From mboxrd@z Thu Jan  1 00:00:00 1970
From: Borislav Petkov <bp@alien8.de>
Subject: Re: [PATCH v0 42/42] notifier: Return an error when callback is
 already registered
Date: Mon, 8 Nov 2021 16:58:57 +0100
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To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: LKML <linux-kernel@vger.kernel.org>, Thomas Gleixner <tglx@linutronix.de>, Arnd Bergmann <arnd@arndb.de>, Ayush Sawal <ayush.sawal@chelsio.com>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Rohit Maheshwari <rohitm@chelsio.com>, Steven Rostedt <rostedt@goodmis.org>, Vinay Kumar Yadav <vinay.yadav@chelsio.com>, ALSA Development Mailing List <alsa-devel@alsa-project.org>, bcm-kernel-feedback-list <bcm-kernel-feedback-list@broadcom.com>, Intel Graphics Development <intel-gfx@lists.freedesktop.org>, intel-gvt-dev@lists.freedesktop.org, alpha <linux-alpha@vger.kernel.org>, Linux ARM <linux-arm-kernel@lists.infradead.org>, linux-clk <linux-clk@vger.kernel.org>, Linux Crypto Mailing List <linux-crypto@vger.kernel.org>, linux-edac@vger.kernel.org, Linux

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.

> Note that in other areas, we are moving in the other direction,
> to a centralized printing of error messages, cfr. e.g. commit
> 7723f4c5ecdb8d83 ("driver core: platform: Add an error message to
> platform_get_irq*()").

Yes, thus my other idea to add a lower level __notifier_chain_register()
to do the checking.

I'll see if I can convert those notifier registration functions to
return void, in the process. But let's see what the others think first.

Thanks for taking the time.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette