linux-kernel - Re: [PATCH v7 03/20] reboot: Print error message if restart handler has duplicated priority

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAJZ5v0gf1J+yPW14TAdLGLGfO+-2s=r0DDP7d+Rgop3=dB0gaQ@mail.gmail.com>
Date:   Wed, 13 Apr 2022 20:48:20 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Dmitry Osipenko <dmitry.osipenko@...labora.com>
Cc:     Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Russell King <linux@...linux.org.uk>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>, Guo Ren <guoren@...nel.org>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Greg Ungerer <gerg@...ux-m68k.org>,
        Joshua Thompson <funaho@...ai.org>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Sebastian Reichel <sre@...nel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Greentime Hu <green.hu@...il.com>,
        Vincent Chen <deanbo422@...il.com>,
        "James E.J. Bottomley" <James.Bottomley@...senpartnership.com>,
        Helge Deller <deller@....de>,
        Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Yoshinori Sato <ysato@...rs.sourceforge.jp>,
        Rich Felker <dalias@...c.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "the arch/x86 maintainers" <x86@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Juergen Gross <jgross@...e.com>,
        Stefano Stabellini <sstabellini@...nel.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Len Brown <lenb@...nel.org>,
        Santosh Shilimkar <ssantosh@...nel.org>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>, Pavel Machek <pavel@....cz>,
        Lee Jones <lee.jones@...aro.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Guenter Roeck <linux@...ck-us.net>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Michał Mirosław <mirq-linux@...e.qmqm.pl>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-csky@...r.kernel.org, linux-ia64@...r.kernel.org,
        linux-m68k@...ts.linux-m68k.org,
        "open list:BROADCOM NVRAM DRIVER" <linux-mips@...r.kernel.org>,
        linux-parisc@...r.kernel.org, linux-riscv@...ts.infradead.org,
        Linux-sh list <linux-sh@...r.kernel.org>,
        xen-devel@...ts.xenproject.org,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        linux-tegra <linux-tegra@...r.kernel.org>
Subject: Re: [PATCH v7 03/20] reboot: Print error message if restart handler
 has duplicated priority

On Tue, Apr 12, 2022 at 1:39 AM Dmitry Osipenko
<dmitry.osipenko@...labora.com> wrote:
>
> Add sanity check which ensures that there are no two restart handlers
> registered using the same priority. This requirement will become mandatory
> once all drivers will be converted to the new API and such errors will be
> fixed.
>
> Signed-off-by: Dmitry Osipenko <dmitry.osipenko@...labora.com>

The first two patches in the series are fine with me and there's only
one minor nit regarding this one (below).

> ---
>  kernel/reboot.c | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
>
> diff --git a/kernel/reboot.c b/kernel/reboot.c
> index ed4e6dfb7d44..acdae4e95061 100644
> --- a/kernel/reboot.c
> +++ b/kernel/reboot.c
> @@ -182,6 +182,21 @@ static ATOMIC_NOTIFIER_HEAD(restart_handler_list);
>   */
>  int register_restart_handler(struct notifier_block *nb)
>  {
> +       int ret;
> +
> +       ret = atomic_notifier_chain_register_unique_prio(&restart_handler_list, nb);
> +       if (ret != -EBUSY)
> +               return ret;
> +
> +       /*
> +        * Handler must have unique priority. Otherwise call order is
> +        * determined by registration order, which is unreliable.
> +        *
> +        * This requirement will become mandatory once all drivers
> +        * will be converted to use new sys-off API.
> +        */
> +       pr_err("failed to register restart handler using unique priority\n");

I would use pr_info() here, because this is not a substantial error AFAICS.

> +
>         return atomic_notifier_chain_register(&restart_handler_list, nb);
>  }
>  EXPORT_SYMBOL(register_restart_handler);
> --