linux-kernel - Re: [PATCH 01/15] genirq/devres: Add error information printing for devm_request_threaded

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Message-ID: <82dc5efc-35fe-15ff-d0ea-e1a19da71c5c@linaro.org>
Date:   Tue, 27 Jun 2023 09:43:54 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Yangtao Li <frank.li@...o.com>, miquel.raynal@...tlin.com,
        rafael@...nel.org, daniel.lezcano@...aro.org, amitk@...nel.org,
        rui.zhang@...el.com, mmayer@...adcom.com,
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        florian.fainelli@...adcom.com, shawnguo@...nel.org,
        s.hauer@...gutronix.de, kernel@...gutronix.de, festevam@...il.com,
        linux-imx@....com, agross@...nel.org, andersson@...nel.org,
        konrad.dybcio@...aro.org, thara.gopinath@...il.com,
        heiko@...ech.de, mcoquelin.stm32@...il.com,
        alexandre.torgue@...s.st.com, thierry.reding@...il.com,
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Cc:     linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
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Subject: Re: [PATCH 01/15] genirq/devres: Add error information printing for
 devm_request_threaded_irq()

On 27/06/2023 09:16, Yangtao Li wrote:
> Ensure that all error handling branches print error information. In this
> way, when this function fails, the upper-layer functions can directly
> return an error code without missing debugging information. Otherwise,
> the error message will be printed redundantly or missing.
> 
> There are more than 700 calls to the devm_request_threaded_irq method.
> If error messages are printed everywhere, more than 1000 lines of code
> can be saved by removing the msg in the driver.
> 
> Signed-off-by: Yangtao Li <frank.li@...o.com>
> ---
>  kernel/irq/devres.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/irq/devres.c b/kernel/irq/devres.c
> index f6e5515ee077..94039a915218 100644
> --- a/kernel/irq/devres.c
> +++ b/kernel/irq/devres.c
> @@ -58,8 +58,10 @@ int devm_request_threaded_irq(struct device *dev, unsigned int irq,
>  
>  	dr = devres_alloc(devm_irq_release, sizeof(struct irq_devres),
>  			  GFP_KERNEL);
> -	if (!dr)
> +	if (!dr) {
> +		dev_err(dev, "Failed to allocate device resource data\n");

Just like any memory allocation, I don't think we print anything for
devres failures. Why do you think we should start doing it?

>  		return -ENOMEM;
> +	}
>  
>  	if (!devname)
>  		devname = dev_name(dev);
> @@ -67,6 +69,7 @@ int devm_request_threaded_irq(struct device *dev, unsigned int irq,
>  	rc = request_threaded_irq(irq, handler, thread_fn, irqflags, devname,
>  				  dev_id);
>  	if (rc) {
> +		dev_err(dev, "Failed to request threaded irq\n");

I don't like that one path - devm() managed - prints error, but regular
path does not. Code should be here consistent. Also error message is too
generic. You need to print at least irq number, maybe also devname?

Best regards,
Krzysztof