From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:56858 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725780AbgLUQwI (ORCPT ); Mon, 21 Dec 2020 11:52:08 -0500 Received: from pps.filterd (m0098420.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 0BLGXNl2171473 for ; Mon, 21 Dec 2020 11:51:27 -0500 Received: from pps.reinject (localhost [127.0.0.1]) by mx0b-001b2d01.pphosted.com with ESMTP id 35jy2v0vfh-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT) for ; Mon, 21 Dec 2020 11:51:27 -0500 Received: from m0098420.ppops.net (m0098420.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.36/8.16.0.36) with SMTP id 0BLGXl1M172836 for ; Mon, 21 Dec 2020 11:51:26 -0500 Date: Mon, 21 Dec 2020 17:51:17 +0100 From: Halil Pasic Subject: Re: [RFC 1/1] s390/cio: Remove uevent-suppress from css driver Message-ID: <20201221175117.2c5f5fcb.pasic@linux.ibm.com> In-Reply-To: <20201221164634.11cd3813.cohuck@redhat.com> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8bit List-ID: To: Cornelia Huck Cc: Vineeth Vijayan , Vineeth Vijayan , oberpar@linux.ibm.com, linux-s390@vger.kernel.org, farman@linux.ibm.com, fiuczy@linux.ibm.com 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. > 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 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