Being lowercase means event name probes can avoid scanning the
directory doing case insensitive comparisons, just the lowercase
version of the name can be checked for existence.

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/tests/pmu.c | 75 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 75 insertions(+)

diff --git a/tools/perf/tests/pmu.c b/tools/perf/tests/pmu.c
index f4e9a39534cb..c49e790248cd 100644
--- a/tools/perf/tests/pmu.c
+++ b/tools/perf/tests/pmu.c
@@ -5,12 +5,17 @@
 #include "pmu.h"
 #include "tests.h"
 #include "debug.h"
+#include "fncache.h"
+#include <api/fs/fs.h>
+#include <ctype.h>
+#include <dirent.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
 #include <sys/stat.h>
+#include <sys/types.h>
 
 /* Fake PMUs created in temp directory. */
 static LIST_HEAD(test_pmus);
@@ -241,9 +246,79 @@ static int test__pmu_events(struct test_suite *test __maybe_unused, int subtest
 	return ret;
 }
 
+static bool permitted_event_name_char(char c)
+{
+	if (islower(c) || isdigit(c))
+		return true;
+
+	return c == '.' || c == '_' || c == '-';
+}
+
+static int test__pmu_event_names(struct test_suite *test __maybe_unused,
+				 int subtest __maybe_unused)
+{
+	char path[PATH_MAX];
+	DIR *pmu_dir, *event_dir;
+	struct dirent *pmu_dent, *event_dent;
+	const char *sysfs = sysfs__mountpoint();
+	int ret = TEST_OK;
+
+	if (!sysfs) {
+		pr_err("Sysfs not mounted\n");
+		return TEST_FAIL;
+	}
+
+	snprintf(path, sizeof(path), "%s/bus/event_source/devices/", sysfs);
+	pmu_dir = opendir(path);
+	if (!pmu_dir) {
+		pr_err("Error opening \"%s\"\n", path);
+		return TEST_FAIL;
+	}
+	while ((pmu_dent = readdir(pmu_dir))) {
+		if (!strcmp(pmu_dent->d_name, ".") ||
+		    !strcmp(pmu_dent->d_name, ".."))
+			continue;
+
+		snprintf(path, sizeof(path), "%s/bus/event_source/devices/%s/type",
+			 sysfs, pmu_dent->d_name);
+
+		/* Does it look like a PMU? */
+		if (!file_available(path))
+			continue;
+
+		/* Process events. */
+		snprintf(path, sizeof(path), "%s/bus/event_source/devices/%s/events",
+			 sysfs, pmu_dent->d_name);
+
+		event_dir = opendir(path);
+		if (!event_dir) {
+			pr_debug("No event directory \"%s\"\n", path);
+			continue;
+		}
+		while ((event_dent = readdir(event_dir))) {
+			const char *event_name = event_dent->d_name;
+
+			if (!strcmp(event_name, ".") || !strcmp(event_name, ".."))
+				continue;
+
+			for (size_t i = 0, n = strlen(event_name); i < n; i++) {
+				if (!permitted_event_name_char(event_name[i])) {
+					pr_err("Sysfs event names should be lower case \"%s/%s\"\n",
+						pmu_dent->d_name, event_name);
+					ret = TEST_FAIL;
+				}
+			}
+		}
+		closedir(event_dir);
+	}
+	closedir(pmu_dir);
+	return ret;
+}
+
 static struct test_case tests__pmu[] = {
 	TEST_CASE("Parsing with PMU format directory", pmu_format),
 	TEST_CASE("Parsing with PMU event", pmu_events),
+	TEST_CASE("PMU event names", pmu_event_names),
 	{	.name = NULL, }
 };
 
-- 
2.44.0.769.g3c40516874-goog