Re: [PATCH] kernel/params.c: defer most of param_sysfs_init() to late_initcall time

[Luis Chamberlain]

On Tue, Oct 25, 2022 at 03:00:02PM +0200, Rasmus Villemoes wrote:
> param_sysfs_init(), and in particular param_sysfs_builtin() is rather
> time-consuming; for my board, it currently takes about 30ms.
> 
> That amounts to about 3% of the time budget I have from U-Boot hands
> over control to linux and linux must assume responsibility for keeping
> the external watchdog happy.
> 
> We must still continue to initialize module_kset at subsys_initcall
> time, since otherwise any request_module() would fail in
> mod_sysfs_init().

It would be good to document this through a comment.

> However, the bulk of the work in
> param_sysfs_builtin(), namely populating /sys/module/*/version and/or
> /sys/module/*/parameters/ for builtin modules, can be deferred to
> late_initcall time - there's no userspace yet anyway to observe
> contents of /sys or the lack thereof.
> 

Other than that, this looks good and looks cautious enough.

Acked-by: Luis Chamberlain <mcgrof@xxxxxxxxxx>

Happy to take this in through moduels and give this a spin on linux-next
to see what blows up early. Can you send a v2 with a small code comment for
the above?

  Luis