From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Andreas Schwab <schwab@linux-m68k.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Linux-Arch <linux-arch@vger.kernel.org>,
"Joseph S. Myers" <joseph@codesourcery.com>,
John Stultz <john.stultz@linaro.org>,
Christoph Hellwig <hch@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ley Foon Tan <lftan@altera.com>, "H. Peter Anvin" <hpa@zytor.com>,
Linux FS Devel <linux-fsdevel@vger.kernel.org>
Subject: Re: [RFC 01/32] fs: introduce new 'struct inode_time'
Date: Sat, 31 May 2014 18:15:30 +0200 [thread overview]
Message-ID: <CAMuHMdVQJfaghsVqJJnsFahu6FGhXm2-DtOQbJTEDd7f=TO_NQ@mail.gmail.com> (raw)
In-Reply-To: <5507335.AOOTyGEum3@wuerfel>
On Sat, May 31, 2014 at 4:54 PM, Arnd Bergmann <arnd@arndb.de> wrote:
> On Saturday 31 May 2014 10:39:02 Andreas Schwab wrote:
>> Geert Uytterhoeven <geert@linux-m68k.org> writes:
>>
>> > Hi Arnd,
>> >
>> > On Fri, May 30, 2014 at 10:01 PM, Arnd Bergmann <arnd@arndb.de> wrote:
>> >> + * The variant using bit fields is less efficient to access, but
>> >> + * small and has a wider range as the 32-bit one, plus it keeps
>> >> + * the signedness of the original timespec.
>> >> + */
>> >> +struct inode_time {
>> >> + long long tv_sec : 34;
>> >> + int tv_nsec : 30;
>> >> +};
>> >
>> > Don't you need 31 bits for tv_nsec, to accommodate for the sign bit?
>> > I know you won't really store negative numbers there, but storing a large
>> > positive number will become negative on read out, won't it?
>>
>> Only if the int bitfield is signed. Bitfields are weird, aren't they?
According to 6.7.2#5 (thanks for the reference), this is implementation defined.
> It was a mistake on my side, as I didn't know about that rule and
> meant write 'unsigned int' really. Also, I always have a bad feeling
IC, but the comment said "plus it keeps the signedness".
So it doesn't keep the signedness for the tv_nsec field.
> about using bitfields in general.
Hehe...
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
next prev parent reply other threads:[~2014-05-31 16:15 UTC|newest]
Thread overview: 124+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-30 20:01 [RFC 00/32] making inode time stamps y2038 ready Arnd Bergmann
2014-05-30 20:01 ` [RFC 01/32] fs: introduce new 'struct inode_time' Arnd Bergmann
2014-05-31 7:56 ` Geert Uytterhoeven
2014-05-31 8:39 ` Andreas Schwab
2014-05-31 13:19 ` Geert Uytterhoeven
2014-05-31 13:46 ` Andreas Schwab
2014-05-31 14:54 ` Arnd Bergmann
2014-05-31 16:15 ` Geert Uytterhoeven [this message]
2014-05-31 9:03 ` H. Peter Anvin
2014-05-31 14:53 ` Arnd Bergmann
2014-05-31 14:55 ` H. Peter Anvin
