On Wed, 2023-05-10 at 08:34 -1000, Tejun Heo wrote: > On Wed, May 10, 2023 at 06:04:26PM +0200, Johannes Berg wrote: > > @@ -2387,7 +2389,13 @@ __acquires(&pool->lock) > > */ > > lockdep_invariant_state(true); > > trace_workqueue_execute_start(work); > > - worker->current_func(work); > > + if (unlikely(pwq->wq->work_mutex)) { > > + mutex_lock(pwq->wq->work_mutex); > > + worker->current_func(work); > > + mutex_unlock(pwq->wq->work_mutex); > > + } else { > > + worker->current_func(work); > > + } > > Ah, I don't know about this. This can't be that difficult to do from the > callee side, right? > Yeah I thought you'd say that :) It isn't difficult, the issue is just that in the case I'm envisioning, you can't just call wiphy_lock() since that would attempt to pause the workqueue, which can't work from on the workqueue itself. So you need wiphy_lock_from_work()/wiphy_unlock_from_work() or remember to use the mutex directly there, which all seemed more error-prone and harder to maintain. But anyway I could easily implement _both_ of these in cfg80211 directly, with just a linked list of works and a single struct work_struct to execute things on the list, with the right locking. That might be easier overall, just at the expense of more churn while converting, but that's not even necessarily _bad_, it would really guarantee that we can tell immediately the work is properly done... I'll play with that idea some, I guess. Would you still want the pause/resume patch anyway, even if I end up not using it then? johannes