Ensure that during a multi-threaded exec and premature thread-group leader exit no exit notification is generated. Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx> --- tools/testing/selftests/pidfd/pidfd_info_test.c | 47 +++++++++++++++++++------ 1 file changed, 36 insertions(+), 11 deletions(-) diff --git a/tools/testing/selftests/pidfd/pidfd_info_test.c b/tools/testing/selftests/pidfd/pidfd_info_test.c index 09bc4ae7aed5..f06b8e2f969a 100644 --- a/tools/testing/selftests/pidfd/pidfd_info_test.c +++ b/tools/testing/selftests/pidfd/pidfd_info_test.c @@ -428,26 +428,37 @@ TEST_F(pidfd_info, thread_group_exec) ASSERT_GE(pidfd_leader_thread, 0); /* - * We can poll and wait for the old thread-group leader to exit - * using a thread-specific pidfd. + * 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. * - * This only works until the thread has execed. When the thread - * has execed it will have taken over the old thread-group - * leaders struct pid. Calling poll after the thread execed will - * thus block again because a new thread-group has started (Yes, - * it's fscked.). + * When the thread has execed it will taken over the old + * thread-group leaders struct pid. Calling poll after the + * thread execed will thus block again because a new + * thread-group has started. */ fds.events = POLLIN; fds.fd = pidfd_leader_thread; - nevents = poll(&fds, 1, -1); - ASSERT_EQ(nevents, 1); - /* The thread-group leader has exited. */ - ASSERT_TRUE(!!(fds.revents & POLLIN)); + nevents = poll(&fds, 1, 2000 /* wait 2 seconds */); + ASSERT_EQ(nevents, 0); + /* The thread-group leader has exited but there's still a live subthread. */ + ASSERT_FALSE(!!(fds.revents & POLLIN)); /* The thread-group leader hasn't been reaped. */ ASSERT_FALSE(!!(fds.revents & POLLHUP)); /* 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)); + + fds.events = POLLIN; + fds.fd = pidfd_leader_thread; + nevents = poll(&fds, 1, 2000 /* wait 2 seconds */); + ASSERT_EQ(nevents, 0); + /* The thread-group leader has exited but there's still a live subthread. */ + ASSERT_FALSE(!!(fds.revents & POLLIN)); + /* The thread-group leader hasn't been reaped. */ + ASSERT_FALSE(!!(fds.revents & POLLHUP)); + EXPECT_EQ(close(ipc_sockets[0]), 0); /* Wait until the kernel has SIGKILLed the thread. */ @@ -482,6 +493,20 @@ TEST_F(pidfd_info, thread_group_exec) /* 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. */ -- 2.47.2
