linux-kernel - [PATCH v3 1/5] rust: miscdevice: Provide accessor to pull out miscdevice::this

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Message-ID: <20241206090515.752267-3-lee@kernel.org>
Date: Fri,  6 Dec 2024 09:05:04 +0000
From: Lee Jones <lee@...nel.org>
To: lee@...nel.org
Cc: linux-kernel@...r.kernel.org,
	arnd@...db.de,
	gregkh@...uxfoundation.org,
	ojeda@...nel.org,
	alex.gaynor@...il.com,
	boqun.feng@...il.com,
	gary@...yguo.net,
	bjorn3_gh@...tonmail.com,
	benno.lossin@...ton.me,
	a.hindborg@...nel.org,
	aliceryhl@...gle.com,
	tmgross@...ch.edu,
	rust-for-linux@...r.kernel.org
Subject: [PATCH v3 1/5] rust: miscdevice: Provide accessor to pull out miscdevice::this_device

There are situations where a pointer to a `struct device` will become
necessary (e.g. for calling into dev_*() functions).  This accessor
allows callers to pull this out from the `struct miscdevice`.

Signed-off-by: Lee Jones <lee@...nel.org>
---
 rust/kernel/miscdevice.rs | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/rust/kernel/miscdevice.rs b/rust/kernel/miscdevice.rs
index 7e2a79b3ae26..55340f316006 100644
--- a/rust/kernel/miscdevice.rs
+++ b/rust/kernel/miscdevice.rs
@@ -10,11 +10,13 @@
 
 use crate::{
     bindings,
+    device::Device,
     error::{to_result, Error, Result, VTABLE_DEFAULT_ERROR},
     prelude::*,
     str::CStr,
     types::{ForeignOwnable, Opaque},
 };
+
 use core::{
     ffi::{c_int, c_long, c_uint, c_ulong},
     marker::PhantomData,
@@ -84,6 +86,13 @@ pub fn register(opts: MiscDeviceOptions) -> impl PinInit<Self, Error> {
     pub fn as_raw(&self) -> *mut bindings::miscdevice {
         self.inner.get()
     }
+
+    /// Returns a pointer to the current Device
+    pub fn device(&self) -> &Device {
+        // SAFETY: This is only accessible after a successful register() which always
+        // initialises this_device with a valid device.
+        unsafe { Device::as_ref((*self.as_raw()).this_device) }
+    }
 }
 
 #[pinned_drop]
-- 
2.47.0.338.g60cca15819-goog