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From: Borislav Petkov <bp@alien8.de>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
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Subject: Re: [PATCH v0 42/42] notifier: Return an error when callback is already registered
Date: Mon, 8 Nov 2021 15:21:04 +0100	[thread overview]
Message-ID: <YYkyUEqcsOwQMb1S@zn.tnic> (raw)
In-Reply-To: <CAMuHMdWH+txiSP_d7Jc4f_bU8Lf9iWpT4E3o5o7BJr-YdA6-VA@mail.gmail.com>

On Mon, Nov 08, 2021 at 03:07:03PM +0100, Geert Uytterhoeven wrote:
> I think the addition of __must_check is overkill, leading to the
> addition of useless error checks and message printing.

See the WARN in notifier_chain_register() - it will already do "message
printing".

> Many callers call this where it cannot fail, and where nothing can
> be done in the very unlikely event that the call would ever start to
> fail.

This is an attempt to remove this WARN() hack in
notifier_chain_register() and have the function return a proper error
value instead of this "Currently always returns zero." which is bad
design.

Some of the registration functions around the tree check that retval and
some don't. So if "it cannot fail" those registration either should not
return a value or callers should check that return value - what we have
now doesn't make a whole lot of sense.

Oh, and then fixing this should avoid stuff like:

+	if (notifier_registered == false) {
+		mce_register_decode_chain(&amdgpu_bad_page_nb);
+		notifier_registered = true;
+	}

from propagating in the code.

The other idea I have is to add another indirection in
notifier_chain_register() which will check the *proper* return value of
a lower level __notifier_chain_register() and then issue that warning.
That would definitely avoid touch so many call sites.

Bottom line is: what we have now needs cleaning up.

Thx.

-- 
Regards/Gruss,
    Boris.

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

  reply	other threads:[~2021-11-08 14:21 UTC|newest]

Thread overview: 77+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-08 10:11 [PATCH v0 00/42] notifiers: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 01/42] x86: Check notifier registration return value Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 02/42] xen/x86: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 03/42] impi: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 04/42] clk: renesas: " Borislav Petkov
2021-11-08 14:12   ` Geert Uytterhoeven
2021-11-08 10:11 ` [PATCH v0 05/42] dca: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 06/42] firmware: " Borislav Petkov
2021-11-12 18:43   ` Cristian Marussi
2021-11-08 10:11 ` [PATCH v0 07/42] drm/i915: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 08/42] Drivers: hv: vmbus: " Borislav Petkov
2021-11-08 11:16   ` Wei Liu
2021-11-08 11:39     ` Borislav Petkov
2021-11-08 11:45       ` Wei Liu
2021-11-08 12:08         ` Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 09/42] iio: proximity: cros_ec: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 10/42] leds: trigger: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 11/42] misc: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 12/42] ethernet: chelsio: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 13/42] power: reset: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 14/42] remoteproc: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 15/42] scsi: target: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 16/42] USB: " Borislav Petkov
2021-11-08 14:05   ` Alan Stern
2021-11-08 14:09     ` Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 17/42] drivers: video: " Borislav Petkov
2021-11-08 11:16   ` Wei Liu
2021-11-08 10:11 ` [PATCH v0 18/42] drivers/xen: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 19/42] kernel/hung_task: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 20/42] rcu: " Borislav Petkov
2021-11-08 16:53   ` Paul E. McKenney
2021-11-08 10:11 ` [PATCH v0 21/42] tracing: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 22/42] net: fib_notifier: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 23/42] ASoC: soc-jack: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 24/42] staging: olpc_dcon: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 25/42] arch/um: " Borislav Petkov
2021-11-08 10:23   ` Johannes Berg
2021-11-08 10:48     ` Borislav Petkov
2021-11-08 10:56       ` Johannes Berg
2021-11-08 10:11 ` [PATCH v0 26/42] alpha: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 27/42] bus: brcmstb_gisb: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 28/42] soc: bcm: brcmstb: pm: pm-arm: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 29/42] arm64: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 30/42] soc/tegra: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 31/42] parisc: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 32/42] macintosh/adb: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 33/42] mips: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 34/42] powerpc: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 35/42] sh: " Borislav Petkov
2021-11-08 13:31   ` Geert Uytterhoeven
2021-11-08 13:49     ` Borislav Petkov
2021-11-08 14:03       ` Geert Uytterhoeven
2021-11-08 14:48   ` Sergey Shtylyov
2021-11-08 10:11 ` [PATCH v0 36/42] s390: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 37/42] sparc: " Borislav Petkov
2021-11-08 19:59   ` David Miller
2021-11-08 10:11 ` [PATCH v0 38/42] xtensa: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 39/42] crypto: ccree - check " Borislav Petkov
2021-11-12 18:32   ` Cristian Marussi
2021-11-12 18:48     ` Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 40/42] EDAC/altera: Check " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 41/42] power: supply: ab8500: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 42/42] notifier: Return an error when callback is already registered Borislav Petkov
2021-11-08 14:07   ` Geert Uytterhoeven
2021-11-08 14:21     ` Borislav Petkov [this message]
2021-11-08 15:25       ` Geert Uytterhoeven
2021-11-08 15:58         ` Borislav Petkov
2021-11-08 16:12           ` Geert Uytterhoeven
2021-11-08 16:21             ` Borislav Petkov
2021-11-08 20:59               ` Alan Stern
2021-11-08 21:18                 ` Borislav Petkov
2021-11-08 10:19 ` [PATCH v0 00/42] notifiers: " Borislav Petkov
2021-11-08 14:17   ` Alan Stern
2021-11-08 14:24     ` Borislav Petkov
2021-11-08 14:35       ` Borislav Petkov
2021-11-08 16:23         ` Steven Rostedt
2021-11-08 16:29           ` Borislav Petkov

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