svn commit: r331605 - head/sys/vm

[Bruce Evans]

On Tue, 27 Mar 2018, Jeff Roberson wrote:

> Log:
>  Move vm_ndomains to vm.h where it can be used with a single header include
>  rather than requiring a half-dozen.  Many non-vm files may want to know
>  the number of valid domains.

Shouldn't it go in vm_extern.h?  What is the point of having vm_extern.h
if you don't declare extern variables in it?

Well, vm_extern.h contains (implicitly extern) prototypes but no externs
variables , so the main style bugs are actually its name and having
prototypes in vm.h instead if in vm_extern.h.

Extern variables should probably go in vm_extern.h too, leaving only
central type definitions and macros in vm.h, and vm_extern.h should
have been named vm_var.h.

There are mounds of other style bugs in vm.h and vm_extern.h.  vm.h was
almost correct in FreeBSD-4.  Then it had no prototypes, no namespace
pollution, and only minor style bugs like naming its include guard VM_H
(which is not namespace pollution since VM_* is reserved for other reasons).

> Modified: head/sys/vm/vm.h
> ==============================================================================
> --- head/sys/vm/vm.h	Tue Mar 27 01:02:42 2018	(r331604)
> +++ head/sys/vm/vm.h	Tue Mar 27 03:27:02 2018	(r331605)
> @@ -148,6 +148,8 @@ extern void vm_ksubmap_init(struct kva_md_info *);
>
> extern int old_mlock;

This is especially gratuitous namespace pollution.  The obj* names at
least have something to do with vm.

>
> +extern int vm_ndomains;
> +
> struct ucred;
> int swap_reserve(vm_ooffset_t incr);
> int swap_reserve_by_cred(vm_ooffset_t incr, struct ucred *cred);

swap_* also has something to do with vm, but needs a vm_ prefix more
for exporting out of vm.

Kernel prototypes don't belong here.  One reason they are supposed to
be in vm_extern.h is to keep them out of here so that userland can
include this without getting kernel prototypes and/or so this file
doesn't need so many ifdefs.

Parameter names in prototypes are documented as being kernel style in
style(9), but this is a bug in style(9).  This is optional, and old vm
prototypes in vm_extern.h don't do it.

Bruce