Commit 99214efe authored Dec 12, 2024 by Jason Devers Committed by Boqun Feng Jul 11, 2025

rust: sync: Add #[must_use] to Lock::try_lock()

The `Lock::try_lock()` function returns an `Option<Guard<...>>`, but it
currently does not issue a warning if the return value is unused.
To avoid potential bugs, the `#[must_use]` annotation is added to ensure
proper usage.

Note that `T` is `#[must_use]` but `Option<T>` is not.
For more context, see: https://github.com/rust-lang/rust/issues/71368

.

Suggested-by: Alice Ryhl <aliceryhl@google.com>
Link: https://github.com/Rust-for-Linux/linux/issues/1133


Signed-off-by: Jason Devers <dev.json2@gmail.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://lore.kernel.org/r/20241212154753.139563-1-dev.json2@gmail.com

parent daec29dc

rust/kernel/sync/lock.rs

+2 −0

Original line number	Diff line number	Diff line
		@@ -175,6 +175,8 @@ pub fn lock(&self) -> Guard<'_, T, B> {
		/// Tries to acquire the lock.
		///
		/// Returns a guard that can be used to access the data protected by the lock if successful.
		// `Option<T>` is not `#[must_use]` even if `T` is, thus the attribute is needed here.
		#[must_use = "if unused, the lock will be immediately unlocked"]
		pub fn try_lock(&self) -> Option<Guard<'_, T, B>> {
		// SAFETY: The constructor of the type calls `init`, so the existence of the object proves
		// that `init` was called.