linux-kernel - [PATCH 3/3] rust: miscdevice: adjust the rust_misc

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Message-Id: <20250119-b4-rust_miscdevice_registrationdata-v1-3-edbf18dde5fc@gmail.com>
Date: Sun, 19 Jan 2025 23:11:15 +0100
From: Christian Schrefl <chrisi.schrefl@...il.com>
To: Miguel Ojeda <ojeda@...nel.org>, Alex Gaynor <alex.gaynor@...il.com>, 
 Boqun Feng <boqun.feng@...il.com>, Gary Guo <gary@...yguo.net>, 
 Björn Roy Baron <bjorn3_gh@...tonmail.com>, 
 Benno Lossin <benno.lossin@...ton.me>, 
 Andreas Hindborg <a.hindborg@...nel.org>, Alice Ryhl <aliceryhl@...gle.com>, 
 Trevor Gross <tmgross@...ch.edu>, Arnd Bergmann <arnd@...db.de>, 
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Lee Jones <lee@...nel.org>
Cc: rust-for-linux@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Christian Schrefl <chrisi.schrefl@...il.com>
Subject: [PATCH 3/3] rust: miscdevice: adjust the rust_misc_device sample
 to use RegistrationData.

Share the mutex stored in RustMiscDevice between all instances using an Arc
and the RegistrationData of MiscDeviceRegistration.

This is mostly to Demonstrate the capability to share data in this way.

Signed-off-by: Christian Schrefl <chrisi.schrefl@...il.com>
---
 samples/rust/rust_misc_device.rs | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/samples/rust/rust_misc_device.rs b/samples/rust/rust_misc_device.rs
index 779fcfd64119bdd5b4f8be740f7e8336c652b4d3..956b3b2bd8ef7455fcfe283dd140690ac325c0fb 100644
--- a/samples/rust/rust_misc_device.rs
+++ b/samples/rust/rust_misc_device.rs
@@ -104,7 +104,7 @@
     miscdevice::{MiscDevice, MiscDeviceOptions, MiscDeviceRegistration},
     new_mutex,
     prelude::*,
-    sync::Mutex,
+    sync::{Arc, Mutex},
     types::ARef,
     uaccess::{UserSlice, UserSliceReader, UserSliceWriter},
 };
@@ -136,7 +136,10 @@ fn init(_module: &'static ThisModule) -> impl PinInit<Self, Error> {
         };
 
         try_pin_init!(Self {
-            _miscdev <- MiscDeviceRegistration::register(options, ()),
+            _miscdev <- MiscDeviceRegistration::register(
+                options,
+                Arc::pin_init(new_mutex!(Inner { value: 0_i32 }), GFP_KERNEL)?
+            ),
         })
     }
 }
@@ -145,10 +148,8 @@ struct Inner {
     value: i32,
 }
 
-#[pin_data(PinnedDrop)]
 struct RustMiscDevice {
-    #[pin]
-    inner: Mutex<Inner>,
+    inner: Arc<Mutex<Inner>>,
     dev: ARef<Device>,
 }
 
@@ -156,7 +157,7 @@ struct RustMiscDevice {
 impl MiscDevice for RustMiscDevice {
     type Ptr = Pin<KBox<Self>>;
 
-    type RegistrationData = ();
+    type RegistrationData = Arc<Mutex<Inner>>;
 
     fn open(_file: &File, misc: &MiscDeviceRegistration<Self>) -> Result<Pin<KBox<Self>>> {
         let dev = ARef::from(misc.device());
@@ -164,9 +165,9 @@ fn open(_file: &File, misc: &MiscDeviceRegistration<Self>) -> Result<Pin<KBox<Se
         dev_info!(dev, "Opening Rust Misc Device Sample\n");
 
         KBox::try_pin_init(
-            try_pin_init! {
+            try_init! {
                 RustMiscDevice {
-                    inner <- new_mutex!( Inner{ value: 0_i32 } ),
+                    inner: misc.data().clone(),
                     dev: dev,
                 }
             },
@@ -193,9 +194,8 @@ fn ioctl(me: Pin<&RustMiscDevice>, _file: &File, cmd: u32, arg: usize) -> Result
     }
 }
 
-#[pinned_drop]
-impl PinnedDrop for RustMiscDevice {
-    fn drop(self: Pin<&mut Self>) {
+impl Drop for RustMiscDevice {
+    fn drop(&mut self) {
         dev_info!(self.dev, "Exiting the Rust Misc Device Sample\n");
     }
 }

-- 
2.48.1