netdev - Re: [Suggestion] net/atm : for sprintf, need check the total write length whether larger than a page.

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Message-ID: <50BEE2BE.2030704@asianux.com>
Date:	Wed, 05 Dec 2012 13:59:26 +0800
From:	Chen Gang <gang.chen@...anux.com>
To:	"Chas Williams (CONTRACTOR)" <chas@....nrl.navy.mil>
CC:	David Miller <davem@...emloft.net>, netdev <netdev@...r.kernel.org>
Subject: Re: [Suggestion] net/atm : for sprintf, need check the total write
 length whether larger than a page.

于 2012年12月05日 13:40, Chen Gang 写道:
> 于 2012年12月05日 12:56, Chen Gang 写道:
>>>>>>>> -		pos += sprintf(pos, "\n");
>>>>>>>> +		count += scnprintf(buf + count, PAGE_SIZE - count, "\n");
>>>> ..
>>>>>>  need we judge whether count >= PAGE_SIZE ?
>>>>
>>>> count will eventually make PAGE_SIZE - count reach 0 at which point,
>>>> scnprintf() won't be able to write into the buffer.
>>   I also think so.
>>
>>   I think, maybe it will be better to break the loop when we already
>> know that "count >= PAGE_SIZE" (it can save waste looping, although it
>> seems unlikly happen, for example, using unlikly(...) ).
>>
>> By the way:
>>   will it be better that always let "\n" at the end ?
>>   (if count == PAGE_SIZE in a loop, we can not let "\n" at the end).
> 
>    oh, sorry ! count will never >= PAGE_SIZE.
> 
>    I think let "PAGE_SIZE - 2" instead of "PAGE_SIZE" in the loop, so we
> can make the room for the end of "\n".
> 
> 
> 
   sorry, "PAGE_SIZE - 1" is enough, not need "PAGE_SIZE - 2".


-- 
Chen Gang

Asianux Corporation
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