From: Richard Gooch <rgooch@ras.ucalgary.ca>
To: Andries Brouwer <aebr@win.tue.nl>
Cc: Elladan <elladan@eskimo.com>, Stevie O <stevie@qrpff.net>,
Alan Cox <alan@lxorguk.ukuu.org.uk>,
Zack Weinberg <zack@codesourcery.com>,
linux-kernel@vger.kernel.org
Subject: Re: close return value (was Re: [ANNOUNCE] Ext3 vs Reiserfs benchmarks)
Date: Wed, 17 Jul 2002 11:51:31 -0600 [thread overview]
Message-ID: <200207171751.g6HHpVc07197@vindaloo.ras.ucalgary.ca> (raw)
In-Reply-To: <20020717171722.GA1352@win.tue.nl>
Andries Brouwer writes:
> On Tue, Jul 16, 2002 at 09:38:53PM -0700, Elladan wrote:
>
> > The question is, does the OS standard guarantee that the fd is closed,
> > even if close() returns EINTR or EIO? Just going by the normal usage of
> > EINTR, one might think otherwise. It doesn't appear to be documented
> > one way or another.
> >
> > Alan said you could just issue close again to make sure - the example
> > shows that this is not the case. A second close is either required or
> > forbidden in that example - and the behavior has to be well defined or
> > you won't know which to do.
>
> No, the behaviour is not well-defined at all.
> The standard explicitly leaves undefined what happens when close
> returns EINTR or EIO.
However, the only sane thing to do is to explicitly define one way or
another. The standard is broken. Consider a threaded application,
where one thread tries to call close(), gets an error and re-tries,
because it's not sure if the fd was closed or not. If the fd *is*
closed, and the thread loops calling close(), checking for EBADF,
there is a race if another thread tries calling open()/creat()/dup().
The ambiguity in the standard thus results in the impossibility of
writing a race-free application. And no, forcing the application to
protect system calls with mutexes isn't a solution.
Linux should define explicitly what happens on error return from
close(). Let that be the new standard.
Regards,
Richard....
Permanent: rgooch@atnf.csiro.au
Current: rgooch@ras.ucalgary.ca
next prev parent reply other threads:[~2002-07-17 17:48 UTC|newest]
Thread overview: 83+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20020712162306$aa7d@traf.lcs.mit.edu>
[not found] ` <mit.lcs.mail.linux-kernel/20020712162306$aa7d@traf.lcs.mit.edu>
2002-07-15 15:22 ` [ANNOUNCE] Ext3 vs Reiserfs benchmarks Patrick J. LoPresti
2002-07-15 17:31 ` Chris Mason
2002-07-15 18:33 ` Matthias Andree
[not found] ` <20020715173337$acad@traf.lcs.mit.edu>
[not found] ` <mit.lcs.mail.linux-kernel/20020715173337$acad@traf.lcs.mit.edu>
2002-07-15 19:13 ` Patrick J. LoPresti
2002-07-15 20:55 ` Matthias Andree
2002-07-15 21:23 ` Patrick J. LoPresti
2002-07-15 21:38 ` Thunder from the hill
2002-07-16 12:31 ` Matthias Andree
2002-07-16 15:53 ` Thunder from the hill
2002-07-16 19:26 ` Matthias Andree
2002-07-16 19:38 ` Thunder from the hill
2002-07-16 23:22 ` close return value (was Re: [ANNOUNCE] Ext3 vs Reiserfs benchmarks) Zack Weinberg
2002-07-17 1:03 ` Alan Cox
2002-07-16 23:52 ` close return value David S. Miller
