Claude review: rust: add Work::disable_sync

[Claude Code Review Bot <claude-review@example.com>]

Patch Review

**Minor concern: should this really be `unsafe`?**

```rust
+    pub unsafe fn disable_sync(&self) {
+        let ptr: *const Self = self;
+        // SAFETY: `self` points to a valid initialized work.
+        let raw_work = unsafe { Self::raw_get(ptr) };
+        // SAFETY: `raw_work` is a valid embedded `work_struct`.
+        unsafe { bindings::disable_work_sync(raw_work) };
+    }
```

The safety doc says:

```rust
+    /// # Safety
+    ///
+    /// Must be called from a sleepable context if the work was last queued on a non-BH
+    /// workqueue.
```

This is reasonable — `disable_work_sync()` can sleep, so calling it from atomic context would be a bug. However, this pattern ("must be called from sleepable context") is very common in kernel APIs and many Rust wrappers handle it differently (e.g., via type-level guarantees or just making it safe with a documented precondition, since calling from atomic context is already UB-adjacent behavior the kernel catches with `might_sleep()` debugging). Consider whether making this `unsafe` is the right abstraction level — the Rust workqueue `Queue` type's methods like `enqueue` are safe despite having their own context requirements.

Also, the `# Safety` section is documenting a caller requirement but this is a method on `&self` — the naming convention in kernel Rust is typically to use `# Safety` for `unsafe` preconditions, which this does, but you might also want a `# Panics` or general doc section clarifying when it's valid to call. Minor style nit.

**Missing C helper**: The patch adds a Rust wrapper for `disable_work_sync` but doesn't add a corresponding C helper in `rust/helpers/workqueue.c`. Looking at the binding, `bindings::disable_work_sync` would need to resolve to the C function. Since `disable_work_sync()` in `include/linux/workqueue.h` is a regular (non-inline, non-macro) extern function, this should work via direct bindgen without a helper. This is fine.

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