On Thu 17 Dec 12:49 CST 2020, Alex Elder wrote: > On 12/17/20 12:21 PM, rishabhb@xxxxxxxxxxxxxx wrote: > > On 2020-12-17 08:12, Alex Elder wrote: > > > On 12/15/20 4:55 PM, Bjorn Andersson wrote: > > > > On Sat 12 Dec 14:48 CST 2020, Rishabh Bhatnagar wrote: > > > > > > > > > Create an unbound high priority workqueue for recovery tasks. > > > > > > I have been looking at a different issue that is caused by > > > crash notification. > > > > > > What happened was that the modem crashed while the AP was > > > in system suspend (or possibly even resuming) state. And > > > there is no guarantee that the system will have called a > > > driver's ->resume callback when the crash notification is > > > delivered. > > > > > > In my case (in the IPA driver), handling a modem crash > > > cannot be done while the driver is suspended; i.e. the > > > activities in its ->resume callback must be completed > > > before we can recover from the crash. > > > > > > For this reason I might like to change the way the > > > crash notification is handled, but what I'd rather see > > > is to have the work queue not run until user space > > > is unfrozen, which would guarantee that all drivers > > > that have registered for a crash notification will > > > be resumed when the notification arrives. > > > > > > I'm not sure how that interacts with what you are > > > looking for here. I think the workqueue could still > > > be unbound, but its work would be delayed longer before > > > any notification (and recovery) started. > > > > > > -Alex > > > > > > > > In that case, maybe adding a "WQ_FREEZABLE" flag might help? > > Yes, exactly. But how does that affect whatever you were > trying to do with your patch? > I don't see any impact on Rishabh's change in particular, syntactically it would just be a matter of adding another flag and the impact would be separate from his patch. In other words, creating a separate work queue to get the long running work off the system_wq and making sure that these doesn't run during suspend & resume seems very reasonable to me. The one piece that I'm still contemplating is the HIPRIO, I would like to better understand the actual impact - or perhaps is this a result of everyone downstream moving all their work to HIPRIO work queues, starving the recovery? Regards, Bjorn
