On Wed, Jan 06, 2010 at 05:13:54PM +0800, Andreas Schwab wrote:
> Wu Fengguang <fengguang.wu@xxxxxxxxx> 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@xxxxxxxxxxxxx>
> >> > CC: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
> >> > CC: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
> >> > CC: Christoph Hellwig <hch@xxxxxxxxxxxxx>
> >> > CC: Eric Paris <eparis@xxxxxxxxxx>
> >> > Signed-off-by: Wu Fengguang <fengguang.wu@xxxxxxxxx>
> >> > ---
> >> > {
> >> > + /* 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)?
You mean to test __O_SYNC | O_DSYNC instead of O_SYNC?
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