Implement TryFrom<&device::Device> for &Device.
This allows us to get a &platform::Device from a generic &Device in a safe
way; the conversion fails if the device' bus type does not match with
the platform bus type.
Reviewed-by: Alice Ryhl <aliceryhl@xxxxxxxxxx>
Reviewed-by: Benno Lossin <benno.lossin@xxxxxxxxx>
Signed-off-by: Danilo Krummrich <dakr@xxxxxxxxxx>
---
rust/kernel/platform.rs | 25 +++++++++++++++++++++++--
1 file changed, 23 insertions(+), 2 deletions(-)
diff --git a/rust/kernel/platform.rs b/rust/kernel/platform.rs
index e37531bae8e9..b39ca2573020 100644
--- a/rust/kernel/platform.rs
+++ b/rust/kernel/platform.rs
@@ -5,7 +5,7 @@
//! C header: [`include/linux/platform_device.h`](srctree/include/linux/platform_device.h)
use crate::{
- bindings, device, driver,
+ bindings, container_of, device, driver,
error::{to_result, Result},
of,
prelude::*,
@@ -17,7 +17,7 @@
use core::{
marker::PhantomData,
ops::Deref,
- ptr::{addr_of_mut, NonNull},
+ ptr::{addr_of, addr_of_mut, NonNull},
};
/// An adapter for the registration of platform drivers.
@@ -234,6 +234,27 @@ fn as_ref(&self) -> &device::Device {
}
}
+impl TryFrom<&device::Device> for &Device {
+ type Error = kernel::error::Error;
+
+ fn try_from(dev: &device::Device) -> Result<Self, Self::Error> {
+ #[allow(unused_unsafe)]
+ // SAFETY: rustc < 1.82 falsely treats this as unsafe, see:
+ // https://blog.rust-lang.org/2024/10/17/Rust-1.82.0.html#safely-addressing-unsafe-statics
+ if dev.bus_type_raw() != unsafe { addr_of!(bindings::platform_bus_type) } {
+ return Err(EINVAL);
+ }
+
+ // SAFETY: We've just verified that the bus type of `dev` equals
+ // `bindings::platform_bus_type`, hence `dev` must be embedded in a valid
+ // `struct platform_device` as guaranteed by the corresponding C code.
+ let pdev = unsafe { container_of!(dev.as_raw(), bindings::platform_device, dev) };
+
+ // SAFETY: `pdev` is a valid pointer to a `struct platform_device`.
+ Ok(unsafe { &*pdev.cast() })
+ }
+}
+
// SAFETY: A `Device` is always reference-counted and can be released from any thread.
unsafe impl Send for Device {}
--
2.48.1
