selftests/user_events: Fix to unmount tracefs when test created mount

Fix to unmount tracefs if the self-test mounted it to allow testing.
If tracefs was already mounted, this does nothing.

Suggested-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/all/29fce076-746c-4650-8358-b4e0fa215cf7@sirena.org.uk/
Fixes: a06023a8f7 ("selftests/user_events: Fix failures when user_events is not installed")

Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

tools/testing/selftests/user_events/abi_test.c

@@ -91,16 +91,18 @@ static int reg_disable(long *enable, int bit)
 
 FIXTURE(user) {
 	long check;
+	bool umount;
 };
 
 FIXTURE_SETUP(user) {
-	USER_EVENT_FIXTURE_SETUP(return);
+	USER_EVENT_FIXTURE_SETUP(return, self->umount);
 
 	change_event(false);
 	self->check = 0;
 }
 
 FIXTURE_TEARDOWN(user) {
+	USER_EVENT_FIXTURE_TEARDOWN(self->umount);
 }
 
 TEST_F(user, enablement) {

tools/testing/selftests/user_events/dyn_test.c

@@ -144,13 +144,16 @@ do { \
 
 FIXTURE(user) {
 	int check;
+	bool umount;
 };
 
 FIXTURE_SETUP(user) {
-	USER_EVENT_FIXTURE_SETUP(return);
+	USER_EVENT_FIXTURE_SETUP(return, self->umount);
 }
 
 FIXTURE_TEARDOWN(user) {
+	USER_EVENT_FIXTURE_TEARDOWN(self->umount);
+
 	wait_for_delete();
 }
 

tools/testing/selftests/user_events/ftrace_test.c

@@ -204,10 +204,11 @@ FIXTURE(user) {
 	int data_fd;
 	int enable_fd;
 	int check;
+	bool umount;
 };
 
 FIXTURE_SETUP(user) {
-	USER_EVENT_FIXTURE_SETUP(return);
+	USER_EVENT_FIXTURE_SETUP(return, self->umount);
 
 	self->status_fd = open(status_file, O_RDONLY);
 	ASSERT_NE(-1, self->status_fd);
@@ -219,6 +220,8 @@ FIXTURE_SETUP(user) {
 }
 
 FIXTURE_TEARDOWN(user) {
+	USER_EVENT_FIXTURE_TEARDOWN(self->umount);
+
 	close(self->status_fd);
 	close(self->data_fd);
 

tools/testing/selftests/user_events/perf_test.c

@@ -111,16 +111,19 @@ static int clear(int *check)
 FIXTURE(user) {
 	int data_fd;
 	int check;
+	bool umount;
 };
 
 FIXTURE_SETUP(user) {
-	USER_EVENT_FIXTURE_SETUP(return);
+	USER_EVENT_FIXTURE_SETUP(return, self->umount);
 
 	self->data_fd = open(data_file, O_RDWR);
 	ASSERT_NE(-1, self->data_fd);
 }
 
 FIXTURE_TEARDOWN(user) {
+	USER_EVENT_FIXTURE_TEARDOWN(self->umount);
+
 	close(self->data_fd);
 
 	if (clear(&self->check) != 0)

tools/testing/selftests/user_events/user_events_selftests.h

@@ -11,13 +11,19 @@
 
 #include "../kselftest.h"
 
-static inline bool tracefs_enabled(char **message, bool *fail)
+static inline void tracefs_unmount(void)
+{
+	umount("/sys/kernel/tracing");
+}
+
+static inline bool tracefs_enabled(char **message, bool *fail, bool *umount)
 {
 	struct stat buf;
 	int ret;
 
 	*message = "";
 	*fail = false;
+	*umount = false;
 
 	/* Ensure tracefs is installed */
 	ret = stat("/sys/kernel/tracing", &buf);
@@ -37,6 +43,8 @@ static inline bool tracefs_enabled(char **message, bool *fail)
 			return false;
 		}
 
+		*umount = true;
+
 		ret = stat("/sys/kernel/tracing/README", &buf);
 	}
 
@@ -49,13 +57,14 @@ static inline bool tracefs_enabled(char **message, bool *fail)
 	return true;
 }
 
-static inline bool user_events_enabled(char **message, bool *fail)
+static inline bool user_events_enabled(char **message, bool *fail, bool *umount)
 {
 	struct stat buf;
 	int ret;
 
 	*message = "";
 	*fail = false;
+	*umount = false;
 
 	if (getuid() != 0) {
 		*message = "Must be run as root";
@@ -63,7 +72,7 @@ static inline bool user_events_enabled(char **message, bool *fail)
 		return false;
 	}
 
-	if (!tracefs_enabled(message, fail))
+	if (!tracefs_enabled(message, fail, umount))
 		return false;
 
 	/* Ensure user_events is installed */
@@ -85,10 +94,10 @@ static inline bool user_events_enabled(char **message, bool *fail)
 	return true;
 }
 
-#define USER_EVENT_FIXTURE_SETUP(statement) do { \
+#define USER_EVENT_FIXTURE_SETUP(statement, umount) do { \
 	char *message; \
 	bool fail; \
-	if (!user_events_enabled(&message, &fail)) { \
+	if (!user_events_enabled(&message, &fail, &(umount))) { \
 		if (fail) { \
 			TH_LOG("Setup failed due to: %s", message); \
 			ASSERT_FALSE(fail); \
@@ -97,4 +106,9 @@ static inline bool user_events_enabled(char **message, bool *fail)
 	} \
 } while (0)
 
+#define USER_EVENT_FIXTURE_TEARDOWN(umount) do { \
+	if ((umount))  \
+		tracefs_unmount(); \
+} while (0)
+
 #endif /* _USER_EVENTS_SELFTESTS_H */