On Tue, 19 Jan 2021 12:47:24 +0100 Halil Pasic <pasic@xxxxxxxxxxxxx> wrote: > On Thu, 14 Jan 2021 14:03:25 +0100 > Boris Fiuczynski <fiuczy@xxxxxxxxxxxxx> wrote: > > > On 12/21/20 5:51 PM, Halil Pasic wrote: > > > On Mon, 21 Dec 2020 16:46:34 +0100 > > > Cornelia Huck <cohuck@xxxxxxxxxx> wrote: > > > > > >> On Sat, 19 Dec 2020 07:33:16 +0100 > > >> Halil Pasic <pasic@xxxxxxxxxxxxx> wrote: > > >> > > >>> I finally came around to test this. In my experience driverctl works for > > >>> subchannels and vfio_ccw without this patch, and continues to work with > > >>> it. I found the code in driverctl that does the unbind and the implicit > > >>> bind (via drivers_probe after after driver_override was set). > > >>> > > >>> So now I have to ask, how exactly was the original problem diagnosed? > > >>> > > >>> In https://marc.info/?l=linux-s390&m=158591045732735&w=2 there is a > > >>> paragraph like: > > >>> > > >>> """ > > >>> So while there's definitely a good reason for wanting to delay uevents, > > >>> it is also introducing problems. One is udev rules for subchannels that > > >>> are supposed to do something before a driver binds (e.g. setting > > >>> driver_override to bind an I/O subchannel to vfio_ccw instead of > > >>> io_subchannel) are not effective, as the ADD uevent will only be > > >>> generated when the io_subchannel driver is already done with doing all > > >>> setup. Another one is that only the ADD uevent is generated after > > >>> uevent suppression is lifted; any other uevents that might have been > > >>> generated are lost. > > >>> """ > > >>> > > >>> This is not how driverclt works! I.e. it deals with the situation that > > >>> the I/O subchannel was already bound to the io_subchannel driver at > > >>> the time the udev rule installed by driverctl activates (via the > > >>> mechanism I described above). > > >> > > >> That's... weird. It definitely did not work on the LPAR I initially > > >> tried it out on! > > >> > > > > > > I think Boris told me some weeks ago that it didn't work for him either. > > > I will check with him after the winter sleep. > > > > Yesterday I used driverctl successfully for a subchannel on F33. > > > > Not sure what went wrong a couple of months ago but I cannot reproduce > > driverctl not working now. > > Thanks Boris! > > @Conny: IMHO driver_override has to work without this patch. Can you > figure out, why did you claim it does not (and provide instructions > on how to reproduce the problem)? This may have been due to other reasons and only looking like a uevent issue at the first glance; however, I do not have that particular setup anymore, so I guess we'll never know. > > > > > > > > >> However, I think removing the suppression still looks like a good idea: > > >> we still have the "any uevent other than ADD will have been lost" > > >> problem. > > >> > > I totally agree with this. > > @Vineeth: I think the best way to move forward is to respin this patch > with a commit message, that doesn't argue about driver_override. That sounds good to me.
