On Tue, 23 Aug 2022 08:41:00 +0200, Greg Kroah-Hartman wrote: > > On Tue, Aug 23, 2022 at 10:26:59AM +0800, Linyu Yuan wrote: > > > > On 8/22/2022 9:24 PM, Heikki Krogerus wrote: > > > Hi, > > > > > > On Sat, Aug 20, 2022 at 08:40:52PM +0200, Greg Kroah-Hartman wrote: > > > > On Fri, Aug 19, 2022 at 06:32:43PM +0200, Takashi Iwai wrote: > > > > > Hi, > > > > > > > > > > we've got multiple reports about 5.19 kernel starting crashing after > > > > > some time, and this turned out to be triggered by ucsi_acpi driver. > > > > > The details are found in: > > > > > https://bugzilla.suse.com/show_bug.cgi?id=1202386 > > > > > > > > > > The culprit seems to be the commit 87d0e2f41b8c > > > > > usb: typec: ucsi: add a common function ucsi_unregister_connectors() > > > > Adding Heikki to the thread... > > > > > > > > > This commit looks as if it were a harmless cleanup, but this failed in > > > > > a subtle way. Namely, in the error scenario, the driver gets an error > > > > > at ucsi_register_altmodes(), and goes to the error handling to release > > > > > the resources. Through this refactoring, the release part was unified > > > > > to a funciton ucsi_unregister_connectors(). And there, it has a NULL > > > > > check of con->wq, and it bails out the loop if it's NULL. > > > > > Meanwhile, ucsi_register_port() itself still calls destroy_workqueue() > > > > > and clear con->wq at its error path. This ended up in the leftover > > > > > power supply device with the uninitialized / cleared device. > > > > > > > > > > It was confirmed that the problem could be avoided by a simple > > > > > revert. > > > > I'll be glad to revert this now, unless Heikki thinks: > > > > > > > > > I guess another fix could be removing the part clearing con->wq, i.e. > > > > > > > > > > --- a/drivers/usb/typec/ucsi/ucsi.c > > > > > +++ b/drivers/usb/typec/ucsi/ucsi.c > > > > > @@ -1192,11 +1192,6 @@ static int ucsi_register_port(struct ucsi *ucsi, int index) > > > > > out_unlock: > > > > > mutex_unlock(&con->lock); > > > > > - if (ret && con->wq) { > > > > > - destroy_workqueue(con->wq); > > > > > - con->wq = NULL; > > > > > - } > > > > > - > > > > > return ret; > > > > > } > > > > > > > > > > ... but it's totally untested and I'm not entirely sure whether it's > > > > > better. > > > > that is any better? > > > No, I don't think that's better. Right now I would prefer that we play > > > it safe and revert. > > > > > > The conditions are different in the two places where the ports are > > > unregistered in this driver. Therefore I don't think it makes sense > > > to use a function like ucsi_unregister_connectors() that tries to > > > cover both cases. It will always be a little bit fragile. > > > > > > Instead we could introduce a function that can be used to remove a > > > single port. That would leave the handling of the conditions to the > > > callers of the function, but it would still remove the boilerplate. > > > That would be much safer IMO. > > > > > > But to fix this problem, I think we should revert. > > > > but revert will happen on several stable branch, right ? > > If someone sends it to me, yes :) > > {hint} OK, will submit :) Takashi
