linux-kernel - Re: [PATCH] perf jevents: Fix resource leak in process

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Message-ID: <6dc4d5bc-3a1e-3849-a0d3-0f9635bb77fe@huawei.com>
Date:   Wed, 16 Oct 2019 20:49:06 +0800
From:   Yunfeng Ye <yeyunfeng@...wei.com>
To:     John Garry <john.garry@...wei.com>, <peterz@...radead.org>,
        <mingo@...hat.com>, <acme@...nel.org>, <mark.rutland@....com>,
        <alexander.shishkin@...ux.intel.com>, <jolsa@...hat.com>,
        <namhyung@...nel.org>, <ak@...ux.intel.com>,
        <lukemujica@...gle.com>, <kan.liang@...ux.intel.com>,
        <yuzenghui@...wei.com>
CC:     <linux-kernel@...r.kernel.org>, <hushiyuan@...wei.com>,
        <linfeilong@...wei.com>
Subject: Re: [PATCH] perf jevents: Fix resource leak in process_mapfile()



On 2019/10/16 20:08, John Garry wrote:
>>>> +            ret = -1;
>>>> +            goto out;
>>>
>>> There's a subtle change of behaviour here, i.e. now calling print_mapping_table_suffix(), but I don't think that it makes any difference.
>>>
>> yes, I know that "goto out" will run print_mapping_table_suffix(outfp), because the error path before is done like this.
>> so I think it should be use "goto out" to run run print_mapping_table_suffix(outfp).
>>
>>> However, does outfp remain open also in this case:
>>>
>> Because it has a comment that "Make build fail", so I am not handle the outfp, only modify the process_mapfile() function.
>>
>>> main(int argc, char *argv[])
>>> {
>>> ...
>>>
>>> if (process_mapfile(eventsfp, mapfile)) {
>>>     pr_info("%s: Error processing mapfile %s\n", prog, mapfile);
>>>     /* Make build fail */
>>>     return 1;
>>> }
>>>
>>> return 0;
>>>
>>> empty_map:
>>>     fclose(eventsfp);
>>>     ...
>>> }
>>>
>>> I think that this code works on the basis that the program exits on any sort of error and releases resources automatically. Having said that, it is a good practice to tidy up.
>>>
>> I agree with you, when program exits, it will releases resources automatically. It's just to make the program clearer and more correct.
> 
> So can you make that change also (to close outfp)?
> 
ok, I will modify by adding fclose(eventsfp) on the error path, In addition, free_arch_std_events() is need too.

> Thanks,
> John
> 
>>
>>> John
>>>
>>>>          }
>>>>          line[strlen(line)-1] = '\0';
>>>>
>>>> @@ -825,7 +828,9 @@ static int process_mapfile(FILE *outfp, char *fpath)
>>>>
>>>>  out:
>>>>      print_mapping_table_suffix(outfp);
>>>> -    return 0;
>>>> +    fclose(mapfp);
>>>> +    free(line);
>>>> +    return ret;
>>>>  }
>>>>
>>>>  /*
>>>>
>>>
>>>
>>>
>>> .
>>>
>>
>>
>> .
>>
> 
> 
> 
> .
>