Re: [PATCH v2] tracing: fix missing osnoise tracer on max_latency

[Daniel Bristot de Oliveira]

On 9/22/21 4:51 AM, Jackie Liu wrote:
> From: Jackie Liu <liuyun01@xxxxxxxxxx>
> 
> The compiler warns when the data are actually unused:
> 
>   kernel/trace/trace.c:1712:13: error: ‘trace_create_maxlat_file’ defined but not used [-Werror=unused-function]
>    1712 | static void trace_create_maxlat_file(struct trace_array *tr,
>         |             ^~~~~~~~~~~~~~~~~~~~~~~~
> 
> [Why]
> CONFIG_HWLAT_TRACER=n, CONFIG_TRACER_MAX_TRACE=n, CONFIG_OSNOISE_TRACER=y
> gcc report warns.
> 
> [How]
> Now trace_create_maxlat_file will only take effect when
> CONFIG_HWLAT_TRACER=y or CONFIG_TRACER_MAX_TRACE=y. In fact, after
> adding osnoise trace, it also needs to take effect.
> 
> Fixes: bce29ac9ce0b ("trace: Add osnoise tracer")
> Cc: Daniel Bristot de Oliveira <bristot@xxxxxxxxxx>

Reviewed-by: Daniel Bristot de Oliveira <bristot@xxxxxxxxxx>

Thanks!
-- Daniel
> Suggested-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
> Signed-off-by: Jackie Liu <liuyun01@xxxxxxxxxx>
> ---
>  kernel/trace/trace.c | 11 ++++-------
>  1 file changed, 4 insertions(+), 7 deletions(-)
> 
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index 7896d30d90f7..bc677cd64224 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -1744,16 +1744,15 @@ 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(CONFIG_TRACER_MAX_TRACE) || defined(CONFIG_HWLAT_TRACER)	\
> +	|| defined(CONFIG_OSNOISE_TRACER)
>  
>  #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 +9472,7 @@ 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");
>