linux-kernel - Re: [PATCH] perf tools: Fix parser for empty pmu terms case

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Date:   Mon, 7 May 2018 10:12:03 +0200
From:   Jiri Olsa <jolsa@...hat.com>
To:     Adrian Hunter <adrian.hunter@...el.com>
Cc:     Andi Kleen <ak@...ux.intel.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Clark Williams <williams@...hat.com>,
        linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        Jiri Olsa <jolsa@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        David Ahern <dsahern@...il.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        kan.liang@...ux.intel.com
Subject: Re: [PATCH] perf tools: Fix parser for empty pmu terms case

On Mon, May 07, 2018 at 10:21:42AM +0300, Adrian Hunter wrote:
> On 06/05/18 17:28, Jiri Olsa wrote:
> > On Sat, May 05, 2018 at 08:43:11PM -0700, Andi Kleen wrote:
> >> Jiri Olsa <jolsa@...hat.com> writes:
> >>
> >> Please fix this quickly, PT is currently totally non functional in Linus
> >> mainline.
> > 
> > attached.. Kan, could you please test it wrt your latest changes?
> > 
> > thanks,
> > jirka
> > 
> > 
> > ---
> > Adrian reported broken event parsing for Intel PT:
> > 
> >   $ perf record -e intel_pt//u uname
> >   event syntax error: 'intel_pt//u'
> >                                \___ parser error
> >   Run 'perf list' for a list of valid events
> > 
> > It's caused by recent change in parsing grammar
> > (see Fixes: for commit).
> > 
> > Adding special rule with empty terms config to handle
> > the reported case and moving the common rule code into
> > new parse_events_pmu function.
> 
> Hi
> 
> Can you explain why that is needed instead of just changing the grammar e.g.

well, for one, mine is working ;-)

[jolsa@...va perf]$ sudo ./perf record -e intel_pt//u uname
event syntax error: 'intel_pt//u'
                              \___ parser error
Run 'perf list' for a list of valid events

 Usage: perf record [<options>] [<command>]
    or: perf record [<options>] -- <command> [<options>]

    -e, --event <event>   event selector. use 'perf list' to list available events


but yep, it's better solution.. with extra changes like below

jirka


---
diff --git a/tools/perf/util/parse-events.y b/tools/perf/util/parse-events.y
index 47f6399a309a..155d2570274f 100644
--- a/tools/perf/util/parse-events.y
+++ b/tools/perf/util/parse-events.y
@@ -73,6 +73,7 @@ static void inc_group_count(struct list_head *list,
 %type <num> value_sym
 %type <head> event_config
 %type <head> opt_event_config
+%type <head> opt_pmu_config
 %type <term> event_term
 %type <head> event_pmu
 %type <head> event_legacy_symbol
@@ -224,15 +225,15 @@ event_def: event_pmu |
 	   event_bpf_file
 
 event_pmu:
-PE_NAME '/' event_config '/'
+PE_NAME opt_pmu_config
 {
 	struct list_head *list, *orig_terms, *terms;
 
-	if (parse_events_copy_term_list($3, &orig_terms))
+	if (parse_events_copy_term_list($2, &orig_terms))
 		YYABORT;
 
 	ALLOC_LIST(list);
-	if (parse_events_add_pmu(_parse_state, list, $1, $3, false, false)) {
+	if (parse_events_add_pmu(_parse_state, list, $1, $2, false, false)) {
 		struct perf_pmu *pmu = NULL;
 		int ok = 0;
 		char *pattern;
@@ -262,7 +263,7 @@ PE_NAME '/' event_config '/'
 		if (!ok)
 			YYABORT;
 	}
-	parse_events_terms__delete($3);
+	parse_events_terms__delete($2);
 	parse_events_terms__delete(orig_terms);
 	$$ = list;
 }
@@ -496,6 +497,17 @@ opt_event_config:
 	$$ = NULL;
 }
 
+opt_pmu_config:
+'/' event_config '/'
+{
+	$$ = $2;
+}
+|
+'/' '/'
+{
+	$$ = NULL;
+}
+
 start_terms: event_config
 {
 	struct parse_events_state *parse_state = _parse_state;