linux-kernel - [PATCH 3/8] rust: platform: use generic device drvdata accessors

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Message-ID: <20250621195118.124245-4-dakr@kernel.org>
Date: Sat, 21 Jun 2025 21:43:29 +0200
From: Danilo Krummrich <dakr@...nel.org>
To: gregkh@...uxfoundation.org,
	rafael@...nel.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,
	david.m.ertman@...el.com,
	ira.weiny@...el.com,
	leon@...nel.org,
	kwilczynski@...nel.org,
	bhelgaas@...gle.com
Cc: rust-for-linux@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-pci@...r.kernel.org,
	Danilo Krummrich <dakr@...nel.org>
Subject: [PATCH 3/8] rust: platform: use generic device drvdata accessors

Take advantage of the generic drvdata accessors of the generic Device
type.

While at it, use from_result() instead of match.

Signed-off-by: Danilo Krummrich <dakr@...nel.org>
---
 rust/helpers/platform.c | 10 ----------
 rust/kernel/platform.rs | 36 +++++++++++++++++-------------------
 2 files changed, 17 insertions(+), 29 deletions(-)

diff --git a/rust/helpers/platform.c b/rust/helpers/platform.c
index 82171233d12f..1ce89c1a36f7 100644
--- a/rust/helpers/platform.c
+++ b/rust/helpers/platform.c
@@ -2,16 +2,6 @@
 
 #include <linux/platform_device.h>
 
-void *rust_helper_platform_get_drvdata(const struct platform_device *pdev)
-{
-	return platform_get_drvdata(pdev);
-}
-
-void rust_helper_platform_set_drvdata(struct platform_device *pdev, void *data)
-{
-	platform_set_drvdata(pdev, data);
-}
-
 bool rust_helper_dev_is_platform(const struct device *dev)
 {
 	return dev_is_platform(dev);
diff --git a/rust/kernel/platform.rs b/rust/kernel/platform.rs
index 5b21fa517e55..dc0c36d70963 100644
--- a/rust/kernel/platform.rs
+++ b/rust/kernel/platform.rs
@@ -6,11 +6,11 @@
 
 use crate::{
     bindings, container_of, device, driver,
-    error::{to_result, Result},
+    error::{from_result, to_result, Result},
     of,
     prelude::*,
     str::CStr,
-    types::{ForeignOwnable, Opaque},
+    types::Opaque,
     ThisModule,
 };
 
@@ -61,30 +61,28 @@ extern "C" fn probe_callback(pdev: *mut bindings::platform_device) -> kernel::ff
         // `struct platform_device`.
         //
         // INVARIANT: `pdev` is valid for the duration of `probe_callback()`.
-        let pdev = unsafe { &*pdev.cast::<Device<device::Core>>() };
-
+        let pdev = unsafe { &*pdev.cast::<Device<device::Internal>>() };
         let info = <Self as driver::Adapter>::id_info(pdev.as_ref());
-        match T::probe(pdev, info) {
-            Ok(data) => {
-                // Let the `struct platform_device` own a reference of the driver's private data.
-                // SAFETY: By the type invariant `pdev.as_raw` returns a valid pointer to a
-                // `struct platform_device`.
-                unsafe { bindings::platform_set_drvdata(pdev.as_raw(), data.into_foreign() as _) };
-            }
-            Err(err) => return Error::to_errno(err),
-        }
 
-        0
+        from_result(|| {
+            let data = T::probe(pdev, info)?;
+
+            pdev.as_ref().set_drvdata(data);
+            Ok(0)
+        })
     }
 
     extern "C" fn remove_callback(pdev: *mut bindings::platform_device) {
-        // SAFETY: `pdev` is a valid pointer to a `struct platform_device`.
-        let ptr = unsafe { bindings::platform_get_drvdata(pdev) }.cast();
+        // SAFETY: The platform bus only ever calls the remove callback with a valid pointer to a
+        // `struct platform_device`.
+        //
+        // INVARIANT: `pdev` is valid for the duration of `probe_callback()`.
+        let pdev = unsafe { &*pdev.cast::<Device<device::Internal>>() };
 
         // SAFETY: `remove_callback` is only ever called after a successful call to
-        // `probe_callback`, hence it's guaranteed that `ptr` points to a valid and initialized
-        // `KBox<T>` pointer created through `KBox::into_foreign`.
-        let _ = unsafe { KBox::<T>::from_foreign(ptr) };
+        // `probe_callback`, hence it's guaranteed that `Device::set_drvdata()` has been called
+        // and stored a `Pin<KBox<T>>`.
+        let _ = unsafe { pdev.as_ref().drvdata_obtain::<Pin<KBox<T>>>() };
     }
 }
 
-- 
2.49.0