linux-kernel - Re: [PATCH v2 2/5] perf pmu: Support more complex PMU event aliasing

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Message-ID: <004cb11b-e0ee-5af1-33d4-437fb8be03c0@huawei.com>
Date:   Fri, 28 Jun 2019 11:45:43 +0100
From:   John Garry <john.garry@...wei.com>
To:     Jiri Olsa <jolsa@...hat.com>
CC:     <peterz@...radead.org>, <mingo@...hat.com>, <acme@...nel.org>,
        <alexander.shishkin@...ux.intel.com>, <namhyung@...nel.org>,
        <tmricht@...ux.ibm.com>, <brueckner@...ux.ibm.com>,
        <kan.liang@...ux.intel.com>, <ben@...adent.org.uk>,
        <mathieu.poirier@...aro.org>, <mark.rutland@....com>,
        <will.deacon@....com>, <linux-kernel@...r.kernel.org>,
        <linuxarm@...wei.com>, <linux-arm-kernel@...ts.infradead.org>,
        <zhangshaokun@...ilicon.com>
Subject: Re: [PATCH v2 2/5] perf pmu: Support more complex PMU event aliasing

On 28/06/2019 11:40, Jiri Olsa wrote:
> On Thu, Jun 27, 2019 at 05:27:32PM +0100, John Garry wrote:
>
> SNIP
>
>>>>
>>>> heya,
>>>> sry for late reply
>>>>
>>>>>
>>>>>> if tok is NULL in here we crash
>>>>>>
>>>>>
>>>>> As I see, tok could not be NULL. If str contains no delimiters, then
>>>>> we just
>>>>> return same as str in tok.
>>>>>
>>>>> Can you see tok being NULL?
>>>>
>>>> well, if there's no ',' in the str it returns NULL, right?
>>>
>>> No, it would return str in tok.
>
> ok
>
>>>
>>>> and IIUC this function is still called for standard uncore
>>>> pmu names
>>>>
>>>>>
>>>>>>> +        res = false;
>>>>>>> +        goto out;
>>>>>>> +    }
>>>>>>> +
>>>>>>> +    for (; tok; name += strlen(tok), tok = strtok_r(NULL, ",",
>>>>>>> &tmp)) {
>>>>>>
>>>>>> why is name shifted in here?
>>>>>
>>>>> I want to ensure that we match the tokens in order and also guard
>>>>> against
>>>>> possible repeated token matches in 'name'.
>>>>
>>>> i might not understand this correctly.. so
>>>>
>>>> str is the alias name that can contain ',' now, like:
>>>>   hisi_sccl,ddrc
>>>
>>> For example of pmu_nmame=hisi_sccl,ddrc and pmu=hisi_sccl1_ddrc0, we
>>> match in this sequence:
>>>
>>> loop 1. tok=hisi_sccl name=hisi_sccl1_ddrc0
>>> loop 2. tok=ddrc name=ddrc0
>>> loop 3. tok=NULL -> breakout and return true
>

Hi jirka,

> ok, plz put something like above into comment
>

ok, can do.

Thanks again,
John

> thanks,
> jirka
>
> .
>