Re: [patch V3 17/17] Bluetooth: hci_qca: Fix the teardown problem for real

[Anna-Maria Behnsen]

On Wed, 23 Nov 2022, Thomas Gleixner wrote:

> While discussing solutions for the teardown problem which results from
> circular dependencies between timers and workqueues, where timers schedule
> work from their timer callback and workqueues arm the timers from work
> items, it was discovered that the recent fix to the QCA code is incorrect.
> 
> That commit fixes the obvious problem of using del_timer() instead of
> del_timer_sync() and reorders the teardown calls to
> 
>    destroy_workqueue(wq);
>    del_timer_sync(t);
> 
> This makes it less likely to explode, but it's still broken:
> 
>    destroy_workqueue(wq);
>    /* After this point @wq cannot be touched anymore */
> 
>    ---> timer expires
>          queue_work(wq) <---- Results in a NULl pointer dereference

The last NIT (for now...): s/NULl/NULL

Thanks,

	Anna-Maria