From: Christian Brauner <christian.brauner@ubuntu.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Kyle Evans <self@kyle-evans.net>,
Victor Stinner <victor.stinner@gmail.com>,
Al Viro <viro@zeniv.linux.org.uk>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Linux API <linux-api@vger.kernel.org>,
Florian Weimer <fweimer@redhat.com>, Jann Horn <jannh@google.com>,
Oleg Nesterov <oleg@redhat.com>, Arnd Bergmann <arnd@arndb.de>,
Shuah Khan <shuah@kernel.org>,
David Howells <dhowells@redhat.com>,
"Dmitry V. Levin" <ldv@altlinux.org>
Subject: Re: [PATCH v5 0/3] close_range()
Date: Thu, 4 Jun 2020 03:15:09 +0200 [thread overview]
Message-ID: <20200604011509.jcagqr3e3qxru6cl@wittgenstein> (raw)
In-Reply-To: <CAHk-=wgTpLOeMjpLOc8hY7KC6Qv+jR-hBacyBSajJ6iUKasmKA@mail.gmail.com>
On Wed, Jun 03, 2020 at 05:13:36PM -0700, Linus Torvalds wrote:
> On Wed, Jun 3, 2020 at 4:24 PM Christian Brauner
> <christian.brauner@ubuntu.com> wrote:
> >
> > Ok, here's what I have. Does the below look somewhat sane?
>
> Probably. Needs lots of testing. But this one looks wrong:
Right, there's a patch for a test-suite for the new flag too using
CLONE_FILES to create a shared fdtable and the proceeds to close all
(or subsets of) fds:
https://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux.git/commit/?h=close_range&id=498e7e844fe6e3f3306b2cd1b5e926e1cd394b99
I've been running that in an endless loop for a while.
>
> > +int __close_range(unsigned fd, unsigned max_fd, unsigned int flags)
> > {
> > + if ((max_fd + 1) >= cur_max)
> > + max_unshare_fds = fd;
>
> A normal value for "close everything starting at X" would have a
> max_fd value of ~0.
Ugh, obvious braino from my side. This should just be:
if (max_fd >= cur_max)
max_unshare_fds = fd;
>
> So "max_fd+1" would overflow to 0, and then this would never trigger.
>
> Other than that it looks what what I imagine my feverdreams were about.
Thanks!
Christian
next prev parent reply other threads:[~2020-06-04 1:15 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-02 20:42 [PATCH v5 0/3] close_range() Christian Brauner
2020-06-02 20:42 ` [PATCH v5 1/3] open: add close_range() Christian Brauner
2020-06-02 23:30 ` Florian Weimer
2020-06-02 23:37 ` Christian Brauner
2020-06-03 10:24 ` Michael Kerrisk (man-pages)
2020-09-17 7:52 ` Michael Kerrisk (man-pages)
2020-06-05 14:55 ` Szabolcs Nagy
2020-06-06 2:54 ` Kyle Evans
2020-06-06 3:11 ` Kyle Evans
2020-06-06 11:55 ` Szabolcs Nagy
2020-06-06 14:43 ` Kyle Evans
2020-06-07 13:22 ` David Laight
2020-06-02 20:42 ` [PATCH v5 2/3] arch: wire-up close_range() Christian Brauner
2020-06-02 20:42 ` [PATCH v5 3/3] tests: add close_range() tests Christian Brauner
2020-06-02 21:03 ` [PATCH v5 0/3] close_range() Linus Torvalds
2020-06-02 23:33 ` Christian Brauner
2020-06-03 0:08 ` Linus Torvalds
2020-06-03 23:24 ` Christian Brauner
2020-06-04 0:13 ` Linus Torvalds
2020-06-04 1:15 ` Christian Brauner [this message]
2020-06-07 12:31 ` David Laight
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