linux-kernel - Re: [PATCH v0 42/42] notifier: Return an error when callback is already registered

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]

Date:   Mon, 8 Nov 2021 17:12:16 +0100
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Borislav Petkov <bp@...en8.de>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Arnd Bergmann <arnd@...db.de>,
        Ayush Sawal <ayush.sawal@...lsio.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Rohit Maheshwari <rohitm@...lsio.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Vinay Kumar Yadav <vinay.yadav@...lsio.com>,
        ALSA Development Mailing List <alsa-devel@...a-project.org>,
        bcm-kernel-feedback-list <bcm-kernel-feedback-list@...adcom.com>,
        Intel Graphics Development <intel-gfx@...ts.freedesktop.org>,
        intel-gvt-dev@...ts.freedesktop.org,
        alpha <linux-alpha@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        linux-clk <linux-clk@...r.kernel.org>,
        Linux Crypto Mailing List <linux-crypto@...r.kernel.org>,
        linux-edac@...r.kernel.org,
        Linux Fbdev development list <linux-fbdev@...r.kernel.org>,
        linux-hyperv@...r.kernel.org, linux-iio@...r.kernel.org,
        linux-leds <linux-leds@...r.kernel.org>,
        "open list:BROADCOM NVRAM DRIVER" <linux-mips@...r.kernel.org>,
        Parisc List <linux-parisc@...r.kernel.org>,
        Linux PM list <linux-pm@...r.kernel.org>,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        "open list:REMOTE PROCESSOR (REMOTEPROC) SUBSYSTEM" 
        <linux-remoteproc@...r.kernel.org>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        linux-s390 <linux-s390@...r.kernel.org>,
        scsi <linux-scsi@...r.kernel.org>,
        Linux-sh list <linux-sh@...r.kernel.org>,
        linux-staging@...ts.linux.dev,
        linux-tegra <linux-tegra@...r.kernel.org>,
        linux-um <linux-um@...ts.infradead.org>,
        USB list <linux-usb@...r.kernel.org>,
        "open list:TENSILICA XTENSA PORT (xtensa)" 
        <linux-xtensa@...ux-xtensa.org>, netdev <netdev@...r.kernel.org>,
        openipmi-developer@...ts.sourceforge.net, rcu@...r.kernel.org,
        sparclinux <sparclinux@...r.kernel.org>,
        "the arch/x86 maintainers" <x86@...nel.org>,
        xen-devel@...ts.xenproject.org
Subject: Re: [PATCH v0 42/42] notifier: Return an error when callback is
 already registered

Hi Borislav,

On Mon, Nov 8, 2021 at 4:59 PM Borislav Petkov <bp@...en8.de> wrote:
> On Mon, Nov 08, 2021 at 04:25:47PM +0100, Geert Uytterhoeven wrote:
> > I'm not against returning proper errors codes.  I'm against forcing
> > callers to check things that cannot fail and to add individual error
> > printing to each and every caller.
>
> If you're against checking things at the callers, then the registration
> function should be void. IOW, those APIs are not optimally designed atm.

Returning void is the other extreme ;-)

There are 3 levels (ignoring BUG_ON()/panic () inside the callee):
  1. Return void: no one can check success or failure,
  2. Return an error code: up to the caller to decide,
  3. Return a __must_check error code: every caller must check.

I'm in favor of 2, as there are several places where it cannot fail.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds