lkml.org 
[lkml]   [2010]   [Jan]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [PATCH] fs: O_* bit numbers uniqueness check
Date
Wu Fengguang <fengguang.wu@intel.com> writes:

> On Wed, Jan 06, 2010 at 03:07:01PM +0800, Eric Dumazet wrote:
>> Le 06/01/2010 07:55, Wu Fengguang a écrit :
>> > 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.
>> >
>> > CC: David Miller <davem@davemloft.net>
>> > CC: Stephen Rothwell <sfr@canb.auug.org.au>
>> > CC: Al Viro <viro@zeniv.linux.org.uk>
>> > CC: Christoph Hellwig <hch@infradead.org>
>> > CC: Eric Paris <eparis@redhat.com>
>> > Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
>> > ---
>> > {
>> > + /* please add new bits here to ensure allocation uniqueness */
>> > + 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));
>> > +
>>
>> I cannot test it, but given O_RDONLY is 0, are you sure 20 bits are actually set ?
>
> Yes, I tested it. The tricky one is O_SYNC, which actually has two bits..

What if a new architecture wants to use a single bit value (since it
does not need backwards compatibility)?

Andreas.

--
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5
"And now for something completely different."
--
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/

\
 
 \ /
  Last update: 2010-01-09 13:41    [W:0.111 / U:0.148 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site