Re: [PATCH] gpio: gpiolib-cdev: Fix potential &lr->wait.lock deadlock issue

[Andy Shevchenko <andy.shevchenko@xxxxxxxxx>]

On Sun, Jun 25, 2023 at 5:45 PM YE Chengfeng <cyeaa@xxxxxxxxxxxxxx> wrote:
>
> linereq_put_event is called from both interrupt context (e.g.,
> edge_irq_thread) and process context (process_hw_ts_thread).
> Therefore, interrupt should be disabled before acquiring lock
> &lr->wait.lock inside linereq_put_event to avoid deadlock when
> the lock is held in process context and edge_irq_thread comes.
>
> Similarly, linereq_read_unlocked running in process context
> also acquies the same lock. It also need to disable interrupt

acquires

> otherwise deadlock could happen if the irq edge_irq_thread
> comes to execution while the lock is held.
>
> Fix the two potential deadlock issues by spin_lock_irqsave.

Sounds legit to me, but
1) do you have any warning/oops/etc to show the real case?
2) shouldn't we annotate with respective lockdep asserts this code?

-- 
With Best Regards,
Andy Shevchenko