1 files changed, 14 insertions, 9 deletions

diff --git a/rust/kernel/miscdevice.rs b/rust/kernel/miscdevice.rs
index 939278bc7b03..6373fe183b27 100644
--- a/rust/kernel/miscdevice.rs
+++ b/rust/kernel/miscdevice.rs
@@ -17,7 +17,6 @@ use crate::{
     mm::virt::VmaNew,
     prelude::*,
     seq_file::SeqFile,
-    str::CStr,
     types::{ForeignOwnable, Opaque},
 };
 use core::{marker::PhantomData, mem::MaybeUninit, pin::Pin};
@@ -34,7 +33,7 @@ impl MiscDeviceOptions {
     pub const fn into_raw<T: MiscDevice>(self) -> bindings::miscdevice {
         // SAFETY: All zeros is valid for this C type.
         let mut result: bindings::miscdevice = unsafe { MaybeUninit::zeroed().assume_init() };
-        result.minor = bindings::MISC_DYNAMIC_MINOR as _;
+        result.minor = bindings::MISC_DYNAMIC_MINOR as ffi::c_int;
         result.name = self.name.as_char_ptr();
         result.fops = MiscdeviceVTable::<T>::build();
         result
@@ -45,7 +44,13 @@ impl MiscDeviceOptions {
 ///
 /// # Invariants
 ///
-/// `inner` is a registered misc device.
+/// - `inner` contains a `struct miscdevice` that is registered using
+///   `misc_register()`.
+/// - This registration remains valid for the entire lifetime of the
+///   [`MiscDeviceRegistration`] instance.
+/// - Deregistration occurs exactly once in [`Drop`] via `misc_deregister()`.
+/// - `inner` wraps a valid, pinned `miscdevice` created using
+///   [`MiscDeviceOptions::into_raw`].
 #[repr(transparent)]
 #[pin_data(PinnedDrop)]
 pub struct MiscDeviceRegistration<T> {
@@ -92,7 +97,7 @@ impl<T: MiscDevice> MiscDeviceRegistration<T> {
         // function tells the borrow-checker that the `&Device` reference must not outlive the
         // `&MiscDeviceRegistration<T>` used to obtain it, so the last use of the reference must be
         // before the underlying `struct miscdevice` is destroyed.
-        unsafe { Device::as_ref((*self.as_raw()).this_device) }
+        unsafe { Device::from_raw((*self.as_raw()).this_device) }
     }
 }
 
@@ -217,7 +222,7 @@ impl<T: MiscDevice> MiscdeviceVTable<T> {
         // type.
         //
         // SAFETY: The open call of a file can access the private data.
-        unsafe { (*raw_file).private_data = ptr.into_foreign().cast() };
+        unsafe { (*raw_file).private_data = ptr.into_foreign() };
 
         0
     }
@@ -228,7 +233,7 @@ impl<T: MiscDevice> MiscdeviceVTable<T> {
     /// must be associated with a `MiscDeviceRegistration<T>`.
     unsafe extern "C" fn release(_inode: *mut bindings::inode, file: *mut bindings::file) -> c_int {
         // SAFETY: The release call of a file owns the private data.
-        let private = unsafe { (*file).private_data }.cast();
+        let private = unsafe { (*file).private_data };
         // SAFETY: The release call of a file owns the private data.
         let ptr = unsafe { <T::Ptr as ForeignOwnable>::from_foreign(private) };
 
@@ -272,7 +277,7 @@ impl<T: MiscDevice> MiscdeviceVTable<T> {
     /// `file` must be a valid file that is associated with a `MiscDeviceRegistration<T>`.
     unsafe extern "C" fn ioctl(file: *mut bindings::file, cmd: c_uint, arg: c_ulong) -> c_long {
         // SAFETY: The ioctl call of a file can access the private data.
-        let private = unsafe { (*file).private_data }.cast();
+        let private = unsafe { (*file).private_data };
         // SAFETY: Ioctl calls can borrow the private data of the file.
         let device = unsafe { <T::Ptr as ForeignOwnable>::borrow(private) };
 
@@ -297,7 +302,7 @@ impl<T: MiscDevice> MiscdeviceVTable<T> {
         arg: c_ulong,
     ) -> c_long {
         // SAFETY: The compat ioctl call of a file can access the private data.
-        let private = unsafe { (*file).private_data }.cast();
+        let private = unsafe { (*file).private_data };
         // SAFETY: Ioctl calls can borrow the private data of the file.
         let device = unsafe { <T::Ptr as ForeignOwnable>::borrow(private) };
 
@@ -318,7 +323,7 @@ impl<T: MiscDevice> MiscdeviceVTable<T> {
     /// - `seq_file` must be a valid `struct seq_file` that we can write to.
     unsafe extern "C" fn show_fdinfo(seq_file: *mut bindings::seq_file, file: *mut bindings::file) {
         // SAFETY: The release call of a file owns the private data.
-        let private = unsafe { (*file).private_data }.cast();
+        let private = unsafe { (*file).private_data };
         // SAFETY: Ioctl calls can borrow the private data of the file.
         let device = unsafe { <T::Ptr as ForeignOwnable>::borrow(private) };
         // SAFETY: