Message-ID: <4B258FF2.3070600@cn.fujitsu.com>
Date: Mon, 14 Dec 2009 09:08:02 +0800
From: Li Zefan <lizf@cn.fujitsu.com>
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To: rostedt@goodmis.org
CC: Ingo Molnar <mingo@elte.hu>, Frederic Weisbecker <fweisbec@gmail.com>,
       Wenji Huang <wenji.huang@oracle.com>,
       LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 4/4] tracing/filters: Fix MATCH_EBD_ONLY filter matching
References: <4B2217D0.5000308@cn.fujitsu.com>	 <4B22180E.6090907@cn.fujitsu.com> <1260544458.2146.362.camel@gandalf.stny.rr.com>
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>>  static int regex_match_end(char *str, struct regex *r, int len)
>>  {
>> -	char *ptr = strstr(str, r->pattern);
>> +	int strlen = len - 1;
>>  
>> -	if (ptr && (ptr[r->len] == 0))
>> +	if (strlen >= r->len &&
>> +	    !memcmp(str + strlen - r->len, r->pattern, r->len))
> 
> Please use memcmp() == 0, I've seen too many bugs with !*cmp as well as
> with *cmp, because humans tend to think instinctively when reading this
> that ! is not a match. With "== 0" we think that "==" is a match and
>  "!=" is a miss.
> 

Though I sometimes don't care much about this, I do
think memcmp() == 0 is better.

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