x) & (1u << 0)) + \ + !!((x) & (1u << 1)) + \ + !!((x) & (1u << 2)) + \ + !!((x) & (1u << 3)) + \ + !!((x) & (1u << 4)) + \ + !!((x) & (1u << 5)) + \ + !!((x) & (1u << 6)) + \ + !!((x) & (1u << 7)) + \ + !!((x) & (1u << 8)) + \ + !!((x) & (1u << 9)) + \ + !!((x) & (1u << 10)) + \ + !!((x) & (1u << 11)) + \ + !!((x) & (1u << 12)) + \ + !!((x) & (1u << 13)) + \ + !!((x) & (1u << 14)) + \ + !!((x) & (1u << 15)) + \ + !!((x) & (1u << 16)) + \ + !!((x) & (1u << 17)) + \ + !!((x) & (1u << 18)) + \ + !!((x) & (1u << 19)) + \ + !!((x) & (1u << 20)) + \ + !!((x) & (1u << 21)) + \ + !!((x) & (1u << 22)) + \ + !!((x) & (1u << 23)) + \ + !!((x) & (1u << 24)) + \ + !!((x) & (1u << 25)) + \ + !!((x) & (1u << 26)) + \ + !!((x) & (1u << 27)) + \ + !!((x) & (1u << 28)) + \ + !!((x) & (1u << 29)) + \ + !!((x) & (1u << 30)) + \ + !!((x) & (1u << 31))) #endif /* -- 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/