Unverified Commit 1c4f2dbe authored by Christian Brauner's avatar Christian Brauner
Browse files

selftests/pidfd: add sixth PIDFD_INFO_EXIT selftest 

Add a selftest for PIDFD_INFO_EXIT behavior.

Link: https://lore.kernel.org/r/20250305-work-pidfs-kill_on_last_close-v3-15-c8c3d8361705@kernel.org


Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent 2adf6ca6

tools/testing/selftests/pidfd/pidfd.h

+4 −0
Original line number Diff line number Diff line
@@ -131,6 +131,10 @@ 
#define PIDFD_INFO_EXIT			(1UL << 3) /* Always returned if available, even if not requested */

#endif



#ifndef PIDFD_THREAD

#define PIDFD_THREAD O_EXCL

#endif



struct pidfd_info {

	__u64 mask;

	__u64 cgroupid;

tools/testing/selftests/pidfd/pidfd_info_test.c

+151 −0
Original line number Diff line number Diff line
@@ -218,4 +218,155 @@ TEST_F(pidfd_info, success_reaped_poll) 
	ASSERT_EQ(WTERMSIG(info.exit_code), SIGKILL);

}



static void *pidfd_info_pause_thread(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;



	close(ipc_socket);



	/* Sleep untill we're killed. */

	pause();

	return NULL;

}



TEST_F(pidfd_info, thread_group)

{

	pid_t pid_leader, pid_thread;

	pthread_t thread;

	int nevents, pidfd_leader, pidfd_thread, pidfd_leader_thread, ret;

	int ipc_sockets[2];

	struct pollfd fds = {};

	struct pidfd_info info = {

		.mask = PIDFD_INFO_CGROUPID | PIDFD_INFO_EXIT,

	}, info2;



	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_pause_thread, &ipc_sockets[1]))

			syscall(__NR_exit, EXIT_FAILURE);



		/* Make the thread-group leader exit prematurely. */

		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));

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



	/* Opening a thread as a thread-group leader must fail. */

	pidfd_thread = sys_pidfd_open(pid_thread, 0);

	ASSERT_LT(pidfd_thread, 0);



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

	pidfd_thread = sys_pidfd_open(pid_thread, PIDFD_THREAD);

	ASSERT_GE(pidfd_thread, 0);



	/*

	 * Opening a PIDFD_THREAD aka thread-specific pidfd based on a

	 * thread-group leader must succeed.

	 */

	pidfd_leader_thread = sys_pidfd_open(pid_leader, PIDFD_THREAD);

	ASSERT_GE(pidfd_leader_thread, 0);



	/*

	 * Note that pidfd_leader is a thread-group pidfd, so polling on it

	 * would only notify us once all thread in the thread-group have

	 * exited. So we can't poll before we have taken down the whole

	 * thread-group.

	 */



	/* Get PIDFD_GET_INFO using the thread-group leader pidfd. */

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

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

	/* Process has exited but not been reaped, so no PIDFD_INFO_EXIT information yet. */

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

	ASSERT_EQ(info.pid, pid_leader);



	/*

	 * Now retrieve the same info using the thread specific pidfd

	 * for the thread-group leader.

	 */

	info2.mask = PIDFD_INFO_CGROUPID | PIDFD_INFO_EXIT;

	ASSERT_EQ(ioctl(pidfd_leader_thread, PIDFD_GET_INFO, &info2), 0);

	ASSERT_TRUE(!!(info2.mask & PIDFD_INFO_CREDS));

	/* Process has exited but not been reaped, so no PIDFD_INFO_EXIT information yet. */

	ASSERT_FALSE(!!(info2.mask & PIDFD_INFO_EXIT));

	ASSERT_EQ(info2.pid, pid_leader);



	/* Now try the thread-specific pidfd. */

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

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

	/* The thread hasn't exited, so no PIDFD_INFO_EXIT information yet. */

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

	ASSERT_EQ(info.pid, pid_thread);



	/*

	 * Take down the whole thread-group. The thread-group leader

	 * exited successfully but the thread will now be SIGKILLed.

	 * This must be reflected in the recorded exit information.

	 */

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

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



	fds.events = POLLIN;

	fds.fd = pidfd_leader;

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

	ASSERT_EQ(nevents, 1);

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

	/* The thread-group leader has been reaped. */

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



	/*

	 * Retrieve exit information for the thread-group leader via the

	 * thread-group leader pidfd.

	 */

	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));

	/* The thread-group leader exited successfully. Only the specific thread was SIGKILLed. */

	ASSERT_TRUE(WIFEXITED(info.exit_code));

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



	/*

	 * Retrieve exit information for the thread-group leader via the

	 * thread-specific pidfd.

	 */

	info2.mask = PIDFD_INFO_CGROUPID | PIDFD_INFO_EXIT;

	ASSERT_EQ(ioctl(pidfd_leader_thread, PIDFD_GET_INFO, &info2), 0);

	ASSERT_FALSE(!!(info2.mask & PIDFD_INFO_CREDS));

	ASSERT_TRUE(!!(info2.mask & PIDFD_INFO_EXIT));



	/* The thread-group leader exited successfully. Only the specific thread was SIGKILLed. */

	ASSERT_TRUE(WIFEXITED(info2.exit_code));

	ASSERT_EQ(WEXITSTATUS(info2.exit_code), 0);



	/* Retrieve exit information for the thread. */

	info.mask = PIDFD_INFO_CGROUPID | PIDFD_INFO_EXIT;

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

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

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



	/* The thread got SIGKILLed. */

	ASSERT_TRUE(WIFSIGNALED(info.exit_code));

	ASSERT_EQ(WTERMSIG(info.exit_code), SIGKILL);



	EXPECT_EQ(close(pidfd_leader), 0);

	EXPECT_EQ(close(pidfd_thread), 0);

}



TEST_HARNESS_MAIN