From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B03A6C43381 for ; Thu, 14 Feb 2019 16:57:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8ACD6222DD for ; Thu, 14 Feb 2019 16:57:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2502968AbfBNQ56 (ORCPT ); Thu, 14 Feb 2019 11:57:58 -0500 Received: from mx1.redhat.com ([209.132.183.28]:56688 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2502954AbfBNQ5p (ORCPT ); Thu, 14 Feb 2019 11:57:45 -0500 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 455EE2D7EE; Thu, 14 Feb 2019 16:57:44 +0000 (UTC) Received: from gondolin (dhcp-192-213.str.redhat.com [10.33.192.213]) by smtp.corp.redhat.com (Postfix) with ESMTP id 6C468611B0; Thu, 14 Feb 2019 16:57:33 +0000 (UTC) Date: Thu, 14 Feb 2019 17:57:30 +0100 From: Cornelia Huck To: Pierre Morel Cc: borntraeger@de.ibm.com, alex.williamson@redhat.com, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, kvm@vger.kernel.org, frankja@linux.ibm.com, akrowiak@linux.ibm.com, pasic@linux.ibm.com, david@redhat.com, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, freude@linux.ibm.com, mimu@linux.ibm.com Subject: Re: [PATCH v3 1/9] s390: vfio_ap: link the vfio_ap devices to the vfio_ap bus subsystem Message-ID: <20190214175730.4ab609ae.cohuck@redhat.com> In-Reply-To: <9403117a-04a6-8f69-2a61-f96d35a59555@linux.ibm.com> References: <1550152269-6317-1-git-send-email-pmorel@linux.ibm.com> <1550152269-6317-2-git-send-email-pmorel@linux.ibm.com> <20190214155441.087d2a68.cohuck@redhat.com> <9403117a-04a6-8f69-2a61-f96d35a59555@linux.ibm.com> Organization: Red Hat GmbH MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Thu, 14 Feb 2019 16:57:44 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 14 Feb 2019 16:47:30 +0100 Pierre Morel wrote: > On 14/02/2019 15:54, Cornelia Huck wrote: > > On Thu, 14 Feb 2019 14:51:01 +0100 > > Pierre Morel wrote: > >> +++ b/drivers/s390/crypto/vfio_ap_drv.c > >> @@ -24,8 +24,9 @@ MODULE_LICENSE("GPL v2"); > >> > >> static struct ap_driver vfio_ap_drv; > >> > >> -static struct device_type vfio_ap_dev_type = { > >> - .name = VFIO_AP_DEV_TYPE_NAME, > >> +struct matrix_driver { > >> + struct device_driver drv; > >> + int device_count; > > > > This counter basically ensures that at most one device may bind with > > this driver... you'd still have that device on the bus, though. > > yes, this is what is wanted: this driver can only support one device. > May be another matrix driver can support one or more other devices. > > I should update comment message my be. > > > > >> }; > >> > >> struct ap_matrix_dev *matrix_dev; > > >> > >> - matrix_dev->device.type = &vfio_ap_dev_type; > >> dev_set_name(&matrix_dev->device, "%s", VFIO_AP_DEV_NAME); > >> matrix_dev->device.parent = root_device; > >> + matrix_dev->device.bus = &matrix_bus; > >> matrix_dev->device.release = vfio_ap_matrix_dev_release; > >> - matrix_dev->device.driver = &vfio_ap_drv.driver; > >> + matrix_dev->vfio_ap_drv = &vfio_ap_drv; > > > > Can't you get that structure through matrix_dev->device.driver instead > > when you need it in the function below? > > Not anymore. > We have two different drivers and devices > matrix_drv <-> matrix_dev > and > vfio_ap_drv <-> ap_devices > > The driver behind the matrix_dev->dev->driver is matrix_drv > what is needed here is vfio_ap_drv. Wait, we had tacked a driver for ap devices unto a matrix device, which is not on the ap bus? Maybe that's what trips libudev? (And reading further in the current code, it seems we clear that structure _after_ the matrix device had been setup, so how can that even work? Where am I confused?) > > > > >> > >> ret = device_register(&matrix_dev->device); > >> if (ret) > >> goto matrix_reg_err; > >> > >> + ret = driver_register(&matrix_driver.drv); > >> + if (ret) > >> + goto matrix_drv_err; > >> + > > > > As you already have several structures that can be registered exactly > > once (the root device, the bus, the driver, ...), you can already be > > sure that there's only one device on the bus, can't you? > > hum, no I don't think so, no device can register before this module is > loaded, but what does prevent a device to register later from another > module? Not unless you export the interface, I guess.