netdev - Re: [PATCH V2 resend] ipv6: fix incorrect route 'expires' value passed to userspace

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Message-ID: <500CA2B8.4050305@cn.fujitsu.com>
Date:	Mon, 23 Jul 2012 09:02:48 +0800
From:	Li Wei <lw@...fujitsu.com>
To:	David Laight <David.Laight@...LAB.COM>
CC:	David Miller <davem@...emloft.net>, netdev@...r.kernel.org,
	shemminger@...tta.com
Subject: Re: [PATCH V2 resend] ipv6: fix incorrect route 'expires' value passed
 to userspace

On 07/20/2012 06:32 PM, David Laight wrote:
>> -	else if (rt->dst.expires - jiffies < INT_MAX)
>> -		expires = rt->dst.expires - jiffies;
>> +	else if ((long)rt->dst.expires - (long)jiffies > INT_MIN
>> +			&& (long)rt->dst.expires - (long)jiffies <
> INT_MAX)
>> +		expires = (long)rt->dst.expires - (long)jiffies;
>>  	else
>> -		expires = INT_MAX;
>> +		expires = time_is_after_jiffies(rt->dst.expires) ?
> INT_MAX : INT_MIN;
> 
> I can't help feeling there is a better way to do this.
> Maybe:
> 	long expires = rt->dst.expires - jiffies;
> 	if (expires != (int)expires)
> 		expires = expires > 0 ? INT_MAX : INT_MIN;
> Although maybe -INT_MAX instead of INT_MIN.
> 
> 	David
> 

Thanks David, your code looks much cleaner and can archieve the same
function except we should use
	long expires = (long)rt->dst.expires - (long)jiffies;
to avoid the wrapping of jiffies.

Thanks, 
Wei
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