perf test pmu: Test all sysfs PMU event names are the same case

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

For the majority of PMUs event names are all lower case, upper case
names are present on S390.

Reviewed-by: Kan Liang <[e-mail]>
Signed-off-by: Ian Rogers <[e-mail]>
Cc: Alexander Shishkin <[e-mail]>
Cc: Bjorn Helgaas <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: James Clark <[e-mail]>
Cc: Jing Zhang <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Jonathan Corbet <[e-mail]>
Cc: Mark Rutland <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Randy Dunlap <[e-mail]>
Cc: Ravi Bangoria <[e-mail]>
Cc: Thomas Richter <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/tests/pmu.c

···
 #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);
···
 	return ret;
 }
 
+static bool permitted_event_name(const char *name)
+{
+	bool has_lower = false, has_upper = false;
+
+	for (size_t i = 0; i < strlen(name); i++) {
+		char c = name[i];
+
+		if (islower(c)) {
+			if (has_upper)
+				return false;
+			has_lower = true;
+			continue;
+		}
+		if (isupper(c)) {
+			if (has_lower)
+				return false;
+			has_upper = true;
+			continue;
+		}
+		if (!isdigit(c) && c != '.' && c != '_' && c != '-')
+			return false;
+	}
+	return true;
+}
+
+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("Skipping as 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;
+
+			if (!permitted_event_name(event_name)) {
+				pr_err("Invalid sysfs event name: %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, }
 };