Skip to content

Tracking allocator: mark Spinlock::unlock() as unsafe and provide a safety contract #2156

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 2 commits into from
Nov 5, 2023
Merged

Tracking allocator: mark Spinlock::unlock() as unsafe and provide a safety contract #2156

Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
bc9f073
Provide safety contract for `unlock`
s0me0ne-unkn0wn Nov 5, 2023
b6cc055
Improve comment
s0me0ne-unkn0wn Nov 5, 2023
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
9 changes: 7 additions & 2 deletions polkadot/node/tracking-allocator/src/lib.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -72,8 +72,11 @@ impl<T> Spinlock<T> {
}
}

// SAFETY: It should be only called from the guard's destructor. Calling it explicitly while
// the guard is alive is undefined behavior, as it breaks the security contract of `Deref` and
// `DerefMut`, which implies that lock is held at the moment of dereferencing.
#[inline]
fn unlock(&self) {
unsafe fn unlock(&self) {
self.lock.store(false, Ordering::Release);
}
}
Expand All @@ -97,7 +100,9 @@ impl<T> DerefMut for SpinlockGuard<'_, T> {

impl<T> Drop for SpinlockGuard<'_, T> {
fn drop(&mut self) {
self.lock.unlock();
// SAFETY: Calling `unlock` is only safe when it's guaranteed no guard outlives the
// unlocking point; here, the guard is dropped, so it is safe.
unsafe { self.lock.unlock() }
}
}

Expand Down