linux-kernel - Re: [PATCH] acpi_system_write_wakeup_device(): fix error check for unsigned variable.

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Message-ID: <50AD6C4A.4030809@gmail.com>
Date:	Thu, 22 Nov 2012 01:05:30 +0100
From:	Cyril Roelandt <tipecaml@...il.com>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
CC:	linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
	lenb@...nel.org, kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] acpi_system_write_wakeup_device(): fix error check for
 unsigned variable.

On 11/21/2012 01:44 AM, Rafael J. Wysocki wrote:
> On Saturday, November 17, 2012 02:54:23 AM Cyril Roelandt wrote:
>> The LEN variable is unsigned, therefore checking whether it is less than 0 is
>> useless.
>>
>> Signed-off-by: Cyril Roelandt<tipecaml@...il.com>
>> ---
>>   drivers/acpi/proc.c |    2 --
>>   1 file changed, 2 deletions(-)
>>
>> diff --git a/drivers/acpi/proc.c b/drivers/acpi/proc.c
>> index 27adb09..37871a7 100644
>> --- a/drivers/acpi/proc.c
>> +++ b/drivers/acpi/proc.c
>> @@ -366,8 +366,6 @@ acpi_system_write_wakeup_device(struct file *file,
>>
>>   	if (len>  4)
>>   		len = 4;
>> -	if (len<  0)
>> -		return -EFAULT;
>
> I would prefer to check if count<  0 instead.
>


count has type size_t, so it is also an unsigned variable. I think that 
acpi_system_write_wakeup_device really cannot be called with a "count" 
parameter that is less than 0.

WBR,
Cyril Roelandt.
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