Re: [PATCH v2 05/12] nbd: Enable lock context analysis

On Mon, 3 Aug 2026 at 20:03, Bart Van Assche <[email protected]> wrote:
>
> On 8/3/26 6:26 AM, Nilay Shroff wrote:
> > On 7/31/26 1:28 AM, Bart Van Assche wrote:
> >> @@ -2773,7 +2776,11 @@ static void __exit nbd_cleanup(void)
> >>       /* Also wait for nbd_dev_remove_work() completes */
> >>       destroy_workqueue(nbd_del_wq);
> >> -    idr_destroy(&nbd_index_idr);
> >> +    {
> >> +        __assume_ctx_lock(&nbd_index_mutex);
> >> +        idr_destroy(&nbd_index_idr);
> >> +    }
> >> +
> >
> > Could we instead introduce a scoped __assume_ctx_lock() helper so we
> > don't need the explicit scope here? Alternatively, would annotating
> > nbd_cleanup() with __context_unsafe be a better fit?
> There is code in nbd_cleanup() that must be protected by a mutex so I
> think that we shouldn't annotate nbd_cleanup() with __context_unsafe().

Just 'context_unsafe(idr_destroy(&nbd_index_idr)); /* comment */'
would be fine here I think. I've used that elsewhere for destructors.
It makes sure that the rest of the code is still checked and is as
simple as it gets.

> Introducing a scoped __assume_ctx_lock() might be overkill.

Agree. Note that __assume_ctx_lock() leaks outside the scope, so a
real scoped __assume_ctx_lock() would just do no-op __acquire() and
__release() using the cleanup.h infrastructure (similar to the init
guards I suppose).