[PATCH v2 2/4] perf tools: Prompt error message for wrong terms of hw/sw events

[He Kuang]

Prompt proper error message when wrong config terms is specificed for
hw/sw type perf events. This patch makes the original error prompt
function formats_error_string() more generic, which only outputs the
static config terms for hw/sw perf events, and prepends pmu formats
for pmu events.

Before this patch:

  $ perf record -e 'cpu-clock/freq=200/' -a sleep 1
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.028 MB perf.data (202 samples) ]

  $ perf record -e 'cpu-clock/freqx=200/' -a sleep 1
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.042 MB perf.data (506 samples) ]

After this patch:

  $ perf record -e 'cpu-clock/freqx=200/' -a sleep 1
  event syntax error: 'cpu-clock/freqx=200/'
                                 \___ unknown term

  valid terms: config,config1,config2,name,period,freq,branch_type,time,call-graph,stack-size

  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

Signed-off-by: He Kuang <hekuang@xxxxxxxxxx>
---
 tools/perf/util/parse-events.c | 26 ++++++++++++++++++++++++++
 tools/perf/util/parse-events.h |  1 +
 tools/perf/util/pmu.c          | 35 ++++++++++++-----------------------
 3 files changed, 39 insertions(+), 23 deletions(-)

diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index aa64cf3..f624b99 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -656,6 +656,9 @@ do {									   \
 		CHECK_TYPE_VAL(STR);
 		break;
 	default:
+		err->str = strdup("unknown term");
+		err->idx = term->err_term;
+		err->help = parse_events_formats_error_string(NULL);
 		return -EINVAL;
 	}
 
@@ -1875,3 +1878,26 @@ void parse_events_evlist_error(struct parse_events_evlist *data,
 	err->str = strdup(str);
 	WARN_ONCE(!err->str, "WARNING: failed to allocate error string");
 }
+
+char *parse_events_formats_error_string(char *additional_terms)
+{
+	char *str;
+	static const char *static_terms = "config,config1,config2,name,"
+					  "period,freq,branch_type,time,"
+					  "call-graph,stack-size\n";
+
+	/* valid terms */
+	if (additional_terms) {
+		if (!asprintf(&str, "valid terms: %s,%s",
+			      additional_terms, static_terms))
+			goto fail;
+		free(additional_terms);
+	} else {
+		if (!asprintf(&str, "valid terms: %s", static_terms))
+			goto fail;
+	}
+	return str;
+
+fail:
+	return NULL;
+}
diff --git a/tools/perf/util/parse-events.h b/tools/perf/util/parse-events.h
index ffee7ec..c7b904a 100644
--- a/tools/perf/util/parse-events.h
+++ b/tools/perf/util/parse-events.h
@@ -156,5 +156,6 @@ int print_hwcache_events(const char *event_glob, bool name_only);
 extern int is_valid_tracepoint(const char *event_string);
 
 int valid_event_mount(const char *eventfs);
+char *parse_events_formats_error_string(char *additional_terms);
 
 #endif /* __PERF_PARSE_EVENTS_H */
diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index 89c91a1..ea3dd04 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -626,38 +626,26 @@ static int pmu_resolve_param_term(struct parse_events_term *term,
 	return -1;
 }
 
-static char *formats_error_string(struct list_head *formats)
+static char *pmu_formats_string(struct list_head *formats)
 {
 	struct perf_pmu_format *format;
-	char *err, *str;
-	static const char *static_terms = "config,config1,config2,name,"
-					  "period,freq,branch_type,time,"
-					  "call-graph,stack-size\n";
+	char *str;
+	struct strbuf buf;
 	unsigned i = 0;
 
-	if (!asprintf(&str, "valid terms:"))
+	if (!formats)
 		return NULL;
 
+	strbuf_init(&buf, 0);
 	/* sysfs exported terms */
-	list_for_each_entry(format, formats, list) {
-		char c = i++ ? ',' : ' ';
-
-		err = str;
-		if (!asprintf(&str, "%s%c%s", err, c, format->name))
-			goto fail;
-		free(err);
-	}
+	list_for_each_entry(format, formats, list)
+		strbuf_addf(&buf, i++ ? ",%s" : "%s",
+			    format->name);
 
-	/* static terms */
-	err = str;
-	if (!asprintf(&str, "%s,%s", err, static_terms))
-		goto fail;
+	str = strbuf_detach(&buf, NULL);
+	strbuf_release(&buf);
 
-	free(err);
 	return str;
-fail:
-	free(err);
-	return NULL;
 }
 
 /*
@@ -695,7 +683,8 @@ static int pmu_config_term(struct list_head *formats,
 		if (err) {
 			err->idx  = term->err_term;
 			err->str  = strdup("unknown term");
-			err->help = formats_error_string(formats);
+			err->help = parse_events_formats_error_string(
+				pmu_formats_string(formats));
 		}
 		return -EINVAL;
 	}
-- 
1.8.5.2

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