linux-kernel - Re: [RFC][PATCH 09/14] genirq: add irq_kmemdump

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Message-ID: <87h61wn2qq.ffs@tglx>
Date: Wed, 07 May 2025 12:18:05 +0200
From: Thomas Gleixner <tglx@...utronix.de>
To: Eugen Hristev <eugen.hristev@...aro.org>, linux-kernel@...r.kernel.org,
 linux-arm-msm@...r.kernel.org, andersson@...nel.org
Cc: linux-doc@...r.kernel.org, corbet@....net, mingo@...hat.com,
 rostedt@...dmis.org, john.ogness@...utronix.de, senozhatsky@...omium.org,
 pmladek@...e.com, peterz@...radead.org, mojha@....qualcomm.com,
 linux-arm-kernel@...ts.infradead.org, vincent.guittot@...aro.org,
 konradybcio@...nel.org, dietmar.eggemann@....com, juri.lelli@...hat.com,
 eugen.hristev@...aro.org
Subject: Re: [RFC][PATCH 09/14] genirq: add irq_kmemdump_register

$Subject: ... See

https://www.kernel.org/doc/html/latest/process/maintainer-tip.html#patch-submission-notes

On Tue, Apr 22 2025 at 14:31, Eugen Hristev wrote:
> Add function to register irq info into kmemdump.

What is irq info? Please explain explicitly which information is exposed
and why.

>  
> +void irq_kmemdump_register(void)
> +{
> +	kmemdump_register("irq", (void *)&nr_irqs, sizeof(nr_irqs));
> +}
> +EXPORT_SYMBOL_GPL(irq_kmemdump_register);

Are you going to slap a gazillion of those register a single variable
functions all over the place?

That's a really horrible idea.

The obvious way to deal with that is to annotate the variable:

static unsigned int nr_irqs = NR_IRQS;
KMEMDUMP_VAR(nr_irqs);

Let KMEMDUMP_VAR() store the size and the address of 'nr_irqs' in a
kmemdump specific section and then kmemdump can just walk that section
and dump stuff. No magic register functions and no extra storage
management for static/global variables.

No?

Thanks,

        tglx