Question about aliasing and thread safety

[Nugine]

SQ, CQ and Registrar contain NonNull<io_uring> which point to the same value.

iou/src/submission_queue.rs

Lines 47 to 50 in 045f8d4

	pub struct SubmissionQueue<'ring> {
	ring: NonNull<uring_sys::io_uring>,
	_marker: PhantomData<&'ring mut IoUring>,
	}

iou/src/completion_queue.rs

Lines 14 to 17 in 045f8d4

	pub struct CompletionQueue<'ring> {
	pub(crate) ring: NonNull<uring_sys::io_uring>,
	_marker: PhantomData<&'ring mut IoUring>,
	}

iou/src/registrar/mod.rs

Lines 47 to 50 in 045f8d4

	pub struct Registrar<'ring> {
	ring: NonNull<uring_sys::io_uring>,
	_marker: PhantomData<&'ring mut IoUring>,
	}

NonNull::as_ref and NonNull::as_mut require borrow check.

But if we split (SQ, CQ) into a producer thread and a consumer thread, both of them can access the same value without synchronization and break the borrow rule.

[Nugine]

Here is the only line which calls NonNull::as_mut

iou/src/submission_queue.rs

Line 81 in 045f8d4

prepare_sqe(self.ring.as_mut())

It should be self.ring.as_ptr()