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From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Alexey Dobriyan <adobriyan@gmail.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>,
	akpm@linux-foundation.org, viro@zeniv.linux.org.uk,
	torvalds@linux-foundation.org, drepper@gmail.com,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH] nextfd(2)
Date: Thu, 12 Apr 2012 12:11:24 +0100	[thread overview]
Message-ID: <20120412121124.64aee2f6@pyramind.ukuu.org.uk> (raw)
In-Reply-To: <CACVxJT_RRfW7HknkbA4+41L9hNMBHZNezKs1ifbv_qFx5eB0-w@mail.gmail.com>

On Thu, 12 Apr 2012 13:54:25 +0300
Alexey Dobriyan <adobriyan@gmail.com> wrote:

> On Sat, Apr 7, 2012 at 12:02 AM, H. Peter Anvin <hpa@zytor.com> wrote:
> > On 04/06/2012 01:16 PM, Alexey Dobriyan wrote:
> >>
> >> closefrom(3) written via nextfd(2) loop is reliable and doesn't fail.
> >> closefrom(3) written via /proc/self/fd is reliable and can fail (including ENOMEM).
> >> closefrom(3) written via close(fd++) is unreliable.
> >>
> >
> > I call shenanigans on this.  There is no reason to ENOMEM on the second
> > written using the fdwalk() implementation I already posted, for example.
> 
> open("/proc/self/fd") can fail with ENOMEM.

Any syscall can fail with a process kill due to a stack extend on out of
memory in most configurations. That includes your nextfd stuff

This whole thing is getting stupid. "Perfection is the enemy of
success".

Your code will also fail when the cat pees on the computer, when the
power fails and when disk dies. I suspect that other than the cat these
are all more likely real world cases than your ENOMEM.

Alan

  reply	other threads:[~2012-04-12 11:08 UTC|newest]

Thread overview: 70+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-04-01 12:57 [PATCH] nextfd(2) Alexey Dobriyan
2012-04-01 13:58 ` Konstantin Khlebnikov
2012-04-01 21:30   ` Alexey Dobriyan
2012-04-02  0:09   ` Alan Cox
2012-04-02  8:38     ` Konstantin Khlebnikov
2012-04-02  9:26       ` Cyrill Gorcunov
2012-04-01 15:43 ` Eric Dumazet
2012-04-01 21:31   ` Alexey Dobriyan
2012-04-01 21:36   ` Alan Cox
2012-04-01 17:20 ` Linus Torvalds
2012-04-01 18:28 ` Valentin Nechayev
2012-04-01 21:33   ` Alexey Dobriyan
2012-04-01 19:21 ` Arnd Bergmann
2012-04-01 21:35   ` Alexey Dobriyan
2012-04-01 22:05   ` H. Peter Anvin
2012-04-04 12:13     ` Arnd Bergmann
2012-04-01 22:03 ` H. Peter Anvin
2012-04-01 22:13   ` H. Peter Anvin
2012-04-02  0:08   ` Alan Cox
2012-04-30  9:58     ` Valentin Nechayev
2012-04-02  1:19   ` Kyle Moffett
2012-04-02  1:37     ` H. Peter Anvin
2012-04-02 11:37     ` Ulrich Drepper
2012-04-06  9:54   ` Alexey Dobriyan
2012-04-06 15:27     ` Colin Walters
2012-04-06 16:14     ` H. Peter Anvin
2012-04-06 20:16       ` Alexey Dobriyan
2012-04-06 20:33         ` H. Peter Anvin
2012-04-06 21:02         ` H. Peter Anvin
2012-04-12 10:54           ` Alexey Dobriyan
2012-04-12 11:11             ` Alan Cox [this message]
2012-04-12 13:35               ` Alexey Dobriyan
2012-04-12 13:51                 ` H. Peter Anvin
2012-04-12 19:21                   ` Alexey Dobriyan
2012-04-12 14:09               ` Eric Dumazet
2012-04-06 16:23     ` H. Peter Anvin
2012-04-07 21:21       ` Ben Pfaff
2012-04-11  0:12         ` KOSAKI Motohiro
2012-04-11  0:09       ` KOSAKI Motohiro
2012-04-11 17:58         ` H. Peter Anvin
2012-04-11 18:04           ` Linus Torvalds
2012-04-11 18:11             ` H. Peter Anvin
2012-04-11 19:46               ` KOSAKI Motohiro
2012-04-11 19:49                 ` H. Peter Anvin
2012-04-11 20:23                   ` KOSAKI Motohiro
2012-04-11 20:32                     ` H. Peter Anvin
2012-04-17 18:12                       ` KOSAKI Motohiro
2012-04-11 18:00         ` H. Peter Anvin
2012-04-11 19:20           ` KOSAKI Motohiro
2012-04-11 19:22             ` H. Peter Anvin
2012-04-11 19:26               ` KOSAKI Motohiro
2012-04-11 19:28                 ` H. Peter Anvin
2012-04-11 19:31                   ` KOSAKI Motohiro
2012-04-11 19:32                     ` H. Peter Anvin
2012-04-02 23:17 ` KOSAKI Motohiro
2012-04-02 23:56   ` H. Peter Anvin
2012-04-04 11:51     ` Ulrich Drepper
2012-04-04 16:38       ` KOSAKI Motohiro
2012-04-04 16:43         ` Ulrich Drepper
2012-04-04 17:07           ` KOSAKI Motohiro
2012-04-04 17:49             ` Ulrich Drepper
2012-04-04 18:08               ` KOSAKI Motohiro
2012-04-04 16:31     ` KOSAKI Motohiro
2012-04-04 17:10       ` Colin Walters
2012-04-04 17:25         ` Colin Walters
2012-04-04 23:35         ` KOSAKI Motohiro
2012-04-04 18:44       ` H. Peter Anvin
2012-04-03 19:21   ` Colin Walters
2012-04-04  3:01 ` Al Viro
2012-04-04 17:10   ` KOSAKI Motohiro

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