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Date: Sun, 28 Sep 2025 17:20:59 +0200
Message-Id: <DD4JABIXIZLT.120ZAR2GODC1O@kernel.org>
Cc: "Philipp Stanner" <phasta@kernel.org>, "Miguel Ojeda"
 <ojeda@kernel.org>, "Alex Gaynor" <alex.gaynor@gmail.com>, "Gary Guo"
 <gary@garyguo.net>, =?utf-8?q?Bj=C3=B6rn_Roy_Baron?=
 <bjorn3_gh@protonmail.com>, "Benno Lossin" <lossin@kernel.org>, "Andreas
 Hindborg" <a.hindborg@kernel.org>, "Alice Ryhl" <aliceryhl@google.com>,
 "Trevor Gross" <tmgross@umich.edu>, "Peter Zijlstra"
 <peterz@infradead.org>, "Ingo Molnar" <mingo@redhat.com>, "Will Deacon"
 <will@kernel.org>, "Waiman Long" <longman@redhat.com>, "Nathan Chancellor"
 <nathan@kernel.org>, "Nick Desaulniers" <nick.desaulniers+lkml@gmail.com>,
 "Bill Wendling" <morbo@google.com>, "Justin Stitt"
 <justinstitt@google.com>, "Sumit Semwal" <sumit.semwal@linaro.org>,
 =?utf-8?q?Christian_K=C3=B6nig?= <christian.koenig@amd.com>, "Greg
 Kroah-Hartman" <gregkh@linuxfoundation.org>, "Viresh Kumar"
 <viresh.kumar@linaro.org>, "Asahi Lina" <lina+kernel@asahilina.net>,
 "Daniel Almeida" <daniel.almeida@collabora.com>, "Tamir Duberstein"
 <tamird@gmail.com>, "Wedson Almeida Filho" <wedsonaf@gmail.com>, "FUJITA
 Tomonori" <fujita.tomonori@gmail.com>, "Krishna Ketan Rai"
 <prafulrai522@gmail.com>, "Lyude Paul" <lyude@redhat.com>, "Mitchell Levy"
 <levymitchell0@gmail.com>, <linux-kernel@vger.kernel.org>,
 <rust-for-linux@vger.kernel.org>, <llvm@lists.linux.dev>,
 <dri-devel@lists.freedesktop.org>
To: "Boqun Feng" <boqun.feng@gmail.com>
From: "Danilo Krummrich" <dakr@kernel.org>
Subject: Re: [RFC PATCH] rust: sync: Add dma_fence abstractions
References: <20250918123100.124738-2-phasta@kernel.org>
 <aNa7BDpKS2KA__4M@tardis.local>
In-Reply-To: <aNa7BDpKS2KA__4M@tardis.local>

On Fri Sep 26, 2025 at 6:10 PM CEST, Boqun Feng wrote:
> I missed this part, and I don't think kernel::sync is where dma_fence
> should be, as kernel::sync is mostly for the basic synchronization
> between threads/irqs. dma_fence is probably better to be grouped with
> dma-buf and other dma related primitives. Maybe in kernel::dma? Like:

I agree, kernel::sync may be a bit misleading.

> rust/kernel/dma.rs
> rust/kernel/dma/dma_buf.rs
> rust/kernel/dma/dma_fence.rs
>
> Thoughts? Miguel, Greg, Danilo and Lyude, any idea or suggestion?

To me it depends on if we want to maintain the code under a global
DMA MAPPING & SCATTERLIST API entry or if it will just be added to the
DMA BUFFER SHARING FRAMEWORK entry.

In case of the latter I'd go for rust/kernel/dma-buf/, analogous to
drivers/dma-buf/. (Though, I'm not sure why this is under drivers/, there's
nothing like dma-buf drivers; I think kernel/dma/ would have been the bette=
r
fit.)

In any case, the target tree would probably be the drm-rust tree.