linux-kernel - Re: [RFC 04/42] drivers/dma: don't check resource with devm_ioremap

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Date:	Fri, 10 May 2013 13:25:36 -0600
From:	Stephen Warren <swarren@...dotorg.org>
To:	Wolfram Sang <wsa@...-dreams.de>
CC:	linux-kernel@...r.kernel.org, Vinod Koul <vinod.koul@...el.com>,
	Dan Williams <djbw@...com>, linux-tegra@...r.kernel.org
Subject: Re: [RFC 04/42] drivers/dma: don't check resource with devm_ioremap_resource

On 05/10/2013 11:57 AM, Wolfram Sang wrote:
> On Fri, May 10, 2013 at 10:35:32AM -0600, Stephen Warren wrote:
>> On 05/10/2013 02:16 AM, Wolfram Sang wrote:
>>> devm_ioremap_resource does sanity checks on the given resource. No need to
>>> duplicate this in the driver.
>>
>>> diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c
>>
>>>  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>>> -	if (!res) {
>>> -		dev_err(&pdev->dev, "No mem resource for DMA\n");
>>> -		return -EINVAL;
>>> -	}
>>> -
>>>  	tdma->base_addr = devm_ioremap_resource(&pdev->dev, res);
>>
>> One issue here is that it's not obvious just from reading the code
>> that's left behind that the "missing" error-checking of the
>> platform_get_resource() return value is OK because
>> devm_ioremap_resource() will check it "for us". Everyone now has to
>> mentally maintain a list of exceptions where it's OK not to error-check.
> 
> My goal is to make not-checking the standard case with devm.

OK, if no parameters passed to any devm function every need to be
error-checked, that'll certainly be a bit easier to remember.
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