linux-kernel - Re: v6.1-rc1: Regression in notification of sethostname changes

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Message-ID: <Y0/DlHMIPbRDG+fF@pevik>
Date:   Wed, 19 Oct 2022 11:29:56 +0200
From:   Petr Vorel <pvorel@...e.cz>
To:     Torsten Hilbrich <torsten.hilbrich@...unet.com>
Cc:     linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: v6.1-rc1: Regression in notification of sethostname changes

Hi Torsten,

> Hello Petr,

> your commit

> commit bfca3dd3d0680fc2fc7f659a152234afbac26e4d
> Author: Petr Vorel <pvorel@...e.cz>
> Date:   Thu Sep 1 21:44:03 2022 +0200

>     kernel/utsname_sysctl.c: print kernel arch

>     Print the machine hardware name (UTS_MACHINE) in /proc/sys/kernel/arch.

>     This helps people who debug kernel with initramfs with minimal environment
>     (i.e.  without coreutils or even busybox) or allow to open sysfs file
>     instead of run 'uname -m' in high level languages.

> broke the notification mechanism between the sethostname syscall and the pollers of /proc/sys/kernel/hostname.

> The table uts_kern_table is addressed within uts_proc_notify by the enum value, however no new enum value was added in "enum uts_proc".

> I noticed the problem when journald-systemd failed to detect hostname changes made with the sethostname syscall (as used by the hostname tool).
> When setting the hostname through /proc/sys/kernel/hostname the poll notification was working.

Thanks a lot for your report, working on a fix!
Andrew, Greg, sorry for a regression.

Kind regards,
Petr

> 	Torsten