On Fri, 2023-05-05 at 11:51 -1000, Tejun Heo wrote: > Hello, Johannes. > > On Fri, May 05, 2023 at 11:05:45PM +0200, Johannes Berg wrote: > ... > > The implementation of (2) is a bit ... awkward, @Tejun, @Lai, there's no > > way to "pause" an ordered workqueue, is there? I came up with the below > > patch, but it's a bit ugly and requires a lot of context switches. Just > > flushing isn't enough since then some work might start and hang on > > acquiring the lock. > > There isn't currently but workqueue already does something similar for > freezing by temporarily setting max_active to zero, > Ah, nice. I had thought about it but a lot of places didn't like 0 so wasn't sure whether or not it was allowed :) > [snip] > and then do set_max_active(wq, 0) followed by flush_workqueue(), it should > be paused until max_active is restored to 1. It probably would be better to > add a separate pause / resume interface which sets a per-wq flag which is > read by pwq_adjust_max_active() tho. Anyways, it's not difficult to > implement at all. Ok cool, I'll take a look at it at some point. I think it would greatly simplify the locking etc. in wifi because then we don't need to worry about the cancel_work_sync() or flush_work() or flush_workqueue() deadlocks. Thanks! johannes
