linux-kernel - Re: [PATCH v2 01/12] rust: helpers: Add bindings/wrappers for dma_resv

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Message-ID: <ab32a3ea-84a0-484c-a07b-85aecf99ae00@amd.com>
Date: Thu, 22 May 2025 10:44:34 +0200
From: Christian König <christian.koenig@....com>
To: Lyude Paul <lyude@...hat.com>, dri-devel@...ts.freedesktop.org,
 rust-for-linux@...r.kernel.org, linux-kernel@...r.kernel.org
Cc: Asahi Lina <lina@...hilina.net>, Miguel Ojeda <ojeda@...nel.org>,
 Alex Gaynor <alex.gaynor@...il.com>, Boqun Feng <boqun.feng@...il.com>,
 Gary Guo <gary@...yguo.net>, Björn Roy Baron
 <bjorn3_gh@...tonmail.com>, Benno Lossin <benno.lossin@...ton.me>,
 Andreas Hindborg <a.hindborg@...nel.org>, Alice Ryhl <aliceryhl@...gle.com>,
 Trevor Gross <tmgross@...ch.edu>, Danilo Krummrich <dakr@...nel.org>,
 Sumit Semwal <sumit.semwal@...aro.org>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Viresh Kumar <viresh.kumar@...aro.org>,
 Wedson Almeida Filho <wedsonaf@...il.com>,
 Daniel Almeida <daniel.almeida@...labora.com>,
 "open list:DMA BUFFER SHARING FRAMEWORK:Keyword:bdma_(?:buf|fence|resv)b"
 <linux-media@...r.kernel.org>,
 "moderated list:DMA BUFFER SHARING FRAMEWORK:Keyword:bdma_(?:buf|fence|resv)b"
 <linaro-mm-sig@...ts.linaro.org>
Subject: Re: [PATCH v2 01/12] rust: helpers: Add bindings/wrappers for
 dma_resv_lock

On 5/21/25 22:29, Lyude Paul wrote:
> From: Asahi Lina <lina@...hilina.net>
> 
> This is just for basic usage in the DRM shmem abstractions for implied
> locking, not intended as a full DMA Reservation abstraction yet.

Looks good in general, but my question is if it wouldn't be better to export the higher level drm_exec component instead?

The drm_exec component implements the necessary loop if you want to lock multiple GEM objects at the same time. As well as makes sure that those GEM objects can't be released while working with them.

Regtards,
Christian.

> 
> Signed-off-by: Asahi Lina <lina@...hilina.net>
> Signed-off-by: Daniel Almeida <daniel.almeida@...labora.com>
> Signed-off-by: Lyude Paul <lyude@...hat.com>
> ---
>  rust/bindings/bindings_helper.h |  1 +
>  rust/helpers/dma-resv.c         | 13 +++++++++++++
>  rust/helpers/helpers.c          |  1 +
>  3 files changed, 15 insertions(+)
>  create mode 100644 rust/helpers/dma-resv.c
> 
> diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h
> index 31369b7b23884..409e9a595e051 100644
> --- a/rust/bindings/bindings_helper.h
> +++ b/rust/bindings/bindings_helper.h
> @@ -18,6 +18,7 @@
>  #include <linux/blkdev.h>
>  #include <linux/cpumask.h>
>  #include <linux/cred.h>
> +#include <linux/dma-resv.h>
>  #include <linux/device/faux.h>
>  #include <linux/dma-mapping.h>
>  #include <linux/dma-direction.h>
> diff --git a/rust/helpers/dma-resv.c b/rust/helpers/dma-resv.c
> new file mode 100644
> index 0000000000000..05501cb814513
> --- /dev/null
> +++ b/rust/helpers/dma-resv.c
> @@ -0,0 +1,13 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#include <linux/dma-resv.h>
> +
> +int rust_helper_dma_resv_lock(struct dma_resv *obj, struct ww_acquire_ctx *ctx)
> +{
> +	return dma_resv_lock(obj, ctx);
> +}
> +
> +void rust_helper_dma_resv_unlock(struct dma_resv *obj)
> +{
> +	dma_resv_unlock(obj);
> +}
> diff --git a/rust/helpers/helpers.c b/rust/helpers/helpers.c
> index 20a4ee59acd89..3ba1652899c2b 100644
> --- a/rust/helpers/helpers.c
> +++ b/rust/helpers/helpers.c
> @@ -15,6 +15,7 @@
>  #include "cpumask.c"
>  #include "cred.c"
>  #include "device.c"
> +#include "dma-resv.c"
>  #include "drm.c"
>  #include "err.c"
>  #include "fs.c"