linux-kernel - Re: [PATCH] mtd: oxnas_nand: Fix error handling in oxnas_nand

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Date:   Mon, 18 Sep 2017 12:24:38 +0200
From:   Neil Armstrong <narmstrong@...libre.com>
To:     Boris Brezillon <boris.brezillon@...e-electrons.com>,
        Alexey Khoroshilov <khoroshilov@...ras.ru>
Cc:     Brian Norris <computersforpeace@...il.com>,
        linux-mtd@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-oxnas@...ts.tuxfamily.org, linux-kernel@...r.kernel.org,
        ldv-project@...uxtesting.org
Subject: Re: [PATCH] mtd: oxnas_nand: Fix error handling in oxnas_nand_probe()

On 09/18/2017 12:14 PM, Boris Brezillon wrote:
> Hi Alexey,
> 
> On Sat,  9 Sep 2017 01:00:38 +0300
> Alexey Khoroshilov <khoroshilov@...ras.ru> wrote:
> 
>> oxnas_nand_probe() does not disable clock on error paths.
>> The patch adds disabling using devm interface.
>>
>> Found by Linux Driver Verification project (linuxtesting.org).
>>
>> Signed-off-by: Alexey Khoroshilov <khoroshilov@...ras.ru>
>> ---
>>  drivers/mtd/nand/oxnas_nand.c | 22 +++++++++++++++-------
>>  1 file changed, 15 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/mtd/nand/oxnas_nand.c b/drivers/mtd/nand/oxnas_nand.c
>> index 1b207aac840c..8abc69a285dd 100644
>> --- a/drivers/mtd/nand/oxnas_nand.c
>> +++ b/drivers/mtd/nand/oxnas_nand.c
>> @@ -103,16 +103,26 @@ static int oxnas_nand_probe(struct platform_device *pdev)
>>  	if (IS_ERR(oxnas->io_base))
>>  		return PTR_ERR(oxnas->io_base);
>>  
>> -	oxnas->clk = devm_clk_get(&pdev->dev, NULL);
>> -	if (IS_ERR(oxnas->clk))
>> -		oxnas->clk = NULL;
>> -
>>  	/* Only a single chip node is supported */
>>  	count = of_get_child_count(np);
>>  	if (count > 1)
>>  		return -EINVAL;
>>  
>> -	clk_prepare_enable(oxnas->clk);
>> +	oxnas->clk = devm_clk_get(&pdev->dev, NULL);
>> +	if (IS_ERR(oxnas->clk)) {
>> +		oxnas->clk = NULL;
>> +	} else {
>> +		err = clk_prepare_enable(oxnas->clk);
>> +		if (err)
>> +			return err;
>> +
>> +		err = devm_add_action_or_reset(&pdev->dev,
>> +				(void(*)(void *))clk_disable_unprepare,
>> +				oxnas->clk);
>> +		if (err)
>> +			return err;
>> +	}
>> +
> 
> Looks like something that should be made available at the CCF level
> either with a devm_clk_get_prepare_enable() or with a
> devm_clk_prepare_enable() helper. Would you care proposing this change
> to the CCF ML?
> 
> In the meantime can you provide a simpler fix that just adds the
> missing clk_disable_unprepare() call in the error path?
> 
>>  	device_reset_optional(&pdev->dev);
>>  
>>  	for_each_child_of_node(np, nand_np) {
>> @@ -167,8 +177,6 @@ static int oxnas_nand_remove(struct platform_device *pdev)
>>  	if (oxnas->chips[0])
>>  		nand_release(nand_to_mtd(oxnas->chips[0]));
>>  
>> -	clk_disable_unprepare(oxnas->clk);
>> -
>>  	return 0;
>>  }
>>  
> 

Hi Boris,

I would also like this to be simpler, but this is the actual way to workaround the lack of advanced devm_ calls from CCF.

Is it an issue to keep this change ?

Neil