linux-kernel - Re: [PATCH] leds: ti-lmu-common: Fix coccinelle issue in TI LMU

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Message-ID: <12746d3e-e658-5ce6-5231-33005a74e549@ti.com>
Date:   Tue, 27 Aug 2019 08:37:14 -0500
From:   Dan Murphy <dmurphy@...com>
To:     Jacek Anaszewski <jacek.anaszewski@...il.com>, <pavel@....cz>
CC:     <linux-leds@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] leds: ti-lmu-common: Fix coccinelle issue in TI LMU

Jacek

On 8/26/19 2:34 PM, Jacek Anaszewski wrote:
> Dan,
>
> On 8/26/19 4:53 PM, Dan Murphy wrote:
>> Jacek
>>
>> On 8/24/19 10:18 AM, Jacek Anaszewski wrote:
>>> Hi Dan,
>>>
>>> Thank you for the patch.
>>>
>>> On 8/23/19 9:55 PM, Dan Murphy wrote:
>>>> Fix the coccinelle issues found in the TI LMU common code
>>>>
>>>> drivers/leds/leds-ti-lmu-common.c:97:20-29: WARNING: Unsigned
>>>> expression compared with zero: ramp_down < 0
>>>> drivers/leds/leds-ti-lmu-common.c:97:5-12: WARNING: Unsigned
>>>> expression compared with zero: ramp_up < 0
>>> Wouldn't it make more sense to remove those pointless checks?
>>> Clearly a correct index of an array cannot be negative.
>>> Looking at the code I would make more int -> unsigned int conversions:
>>>
>>> - ramp_table should be unsigned int
>>> - ti_lmu_common_convert_ramp_to_index should return unsigned int
>>>
>> Yeah I was going to just remove the code but when I was writing the
>> original code my intent was
>>
>> to extend the ramp call to allow other TI LMU driver to pass in the
>> device specific ramp table.
>>
>> But since I don't currently have any devices on my plate that require
>> that I can just remove the code as well
> You don't need to remove, just do the conversions I proposed.
> Unless it introduces some other problems I am currently not aware of.
>
Well just converting those two would/did not fix the issue.

But actually there is only 1 possibility that could happen if the 
convert function returns -EINVAL

So the check should be

if (ramp_up == -EINVAL || ramp_down == -EINVAL)

Because ramp_up/down should never be less then zero otherwise.

Dan