linux-kernel - Re: [PATCH v1 3/5] soc: qcom: memory

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Date:   Mon, 23 Oct 2023 13:46:54 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Zhenhua Huang <quic_zhenhuah@...cinc.com>, agross@...nel.org,
        andersson@...nel.org, konrad.dybcio@...aro.org, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org
Cc:     linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, kernel@...cinc.com,
        quic_tingweiz@...cinc.com
Subject: Re: [PATCH v1 3/5] soc: qcom: memory_dump: Add memory dump driver

On 23/10/2023 13:43, Zhenhua Huang wrote:
>>> +
>>> +			mem_dump_apply_offset(&dump_vaddr, &phys_addr,
>>> +					      size + QCOM_DUMP_DATA_SIZE);
>>> +			if (phys_addr > phys_end_addr) {
>>> +				dev_err_probe(dev, -ENOMEM, "Exceeding allocated region\n");
>>
>> ENOMEM? Does not look right then.
> 
> ENOMEM means the memory allocated not enough? any suggestion? Thanks.

The error code is okay, but we rarely need to print error messages for
memory allocation failures. Core prints it already.

> 
>>
>>> +				return -ENOMEM;
>>> +			}
>>> +		} else {
>>> +			continue;
>>> +		}
>>> +	}
>>> +
>>> +	return ret;
>>> +}
>>> +
>>> +static int __init mem_dump_probe(struct platform_device *pdev)
>>> +{
>>> +	struct qcom_memory_dump *memdump;
>>> +	struct device *dev = &pdev->dev;
>>> +	struct page *page;
>>> +	size_t total_size;
>>> +	int ret = 0;
>>> +
>>> +	memdump = devm_kzalloc(dev, sizeof(struct qcom_memory_dump),
>>> +			       GFP_KERNEL);
>>> +	if (!memdump)
>>> +		return -ENOMEM;
>>> +
>>> +	dev_set_drvdata(dev, memdump);
>>> +
>>> +	/* check and initiate CMA region */
>>> +	ret = mem_dump_reserve_mem(dev);
>>> +	if (ret)
>>> +		return ret;
>>> +
>>> +	/* allocate and populate */
>>> +	page = mem_dump_alloc_mem(dev, &total_size);
>>> +	if (IS_ERR(page)) {
>>> +		ret = PTR_ERR(page);
>>> +		dev_err_probe(dev, ret, "mem dump alloc failed\n");
>>
>> No, the syntax is:
>> ret = dev_err_probe
>>
>> But why do you print messgaes for memory allocations?
> 
> Do you think it's useless because mm codes should print error as well if 
> failure ?

We fixed this in kernel long, long, long time ago so we have even
coccicheck scripts to find misuses.



Best regards,
Krzysztof