From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:29470 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726579AbhANNEN (ORCPT ); Thu, 14 Jan 2021 08:04:13 -0500 Received: from pps.filterd (m0098416.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 10ED2wQ9074497 for ; Thu, 14 Jan 2021 08:03:32 -0500 Received: from pps.reinject (localhost [127.0.0.1]) by mx0b-001b2d01.pphosted.com with ESMTP id 362p9prch8-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT) for ; Thu, 14 Jan 2021 08:03:32 -0500 Received: from m0098416.ppops.net (m0098416.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.36/8.16.0.36) with SMTP id 10ED3TNB079056 for ; Thu, 14 Jan 2021 08:03:31 -0500 Subject: Re: [RFC 1/1] s390/cio: Remove uevent-suppress from css driver References: <20201124093407.23189-1-vneethv@linux.ibm.com> <20201124093407.23189-2-vneethv@linux.ibm.com> <20201124140220.77c65539.cohuck@redhat.com> <4be7e163-1118-d365-7d25-df39ba78181f@linux.vnet.ibm.com> <0b4e34b7-7a4e-71b0-8a64-ea909e64f416@linux.ibm.com> <20201208183054.44f4fc2d.cohuck@redhat.com> <20201209135203.0008ab18.pasic@linux.ibm.com> <20201215191307.281c6e6f.cohuck@redhat.com> <20201219073316.1be609d5.pasic@linux.ibm.com> <20201221164634.11cd3813.cohuck@redhat.com> <20201221175117.2c5f5fcb.pasic@linux.ibm.com> From: Boris Fiuczynski Message-ID: Date: Thu, 14 Jan 2021 14:03:25 +0100 MIME-Version: 1.0 In-Reply-To: <20201221175117.2c5f5fcb.pasic@linux.ibm.com> Content-Type: text/plain; charset="utf-8"; format="flowed" Content-Language: en-US Content-Transfer-Encoding: 8bit List-ID: To: Halil Pasic , Cornelia Huck Cc: Vineeth Vijayan , Vineeth Vijayan , oberpar@linux.ibm.com, linux-s390@vger.kernel.org, farman@linux.ibm.com On 12/21/20 5:51 PM, Halil Pasic wrote: > On Mon, 21 Dec 2020 16:46:34 +0100 > Cornelia Huck wrote: > >> On Sat, 19 Dec 2020 07:33:16 +0100 >> Halil Pasic 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. > >> 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. > > I agree. I didn't look into the details, in general I think removing > quirks specific to 390 (when possible) is a good thing. > > Regards, > Halil > -- Mit freundlichen Grüßen/Kind regards Boris Fiuczynski IBM Deutschland Research & Development GmbH Vorsitzender des Aufsichtsrats: Gregor Pillen Geschäftsführung: Dirk Wittkopp Sitz der Gesellschaft: Böblingen Registergericht: Amtsgericht Stuttgart, HRB 243294