Re: [PATCH v3 03/10] cxl: add common function to enable event trace

[Steven Rostedt <rostedt@goodmis.org>]

On Wed, 02 Nov 2022 14:20:21 -0700
Dave Jiang <dave.jiang@intel.com> wrote:

> Add a common function for cxl command to enable event tracing for the
> instance created. The interested "systems" will be enabled for tracing
> as well.
> 
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
> ---
>  cxl/event_trace.c |   21 +++++++++++++++++++++
>  cxl/event_trace.h |    1 +
>  2 files changed, 22 insertions(+)
> 
> diff --git a/cxl/event_trace.c b/cxl/event_trace.c
> index cf63d2346f6e..d59e54c33df6 100644
> --- a/cxl/event_trace.c
> +++ b/cxl/event_trace.c
> @@ -200,3 +200,24 @@ int cxl_parse_events(struct tracefs_instance *inst, struct event_ctx *ectx)
>  	tep_free(tep);
>  	return rc;
>  }
> +
> +int cxl_event_tracing_enable(struct tracefs_instance *inst, const char *system)
> +{
> +	int rc;
> +	char *path;
> +
> +	rc = asprintf(&path, "events/%s/enable", system);
> +	if (rc == -1)
> +		return -errno;
> +
> +	rc = tracefs_instance_file_write(inst, path, "1");
> +	free(path);
> +	if (rc == -1)
> +		return -errno;

Latest libtracefs has:

	tracefs_event_enable(inst, system, NULL);

That enables all events for a system in the instance "inst".

-- Steve


> +
> +	if (tracefs_trace_is_on(inst))
> +		return 0;
> +
> +	tracefs_trace_on(inst);
> +	return 0;
> +}
> diff --git a/cxl/event_trace.h b/cxl/event_trace.h
> index 582882c1eb35..0258b8dc65a3 100644
> --- a/cxl/event_trace.h
> +++ b/cxl/event_trace.h
> @@ -20,5 +20,6 @@ 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);
>  
>  #endif
>