Re: [PATCH 2/3] rust: sync: Assert Lock::is_locked in Guard::new for debug builds

Boqun Feng
2024-11-20T23:59:51Z

On Wed, Nov 20, 2024 at 05:30:42PM -0500, Lyude Paul wrote:
> Since we're allowing code to unsafely claim that it's acquired a lock
> let's use the new Lock::is_locked() function so that when debug assertions
> are enabled, we can verify that the lock has actually been acquired.
>
> Signed-off-by: Lyude Paul <lyude@redhat.com>
> ---
> rust/kernel/sync/lock.rs | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/rust/kernel/sync/lock.rs b/rust/kernel/sync/lock.rs
> index 542f846ac02b2..0a7f2ed767423 100644
> --- a/rust/kernel/sync/lock.rs
> +++ b/rust/kernel/sync/lock.rs
> @@ -244,10 +244,17 @@ fn drop(&mut self) {
> impl<'a, T: ?Sized, B: Backend> Guard<'a, T, B> {
> /// Constructs a new immutable lock guard.
> ///
> + /// # Panics
> + ///
> + /// This function will panic if debug assertions are enabled and `lock` is not actually
> + /// acquired.
> + ///
> /// # Safety
> ///
> /// The caller must ensure that it owns the lock.
> pub unsafe fn new(lock: &'a Lock<T, B>, state: B::GuardState) -> Self {
> + debug_assert!(lock.is_locked());

You should just use lockdep_assert_held() here, and there's no need for
new_unchecked().

Regards,
Boqun

> +
> Self {
> lock,
> state,
> --
> 2.47.0
>