Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
From:   Petr Vorel <pvorel@suse.cz>
To:     linux-kernel@vger.kernel.org
Cc:     Petr Vorel <pvorel@suse.cz>,
        Andrew Morton <akpm@linux-foundation.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Torsten Hilbrich <torsten.hilbrich@secunet.com>
Subject: [PATCH 1/1] kernel/utsname_sysctl.c: Add missing enum uts_proc value
Date:   Thu, 20 Oct 2022 17:06:45 +0200
Message-Id: <20221020150645.11719-1-pvorel@suse.cz>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

bfca3dd3d068 added new struct ctl_table uts_kern_table[], but not new
enum uts_proc value. It 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, that's why new enum value is needed.

Fixes: bfca3dd3d068 ("kernel/utsname_sysctl.c: print kernel arch")

Reported-by: Torsten Hilbrich <torsten.hilbrich@secunet.com>
Signed-off-by: Petr Vorel <pvorel@suse.cz>
---
Hi all,

I'm sorry to introduce a regression.

Torsten Hilbrich reported [1] that hostnamectl set-hostname foo
which does poll() got affected by bfca3dd3d068. He also wrote a
reproducer [2] which does not require systemd, I tested the patch on
dracut initramfs.

Kind regards,
Petr

[1] https://lore.kernel.org/lkml/0c2b92a6-0f25-9538-178f-eee3b06da23f@secunet.com/
[2] https://lore.kernel.org/lkml/ec9e00b9-8b47-7918-c39b-8b0069003169@secunet.com/2-hostname-poll-test.c

 include/linux/utsname.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/linux/utsname.h b/include/linux/utsname.h
index 2b1737c9b244..bf7613ba412b 100644
--- a/include/linux/utsname.h
+++ b/include/linux/utsname.h
@@ -10,6 +10,7 @@
 #include <uapi/linux/utsname.h>
 
 enum uts_proc {
+	UTS_PROC_ARCH,
 	UTS_PROC_OSTYPE,
 	UTS_PROC_OSRELEASE,
 	UTS_PROC_VERSION,
-- 
2.38.0