selftests/pidfd: adapt to recent changes

Adapt to changes in commit 9133607de37a ("exit: fix the usage of
delay_group_leader->exit_code in do_notify_parent() and pidfs_exit()").

Even if the thread-group leader exited early and succesfully it's exit
status will only be reported once the whole thread-group has exited and
it will share the exit code of the thread-group. So if the thread-group
was SIGKILLed the thread-group leader will also be reported as having
been SIGKILLed.

Link: https://lore.kernel.org/r/[e-mail]
Reviewed-by: Oleg Nesterov <[e-mail]>
Signed-off-by: Christian Brauner <[e-mail]>

tools/testing/selftests/pidfd/pidfd_info_test.c

···
 	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);
+	/* Even though the thread-group exited successfully it will still report the group exit code. */
+	ASSERT_TRUE(WIFSIGNALED(info.exit_code));
+	ASSERT_EQ(WTERMSIG(info.exit_code), SIGKILL);
 
 	/*
 	 * Retrieve exit information for the thread-group leader via the
···
 	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);
+	/* Even though the thread-group exited successfully it will still report the group exit code. */
+	ASSERT_TRUE(WIFSIGNALED(info2.exit_code));
+	ASSERT_EQ(WTERMSIG(info2.exit_code), SIGKILL);
 
 	/* Retrieve exit information for the thread. */
 	info.mask = PIDFD_INFO_CGROUPID | PIDFD_INFO_EXIT;