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

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Message-ID: <CAMuHMdXHikGrmUzuq0WG5JRHUUE=5zsaVCTF+e4TiHpM5tc5kA@mail.gmail.com>
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>,
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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