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Subject: Re: [PATCH v2] ftrace: avoid potential division by zero
To:     Justin Capella <justincapella@gmail.com>
Cc:     Steven Rostedt <rostedt@goodmis.org>,
        Ingo Molnar <mingo@redhat.com>, xlpang@linux.alibaba.com,
        LKML <linux-kernel@vger.kernel.org>
References: <20200103030248.14516-1-wenyang@linux.alibaba.com>
 <CAMrEMU8wB4c0TFTSJ4ixQg_gSnW72n_T3ip8ZfZFAk8xWjaKsA@mail.gmail.com>
From:   Wen Yang <wenyang@linux.alibaba.com>
Message-ID: <a2468cc8-cdc1-0a03-6de1-6607bff4d0fa@linux.alibaba.com>
Date:   Fri, 3 Jan 2020 19:31:49 +0800
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On 2020/1/3 4:00 下午, Justin Capella wrote:
>> -               do_div(stddev, rec->counter * (rec->counter - 1) * 1000);
>>
>> +               stddev = div64_ul(stddev,
>> +                                 rec->counter * (rec->counter - 1) * 1000);
> 
> 
> Is a rec->counter > 1 assertion needed here?
> 

Hello, the above lines deal with this situation:

         if (rec->counter <= 1)
                 stddev = 0;
         else {


--
Regards,
Wen