linux-kernel - Re: [PATCH v4 1/3] tracing: eprobe: remove duplicate is_good

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Date:   Tue, 14 Jun 2022 08:48:28 +0800
From:   Linyu Yuan <quic_linyyuan@...cinc.com>
To:     Tom Zanussi <zanussi@...nel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Ingo Molnar <mingo@...hat.com>
CC:     <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 1/3] tracing: eprobe: remove duplicate is_good_name()
 operation

hi Tom,

On 6/14/2022 5:01 AM, Tom Zanussi wrote:
> Hi Linhu,
>
> On Thu, 2022-06-02 at 20:10 +0800, Linyu Yuan wrote:
>> traceprobe_parse_event_name() already validate group and event name,
>> there is no need to call is_good_name() after it.
>>
>> Signed-off-by: Linyu Yuan <quic_linyyuan@...cinc.com>
>> ---
>> v2: drop v1 change as it is NACK.
>>      add it to remove duplicate is_good_name().
>> v3: move it as first patch.
>> v4: no change
>>
>>   kernel/trace/trace_eprobe.c | 4 ----
>>   1 file changed, 4 deletions(-)
>>
>> diff --git a/kernel/trace/trace_eprobe.c
>> b/kernel/trace/trace_eprobe.c
>> index 7d44785..17d64e3 100644
>> --- a/kernel/trace/trace_eprobe.c
>> +++ b/kernel/trace/trace_eprobe.c
>> @@ -878,16 +878,12 @@ static int __trace_eprobe_create(int argc,
>> const char *argv[])
>>                  sanitize_event_name(buf1);
>>                  event = buf1;
>>          }
>> -       if (!is_good_name(event) || !is_good_name(group))
>> -               goto parse_error;
> traceprobe_parse_event_name() is only called if (event).  In the
> !event case, wouldn't the is_good_name() checks still be needed (since
> in that case buf1 is assigned to event)?

when user input no  event name, it will generate event name from second  
SYSTEM.EVENT,

and it will validate with following traceprobe_parse_event_name().


(

if you agree, i will send a new version to update a minor issue in 
second patch,


         sys_event = argv[1];
-       ret = traceprobe_parse_event_name(&sys_event, &sys_name, buf2,
-                                         sys_event - argv[1]);
-       if (ret || !sys_name)
+       ret = traceprobe_parse_event_name(&sys_event, &sys_name, buf2, 0);
+       if (!sys_event || !sys_name)
                 goto parse_error;

)

>
>>   
>>          sys_event = argv[1];
>>          ret = traceprobe_parse_event_name(&sys_event, &sys_name,
>> buf2,
>>                                            sys_event - argv[1]);
>>          if (ret || !sys_name)
>>                  goto parse_error;
>> -       if (!is_good_name(sys_event) || !is_good_name(sys_name))
>> -               goto parse_error;
> I agree this one isn't needed.
>
> Thanks,
>
> Tom
>
>>   
>>          mutex_lock(&event_mutex);
>>          event_call = find_and_get_event(sys_name, sys_event);