Currently, the Devres<T> container uses devm_add_action() to register a
devres callback.

devm_add_action() allocates a struct action_devres, which on top of
struct devres_node, just keeps a data pointer and release function
pointer.

This is an unnecessary indirection, given that analogous to struct
devres, the Devres<T> container can just embed a struct devres_node
directly without an additional allocation.

In contrast to struct devres, we don't need to force an alignment of
ARCH_DMA_MINALIGN (as struct devres does to account for the worst case)
since we have generics in Rust. I.e. the compiler already ensures
correct alignment of the embedded T in Devres<T>.

Thus, get rid of devm_add_action() and instead embed a struct
devres_node directly.

This patch series is based on [1].

[1] https://lore.kernel.org/lkml/20260202235210.55176-1-dakr@kernel.org/

Changes in v2:
  - Prevent driver-core internal C APIs from potentially being called directly
    from driver modules due to monomorphisation, to prevent unnecessary symbol
    exports.

Danilo Krummrich (5):
  devres: move struct devres_node into base.h
  devres: export devres_node_init() and devres_node_add()
  devres: add devres_node_remove()
  devres: rename and export set_node_dbginfo()
  rust: devres: embed struct devres_node directly

 drivers/base/base.h   |  18 +++++
 drivers/base/devres.c |  50 ++++++------
 rust/kernel/devres.rs | 182 +++++++++++++++++++++++++++++++-----------
 3 files changed, 180 insertions(+), 70 deletions(-)


base-commit: 1680377f05a809e4489731ad0e5a5fd5471ec40e
-- 
2.53.0

On Fri Feb 13, 2026 at 11:07 PM CET, Danilo Krummrich wrote:

Applied to driver-core-testing, thanks!

> Danilo Krummrich (5):
>   devres: move struct devres_node into base.h
>   devres: export devres_node_init() and devres_node_add()
>   devres: add devres_node_remove()
>   devres: rename and export set_node_dbginfo()
>   rust: devres: embed struct devres_node directly

    [ * Improve comment about core::any::type_name(),
      * add #[must_use] to devres_node_remove(),
      * use container_of!() in devres_node_free_node().

        - Danilo ]

On Fri, Feb 13, 2026 at 11:07:10PM +0100, Danilo Krummrich wrote:
> Currently, the Devres<T> container uses devm_add_action() to register a
> devres callback.
> 
> devm_add_action() allocates a struct action_devres, which on top of
> struct devres_node, just keeps a data pointer and release function
> pointer.
> 
> This is an unnecessary indirection, given that analogous to struct
> devres, the Devres<T> container can just embed a struct devres_node
> directly without an additional allocation.
> 
> In contrast to struct devres, we don't need to force an alignment of
> ARCH_DMA_MINALIGN (as struct devres does to account for the worst case)
> since we have generics in Rust. I.e. the compiler already ensures
> correct alignment of the embedded T in Devres<T>.
> 
> Thus, get rid of devm_add_action() and instead embed a struct
> devres_node directly.
> 
> This patch series is based on [1].
> 
> [1] https://lore.kernel.org/lkml/20260202235210.55176-1-dakr@kernel.org/
> 
> Changes in v2:
>   - Prevent driver-core internal C APIs from potentially being called directly
>     from driver modules due to monomorphisation, to prevent unnecessary symbol
>     exports.
> 
> Danilo Krummrich (5):
>   devres: move struct devres_node into base.h
>   devres: export devres_node_init() and devres_node_add()
>   devres: add devres_node_remove()
>   devres: rename and export set_node_dbginfo()
>   rust: devres: embed struct devres_node directly
> 
>  drivers/base/base.h   |  18 +++++
>  drivers/base/devres.c |  50 ++++++------
>  rust/kernel/devres.rs | 182 +++++++++++++++++++++++++++++++-----------
>  3 files changed, 180 insertions(+), 70 deletions(-)

Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>