2014-05-30 20:01 ` [RFC 02/32] uapi: add struct __kernel_timespec{32,64} Arnd Bergmann
2014-05-30 20:18 ` H. Peter Anvin
2014-05-31 15:09 ` Arnd Bergmann
2014-05-30 20:01 ` [RFC 03/32] fs: introduce sys_utimens64at Arnd Bergmann
2014-05-31 9:22 ` Andreas Schwab
2014-05-31 14:55 ` Arnd Bergmann
2014-05-30 20:01 ` [RFC 04/32] fs: introduce sys_newfstat64/sys_newfstatat64 Arnd Bergmann
2014-05-30 20:01 ` [RFC 05/32] arch: hook up new stat and utimes syscalls Arnd Bergmann
2014-05-30 20:01 ` [RFC 06/32] isofs: fix timestamps beyond 2027 Arnd Bergmann
2014-05-31 7:59 ` Geert Uytterhoeven
2014-05-31 8:47 ` H. Peter Anvin
2014-05-30 20:01 ` [RFC 07/32] fs/nfs: convert to struct inode_time Arnd Bergmann
2014-05-30 20:01 ` [RFC 08/32] fs/ceph: convert to 'struct inode_time' Arnd Bergmann
2014-05-30 20:01 ` [RFC 09/32] fs/pstore: convert to struct inode_time Arnd Bergmann
2014-05-30 21:14 ` Kees Cook
2014-05-30 20:01 ` [RFC 10/32] fs/coda: " Arnd Bergmann
2014-05-30 20:01 ` [RFC 11/32] xfs: " Arnd Bergmann
2014-05-31 0:37 ` Dave Chinner
2014-05-31 0:41 ` H. Peter Anvin
2014-05-31 1:14 ` Dave Chinner
2014-05-31 1:22 ` H. Peter Anvin
2014-05-31 5:54 ` Dave Chinner
2014-05-31 8:41 ` H. Peter Anvin
2014-05-31 15:46 ` Nicolas Pitre
2014-06-01 19:56 ` Arnd Bergmann
2014-06-01 20:26 ` H. Peter Anvin
2014-06-02 11:02 ` Arnd Bergmann
2014-06-02 1:36 ` Nicolas Pitre
2014-06-02 2:22 ` Dave Chinner
2014-06-02 7:09 ` Geert Uytterhoeven
2014-06-02 10:56 ` Arnd Bergmann
2014-06-02 11:57 ` Theodore Ts'o
2014-06-02 12:38 ` Arnd Bergmann
2014-06-02 13:15 ` Theodore Ts'o
2014-06-02 12:52 ` Arnd Bergmann
2014-06-02 13:07 ` Theodore Ts'o
2014-06-02 15:01 ` Arnd Bergmann
2014-06-02 14:52 ` H. Peter Anvin
2014-06-02 15:04 ` Chuck Lever
2014-06-02 15:31 ` Theodore Ts'o
2014-06-02 17:12 ` H. Peter Anvin
2014-06-02 18:50 ` Arnd Bergmann
2014-06-02 22:29 ` Theodore Ts'o
2014-06-02 22:32 ` H. Peter Anvin
2014-06-02 23:32 ` Theodore Ts'o
2014-06-02 23:33 ` H. Peter Anvin
2014-06-03 13:09 ` Roger Willcocks
2014-06-02 18:52 ` Arnd Bergmann
2014-06-02 18:58 ` Roger Willcocks
2014-06-02 19:04 ` Chuck Lever
2014-06-02 19:10 ` Arnd Bergmann
2014-06-01 0:39 ` Dave Chinner
2014-06-02 14:00 ` Joseph S. Myers
2014-05-31 15:37 ` Arnd Bergmann
2014-06-01 0:24 ` Dave Chinner
2014-06-02 0:28 ` Dave Chinner
2014-06-02 11:35 ` Roger Willcocks
2014-06-02 11:43 ` Arnd Bergmann
2014-06-03 0:32 ` Dave Chinner
2014-06-03 7:33 ` Arnd Bergmann
2014-06-03 8:41 ` Dave Chinner
2014-06-03 9:16 ` Arnd Bergmann
2014-05-30 20:01 ` [RFC 12/32] btrfs: " Arnd Bergmann
2014-05-30 20:01 ` [RFC 13/32] ext3: " Arnd Bergmann
2014-05-31 9:10 ` H. Peter Anvin
2014-05-31 14:32 ` Arnd Bergmann
