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From: Jason Gunthorpe <jgg@ziepe.ca>
To: Abdiel Janulgue <abdiel.janulgue@gmail.com>
Cc: rust-for-linux@vger.kernel.org, daniel.almeida@collabora.com,
	dakr@kernel.org, robin.murphy@arm.com, aliceryhl@google.com,
	"Miguel Ojeda" <ojeda@kernel.org>,
	"Alex Gaynor" <alex.gaynor@gmail.com>,
	"Boqun Feng" <boqun.feng@gmail.com>,
	"Gary Guo" <gary@garyguo.net>,
	"Björn Roy Baron" <bjorn3_gh@protonmail.com>,
	"Benno Lossin" <benno.lossin@proton.me>,
	"Andreas Hindborg" <a.hindborg@kernel.org>,
	"Trevor Gross" <tmgross@umich.edu>,
	"Valentin Obst" <kernel@valentinobst.de>,
	"open list" <linux-kernel@vger.kernel.org>,
	"Christoph Hellwig" <hch@lst.de>,
	"Marek Szyprowski" <m.szyprowski@samsung.com>,
	airlied@redhat.com,
	"open list:DMA MAPPING HELPERS" <iommu@lists.linux.dev>
Subject: Re: [PATCH v13 2/7] rust: add dma coherent allocator abstraction.
Date: Fri, 21 Mar 2025 14:23:53 -0300	[thread overview]
Message-ID: <20250321172353.GO126678@ziepe.ca> (raw)
In-Reply-To: <20250307110821.1703422-3-abdiel.janulgue@gmail.com>

On Fri, Mar 07, 2025 at 01:06:19PM +0200, Abdiel Janulgue wrote:

> +        // SAFETY: Device pointer is guaranteed as valid by the type invariant on `Device`.
> +        let ret = unsafe {
> +            bindings::dma_alloc_attrs(
> +                dev.as_raw(),
> +                size,
> +                &mut dma_handle,
> +                gfp_flags.as_raw(),
> +                dma_attrs.as_raw(),
> +            )

This is not the correct safety statement, the device must have a driver
bound to call this function, a struct device reference is not
sufficient.

I belive Danilo was suggesting to ignore this unsafety for now, but if
so it should be documented correctly.

Also think the use of devres here is going to be very problematic for
drivers to use as I said in other emails. :(

Jason

  parent reply	other threads:[~2025-03-21 17:23 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-03-07 11:06 [PATCH v13 0/7] " Abdiel Janulgue
2025-03-07 11:06 ` [PATCH v13 1/7] rust: error: Add EOVERFLOW Abdiel Janulgue
2025-03-07 11:06 ` [PATCH v13 2/7] rust: add dma coherent allocator abstraction Abdiel Janulgue
2025-03-07 11:17   ` Alice Ryhl
2025-03-07 20:40   ` Andreas Hindborg
2025-03-21 17:23   ` Jason Gunthorpe [this message]
2025-03-21 17:34     ` Danilo Krummrich
2025-03-21 18:29       ` Jason Gunthorpe
2025-03-21 19:16         ` Danilo Krummrich
2025-03-07 11:06 ` [PATCH v13 3/7] rust: pci: impl AsMut<Device> for pci::Device Abdiel Janulgue
2025-03-07 11:18   ` Alice Ryhl
2025-03-07 11:45     ` Danilo Krummrich
2025-03-07 14:18   ` Greg KH
2025-03-07 17:53     ` Abdiel Janulgue
2025-03-07 11:06 ` [PATCH v13 4/7] rust: device: add dma addressing capabilities Abdiel Janulgue
2025-03-07 20:12   ` Andreas Hindborg
2025-03-11 17:45     ` Abdiel Janulgue
2025-03-11 18:35       ` Miguel Ojeda
2025-03-11 20:16         ` Andreas Hindborg
2025-03-07 11:06 ` [PATCH v13 5/7] samples: rust: add Rust dma test sample driver Abdiel Janulgue
2025-03-07 11:06 ` [PATCH v13 6/7] MAINTAINERS: add entry for Rust dma mapping helpers device driver API Abdiel Janulgue
2025-03-07 11:06 ` [PATCH v13 7/7] rust: dma: add as_slice/write functions for CoherentAllocation Abdiel Janulgue
2025-03-07 11:12 ` [PATCH v13 0/7] rust: add dma coherent allocator abstraction Danilo Krummrich

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