linux-kernel - Re: [PATCH 4/9] perf tools: Fix pmu events parsing rule

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Message-ID: <20180423142057.GC30324@kernel.org>
Date:   Mon, 23 Apr 2018 11:20:57 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Jiri Olsa <jolsa@...nel.org>
Cc:     lkml <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        David Ahern <dsahern@...il.com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: [PATCH 4/9] perf tools: Fix pmu events parsing rule

Em Mon, Apr 23, 2018 at 11:08:18AM +0200, Jiri Olsa escreveu:
> Currently all the event parsing fails end up
> in the event_pmu rule, and display misleading
> help like:
> 
>   $ perf stat -e inst kill
>   event syntax error: 'inst'
>                        \___ Cannot find PMU `inst'. Missing kernel support?
>   ...
> 
> The reason is that the event_pmu is too strong
> and match also single string. Changing it to
> force the '/' separators to be part of the rule,
> and getting the proper error now:
> 
>   $ perf stat -e inst kill
>   event syntax error: 'inst'
>                        \___ parser error
>   Run 'perf list' for a list of valid events

I added a Reported-by: Ingo after checking that that was the case in tha
private conversation we had, but I think this has to be further
improved: do we have enough context at this point to change that into:

   $ perf stat -e inst kill
   event syntax error: 'inst'
                        \___ unknown event
   Run 'perf list' for a list of valid events

Instead of the generic "parser error"? That "list of valid events" helps
tho, but if we're going to say something at that \___ MSG part...

- Arnaldo

>   ...
> 
> Link: http://lkml.kernel.org/n/tip-vgf5a8wk0eyayo7omvutwhqo@git.kernel.org
> Signed-off-by: Jiri Olsa <jolsa@...nel.org>
> ---
>  tools/perf/util/parse-events.y | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/tools/perf/util/parse-events.y b/tools/perf/util/parse-events.y
> index 7afeb80cc39e..d14464c42714 100644
> --- a/tools/perf/util/parse-events.y
> +++ b/tools/perf/util/parse-events.y
> @@ -224,15 +224,15 @@ event_def: event_pmu |
>  	   event_bpf_file
>  
>  event_pmu:
> -PE_NAME opt_event_config
> +PE_NAME '/' event_config '/'
>  {
>  	struct list_head *list, *orig_terms, *terms;
>  
> -	if (parse_events_copy_term_list($2, &orig_terms))
> +	if (parse_events_copy_term_list($3, &orig_terms))
>  		YYABORT;
>  
>  	ALLOC_LIST(list);
> -	if (parse_events_add_pmu(_parse_state, list, $1, $2, false)) {
> +	if (parse_events_add_pmu(_parse_state, list, $1, $3, false)) {
>  		struct perf_pmu *pmu = NULL;
>  		int ok = 0;
>  		char *pattern;
> @@ -262,7 +262,7 @@ PE_NAME opt_event_config
>  		if (!ok)
>  			YYABORT;
>  	}
> -	parse_events_terms__delete($2);
> +	parse_events_terms__delete($3);
>  	parse_events_terms__delete(orig_terms);
>  	$$ = list;
>  }
> -- 
> 2.13.6