Re: [RFC 2/3] headers: introduce linux/struct_types.h

From: Arnd Bergmann <arnd@kernel.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Arnd Bergmann <arnd@arndb.de>, Al Viro <viro@zeniv.linux.org.uk>,
	Andrew Morton <akpm@linux-foundation.org>,
	Guenter Roeck <groeck@chromium.org>,
	Kees Cook <keescook@chromium.org>,
	Masahiro Yamada <masahiroy@kernel.org>,
	Matthew Wilcox <willy@infradead.org>,
	Nathan Chancellor <nathan@kernel.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Stephen Rothwell <sfr@canb.auug.org.au>,
	kernel test robot <lkp@intel.com>, Ingo Molnar <mingo@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Will Deacon <will@kernel.org>, Waiman Long <longman@redhat.com>,
	Boqun Feng <boqun.feng@gmail.com>,
	Thomas Gleixner <tglx@linutronix.de>, Tejun Heo <tj@kernel.org>,
	kernelci@groups.io, linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
	llvm@lists.linux.dev
Subject: Re: [RFC 2/3] headers: introduce linux/struct_types.h
Date: Wed, 8 Dec 2021 09:55:47 +0100	[thread overview]
Message-ID: <CAK8P3a3Uy0k+SnWYqz7FMsQsu14VzivMJcjGDRBLv17adFYywA@mail.gmail.com> (raw)
In-Reply-To: <CAHk-=wgwQg=5gZZ6ewusLHEAw-DQm7wWm7aoQt6TYO_xb0cBog@mail.gmail.com>

On Tue, Dec 7, 2021 at 7:17 PM Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> On Tue, Dec 7, 2021 at 7:10 AM Arnd Bergmann <arnd@kernel.org> wrote:
> >
> > From: Arnd Bergmann <arnd@arndb.de>
> >
> > Working towards a cleaner header structure, start by moving the most
> > commonly embedded structures into a single header file that itself
> > has only a minimum set of indirect includes. At this moment, this
> > include structures for
>
> Ugh. I liked your 1/3 patch, but I absolutely detest this one.
>
> It makes no sense to me, and just makes that header file a completely
> random collection of some random structure types.
>
> And I absolutely hate how it splits out the definition of the struct
> from basic core infrastructure (initializers etc random inline
> functions) for said structures.
>
> So no. NAK on this one. I think it's a disaster.

Ok, thank you for taking a look!

Here is what I'd try next based on the feedback:

- reduce patch 1 somewhat to only include the types that have a strong reason
  to get moved to linux/types.h, describing them individually but leaving them
  it as a single combined patch

- keep patch 3, but leave 'struct super_block' in linux/fs.h for the moment
  because  of 'struct list_lru'.

- drop patch 2, but instead find a new home for each structure (along with
  its initializers) if needed for defining the types in the new linux/fs_types.h
  without too many indirect includes. I'll skip the structs that would be needed
  later for mm.h/sched.h/device.h/.... for the moment.

For the added headers, do you have a preference for whether to try grouping
them logically or not? I could either split them out individually into many new
headers (xarray_types.h, idr_types.h, percpu_rwsem_types.h, rwsem_types.h,
...), or combine some of them when they define related types.

        Arnd