From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 1D05CF54ABA for ; Tue, 24 Mar 2026 14:00:57 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 83A1310E6E7; Tue, 24 Mar 2026 14:00:56 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.b="c+GG5n3k"; dkim-atps=neutral Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by gabe.freedesktop.org (Postfix) with ESMTPS id 81BF710E6E9; Tue, 24 Mar 2026 14:00:53 +0000 (UTC) Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 01BF460120; Tue, 24 Mar 2026 14:00:53 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0E4D8C2BCB2; Tue, 24 Mar 2026 14:00:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774360852; bh=nFDs461qGRQbZs3PvToXFNe9Yue8j0z6IlgIHuLx5a4=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=c+GG5n3k/xxHG4snLQ1EG5kug4Nq1Cmfjoz9ogNaXvCvfIBd5iAXGuxp7qggPkxj5 AqyiHCNzem3YnkLqqsZnt7zkALfB6K2GMfiUcLDTGcHwva7ASJNqg8F1ZEWiVEDfb1 yDzgBpJmUTp3QhkPZQxPHMdrSJFRZFmvkVv1kgtETcfKmPxRoCO3mY3gNoG8HL70pY UCgOUeIq4JlysINNVPNLQUHHFge1cemwUbsPNMM4TxE1rNcCmREQbR24j6dX/Cs10s ywV8Hgqr3S5Av0TBfFEsZ5Ys+WeCNz33hZkE+S9bx3Z/0bh//ZcGpKuinGq1qTRvBV GAKXlR2CxyDHQ== From: Andreas Hindborg To: Danilo Krummrich , aliceryhl@google.com, acourbot@nvidia.com, ojeda@kernel.org, boqun@kernel.org, gary@garyguo.net, bjorn3_gh@protonmail.com, lossin@kernel.org, tmgross@umich.edu, abdiel.janulgue@gmail.com, daniel.almeida@collabora.com, robin.murphy@arm.com Cc: driver-core@lists.linux.dev, nouveau@lists.freedesktop.org, dri-devel@lists.freedesktop.org, rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, Danilo Krummrich Subject: Re: [PATCH v2 5/8] rust: dma: add Coherent:init() and Coherent::init_with_attrs() In-Reply-To: <20260320194626.36263-6-dakr@kernel.org> References: <20260320194626.36263-1-dakr@kernel.org> <4yknLBbwY93Ty2ltbpxjHgto-m99xkoTgDlKv8cJTK2tbFL0_V6eQDjwbbXI70M6uMKT6RLRxBoYR_XeymmnHA==@protonmail.internalid> <20260320194626.36263-6-dakr@kernel.org> Date: Tue, 24 Mar 2026 15:00:38 +0100 Message-ID: <87y0jhpbsp.fsf@kernel.org> MIME-Version: 1.0 Content-Type: text/plain X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" "Danilo Krummrich" writes: > Analogous to Coherent::zeroed() and Coherent::zeroed_with_attrs(), add > Coherent:init() and Coherent::init_with_attrs() which both take an impl > Init argument initializing the DMA coherent memory. > > Compared to CoherentInit, Coherent::init() is a one-shot constructor > that runs an Init closure and immediately exposes the DMA handle, > whereas CoherentInit is a multi-stage initializer that provides safe > &mut T access by withholding the DMA address until converted to > Coherent. You forgot to update this to CoherentBox > > Signed-off-by: Danilo Krummrich > --- > rust/kernel/dma.rs | 38 ++++++++++++++++++++++++++++++++++++++ > 1 file changed, 38 insertions(+) > > diff --git a/rust/kernel/dma.rs b/rust/kernel/dma.rs > index cefb54f0424a..6d2bec52806b 100644 > --- a/rust/kernel/dma.rs > +++ b/rust/kernel/dma.rs > @@ -709,6 +709,44 @@ pub fn zeroed(dev: &device::Device, gfp_flags: kernel::alloc::Flags) -> R > Self::zeroed_with_attrs(dev, gfp_flags, Attrs(0)) > } > > + /// Same as [`Coherent::zeroed_with_attrs`], but instead of a zero-initialization the memory is > + /// initialized with `init`. > + pub fn init_with_attrs( > + dev: &device::Device, > + gfp_flags: kernel::alloc::Flags, > + dma_attrs: Attrs, > + init: impl Init, > + ) -> Result > + where > + Error: From, > + { > + let dmem = Self::alloc_with_attrs(dev, gfp_flags, dma_attrs)?; > + let ptr = dmem.as_mut_ptr(); > + > + // SAFETY: > + // - `ptr` is valid, properly aligned, and points to exclusively owned memory. > + // - If `__init` fails, `self` is dropped, which safely frees the underlying `Coherent`'s > + // DMA memory. `T: AsBytes + FromBytes` ensures there are no complex `Drop` requirements > + // we are bypassing. > + unsafe { init.__init(ptr)? }; > + > + Ok(dmem) > + } > + > + /// Same as [`Coherent::zeroed`], but instead of a zero-initialization the memory is initialized > + /// with `init`. > + #[inline] > + pub fn init( > + dev: &device::Device, > + gfp_flags: kernel::alloc::Flags, > + init: impl Init, > + ) -> Result > + where > + Error: From, > + { > + Self::init_with_attrs(dev, gfp_flags, Attrs(0), init) > + } > + I think we are missing an array initializer for `Coherent<[T]>`. Reviewed-by: Andreas Hindborg Best regards, Andreas Hindborg