2014-05-30 20:01 ` [RFC 14/32] ext4: " Arnd Bergmann
2014-05-30 20:01 ` [RFC 15/32] cifs: " Arnd Bergmann
2014-05-30 20:01 ` [RFC 16/32] ntfs: " Arnd Bergmann
2014-05-30 20:01 ` [RFC 17/32] ubifs: " Arnd Bergmann
2014-06-02 7:54 ` Artem Bityutskiy
2014-05-30 20:01 ` [RFC 18/32] ocfs2: " Arnd Bergmann
2014-05-30 20:01 ` [RFC 19/32] fs/fat: " Arnd Bergmann
2014-05-30 20:01 ` [RFC 20/32] afs: " Arnd Bergmann
2014-05-30 20:01 ` [RFC 21/32] udf: " Arnd Bergmann
2014-05-30 20:01 ` [RFC 22/32] fs: convert simple fs to inode_time Arnd Bergmann
2014-05-30 23:06 ` Greg Kroah-Hartman
2014-05-30 20:01 ` [RFC 23/32] logfs: convert to struct inode_time Arnd Bergmann
2014-05-30 20:01 ` [RFC 24/32] hfs, hfsplus: " Arnd Bergmann
2014-05-31 14:23 ` Vyacheslav Dubeyko
2014-05-30 20:01 ` [RFC 25/32] gfs2: " Arnd Bergmann
2014-06-02 9:52 ` Steven Whitehouse
2014-05-30 20:01 ` [RFC 26/32] reiserfs: " Arnd Bergmann
2014-05-30 20:01 ` [RFC 27/32] jffs2: " Arnd Bergmann
2014-05-30 20:01 ` [RFC 28/32] adfs: " Arnd Bergmann
2014-05-30 20:01 ` [RFC 29/32] f2fs: " Arnd Bergmann
2014-05-30 20:01 ` [RFC 30/32] fuse: " Arnd Bergmann
2014-05-30 20:01 ` [RFC 31/32] scsi: fnic: use current_kernel_time() for timestamp Arnd Bergmann
2014-05-30 20:01 ` [RFC 32/32] fs: use new inode_time definition unconditionally Arnd Bergmann
2014-05-31 14:30 ` [RFC 00/32] making inode time stamps y2038 ready Vyacheslav Dubeyko
2014-06-03 12:21 ` Arnd Bergmann
2014-05-31 14:51 ` Richard Cochran
2014-05-31 15:23 ` Arnd Bergmann
2014-05-31 18:22 ` Richard Cochran
2014-05-31 19:34 ` H. Peter Anvin
2014-06-01 4:46 ` Richard Cochran
2014-06-01 4:44 ` Richard Cochran
2014-06-02 13:52 ` Joseph S. Myers
2014-06-02 19:19 ` Arnd Bergmann
2014-06-02 19:26 ` H. Peter Anvin
2014-06-02 19:55 ` Arnd Bergmann
2014-06-02 21:57 ` H. Peter Anvin
2014-06-03 14:22 ` Arnd Bergmann
2014-06-03 14:33 ` Joseph S. Myers
2014-06-03 14:37 ` Arnd Bergmann
2014-06-03 21:38 ` Dave Chinner
2014-06-04 15:03 ` Arnd Bergmann
2014-06-04 17:30 ` Nicolas Pitre
2014-06-04 19:24 ` Arnd Bergmann
2014-06-05 0:10 ` H. Peter Anvin
2014-06-10 9:54 ` Arnd Bergmann
2014-06-02 21:02 ` Joseph S. Myers
2014-06-04 15:05 ` Arnd Bergmann
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAMuHMdVQJfaghsVqJJnsFahu6FGhXm2-DtOQbJTEDd7f=TO_NQ@mail.gmail.com' \
--to=geert@linux-m68k.org \
--cc=arnd@arndb.de \
--cc=hch@infradead.org \
--cc=hpa@zytor.com \
--cc=john.stultz@linaro.org \
--cc=joseph@codesourcery.com \
--cc=lftan@altera.com \
--cc=linux-arch@vger.kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=schwab@linux-m68k.org \
--cc=tglx@linutronix.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).