linux-kernel - [PATCH 1/4] perf pmu: Add function to check if a pmu file exists

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Date:   Wed,  4 May 2022 16:02:12 +0100
From:   German Gomez <german.gomez@....com>
To:     linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        acme@...nel.org
Cc:     German Gomez <german.gomez@....com>,
        Mike Leach <mike.leach@...aro.org>,
        Leo Yan <leo.yan@...aro.org>,
        John Garry <john.garry@...wei.com>,
        Will Deacon <will@...nel.org>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>, coresight@...ts.linaro.org,
        linux-arm-kernel@...ts.infradead.org
Subject: [PATCH 1/4] perf pmu: Add function to check if a pmu file exists

Add a utility function perf_pmu__file_exists() to check if a given pmu
file exists in the sysfs filesystem.

Signed-off-by: German Gomez <german.gomez@....com>
---
 tools/perf/util/pmu.c | 17 +++++++++++++++++
 tools/perf/util/pmu.h |  2 ++
 2 files changed, 19 insertions(+)

diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index 9a1c7e63e663..9479e9a4da54 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -1854,6 +1854,23 @@ int perf_pmu__scan_file(struct perf_pmu *pmu, const char *name, const char *fmt,
 	return ret;
 }
 
+bool perf_pmu__file_exists(struct perf_pmu *pmu, const char *name)
+{
+	char path[PATH_MAX];
+	struct stat statbuf;
+	const char *sysfs = sysfs__mountpoint();
+
+	if (!sysfs)
+		return false;
+
+	snprintf(path, PATH_MAX,
+		 "%s" EVENT_SOURCE_DEVICE_PATH "%s/%s", sysfs, pmu->name, name);
+	if (!file_available(path))
+		return false;
+
+	return stat(path, &statbuf) == 0;
+}
+
 static int perf_pmu__new_caps(struct list_head *list, char *name, char *value)
 {
 	struct perf_pmu_caps *caps = zalloc(sizeof(*caps));
diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h
index 541889fa9f9c..ab728eaf13b6 100644
--- a/tools/perf/util/pmu.h
+++ b/tools/perf/util/pmu.h
@@ -120,6 +120,8 @@ bool pmu_have_event(const char *pname, const char *name);
 
 int perf_pmu__scan_file(struct perf_pmu *pmu, const char *name, const char *fmt, ...) __scanf(3, 4);
 
+bool perf_pmu__file_exists(struct perf_pmu *pmu, const char *name);
+
 int perf_pmu__test(void);
 
 struct perf_event_attr *perf_pmu__get_default_config(struct perf_pmu *pmu);
-- 
2.25.1