fs: O_* bit numbers uniqueness check
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From: Wu Fengguang on 9 Jan 2010 09:00 On Wed, Jan 06, 2010 at 11:48:14PM +0800, Christoph Hellwig wrote: > On Wed, Jan 06, 2010 at 02:55:26PM +0800, Wu Fengguang wrote: > > 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. > > The right fix is to stop overlyaing the FMODE_ flags into the O_ > namespace. Al has been working towards this. I thinks they are orthogonal problems -- this patch watches for the possible conflicting O_* in so many archs. Anyway here is the new version without the FMODE_ and O_RANDOM. 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. v4: use the nice hweight_long() as suggested by Jamie split O_SYNC to (__O_SYNC | O_DSYNC) as suggested by Andreas take away FMODE_* and O_RANDOM v3: change to BUILD_BUG_ON() as suggested by Roland CC: David Miller <davem(a)davemloft.net> CC: Stephen Rothwell <sfr(a)canb.auug.org.au> CC: Al Viro <viro(a)zeniv.linux.org.uk> CC: Christoph Hellwig <hch(a)infradead.org> CC: Eric Paris <eparis(a)redhat.com> CC: Roland Dreier <rdreier(a)cisco.com> CC: Jamie Lokier <jamie(a)shareable.org> CC: Andreas Schwab <schwab(a)linux-m68k.org> Signed-off-by: Wu Fengguang <fengguang.wu(a)intel.com> --- fs/fcntl.c | 14 ++++++++++++-- include/asm-generic/fcntl.h | 2 ++ 2 files changed, 14 insertions(+), 2 deletions(-) --- linux.orig/fs/fcntl.c 2010-01-09 11:02:57.000000000 +0800 +++ linux/fs/fcntl.c 2010-01-09 21:36:16.000000000 +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(17 != hweight_long( + O_RDONLY | O_WRONLY | O_RDWR | + O_CREAT | O_EXCL | O_NOCTTY | + O_TRUNC | O_APPEND | O_NONBLOCK | + __O_SYNC | O_DSYNC | FASYNC | + O_DIRECT | O_LARGEFILE | O_DIRECTORY | + O_NOFOLLOW | O_NOATIME | O_CLOEXEC + )); + 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 2010-01-09 11:02:57.000000000 +0800 +++ linux/include/asm-generic/fcntl.h 2010-01-09 12:23:17.000000000 +0800 @@ -4,6 +4,8 @@ #include <linux/types.h> /* + * 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(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |