Re: [PATCH v3 04/10] cxl: add common function to disable event trace

[Steven Rostedt <rostedt@goodmis.org>]

On Wed, 02 Nov 2022 14:20:26 -0700
Dave Jiang <dave.jiang@intel.com> wrote:

> Add a common function for cxl command that disables the event trace for the
> instance created.
> 
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
> ---
>  cxl/event_trace.c |    8 ++++++++
>  cxl/event_trace.h |    1 +
>  2 files changed, 9 insertions(+)
> 
> diff --git a/cxl/event_trace.c b/cxl/event_trace.c
> index d59e54c33df6..bcd4f8b2968e 100644
> --- a/cxl/event_trace.c
> +++ b/cxl/event_trace.c
> @@ -221,3 +221,11 @@ int cxl_event_tracing_enable(struct tracefs_instance *inst, const char *system)
>  	tracefs_trace_on(inst);
>  	return 0;
>  }
> +
> +int cxl_event_tracing_disable(struct tracefs_instance *inst)
> +{
> +	if (!tracefs_trace_is_on(inst))
> +		return 0;

Why bother checking if tracing is on or not. It's not any more
efficient. You're not eliminating a system call. You are actually
adding another one.

-- Steve


> +
> +	return tracefs_trace_off(inst);
> +}
> diff --git a/cxl/event_trace.h b/cxl/event_trace.h
> index 0258b8dc65a3..17d922f922c1 100644
> --- a/cxl/event_trace.h
> +++ b/cxl/event_trace.h
> @@ -21,5 +21,6 @@ struct event_ctx {
>  
>  int cxl_parse_events(struct tracefs_instance *inst, struct event_ctx *ectx);
>  int cxl_event_tracing_enable(struct tracefs_instance *inst, const char *system);
> +int cxl_event_tracing_disable(struct tracefs_instance *inst);
>  
>  #endif
>