linux-kernel - [PATCH v1 3/4] perf evsel: Fix uniquification when PMU given without suffix

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Message-ID: <20250821221834.1312002-4-irogers@google.com>
Date: Thu, 21 Aug 2025 15:18:33 -0700
From: Ian Rogers <irogers@...gle.com>
To: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, 
	Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>, 
	Mark Rutland <mark.rutland@....com>, 
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>, 
	Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>, 
	Kan Liang <kan.liang@...ux.intel.com>, Chun-Tse Shao <ctshao@...gle.com>, 
	James Clark <james.clark@...aro.org>, Howard Chu <howardchu95@...il.com>, 
	linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org
Subject: [PATCH v1 3/4] perf evsel: Fix uniquification when PMU given without suffix

The PMU name is appearing twice in:
```
$ perf stat -e uncore_imc_free_running/data_total/ -A true

 Performance counter stats for 'system wide':

CPU0                 1.57 MiB  uncore_imc_free_running_0/uncore_imc_free_running,data_total/
CPU0                 1.58 MiB  uncore_imc_free_running_1/uncore_imc_free_running,data_total/
       0.000892376 seconds time elapsed
```

Use the pmu_name_len_no_suffix to avoid this problem.

Fixes: 7d45f402d311 ("perf evlist: Make uniquifying counter names consistent")
Signed-off-by: Ian Rogers <irogers@...gle.com>
---
 tools/perf/util/evsel.c | 28 ++++++++++++++++++----------
 1 file changed, 18 insertions(+), 10 deletions(-)

diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index d264c143b592..9a6e2d556d35 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -4048,9 +4048,9 @@ bool evsel__set_needs_uniquify(struct evsel *counter, const struct perf_stat_con
 
 void evsel__uniquify_counter(struct evsel *counter)
 {
-	const char *name, *pmu_name;
-	char *new_name, *config;
-	int ret;
+	const char *name, *pmu_name, *config;
+	char *new_name;
+	int len, ret;
 
 	/* No uniquification necessary. */
 	if (!counter->needs_uniquify)
@@ -4064,15 +4064,23 @@ void evsel__uniquify_counter(struct evsel *counter)
 	counter->uniquified_name = true;
 
 	name = evsel__name(counter);
+	config = strchr(name, '/');
 	pmu_name = counter->pmu->name;
-	/* Already prefixed by the PMU name. */
-	if (!strncmp(name, pmu_name, strlen(pmu_name)))
-		return;
 
-	config = strchr(name, '/');
-	if (config) {
-		int len = config - name;
+	/* Already prefixed by the PMU name? */
+	len = pmu_name_len_no_suffix(pmu_name);
+
+	if (!strncmp(name, pmu_name, len)) {
+		/*
+		 * If the PMU name is there, then there is no sense in not
+		 * having a slash. Do this for robustness.
+		 */
+		if (config == NULL)
+			config = name - 1;
 
+		ret = asprintf(&new_name, "%s/%s", pmu_name, config + 1);
+	} else if (config) {
+		len = config - name;
 		if (config[1] == '/') {
 			/* case: event// */
 			ret = asprintf(&new_name, "%s/%.*s/%s", pmu_name, len, name, config + 2);
@@ -4084,7 +4092,7 @@ void evsel__uniquify_counter(struct evsel *counter)
 		config = strchr(name, ':');
 		if (config) {
 			/* case: event:.. */
-			int len = config - name;
+			len = config - name;
 
 			ret = asprintf(&new_name, "%s/%.*s/%s", pmu_name, len, name, config + 1);
 		} else {
-- 
2.51.0.rc2.233.g662b1ed5c5-goog