linux-kernel - [PATCH 4/5] tracing/user_events: Add self-test for auto-del flag

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Message-Id: <20230530235304.2726-5-beaub@linux.microsoft.com>
Date:   Tue, 30 May 2023 16:53:03 -0700
From:   Beau Belgrave <beaub@...ux.microsoft.com>
To:     rostedt@...dmis.org, mhiramat@...nel.org
Cc:     linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org,
        ast@...nel.org, dcook@...ux.microsoft.com
Subject: [PATCH 4/5] tracing/user_events: Add self-test for auto-del flag

A new flag for auto-deleting user_events upon the last reference exists
now. We must ensure this flag works correctly in the common cases.

Update abi self test to ensure when this flag is used the user_event
goes away at the appropriate time. Ensure last fd, enabler, and
trace_event_call refs paths correctly delete the event.

Signed-off-by: Beau Belgrave <beaub@...ux.microsoft.com>
---
 .../testing/selftests/user_events/abi_test.c  | 115 ++++++++++++++++--
 1 file changed, 107 insertions(+), 8 deletions(-)

diff --git a/tools/testing/selftests/user_events/abi_test.c b/tools/testing/selftests/user_events/abi_test.c
index 5125c42efe65..9c726616f763 100644
--- a/tools/testing/selftests/user_events/abi_test.c
+++ b/tools/testing/selftests/user_events/abi_test.c
@@ -22,10 +22,41 @@
 
 const char *data_file = "/sys/kernel/tracing/user_events_data";
 const char *enable_file = "/sys/kernel/tracing/events/user_events/__abi_event/enable";
+const char *temp_enable_file = "/sys/kernel/tracing/events/user_events/__abi_temp_event/enable";
 
-static int change_event(bool enable)
+static bool temp_exists(int grace_ms)
+{
+	int fd;
+
+	usleep(grace_ms * 1000);
+
+	fd = open(temp_enable_file, O_RDONLY);
+
+	if (fd == -1)
+		return false;
+
+	close(fd);
+
+	return true;
+}
+
+static int clear_temp(void)
+{
+	int fd = open(data_file, O_RDWR);
+	int ret = 0;
+
+	if (ioctl(fd, DIAG_IOCSDEL, "__abi_temp_event") == -1)
+		if (errno != ENOENT)
+			ret = -1;
+
+	close(fd);
+
+	return ret;
+}
+
+static int __change_event(const char *path, bool enable)
 {
-	int fd = open(enable_file, O_RDWR);
+	int fd = open(path, O_RDWR);
 	int ret;
 
 	if (fd < 0)
@@ -46,22 +77,48 @@ static int change_event(bool enable)
 	return ret;
 }
 
-static int reg_enable(long *enable, int size, int bit)
+static int change_temp_event(bool enable)
+{
+	return __change_event(temp_enable_file, enable);
+}
+
+static int change_event(bool enable)
+{
+	return __change_event(enable_file, enable);
+}
+
+static int __reg_enable(int *fd, const char *name, long *enable, int size,
+			int bit, int flags)
 {
 	struct user_reg reg = {0};
-	int fd = open(data_file, O_RDWR);
-	int ret;
 
-	if (fd < 0)
+	*fd = open(data_file, O_RDWR);
+
+	if (*fd < 0)
 		return -1;
 
 	reg.size = sizeof(reg);
-	reg.name_args = (__u64)"__abi_event";
+	reg.name_args = (__u64)name;
 	reg.enable_bit = bit;
 	reg.enable_addr = (__u64)enable;
 	reg.enable_size = size;
+	reg.flags = flags;
+
+	return ioctl(*fd, DIAG_IOCSREG, &reg);
+}
 
-	ret = ioctl(fd, DIAG_IOCSREG, &reg);
+static int reg_enable_temp(int *fd, long *enable, int size, int bit)
+{
+	return __reg_enable(fd, "__abi_temp_event", enable, size, bit,
+			    USER_EVENT_REG_AUTO_DEL);
+}
+
+static int reg_enable(long *enable, int size, int bit)
+{
+	int ret;
+	int fd;
+
+	ret = __reg_enable(&fd, "__abi_event", enable, size, bit, 0);
 
 	close(fd);
 
@@ -98,6 +155,7 @@ FIXTURE_SETUP(user) {
 }
 
 FIXTURE_TEARDOWN(user) {
+	clear_temp();
 }
 
 TEST_F(user, enablement) {
@@ -223,6 +281,47 @@ TEST_F(user, clones) {
 	ASSERT_EQ(0, change_event(false));
 }
 
+TEST_F(user, flags) {
+	int grace = 100;
+	int fd;
+
+	/* FLAG: USER_EVENT_REG_AUTO_DEL */
+	/* Removal path 1, close on last fd ref */
+	ASSERT_EQ(0, clear_temp());
+	ASSERT_EQ(0, reg_enable_temp(&fd, &self->check, sizeof(int), 0));
+	ASSERT_EQ(0, reg_disable(&self->check, 0));
+	close(fd);
+	ASSERT_EQ(false, temp_exists(grace));
+
+	/* Removal path 2, close on last enabler */
+	ASSERT_EQ(0, clear_temp());
+	ASSERT_EQ(0, reg_enable_temp(&fd, &self->check, sizeof(int), 0));
+	close(fd);
+	ASSERT_EQ(true, temp_exists(grace));
+	ASSERT_EQ(0, reg_disable(&self->check, 0));
+	ASSERT_EQ(false, temp_exists(grace));
+
+	/* Removal path 3, close on last trace_event ref */
+	ASSERT_EQ(0, clear_temp());
+	ASSERT_EQ(0, reg_enable_temp(&fd, &self->check, sizeof(int), 0));
+	ASSERT_EQ(0, reg_disable(&self->check, 0));
+	ASSERT_EQ(0, change_temp_event(true));
+	close(fd);
+	ASSERT_EQ(true, temp_exists(grace));
+	ASSERT_EQ(0, change_temp_event(false));
+	ASSERT_EQ(false, temp_exists(grace));
+
+	/* FLAG: Non-ABI */
+	/* Unknown flags should fail with EINVAL */
+	ASSERT_EQ(-1, __reg_enable(&fd, "__abi_invalid_event", &self->check,
+				   sizeof(int), 0, USER_EVENT_REG_MAX));
+	ASSERT_EQ(EINVAL, errno);
+
+	ASSERT_EQ(-1, __reg_enable(&fd, "__abi_invalid_event", &self->check,
+				   sizeof(int), 0, USER_EVENT_REG_MAX + 1));
+	ASSERT_EQ(EINVAL, errno);
+}
+
 int main(int argc, char **argv)
 {
 	return test_harness_run(argc, argv);
-- 
2.25.1