linux-kernel - Re: [PATCH 2/3] tracing: Don't return -EINVAL when tracing soft disabled synth events

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Date:   Wed, 12 Feb 2020 12:24:15 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Tom Zanussi <zanussi@...nel.org>
Cc:     rostedt@...dmis.org, artem.bityutskiy@...ux.intel.com,
        mhiramat@...nel.org, linux-kernel@...r.kernel.org,
        linux-rt-users@...r.kernel.org
Subject: Re: [PATCH 2/3] tracing: Don't return -EINVAL when tracing soft
 disabled synth events

On Mon, 10 Feb 2020 17:06:49 -0600
Tom Zanussi <zanussi@...nel.org> wrote:

> There's no reason to return -EINVAL when tracing a synthetic event if
> it's soft disabled - treat it the same as if it were hard disabled and
> return normally.
> 
> Have synth_event_trace() and synth_event_trace_array() just return
> normally, and have synth_event_trace_start set the trace state to
> disabled and return.
> 

Looks good to me.

Reviewed-by: Masami Hiramatsu <mhiramat@...nel.org>

Thanks,

> Signed-off-by: Tom Zanussi <zanussi@...nel.org>
> ---
>  kernel/trace/trace_events_hist.c | 20 ++++++--------------
>  1 file changed, 6 insertions(+), 14 deletions(-)
> 
> diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
> index a546ffa14785..99a02168599b 100644
> --- a/kernel/trace/trace_events_hist.c
> +++ b/kernel/trace/trace_events_hist.c
> @@ -1828,7 +1828,8 @@ int synth_event_trace(struct trace_event_file *file, unsigned int n_vals, ...)
>  	 * called directly by the user, we don't have that but we
>  	 * still need to honor not logging when disabled.
>  	 */
> -	if (!(file->flags & EVENT_FILE_FL_ENABLED))
> +	if (!(file->flags & EVENT_FILE_FL_ENABLED) ||
> +	    trace_trigger_soft_disabled(file))
>  		return 0;
>  
>  	event = file->event_call->data;
> @@ -1836,9 +1837,6 @@ int synth_event_trace(struct trace_event_file *file, unsigned int n_vals, ...)
>  	if (n_vals != event->n_fields)
>  		return -EINVAL;
>  
> -	if (trace_trigger_soft_disabled(file))
> -		return -EINVAL;
> -
>  	fields_size = event->n_u64 * sizeof(u64);
>  
>  	/*
> @@ -1918,7 +1916,8 @@ int synth_event_trace_array(struct trace_event_file *file, u64 *vals,
>  	 * called directly by the user, we don't have that but we
>  	 * still need to honor not logging when disabled.
>  	 */
> -	if (!(file->flags & EVENT_FILE_FL_ENABLED))
> +	if (!(file->flags & EVENT_FILE_FL_ENABLED) ||
> +	    trace_trigger_soft_disabled(file))
>  		return 0;
>  
>  	event = file->event_call->data;
> @@ -1926,9 +1925,6 @@ int synth_event_trace_array(struct trace_event_file *file, u64 *vals,
>  	if (n_vals != event->n_fields)
>  		return -EINVAL;
>  
> -	if (trace_trigger_soft_disabled(file))
> -		return -EINVAL;
> -
>  	fields_size = event->n_u64 * sizeof(u64);
>  
>  	/*
> @@ -2017,7 +2013,8 @@ int synth_event_trace_start(struct trace_event_file *file,
>  	 * trace case, we save the enabed state upon start and just
>  	 * ignore the following data calls.
>  	 */
> -	if (!(file->flags & EVENT_FILE_FL_ENABLED)) {
> +	if (!(file->flags & EVENT_FILE_FL_ENABLED) ||
> +	    trace_trigger_soft_disabled(file)) {
>  		trace_state->enabled = false;
>  		goto out;
>  	}
> @@ -2026,11 +2023,6 @@ int synth_event_trace_start(struct trace_event_file *file,
>  
>  	trace_state->event = file->event_call->data;
>  
> -	if (trace_trigger_soft_disabled(file)) {
> -		ret = -EINVAL;
> -		goto out;
> -	}
> -
>  	fields_size = trace_state->event->n_u64 * sizeof(u64);
>  
>  	/*
> -- 
> 2.14.1
> 


-- 
Masami Hiramatsu <mhiramat@...nel.org>