From mboxrd@z Thu Jan  1 00:00:00 1970
From: linux@roeck-us.net (Guenter Roeck)
Date: Tue, 9 Feb 2016 18:37:46 -0800
Subject: [PATCH] tty/serial: digicolor: Fix bad usage of IS_ERR_VALUE
In-Reply-To: <4571887.rTPndCnv20@wuerfel>
References: <1455030539-10798-1-git-send-email-linux@roeck-us.net>
 <4571887.rTPndCnv20@wuerfel>
Message-ID: <56BAA27A.9050605@roeck-us.net>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On 02/09/2016 07:26 AM, Arnd Bergmann wrote:
> On Tuesday 09 February 2016 07:08:59 Guenter Roeck wrote:
>> IS_ERR_VALUE() assumes that its parameter is an unsigned long.
>> It can not be used to check if an unsigned int reflects an error.
>> Doing so can result in the following build warning.
>>
>> drivers/tty/serial/digicolor-usart.c: In function ?digicolor_uart_probe?:
>> include/linux/err.h:21:38: warning:
>>          comparison is always false due to limited range of data type
>> drivers/tty/serial/digicolor-usart.c:485:6: note:
>>          in expansion of macro ?IS_ERR_VALUE?
>>
>> If that warning is seen, an error return from platform_get_irq() is missed.
>>
>>
>
> The patch looks correct to me, but what compiler version and which kernel
> tree is it that triggered the warning?
>
> Andrzej Hajda just modified the definition of IS_ERR_VALUE(), and the
> changes are still under discussion, but I don't see that warning with
> any of the versions.
>
I see it with gcc 5.1 and 5.2 (and W=1). I did not see / notice Andrzej's patch.

I agree that fixing the problem in IS_ERR_VALUE() is preferrable.

Guenter