per-task data structure in linux kernel module

Question

I am writing a loadable kernel module for Linux. And I need to store some data for each task in Linux kernel (These data would be used in a scheduler callback).

I know that I can modify struct task_struct and insert my own fields. But since I am willing to write a relatively clean kernel module, I cannot modify any code resides in original Linux source tree.

It is also possible to maintain some sort of mapping from struct task_struct to my data in a hash table. But it seem to be a little too heavy-weight.

I've read the answer in Thread local data in linux kernel module. It mentioned using private_data in struct file. But it needs every thread to open it in order to get an struct file. And there's no way the query the per-task data with a struct task_struct. (As I need to use the data in a scheduler callback)

My question is: is there any simple and clean way that allows me registering per-task data-structure in Linux kernel without modifying struct task_struct?

Many thanks!

Answer 1

The only simple and clean way that allows you to register a per-task data structure is to modify struct task_struct.

Modules are designed for optional parts of the kernel; they can use only functions that are explicitly exported from the base kernel. if you have to change the base kernel, you can no longer use modules.