2002-07-17 1:35 ` Alan Cox
2002-07-17 0:20 ` David S. Miller
2002-07-17 1:05 ` Linus Torvalds
2002-07-17 1:05 ` David S. Miller
2002-07-17 1:23 ` Linus Torvalds
2002-07-17 11:51 ` Matthias Andree
2002-07-17 17:23 ` Andries Brouwer
2002-07-20 8:00 ` Florian Weimer
2002-07-20 16:45 ` Linus Torvalds
2002-07-26 0:06 ` EFAULT vs. SIGSEGV [was Re: close return value] Pavel Machek
2002-07-26 14:01 ` (no subject) Alexis Deruelle
[not found] ` <mailman.1026868201.10433.linux-kernel2news@redhat.com>
2002-07-18 0:01 ` close return value Pete Zaitcev
2002-07-18 0:10 ` Thunder from the hill
[not found] ` <mit.lcs.mail.linux-kernel/200207180001.g6I015f02681@devserv.devel.redhat.com>
2002-07-18 14:42 ` Patrick J. LoPresti
2002-07-18 15:13 ` Richard B. Johnson
2002-07-18 15:32 ` Sandy Harris
2002-07-18 23:47 ` Albert D. Cahalan
2002-07-19 16:12 ` Patrick J. LoPresti
2002-07-19 16:24 ` Joseph Malicki
2002-07-19 18:48 ` Patrick J. LoPresti
2002-07-19 19:25 ` Lars Marowsky-Bree
2002-07-19 19:30 ` Arnaldo Carvalho de Melo
2002-07-19 19:45 ` Joseph Malicki
2002-07-19 19:55 ` Arnaldo Carvalho de Melo
2002-07-20 18:25 ` Bernd Eckenfels
2002-07-20 23:06 ` Sandy Harris
2002-07-20 14:42 ` Andries Brouwer
2002-07-18 20:09 ` Hildo.Biersma
2002-07-18 23:55 ` Pete Zaitcev
2002-07-19 11:31 ` Hildo.Biersma
2002-07-19 16:16 ` Pete Zaitcev
2002-07-23 22:19 ` Bill Davidsen
2002-07-17 0:10 ` close return value (was Re: [ANNOUNCE] Ext3 vs Reiserfs benchmarks) Zack Weinberg
2002-07-17 1:45 ` Alan Cox
2002-07-17 18:24 ` Zack Weinberg
2002-07-22 16:42 ` Rogier Wolff
2002-07-17 8:00 ` Lars Marowsky-Bree
2002-07-17 15:49 ` Thunder from the hill
2002-07-17 2:22 ` Elladan
2002-07-17 2:54 ` Thunder from the hill
2002-07-17 3:00 ` Elladan
2002-07-17 3:10 ` Thunder from the hill
2002-07-17 3:31 ` Elladan
2002-07-17 4:17 ` Stevie O
2002-07-17 4:38 ` Elladan
2002-07-17 14:39 ` Andreas Schwab
2002-07-17 16:49 ` Elladan
2002-07-17 17:43 ` Linus Torvalds
2002-07-17 22:07 ` Elladan
2002-07-18 9:48 ` Ketil Froyn
2002-07-17 17:17 ` Andries Brouwer
2002-07-17 17:51 ` Richard Gooch [this message]
2002-07-17 7:34 ` close return value (was Re: [ANNOUNCE] Ext3 vs Reiserfs benchmarks Kai Henningsen
2002-07-15 21:59 ` Ketil Froyn
2002-07-15 23:08 ` Matti Aarnio
2002-07-16 12:33 ` Matthias Andree
2002-07-15 22:55 ` Alan Cox
2002-07-15 21:58 ` Matthias Andree
2002-07-15 21:14 ` Chris Mason
2002-07-15 21:31 ` Patrick J. LoPresti
2002-07-15 22:12 ` Richard A Nelson
2002-07-16 1:02 ` Lawrence Greenfield
[not found] ` <mit.lcs.mail.linux-kernel/200207160102.g6G12BiH022986@lin2.andrew.cmu.edu>
2002-07-16 1:43 ` Patrick J. LoPresti
2002-07-16 1:56 ` Thunder from the hill
2002-07-16 12:47 ` Matthias Andree
2002-07-16 21:09 ` James Antill
2002-07-16 12:35 ` Matthias Andree
2002-07-16 7:07 ` Dax Kelson
[not found] <fa.lfdnrtv.5h8i1j@ifi.uio.no>
[not found] ` <fa.i1e82rv.1digoa4@ifi.uio.no>
2002-07-17 3:46 ` close return value (was Re: [ANNOUNCE] Ext3 vs Reiserfs benchmarks) Russ Allbery
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