1 files changed, 31 insertions, 15 deletions

diff --git a/rust/kernel/drm/device.rs b/rust/kernel/drm/device.rs
index 14c1aa402951..d29c477e89a8 100644
--- a/rust/kernel/drm/device.rs
+++ b/rust/kernel/drm/device.rs
@@ -5,6 +5,7 @@
 //! C header: [`include/linux/drm/drm_device.h`](srctree/include/linux/drm/drm_device.h)
 
 use crate::{
+    alloc::allocator::Kmalloc,
     bindings, device, drm,
     drm::driver::AllocImpl,
     error::from_err_ptr,
@@ -12,7 +13,7 @@ use crate::{
     prelude::*,
     types::{ARef, AlwaysRefCounted, Opaque},
 };
-use core::{mem, ops::Deref, ptr, ptr::NonNull};
+use core::{alloc::Layout, mem, ops::Deref, ptr, ptr::NonNull};
 
 #[cfg(CONFIG_DRM_LEGACY)]
 macro_rules! drm_legacy_fields {
@@ -53,10 +54,8 @@ macro_rules! drm_legacy_fields {
 ///
 /// `self.dev` is a valid instance of a `struct device`.
 #[repr(C)]
-#[pin_data]
 pub struct Device<T: drm::Driver> {
     dev: Opaque<bindings::drm_device>,
-    #[pin]
     data: T::Data,
 }
 
@@ -83,19 +82,23 @@ impl<T: drm::Driver> Device<T> {
         major: T::INFO.major,
         minor: T::INFO.minor,
         patchlevel: T::INFO.patchlevel,
-        name: T::INFO.name.as_char_ptr() as *mut _,
-        desc: T::INFO.desc.as_char_ptr() as *mut _,
+        name: T::INFO.name.as_char_ptr().cast_mut(),
+        desc: T::INFO.desc.as_char_ptr().cast_mut(),
 
         driver_features: drm::driver::FEAT_GEM,
         ioctls: T::IOCTLS.as_ptr(),
         num_ioctls: T::IOCTLS.len() as i32,
-        fops: &Self::GEM_FOPS as _,
+        fops: &Self::GEM_FOPS,
     };
 
     const GEM_FOPS: bindings::file_operations = drm::gem::create_fops();
 
     /// Create a new `drm::Device` for a `drm::Driver`.
     pub fn new(dev: &device::Device, data: impl PinInit<T::Data, Error>) -> Result<ARef<Self>> {
+        // `__drm_dev_alloc` uses `kmalloc()` to allocate memory, hence ensure a `kmalloc()`
+        // compatible `Layout`.
+        let layout = Kmalloc::aligned_layout(Layout::new::<Self>());
+
         // SAFETY:
         // - `VTABLE`, as a `const` is pinned to the read-only section of the compilation,
         // - `dev` is valid by its type invarants,
@@ -103,7 +106,7 @@ impl<T: drm::Driver> Device<T> {
             bindings::__drm_dev_alloc(
                 dev.as_raw(),
                 &Self::VTABLE,
-                mem::size_of::<Self>(),
+                layout.size(),
                 mem::offset_of!(Self, dev),
             )
         }
@@ -117,9 +120,13 @@ impl<T: drm::Driver> Device<T> {
         // - `raw_data` is a valid pointer to uninitialized memory.
         // - `raw_data` will not move until it is dropped.
         unsafe { data.__pinned_init(raw_data) }.inspect_err(|_| {
-            // SAFETY: `__drm_dev_alloc()` was successful, hence `raw_drm` must be valid and the
+            // SAFETY: `raw_drm` is a valid pointer to `Self`, given that `__drm_dev_alloc` was
+            // successful.
+            let drm_dev = unsafe { Self::into_drm_device(raw_drm) };
+
+            // SAFETY: `__drm_dev_alloc()` was successful, hence `drm_dev` must be valid and the
             // refcount must be non-zero.
-            unsafe { bindings::drm_dev_put(ptr::addr_of_mut!((*raw_drm.as_ptr()).dev).cast()) };
+            unsafe { bindings::drm_dev_put(drm_dev) };
         })?;
 
         // SAFETY: The reference count is one, and now we take ownership of that reference as a
@@ -135,11 +142,17 @@ impl<T: drm::Driver> Device<T> {
     ///
     /// `ptr` must be a valid pointer to a `struct device` embedded in `Self`.
     unsafe fn from_drm_device(ptr: *const bindings::drm_device) -> *mut Self {
-        let ptr: *const Opaque<bindings::drm_device> = ptr.cast();
-
         // SAFETY: By the safety requirements of this function `ptr` is a valid pointer to a
         // `struct drm_device` embedded in `Self`.
-        unsafe { crate::container_of!(ptr, Self, dev) }.cast_mut()
+        unsafe { crate::container_of!(Opaque::cast_from(ptr), Self, dev) }.cast_mut()
+    }
+
+    /// # Safety
+    ///
+    /// `ptr` must be a valid pointer to `Self`.
+    unsafe fn into_drm_device(ptr: NonNull<Self>) -> *mut bindings::drm_device {
+        // SAFETY: By the safety requirements of this function, `ptr` is a valid pointer to `Self`.
+        unsafe { &raw mut (*ptr.as_ptr()).dev }.cast()
     }
 
     /// Not intended to be called externally, except via declare_drm_ioctls!()
@@ -154,7 +167,7 @@ impl<T: drm::Driver> Device<T> {
     /// Additionally, callers must ensure that the `struct device`, `ptr` is pointing to, is
     /// embedded in `Self`.
     #[doc(hidden)]
-    pub unsafe fn as_ref<'a>(ptr: *const bindings::drm_device) -> &'a Self {
+    pub unsafe fn from_raw<'a>(ptr: *const bindings::drm_device) -> &'a Self {
         // SAFETY: By the safety requirements of this function `ptr` is a valid pointer to a
         // `struct drm_device` embedded in `Self`.
         let ptr = unsafe { Self::from_drm_device(ptr) };
@@ -191,8 +204,11 @@ unsafe impl<T: drm::Driver> AlwaysRefCounted for Device<T> {
     }
 
     unsafe fn dec_ref(obj: NonNull<Self>) {
+        // SAFETY: `obj` is a valid pointer to `Self`.
+        let drm_dev = unsafe { Self::into_drm_device(obj) };
+
         // SAFETY: The safety requirements guarantee that the refcount is non-zero.
-        unsafe { bindings::drm_dev_put(obj.cast().as_ptr()) };
+        unsafe { bindings::drm_dev_put(drm_dev) };
     }
 }
 
@@ -200,7 +216,7 @@ impl<T: drm::Driver> AsRef<device::Device> for Device<T> {
     fn as_ref(&self) -> &device::Device {
         // SAFETY: `bindings::drm_device::dev` is valid as long as the DRM device itself is valid,
         // which is guaranteed by the type invariant.
-        unsafe { device::Device::as_ref((*self.as_raw()).dev) }
+        unsafe { device::Device::from_raw((*self.as_raw()).dev) }
     }
 }