linux-kernel - Re: [PATCH v4] irqchip/renesas-rzg2l: Fix missing put

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Message-ID: <871q0hdofq.ffs@tglx>
Date: Tue, 15 Oct 2024 23:52:09 +0200
From: Thomas Gleixner <tglx@...utronix.de>
To: Markus Elfring <Markus.Elfring@....de>, Fabrizio Castro
 <fabrizio.castro.jz@...esas.com>, linux-renesas-soc@...r.kernel.org, Geert
 Uytterhoeven <geert+renesas@...der.be>
Cc: LKML <linux-kernel@...r.kernel.org>, kernel-janitors@...r.kernel.org,
 Biju Das <biju.das.jz@...renesas.com>, Chris Paterson
 <Chris.Paterson2@...esas.com>, Lad Prabhakar
 <prabhakar.mahadev-lad.rj@...renesas.com>, Marc Zyngier <maz@...nel.org>
Subject: Re: [PATCH v4] irqchip/renesas-rzg2l: Fix missing put_device

On Fri, Oct 11 2024 at 20:48, Markus Elfring wrote:
>> rzg2l_irqc_common_init calls of_find_device_by_node, but the
>> corresponding put_device call is missing.
>
> How do you think about to append parentheses to function names
> (so that they can be distinguished a bit easier from other identifiers)?
>
>
>> Make use of the cleanup interfaces from cleanup.h to call into
>> __free_put_device (which in turn calls into put_device) when
>
> Can it help to influence the understanding of this programming
> interface by mentioning the usage of a special attribute?

Can you please stop pestering people with incomprehensible word salad?

>> leaving function rzg2l_irqc_common_init and variable "dev" goes
>> out of scope.
>>
>> Mind that we don't want to "put" "dev" when rzg2l_irqc_common_init
>> completes successfully, therefore assign NULL to "dev" to prevent
>> __free_put_device from calling into put_device within the successful
>> path.
>
> Will further software design options become applicable here?
>
> Can any pointer type be used for the return value
> (instead of the data type “int”)?

How is this relevant here?

>
>> "make coccicheck" will still complain about missing put_device calls,
>> but those are false positives now.
>
> Would you like to discuss any adjustment possibilities for this
> development tool?

Would you like to get useful work done insteead of telling everyone what
to do? There is nothing to discuss.

>> +++ b/drivers/irqchip/irq-renesas-rzg2l.c
>> @@ -8,6 +8,7 @@
>>   */
>>
>>  #include <linux/bitfield.h>
>> +#include <linux/cleanup.h>
> …
>
> This header file would usually be included by an other inclusion statement already,
> wouldn't it?

Relying on indirect includes is not necessarily a good idea/

>> @@ -530,12 +531,12 @@ static int rzg2l_irqc_parse_interrupts(struct rzg2l_irqc_priv *priv,
>>  static int rzg2l_irqc_common_init(struct device_node *node, struct device_node *parent,
>>  				  const struct irq_chip *irq_chip)
>>  {
>> +	struct platform_device *pdev = of_find_device_by_node(node);
>> +	struct device *dev __free(put_device) = pdev ? &pdev->dev : NULL;
>>  	struct irq_domain *irq_domain, *parent_domain;
>> -	struct platform_device *pdev;
>>  	struct reset_control *resetn;
>>  	int ret;
>>
>> -	pdev = of_find_device_by_node(node);
>>  	if (!pdev)
>>  		return -ENODEV;
> …
>
> Would you dare to reduce the scopes for any local variables here?
> https://refactoring.com/catalog/reduceScopeOfVariable.html

Can you keep your refactoring links for yourself please? We are aware of
this.

But this change fixes a bug and that's it. We are not doing cleanups in
a bug fix. Please read and understand Documentation/process before
giving people ill defined advise.

Thanks,

        tglx