[PATCH] perf, tools: Improve error messages for missing PMUs

[Andi Kleen]

From: Andi Kleen <ak@xxxxxxxxxxxxxxx>

When a PMU is missing print a better error message mentioning
the missing PMU.

% mkdir empty
% mount --bind empty /sys/devices/msr
% perf stat -M Summary true
event syntax error: '{inst_retired.any,cycles}:W,{cpu_clk_unhalted.thread}:W,{inst_retired.any}:W,{cpu_clk_unhalted.ref_tsc,msr/tsc/}:W,{fp_comp_ops_exe.sse_scalar..'
                     \___ Cannot find PMU `msr'. Missing kernel support?

It still cannot find the right column for aliases, but it's already a vast improvement.

v2: Check asprintf
Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
---
 tools/perf/util/metricgroup.c  |  2 +-
 tools/perf/util/parse-events.c | 18 ++++++++++++------
 tools/perf/util/parse-events.h |  3 +++
 3 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/tools/perf/util/metricgroup.c b/tools/perf/util/metricgroup.c
index 2d60114f1870..0794f02cbb8f 100644
--- a/tools/perf/util/metricgroup.c
+++ b/tools/perf/util/metricgroup.c
@@ -477,7 +477,7 @@ int metricgroup__parse_groups(const struct option *opt,
 	memset(&parse_error, 0, sizeof(struct parse_events_error));
 	ret = parse_events(perf_evlist, extra_events.buf, &parse_error);
 	if (ret) {
-		pr_err("Cannot set up events %s\n", extra_events.buf);
+                parse_events_print_error(&parse_error, extra_events.buf);
 		goto out;
 	}
 	strbuf_release(&extra_events);
diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index 97507d5c37dc..26c59a4009aa 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -1218,11 +1218,17 @@ int parse_events_add_pmu(struct parse_events_state *parse_state,
 	struct perf_pmu_info info;
 	struct perf_pmu *pmu;
 	struct perf_evsel *evsel;
+	struct parse_events_error *err = parse_state->error;
 	LIST_HEAD(config_terms);
 
 	pmu = perf_pmu__find(name);
-	if (!pmu)
+	if (!pmu) {
+		if (asprintf(&err->str,
+				"Cannot find PMU `%s'. Missing kernel support?",
+				name) < 0)
+			err->str = NULL;
 		return -EINVAL;
+	}
 
 	if (pmu->default_config) {
 		memcpy(&attr, pmu->default_config,
@@ -1725,8 +1731,8 @@ static int get_term_width(void)
 	return ws.ws_col > MAX_WIDTH ? MAX_WIDTH : ws.ws_col;
 }
 
-static void parse_events_print_error(struct parse_events_error *err,
-				     const char *event)
+void parse_events_print_error(struct parse_events_error *err,
+			      const char *event)
 {
 	const char *str = "invalid or unsupported event: ";
 	char _buf[MAX_WIDTH];
@@ -1781,8 +1787,6 @@ static void parse_events_print_error(struct parse_events_error *err,
 		zfree(&err->str);
 		zfree(&err->help);
 	}
-
-	fprintf(stderr, "Run 'perf list' for a list of valid events\n");
 }
 
 #undef MAX_WIDTH
@@ -1794,8 +1798,10 @@ int parse_events_option(const struct option *opt, const char *str,
 	struct parse_events_error err = { .idx = 0, };
 	int ret = parse_events(evlist, str, &err);
 
-	if (ret)
+	if (ret) {
 		parse_events_print_error(&err, str);
+		fprintf(stderr, "Run 'perf list' for a list of valid events\n");
+	}
 
 	return ret;
 }
diff --git a/tools/perf/util/parse-events.h b/tools/perf/util/parse-events.h
index 635135125111..3909ca0639f2 100644
--- a/tools/perf/util/parse-events.h
+++ b/tools/perf/util/parse-events.h
@@ -202,6 +202,9 @@ int is_valid_tracepoint(const char *event_string);
 int valid_event_mount(const char *eventfs);
 char *parse_events_formats_error_string(char *additional_terms);
 
+void parse_events_print_error(struct parse_events_error *err,
+			      const char *event);
+
 #ifdef HAVE_LIBELF_SUPPORT
 /*
  * If the probe point starts with '%',
-- 
2.9.5