Unverified Commit db7ce91e authored by Christian Brauner's avatar Christian Brauner
Browse files

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

Add first test for premature thread-group leader exit.

Link: https://lore.kernel.org/r/20250320-work-pidfs-thread_group-v4-2-da678ce805bf@kernel.org


Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent 0fb48272

tools/testing/selftests/pidfd/pidfd_info_test.c

+31 −7
Original line number Diff line number Diff line
@@ -236,7 +236,7 @@ static void *pidfd_info_pause_thread(void *arg) 


TEST_F(pidfd_info, thread_group)

{

	pid_t pid_leader, pid_thread;

	pid_t pid_leader, pid_poller, pid_thread;

	pthread_t thread;

	int nevents, pidfd_leader, pidfd_thread, pidfd_leader_thread, ret;

	int ipc_sockets[2];
@@ -262,6 +262,35 @@ TEST_F(pidfd_info, thread_group) 
		syscall(__NR_exit, EXIT_SUCCESS);

	}



	/*

	 * 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);



	pid_poller = fork();

	ASSERT_GE(pid_poller, 0);

	if (pid_poller == 0) {

		/*

		 * We can't poll and wait for the old thread-group

		 * leader to exit using a thread-specific pidfd. The

		 * thread-group leader exited prematurely and

		 * notification is delayed until all subthreads have

		 * exited.

		 */

		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);

	}



	/* 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));
@@ -275,12 +304,7 @@ TEST_F(pidfd_info, thread_group) 
	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);

	ASSERT_EQ(wait_for_pid(pid_poller), 0);



	/*

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