[PATCH 1/3] firmware: rust: improve safety comments

From: Danilo Krummrich
Date: Wed Jun 19 2024 - 09:21:15 EST


Improve the wording of safety comments to be more explicit about what
exactly is guaranteed to be valid.

Suggested-by: Benno Lossin <benno.lossin@xxxxxxxxx>
Signed-off-by: Danilo Krummrich <dakr@xxxxxxxxxx>
---
rust/kernel/firmware.rs | 13 ++++++-------
1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/rust/kernel/firmware.rs b/rust/kernel/firmware.rs
index b55ea1b45368..386c8fb44785 100644
--- a/rust/kernel/firmware.rs
+++ b/rust/kernel/firmware.rs
@@ -22,8 +22,7 @@
///
/// The pointer is valid, and has ownership over the instance of `struct firmware`.
///
-/// Once requested, the `Firmware` backing buffer is not modified until it is freed when `Firmware`
-/// is dropped.
+/// The `Firmware`'s backing buffer is not modified.
///
/// # Examples
///
@@ -72,22 +71,22 @@ fn as_raw(&self) -> *mut bindings::firmware {

/// Returns the size of the requested firmware in bytes.
pub fn size(&self) -> usize {
- // SAFETY: Safe by the type invariant.
+ // SAFETY: `self.as_raw()` is valid by the type invariant.
unsafe { (*self.as_raw()).size }
}

/// Returns the requested firmware as `&[u8]`.
pub fn data(&self) -> &[u8] {
- // SAFETY: Safe by the type invariant. Additionally, `bindings::firmware` guarantees, if
- // successfully requested, that `bindings::firmware::data` has a size of
- // `bindings::firmware::size` bytes.
+ // SAFETY: `self.as_raw()` is valid by the type invariant. Additionally,
+ // `bindings::firmware` guarantees, if successfully requested, that
+ // `bindings::firmware::data` has a size of `bindings::firmware::size` bytes.
unsafe { core::slice::from_raw_parts((*self.as_raw()).data, self.size()) }
}
}

impl Drop for Firmware {
fn drop(&mut self) {
- // SAFETY: Safe by the type invariant.
+ // SAFETY: `self.as_raw()` is valid by the type invariant.
unsafe { bindings::release_firmware(self.as_raw()) };
}
}

base-commit: de6582833db0e695ba0c548e3cc2ad7dbb6aa260
--
2.45.1