linux-kernel - [PATCH] rust: dma: add `Send` implementation for `CoherentAllocation`

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250324174048.1075597-1-ojeda@kernel.org>
Date: Mon, 24 Mar 2025 18:40:48 +0100
From: Miguel Ojeda <ojeda@...nel.org>
To: Abdiel Janulgue <abdiel.janulgue@...il.com>,
	Danilo Krummrich <dakr@...nel.org>,
	Miguel Ojeda <ojeda@...nel.org>,
	Alex Gaynor <alex.gaynor@...il.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Stephen Rothwell <sfr@...b.auug.org.au>
Cc: Daniel Almeida <daniel.almeida@...labora.com>,
	Robin Murphy <robin.murphy@....com>,
	Andreas Hindborg <a.hindborg@...nel.org>,
	rust-for-linux@...r.kernel.org,
	Boqun Feng <boqun.feng@...il.com>,
	Gary Guo <gary@...yguo.net>,
	Björn Roy Baron <bjorn3_gh@...tonmail.com>,
	Benno Lossin <benno.lossin@...ton.me>,
	Alice Ryhl <aliceryhl@...gle.com>,
	Trevor Gross <tmgross@...ch.edu>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	linux-next@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	patches@...ts.linux.dev
Subject: [PATCH] rust: dma: add `Send` implementation for `CoherentAllocation`

From: Danilo Krummrich <dakr@...nel.org>

Stephen found a future build failure in linux-next [1]:

    error[E0277]: `*mut MyStruct` cannot be sent between threads safely
      --> samples/rust/rust_dma.rs:47:22
       |
    47 | impl pci::Driver for DmaSampleDriver {
       |                      ^^^^^^^^^^^^^^^ `*mut MyStruct` cannot be sent between threads safely

It is caused by the interaction between commit 935e1d90bf6f ("rust: pci:
require Send for Driver trait implementers") from the driver-core tree,
which fixes a missing concurrency requirement, and commit 9901addae63b
("samples: rust: add Rust dma test sample driver") which adds a sample
that does not satisfy that requirement.

Add a `Send` implementation to `CoherentAllocation`, which allows the
sample (and other future users) to satisfy it.

Reported-by: Stephen Rothwell <sfr@...b.auug.org.au>
Closes: https://lore.kernel.org/linux-next/20250324215702.1515ba92@canb.auug.org.au/
Signed-off-by: Danilo Krummrich <dakr@...nel.org>
Signed-off-by: Miguel Ojeda <ojeda@...nel.org>
---
 rust/kernel/dma.rs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/rust/kernel/dma.rs b/rust/kernel/dma.rs
index 9d00f9c49f47..18de693c4924 100644
--- a/rust/kernel/dma.rs
+++ b/rust/kernel/dma.rs
@@ -301,6 +301,10 @@ fn drop(&mut self) {
     }
 }
 
+// SAFETY: It is safe to send a `CoherentAllocation` to another thread if `T`
+// can be send to another thread.
+unsafe impl<T: AsBytes + FromBytes + Send> Send for CoherentAllocation<T> {}
+
 /// Reads a field of an item from an allocated region of structs.
 ///
 /// # Examples
-- 
2.49.0