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

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Date:   Tue, 21 Sep 2021 22:40:48 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Jackie Liu <liu.yun@...ux.dev>
Cc:     mingo@...hat.com, linux-kernel@...r.kernel.org, bristot@...hat.com
Subject: Re: [PATCH] tracing: fix missing osnoise tracer on max_latency

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

> 
>   #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.
>