Merge tag 'dd-lifetimes-7.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/driver-core/driver-core into drm-rust-next

Higher-Ranked Lifetime Types for Rust device drivers

Replace drvdata() with registration data on the auxiliary bus. Private
data is now scoped to the registration object, removing the ordering
constraints and lifetime complications that came with drvdata().

Add Higher-Ranked Lifetime Types (HRT) so driver structs can borrow
device resources like pci::Bar and IoMem directly, tied to the device
binding scope. This removes the need for Devres indirection and
ARef<Device> in most driver code.

This is a stable tag for other trees to merge.

Signed-off-by: Danilo Krummrich <dakr@kernel.org>

1 files changed, 40 insertions, 6 deletions

diff --git a/rust/kernel/alloc/kbox.rs b/rust/kernel/alloc/kbox.rs
index bd6da02c7ab8..2f8c16473c2c 100644
--- a/rust/kernel/alloc/kbox.rs
+++ b/rust/kernel/alloc/kbox.rs
@@ -19,6 +19,7 @@ use crate::ffi::c_void;
 use crate::fmt;
 use crate::init::InPlaceInit;
 use crate::page::AsPageIter;
+use crate::prelude::*;
 use crate::types::ForeignOwnable;
 use pin_init::{InPlaceWrite, Init, PinInit, ZeroableOption};
 
@@ -256,6 +257,27 @@ where
         Ok(Box(ptr.cast(), PhantomData))
     }
 
+    /// Creates a new zero-initialized `Box<T, A>`.
+    ///
+    /// New memory is allocated with `A` and the [`__GFP_ZERO`] flag. The allocation may fail, in
+    /// which case an error is returned. For ZSTs no memory is allocated.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let b = KBox::<[u8; 128]>::zeroed(GFP_KERNEL)?;
+    /// assert_eq!(*b, [0; 128]);
+    /// # Ok::<(), Error>(())
+    /// ```
+    pub fn zeroed(flags: Flags) -> Result<Self, AllocError>
+    where
+        T: Zeroable,
+    {
+        // SAFETY: `__GFP_ZERO` guarantees the memory is zeroed; `T: Zeroable` guarantees that
+        // all-zeroes is a valid bit pattern for `T`.
+        Ok(unsafe { Self::new_uninit(flags | __GFP_ZERO)?.assume_init() })
+    }
+
     /// Constructs a new `Pin<Box<T, A>>`. If `T` does not implement [`Unpin`], then `x` will be
     /// pinned in memory and can't be moved.
     #[inline]
@@ -455,7 +477,7 @@ where
 
 // SAFETY: The pointer returned by `into_foreign` comes from a well aligned
 // pointer to `T` allocated by `A`.
-unsafe impl<T: 'static, A> ForeignOwnable for Box<T, A>
+unsafe impl<T, A> ForeignOwnable for Box<T, A>
 where
     A: Allocator,
 {
@@ -465,8 +487,14 @@ where
         core::mem::align_of::<T>()
     };
 
-    type Borrowed<'a> = &'a T;
-    type BorrowedMut<'a> = &'a mut T;
+    type Borrowed<'a>
+        = &'a T
+    where
+        Self: 'a;
+    type BorrowedMut<'a>
+        = &'a mut T
+    where
+        Self: 'a;
 
     fn into_foreign(self) -> *mut c_void {
         Box::into_raw(self).cast()
@@ -494,13 +522,19 @@ where
 
 // SAFETY: The pointer returned by `into_foreign` comes from a well aligned
 // pointer to `T` allocated by `A`.
-unsafe impl<T: 'static, A> ForeignOwnable for Pin<Box<T, A>>
+unsafe impl<T, A> ForeignOwnable for Pin<Box<T, A>>
 where
     A: Allocator,
 {
     const FOREIGN_ALIGN: usize = <Box<T, A> as ForeignOwnable>::FOREIGN_ALIGN;
-    type Borrowed<'a> = Pin<&'a T>;
-    type BorrowedMut<'a> = Pin<&'a mut T>;
+    type Borrowed<'a>
+        = Pin<&'a T>
+    where
+        Self: 'a;
+    type BorrowedMut<'a>
+        = Pin<&'a mut T>
+    where
+        Self: 'a;
 
     fn into_foreign(self) -> *mut c_void {
         // SAFETY: We are still treating the box as pinned.