Messages in this thread | | | From | Andreas Schwab <> | Subject | Re: [PATCH] fs: O_* bit numbers uniqueness check | Date | Wed, 06 Jan 2010 10:13:54 +0100 |
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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/
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