linux-kernel - Re: [PATCH 05/25] drivers/i2c: Use static const char arrays

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Message-ID: <4C8F7157.9060005@jic23.retrosnub.co.uk>
Date:	Tue, 14 Sep 2010 13:57:59 +0100
From:	Jonathan Cameron <kernel@...23.retrosnub.co.uk>
To:	Lothar Waßmann <LW@...O-electronics.de>
CC:	Jonathan Cameron <arm@...23.retrosnub.co.uk>,
	Joe Perches <joe@...ches.com>,
	Linus Walleij <linus.walleij@...ricsson.com>,
	linux-kernel@...r.kernel.org, linux-i2c@...r.kernel.org,
	"Ben Dooks (embedded platforms)" <ben-linux@...ff.org>,
	"Jean Delvare \(PC drivers\, core\)" <khali@...ux-fr.org>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 05/25] drivers/i2c: Use static const char arrays

On 09/14/10 08:36, Lothar Waßmann wrote:
> Hi,
> 
> Jonathan Cameron writes:
>>  Commit message is  somewhat inaccurate...
>>
>> On 09/13/10 20:47, Joe Perches wrote:
>>> Signed-off-by: Joe Perches <joe@...ches.com>
>>> ---
>>>  drivers/i2c/busses/i2c-stu300.c |    4 ++--
>>>  1 files changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/i2c/busses/i2c-stu300.c b/drivers/i2c/busses/i2c-stu300.c
>>> index 495be45..2f7c09c 100644
>>> --- a/drivers/i2c/busses/i2c-stu300.c
>>> +++ b/drivers/i2c/busses/i2c-stu300.c
>>> @@ -871,7 +871,7 @@ stu300_probe(struct platform_device *pdev)
>>>  	struct resource *res;
>>>  	int bus_nr;
>>>  	int ret = 0;
>>> -	char clk_name[] = "I2C0";
>>> +	char clk_name[sizeof("I2Cx")];
>>>  
>>>  	dev = kzalloc(sizeof(struct stu300_dev), GFP_KERNEL);
>>>  	if (!dev) {
>>> @@ -881,7 +881,7 @@ stu300_probe(struct platform_device *pdev)
>>>  	}
>>>  
>>>  	bus_nr = pdev->id;
>>> -	clk_name[3] += (char)bus_nr;
>>> +	sprintf(clk_name, "I2C%c", '0' + bus_nr);
>> I'm guessing that there are never more than a couple of these.
>> Why is this method a better bet than just putting %d?
>>
> '%c' will only ever produce one byte of output while '%d' may
> produce up to 11 bytes depending on the value of bus_nr thus
> overflowing the buffer.
Then use an snprintf, or apply a check to ensure it isn't bigger than
9.

If you don't mind having clocks named i2c$ or something equally
silly then I guess this is fine.  To my mind, if that is possible
this is a bug that should be fixed rather than avoided.


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