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

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Message-ID: <50AD723B.60605@gmail.com>
Date:	Thu, 22 Nov 2012 01:30:51 +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 11/22/2012 01:23 AM, Rafael J. Wysocki wrote:
> On Thursday, November 22, 2012 01:05:30 AM Cyril Roelandt wrote:
>> 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.
>
> OK
>
> So I suppose we can just drop len entirely and replace it with count, right?
> [And drop the<  0 check too.]
>

Indeed, I'll resend.

Cyril Roelandt.
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