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

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Message-ID: <db14ea3c-c224-e263-e134-70e9acc5008a@vivo.com>
Date:   Mon, 3 Jul 2023 17:10:22 +0800
From:   Yangtao Li <frank.li@...o.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        miquel.raynal@...tlin.com, rafael@...nel.org,
        daniel.lezcano@...aro.org, amitk@...nel.org, rui.zhang@...el.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,
        jonathanh@...dia.com, tglx@...utronix.de, matthias.bgg@...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 2023/6/27 15:43, Krzysztof Kozlowski wrote:

> 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?


And tglx point out that:

Having proper and consistent information why the device cannot be used 
_is_ useful.

>
>>   		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?


v3 has been added.


Thx,

Yangtao


>
> Best regards,
> Krzysztof
>