From: Wu Fengguang <fengguang.wu@intel.com>
To: Andreas Schwab <schwab@linux-m68k.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
David Miller <davem@davemloft.net>,
Stephen Rothwell <sfr@canb.auug.org.au>,
Al Viro <viro@zeniv.linux.org.uk>,
Christoph Hellwig <hch@infradead.org>,
Eric Paris <eparis@redhat.com>,
LKML <linux-kernel@vger.kernel.org>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>
Subject: Re: [PATCH] fs: O_* bit numbers uniqueness check
Date: Sat, 9 Jan 2010 21:33:42 +0800 [thread overview]
Message-ID: <20100109133342.GB20015@localhost> (raw)
In-Reply-To: <m2iqbfwq7h.fsf@whitebox.home>
On Wed, Jan 06, 2010 at 05:13:54PM +0800, Andreas Schwab wrote:
> 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)?
You mean to test __O_SYNC | O_DSYNC instead of O_SYNC?
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next prev parent reply other threads:[~2010-01-09 13:34 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-06 6:55 [PATCH] fs: O_* bit numbers uniqueness check Wu Fengguang
2010-01-06 7:07 ` Eric Dumazet
2010-01-06 7:20 ` Wu Fengguang
2010-01-06 9:13 ` Andreas Schwab
2010-01-09 13:33 ` Wu Fengguang [this message]
2010-01-06 7:08 ` Roland Dreier
2010-01-06 7:18 ` [PATCH v2] " Wu Fengguang
2010-01-06 7:30 ` Roland Dreier
2010-01-06 7:42 ` Wu Fengguang
2010-01-06 16:20 ` [PATCH] " Jamie Lokier
2010-01-09 13:44 ` Wu Fengguang
2010-01-06 15:48 ` Christoph Hellwig
2010-01-09 13:52 ` Wu Fengguang
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