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Date: Thu, 12 Mar 2026 16:12:21 +0100
From: Greg KH <gregkh@linuxfoundation.org>
To: Danilo Krummrich <dakr@kernel.org>
Cc: rafael@kernel.org, ojeda@kernel.org, boqun.feng@gmail.com,
	gary@garyguo.net, bjorn3_gh@protonmail.com, lossin@kernel.org,
	a.hindborg@kernel.org, aliceryhl@google.com, tmgross@umich.edu,
	driver-core@lists.linux.dev, rust-for-linux@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 0/5] Use struct devres_node in Devres<T>
Message-ID: <2026031213-appendage-procedure-0dab@gregkh>
References: <20260213220718.82835-1-dakr@kernel.org>
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In-Reply-To: <20260213220718.82835-1-dakr@kernel.org>

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>