From 3bb1655192aeed68b761891eabdc97d9f2f7fc38 Mon Sep 17 00:00:00 2001
From: Danilo Krummrich <dakr@kernel.org>
Date: Mon, 25 May 2026 22:20:56 +0200
Subject: rust: usb: implement Sync for Device<Bound>
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Implement Sync for Device<Bound> in addition to Device<Normal>.

Device<Bound> uses the same underlying struct usb_device as
Device<Normal>; Bound is a zero-sized type-state marker that does not
affect thread safety.

This is needed for drivers to store &'bound usb::Device<Bound> in their
private data while remaining Send.

Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Uwe Kleine-König <ukleinek@kernel.org>
Tested-by: Dirk Behme <dirk.behme@de.bosch.com>
Link: https://patch.msgid.link/20260525202921.124698-10-dakr@kernel.org
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
 rust/kernel/usb.rs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/rust/kernel/usb.rs b/rust/kernel/usb.rs
index 88721970afcb..6c917d8fa883 100644
--- a/rust/kernel/usb.rs
+++ b/rust/kernel/usb.rs
@@ -468,6 +468,10 @@ unsafe impl Send for Device {}
 // allow any mutation through a shared reference.
 unsafe impl Sync for Device {}
 
+// SAFETY: Same as `Device<Normal>` -- the underlying `struct usb_device` is the same;
+// `Bound` is a zero-sized type-state marker that does not affect thread safety.
+unsafe impl Sync for Device<device::Bound> {}
+
 /// Declares a kernel module that exposes a single USB driver.
 ///
 /// # Examples
-- 
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