From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Hisashi Hifumi <hifumi.hisashi@oss.ntt.co.jp>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>,
torvalds@linux-foundation.org,
Andrew Morton <akpm@linux-foundation.org>,
Andi Kleen <andi@firstfloor.org>,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
"Theodore Ts'o" <tytso@mit.edu>
Subject: Re: [RESEND] [PATCH] VFS: make file->f_pos access atomic on 32bit arch
Date: Wed, 08 Oct 2008 08:51:51 +0200 [thread overview]
Message-ID: <1223448711.1378.16.camel@lappy.programming.kicks-ass.net> (raw)
In-Reply-To: <6.0.0.20.2.20081008132532.056cc400@172.19.0.2>
On Wed, 2008-10-08 at 13:48 +0900, Hisashi Hifumi wrote:
> Simultaneous access by two or more writer can corrupt file content,
> so this case needs some locks(flock or fcntl) to preserve synchronization
> of file content. This is responsibility of user-space application.
> But file->f_pos race issue can occur even if multiple threads just read
> simultaneously. I think this is not responsibility of user-space application.
> To avoid this currently, an application needs some locks to protect file offset
> even if it just read a file. So I think f_pos race should be fixed.
Just to add to all those who already said you're wrong :-)
You're wrong, if two threads would like to read the same file they
either dup() the fd or open() the file twice. There is absolutely no
valid reason to have two threads read from the same fd without
synchronising their access to it - never.
next prev parent reply other threads:[~2008-10-08 6:52 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-10-07 5:07 [RESEND] [PATCH] VFS: make file->f_pos access atomic on 32bit arch Hisashi Hifumi
2008-10-07 6:43 ` Andi Kleen
2008-10-07 10:11 ` Hisashi Hifumi
2008-10-07 10:29 ` Andi Kleen
2008-10-07 16:27 ` Nick Piggin
2008-10-07 17:50 ` Andrew Morton
2008-10-07 18:59 ` Peter Zijlstra
2008-10-08 2:35 ` Nick Piggin
2008-10-08 2:52 ` Matthew Wilcox
2008-10-09 12:23 ` Pavel Machek
2008-10-09 12:49 ` Valdis.Kletnieks
2008-10-09 13:01 ` Matthew Wilcox
2008-10-09 13:38 ` Miklos Szeredi
2008-10-09 14:58 ` Linus Torvalds
2008-10-09 17:29 ` Jeremy Fitzhardinge
2008-10-08 4:48 ` Hisashi Hifumi
2008-10-08 5:10 ` Nick Piggin
2008-10-08 5:16 ` Matthew Wilcox
2008-10-08 6:28 ` Andrew Morton
2008-10-08 6:51 ` Peter Zijlstra [this message]
2008-10-08 8:32 ` Eric Dumazet
2008-10-08 8:48 ` Nick Piggin
2008-10-08 9:17 ` Peter Zijlstra
2008-10-09 21:51 ` dcg
2008-10-10 2:25 ` Nick Piggin
2008-10-09 12:16 ` Pavel Machek
2008-10-08 0:40 ` Nick Piggin
2008-10-07 18:00 ` Matthew Wilcox
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=1223448711.1378.16.camel@lappy.programming.kicks-ass.net \
--to=a.p.zijlstra@chello.nl \
--cc=akpm@linux-foundation.org \
--cc=andi@firstfloor.org \
--cc=aneesh.kumar@linux.vnet.ibm.com \
--cc=hifumi.hisashi@oss.ntt.co.jp \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=nickpiggin@yahoo.com.au \
--cc=torvalds@linux-foundation.org \
--cc=tytso@mit.edu \
/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