Re: [PATCH v1 0/3] list: add primitives for private list manipulations

[Mike Rapoport <rppt@kernel.org>]

(added Dan Carpenter)

On Wed, Nov 26, 2025 at 01:57:22PM -0500, Pasha Tatashin wrote:
> Recently linux introduced the ability to mark structure members as
> __private and access them via ACCESS_PRIVATE(). This mechanism ensures
> that internal implementation details are only accessible by the owning
> subsystem, enforcing better encapsulation.
> 
> However, struct list_head is frequently used as an internal linkage
> mechanism within these private sections. The standard macros in
> <linux/list.h> (such as list_entry and list_for_each_entry) do not
> support ACCESS_PRIVATE() natively. Consequently, subsystems using
> private lists are forced to implement ad-hoc workarounds, verbose
> casting, or local iterator macros to avoid compiler warnings and access
> violations.
> 
> This series introduces <linux/list_private.h>, which provides a set of
> primitives identical in function to those in <linux/list.h>, but
> designed specifically for cases where the embedded struct list_head is a
> private member.
> 
> The series is structured as follows:
> Core Implementation: Adds the list_private.h header with support for
> entry retrieval and iteration (forward, reverse, safe, etc.).
> 
> Testing: Adds a KUnit test suite to verify that the macros compile
> correctly and handle pointer offsets/qualifiers as expected.
> 
> Adoption: Updates the liveupdate subsystem to use the new generic API,
> replacing its local luo_list_for_each_private implementation.
> 
> Pasha Tatashin (3):
>   list: add primitives for private list manipulations
>   list: add kunit test for private list primitives
>   liveupdate: luo_file: Use private list
> 
>  Documentation/core-api/list.rst  |   9 ++
>  include/linux/list_private.h     | 256 +++++++++++++++++++++++++++++++
>  kernel/liveupdate/luo_file.c     |   7 +-
>  kernel/liveupdate/luo_internal.h |   7 -
>  lib/Kconfig.debug                |  14 ++
>  lib/tests/Makefile               |   1 +
>  lib/tests/list-private-test.c    |  76 +++++++++
>  7 files changed, 360 insertions(+), 10 deletions(-)
>  create mode 100644 include/linux/list_private.h
>  create mode 100644 lib/tests/list-private-test.c
> 
> 
> base-commit: 663d0d1af3faefe673cabf4b6b077149a87ad71f
> -- 
> 2.52.0.487.g5c8c507ade-goog
> 

-- 
Sincerely yours,
Mike.