linux-kernel - Re: [PATCH] Staging: comedi: clean up conditional statement in addi_apci

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Date:	Thu, 13 Feb 2014 10:08:42 +0000
From:	Ian Abbott <abbotti@....co.uk>
To:	Chase Southwood <chase.southwood@...oo.com>,
	gregkh@...uxfoundation.org
CC:	hsweeten@...ionengravers.com, devel@...verdev.osuosl.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Staging: comedi: clean up conditional statement in addi_apci_3xxx.c

On 2014-02-13 03:29, Chase Southwood wrote:
> In this if-else conditional statement, if (chan < 16), but
> (data[0] == INSN_CONFIG_DIO_QUERY), the function does not return early,
> but the else-branch does not get executed either.  As a result, mask
> would be used uninitialized in the next line.  What we want here is if
> (chan < 16) and (data[0] != INSN_CONFIG_DIO_QUERY), return an error, but
> in every other case, initialize mask and then proceed.  Found by a static
> checker.
>
> Signed-off-by: Chase Southwood <chase.southwood@...oo.com>
> ---
>   drivers/staging/comedi/drivers/addi_apci_3xxx.c | 12 +++++-------
>   1 file changed, 5 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/staging/comedi/drivers/addi_apci_3xxx.c b/drivers/staging/comedi/drivers/addi_apci_3xxx.c
> index ceadf8e..04c5153 100644
> --- a/drivers/staging/comedi/drivers/addi_apci_3xxx.c
> +++ b/drivers/staging/comedi/drivers/addi_apci_3xxx.c
> @@ -688,13 +688,11 @@ static int apci3xxx_dio_insn_config(struct comedi_device *dev,
>   	 * Port 1 (channels 8-15) are always outputs
>   	 * Port 2 (channels 16-23) are programmable i/o
>   	 */
> -	if (chan < 16) {
> -		if (data[0] != INSN_CONFIG_DIO_QUERY)
> -			return -EINVAL;
> -	} else {
> -		/* changing any channel in port 2 changes the entire port */
> -		mask = 0xff0000;
> -	}
> +	if ((chan < 16) && (data[0] != INSN_CONFIG_DIO_QUERY))
> +		return -EINVAL;
> +
> +	/* changing any channel in port 2 changes the entire port */
> +	mask = 0xff0000;
>
>   	ret = comedi_dio_insn_config(dev, s, insn, data, mask);
>   	if (ret)

Seems correct.

Acked-by: Ian Abbott <abbotti@....co.uk>


-- 
-=( Ian Abbott @ MEV Ltd.    E-mail: <abbotti@....co.uk>        )=-
-=( Tel: +44 (0)161 477 1898   FAX: +44 (0)161 718 3587         )=-
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