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)? > > > > >> 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. Regards, Halil [..]
