selftests/pidfd: third test for multi-threaded exec polling

	EXPECT_EQ(close(pidfd_thread), 0);

}

static void *pidfd_info_thread_exec_sane(void *arg)

{

	pid_t pid_thread = gettid();

	int ipc_socket = *(int *)arg;

	/* Inform the grand-parent what the tid of this thread is. */

	if (write_nointr(ipc_socket, &pid_thread, sizeof(pid_thread)) != sizeof(pid_thread))

		return NULL;

	if (read_nointr(ipc_socket, &pid_thread, sizeof(pid_thread)) != sizeof(pid_thread))

		return NULL;

	close(ipc_socket);

	sys_execveat(AT_FDCWD, "pidfd_exec_helper", NULL, NULL, 0);

	return NULL;

}

TEST_F(pidfd_info, thread_group_exec_thread)

{

	pid_t pid_leader, pid_poller, pid_thread;

	pthread_t thread;

	int nevents, pidfd_leader, pidfd_leader_thread, pidfd_thread, ret;

	int ipc_sockets[2];

	struct pollfd fds = {};

	struct pidfd_info info = {

		.mask = PIDFD_INFO_CGROUPID | PIDFD_INFO_EXIT,

	};

	ret = socketpair(AF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0, ipc_sockets);

	EXPECT_EQ(ret, 0);

	pid_leader = create_child(&pidfd_leader, 0);

	EXPECT_GE(pid_leader, 0);

	if (pid_leader == 0) {

		close(ipc_sockets[0]);

		/* The thread will outlive the thread-group leader. */

		if (pthread_create(&thread, NULL, pidfd_info_thread_exec_sane, &ipc_sockets[1]))

			syscall(__NR_exit, EXIT_FAILURE);

		/*

		 * Pause the thread-group leader. It will be killed once

		 * the subthread execs.

		 */

		pause();

		syscall(__NR_exit, EXIT_SUCCESS);

	}

	/* Retrieve the tid of the thread. */

	EXPECT_EQ(close(ipc_sockets[1]), 0);

	ASSERT_EQ(read_nointr(ipc_sockets[0], &pid_thread, sizeof(pid_thread)), sizeof(pid_thread));

	/* Opening a thread as a PIDFD_THREAD must succeed. */

	pidfd_thread = sys_pidfd_open(pid_thread, PIDFD_THREAD);

	ASSERT_GE(pidfd_thread, 0);

	/* Open a thread-specific pidfd for the thread-group leader. */

	pidfd_leader_thread = sys_pidfd_open(pid_leader, PIDFD_THREAD);

	ASSERT_GE(pidfd_leader_thread, 0);

	pid_poller = fork();

	ASSERT_GE(pid_poller, 0);

	if (pid_poller == 0) {

		/*

		 * The subthread will now exec. The struct pid of the old

		 * thread-group leader will be assumed by the subthread which

		 * becomes the new thread-group leader. So no exit notification

		 * must be generated. Wait for 5 seconds and call it a success

		 * if no notification has been received.

		 */

		fds.events = POLLIN;

		fds.fd = pidfd_leader_thread;

		nevents = poll(&fds, 1, 10000 /* wait 5 seconds */);

		if (nevents != 0)

			_exit(EXIT_FAILURE);

		if (fds.revents & POLLIN)

			_exit(EXIT_FAILURE);

		if (fds.revents & POLLHUP)

			_exit(EXIT_FAILURE);

		_exit(EXIT_SUCCESS);

	}

	/* Now that we've opened a thread-specific pidfd the thread can exec. */

	ASSERT_EQ(write_nointr(ipc_sockets[0], &pid_thread, sizeof(pid_thread)), sizeof(pid_thread));

	EXPECT_EQ(close(ipc_sockets[0]), 0);

	ASSERT_EQ(wait_for_pid(pid_poller), 0);

	/* Wait until the kernel has SIGKILLed the thread. */

	fds.events = POLLHUP;

	fds.fd = pidfd_thread;

	nevents = poll(&fds, 1, -1);

	ASSERT_EQ(nevents, 1);

	/* The thread has been reaped. */

	ASSERT_TRUE(!!(fds.revents & POLLHUP));

	/* Retrieve thread-specific exit info from pidfd. */

	ASSERT_EQ(ioctl(pidfd_thread, PIDFD_GET_INFO, &info), 0);

	ASSERT_FALSE(!!(info.mask & PIDFD_INFO_CREDS));

	ASSERT_TRUE(!!(info.mask & PIDFD_INFO_EXIT));

	/*

	 * While the kernel will have SIGKILLed the whole thread-group

	 * during exec it will cause the individual threads to exit

	 * cleanly.

	 */

	ASSERT_TRUE(WIFEXITED(info.exit_code));

	ASSERT_EQ(WEXITSTATUS(info.exit_code), 0);

	/*

	 * The thread-group leader is still alive, the thread has taken

	 * over its struct pid and thus its pid number.

	 */

	info.mask = PIDFD_INFO_CGROUPID | PIDFD_INFO_EXIT;

	ASSERT_EQ(ioctl(pidfd_leader, PIDFD_GET_INFO, &info), 0);

	ASSERT_TRUE(!!(info.mask & PIDFD_INFO_CREDS));

	ASSERT_FALSE(!!(info.mask & PIDFD_INFO_EXIT));

	ASSERT_EQ(info.pid, pid_leader);

	/* Take down the thread-group leader. */

	EXPECT_EQ(sys_pidfd_send_signal(pidfd_leader, SIGKILL, NULL, 0), 0);

	/*

	 * Afte the exec we're dealing with an empty thread-group so now

	 * we must see an exit notification on the thread-specific pidfd

	 * for the thread-group leader as there's no subthread that can

	 * revive the struct pid.

	 */

	fds.events = POLLIN;

	fds.fd = pidfd_leader_thread;

	nevents = poll(&fds, 1, -1);

	ASSERT_EQ(nevents, 1);

	ASSERT_TRUE(!!(fds.revents & POLLIN));

	ASSERT_FALSE(!!(fds.revents & POLLHUP));

	EXPECT_EQ(sys_waitid(P_PIDFD, pidfd_leader, NULL, WEXITED), 0);

	/* Retrieve exit information for the thread-group leader. */

	info.mask = PIDFD_INFO_CGROUPID | PIDFD_INFO_EXIT;

	ASSERT_EQ(ioctl(pidfd_leader, PIDFD_GET_INFO, &info), 0);

	ASSERT_FALSE(!!(info.mask & PIDFD_INFO_CREDS));

	ASSERT_TRUE(!!(info.mask & PIDFD_INFO_EXIT));

	EXPECT_EQ(close(pidfd_leader), 0);

	EXPECT_EQ(close(pidfd_thread), 0);

}

TEST_HARNESS_MAIN