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

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Message-ID: <20241120223442.2491136-3-lyude@redhat.com>
Date: Wed, 20 Nov 2024 17:30:42 -0500
From: Lyude Paul <lyude@...hat.com>
To: rust-for-linux@...r.kernel.org
Cc: linux-kernel@...r.kernel.org,
	Miguel Ojeda <ojeda@...nel.org>,
	Alex Gaynor <alex.gaynor@...il.com>,
	Boqun Feng <boqun.feng@...il.com>,
	Gary Guo <gary@...yguo.net>,
	Björn Roy Baron <bjorn3_gh@...tonmail.com>,
	Benno Lossin <benno.lossin@...ton.me>,
	Andreas Hindborg <a.hindborg@...nel.org>,
	Alice Ryhl <aliceryhl@...gle.com>,
	Trevor Gross <tmgross@...ch.edu>,
	Martin Rodriguez Reboredo <yakoyoku@...il.com>,
	Valentin Obst <kernel@...entinobst.de>,
	Filipe Xavier <felipe_life@...e.com>
Subject: [PATCH 2/3] rust: sync: Assert Lock::is_locked in Guard::new for debug builds

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@...hat.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());
+
         Self {
             lock,
             state,
-- 
2.47.0