Kernel header inclusion practice

Hi, How do you include the kernel headers? For example, Currently I have the headers: #include <linux/module.h> #include <linux/kthread.h> #include <linux/delay.h> And now I wanna use the `struct workqueue_struct'. It turns out I don't have to include the "linux/workqueue.h". So it must have already been included by the three headers above. My question is: What's the practice of including headers? Should I specifically include "linux/workqueue.h" ? Another question is particular to the above three headers: does any of them guarantee to include the "linux/queue.h"? If there is any documentation about the API of the headers (e.g., what they include), that will be great. Best