linux-kernel - Re: [PATCH] tracing: fix missing osnoise tracer on max

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Date:   Wed, 22 Sep 2021 10:45:21 +0800
From:   Jackie Liu <liu.yun@...ux.dev>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     mingo@...hat.com, linux-kernel@...r.kernel.org, bristot@...hat.com
Subject: Re: [PATCH] tracing: fix missing osnoise tracer on max_latency



在 2021/9/22 上午10:40, Steven Rostedt 写道:
> On Wed, 22 Sep 2021 10:26:24 +0800
> Jackie Liu <liu.yun@...ux.dev> wrote:
> 
>>>> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
>>>> index 7896d30d90f7..d7e3ed82fafd 100644
>>>> --- a/kernel/trace/trace.c
>>>> +++ b/kernel/trace/trace.c
>>>> @@ -1744,11 +1744,7 @@ void latency_fsnotify(struct trace_array *tr)
>>>>    	irq_work_queue(&tr->fsnotify_irqwork);
>>>>    }
>>>>    
>>>> -/*
>>>> - * (defined(CONFIG_TRACER_MAX_TRACE) || defined(CONFIG_HWLAT_TRACER)) && \
>>>> - *  defined(CONFIG_FSNOTIFY)
>>>> - */
>>>> -#else
>>>> +#else /* LATENCY_FS_NOTIFY  >>
>>>>    #define trace_create_maxlat_file(tr, d_tracer)				\
>>>>    	trace_create_file("tracing_max_latency", 0644, d_tracer,	\
>>>
>>> To clean this up even better, we should add here:
>>>
>>> #elif defined(CONFIG_TRACER_MAX_TRACE) || defined(CONFIG_HWLAT_TRACER) \
>>> 	|| defined(CONFIG_OSNOISE_TRACER)
>>
>> This place should need to use LATENCY_FS_NOTIFY, because not only these
>> three Traces, we also need to pay attention to CONFIG_FSNOTIFY, at
>> least, we should not change the original meaning.
>>
>> How about this:
>>
>> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
>> index 7896d30d90f7..6a88d03c6d3b 100644
>> --- a/kernel/trace/trace.c
>> +++ b/kernel/trace/trace.c
>> @@ -1744,16 +1744,14 @@ void latency_fsnotify(struct trace_array *tr)
>>           irq_work_queue(&tr->fsnotify_irqwork);
>>    }
>>
>> -/*
>> - * (defined(CONFIG_TRACER_MAX_TRACE) || defined(CONFIG_HWLAT_TRACER)) && \
>> - *  defined(CONFIG_FSNOTIFY)
>> - */
>> -#else
>> +#elif defined(LATENCY_FS_NOTIFY)
> 
> Um, but isn't the #if before the #else:
> 
>    #ifdef LATENCY_FS_NOTIFY
> 
> ?
> 
> Then, here we have:
> 
> 
> #ifdef LATENCY_FS_NOTIFY
> 
> [..]
> 
> #elif defined(LATENCY_FS_NOTIFY)
> 
> // this will never be called.
> 
> That doesn't make any sense.
> 
> -- Steve

Thanks Steve, I see.  :)

-- 
BR, Jackie Liu

> 
>>
>>    #define trace_create_maxlat_file(tr, d_tracer)                         \
>>           trace_create_file("tracing_max_latency", 0644, d_tracer,        \
>>                             &tr->max_latency, &tracing_max_lat_fops)
>>
>> +#else
>> +#define trace_create_maxlat_file(tr, d_tracer)  do { } while (0)
>>    #endif
>>
>>    #ifdef CONFIG_TRACER_MAX_TRACE
>> @@ -9473,9 +9471,7 @@ init_tracer_tracefs(struct trace_array *tr, struct
>> dentry *d_tracer)
>>
>>           create_trace_options_dir(tr);
>>
>> -#if defined(CONFIG_TRACER_MAX_TRACE) || defined(CONFIG_HWLAT_TRACER)
>>           trace_create_maxlat_file(tr, d_tracer);
>> -#endif
>>
>>           if (ftrace_create_function_files(tr, d_tracer))
>>                   MEM_FAIL(1, "Could not allocate function filter files");
>>
>>
>> ==
>> What do you think? If there is no problem, I will send V2.
>>