Re: [PATCH 1/4] module: Add module_subinit{_noexit} and module_subeixt helper macros

Christoph Hellwig
2024-07-25T14:39:50Z

On Thu, Jul 25, 2024 at 11:01:33AM +0800, Youling Tang wrote:
> - It doesn't feel good to have only one subinit/exit in a file.
>   Assuming that there is only one file in each file, how do we
>   ensure that the files are linked in order?(Is it sorted by *.o
>   in the Makefile?)

Yes, link order already matterns for initialization order for built-in
code, so this is a well known concept.

> - Even if the order of each init is linked correctly, then the
>   runtime will be iterated through the .subinitcall.init section,
>   which executes each initfn in sequence (similar to do_initcalls),
>   which means that no other code can be inserted between each subinit.

I don't understand this comment. What do you mean with no other
code could be inserted?

> If module_subinit is called in module_init, other code can be inserted
> between subinit, similar to the following:
>
> ```
> static int __init init_example(void)
> {
>     module_subinit(inita, exita);
>
>     otherthing...
>
>     module_subinit(initb, exitb);
>
>     return 0;
> }

Yikes. That's really not the point of having init calls, but just
really, really convoluted control flow.

> module_init(init_example);
> ```
>
> IMHO, module_subinit() might be better called in module_init().

I strongly disagree.