From 4ead6c37b04aa35943ea270f09db18ebb38e63ff Mon Sep 17 00:00:00 2001
From: Danilo Krummrich <dakr@redhat.com>
Date: Wed, 19 Jun 2024 15:39:17 +0200
Subject: [PATCH] device: rust: improve safety comments
Improve the wording of safety comments to be more explicit about what
exactly is guaranteed to be valid.
Suggested-by: Benno Lossin <benno.lossin@proton.me>
Signed-off-by: Danilo Krummrich <dakr@redhat.com>
Link: https://lore.kernel.org/r/20240619133949.64638-1-dakr@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
rust/kernel/device.rs | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/rust/kernel/device.rs b/rust/kernel/device.rs
index e445e87fb7d73..851018eef885e 100644
--- a/rust/kernel/device.rs
+++ b/rust/kernel/device.rs
@@ -30,8 +30,10 @@
///
/// # Invariants
///
-/// The pointer stored in `Self` is non-null and valid for the lifetime of the `ARef` instance. In
-/// particular, the `ARef` instance owns an increment on the underlying object’s reference count.
+/// A `Device` instance represents a valid `struct device` created by the C portion of the kernel.
+///
+/// Instances of this type are always reference-counted, that is, a call to `get_device` ensures
+/// that the allocation remains valid at least until the matching call to `put_device`.
///
/// `bindings::device::release` is valid to be called from any thread, hence `ARef<Device>` can be
/// dropped from any thread.
@@ -58,7 +60,8 @@ pub unsafe fn from_raw(ptr: *mut bindings::device) -> ARef<Self> {
// CAST: `Self` is a `repr(transparent)` wrapper around `bindings::device`.
let ptr = ptr.cast::<Self>();
- // SAFETY: By the safety requirements, ptr is valid.
+ // SAFETY: `ptr` is valid by the safety requirements of this function. By the above call to
+ // `bindings::get_device` we also own a reference to the underlying `struct device`.
unsafe { ARef::from_raw(ptr::NonNull::new_unchecked(ptr)) }
}
--
GitLab