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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 46EF2C4321A for ; Fri, 28 Jun 2019 15:56:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 29D5E208C4 for ; Fri, 28 Jun 2019 15:56:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726852AbfF1P4K (ORCPT ); Fri, 28 Jun 2019 11:56:10 -0400 Received: from mx1.redhat.com ([209.132.183.28]:38296 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726707AbfF1P4J (ORCPT ); Fri, 28 Jun 2019 11:56:09 -0400 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 7E08359473; Fri, 28 Jun 2019 15:56:09 +0000 (UTC) Received: from x1.home (ovpn-117-35.phx2.redhat.com [10.3.117.35]) by smtp.corp.redhat.com (Postfix) with ESMTP id 16E9326E64; Fri, 28 Jun 2019 15:56:09 +0000 (UTC) Date: Fri, 28 Jun 2019 09:56:08 -0600 From: Alex Williamson To: Cornelia Huck Cc: kwankhede@nvidia.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mdev: Send uevents around parent device registration Message-ID: <20190628095608.7762d6d0@x1.home> In-Reply-To: <20190627101914.32829440.cohuck@redhat.com> References: <156155924767.11505.11457229921502145577.stgit@gimli.home> <20190627101914.32829440.cohuck@redhat.com> Organization: Red Hat MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Fri, 28 Jun 2019 15:56:09 +0000 (UTC) Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Thu, 27 Jun 2019 10:19:14 +0200 Cornelia Huck wrote: > On Wed, 26 Jun 2019 08:27:58 -0600 > Alex Williamson wrote: > > > This allows udev to trigger rules when a parent device is registered > > or unregistered from mdev. > > > > Signed-off-by: Alex Williamson > > --- > > drivers/vfio/mdev/mdev_core.c | 10 ++++++++-- > > 1 file changed, 8 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c > > index ae23151442cb..ecec2a3b13cb 100644 > > --- a/drivers/vfio/mdev/mdev_core.c > > +++ b/drivers/vfio/mdev/mdev_core.c > > @@ -146,6 +146,8 @@ int mdev_register_device(struct device *dev, const struct mdev_parent_ops *ops) > > { > > int ret; > > struct mdev_parent *parent; > > + char *env_string = "MDEV_STATE=registered"; > > This string is probably reasonable enough. > > > + char *envp[] = { env_string, NULL }; > > > > /* check for mandatory ops */ > > if (!ops || !ops->create || !ops->remove || !ops->supported_type_groups) > > @@ -196,7 +198,8 @@ int mdev_register_device(struct device *dev, const struct mdev_parent_ops *ops) > > list_add(&parent->next, &parent_list); > > mutex_unlock(&parent_list_lock); > > > > - dev_info(dev, "MDEV: Registered\n"); > > + kobject_uevent_env(&dev->kobj, KOBJ_CHANGE, envp); > > I also agree with the positioning here. > > > + > > return 0; > > > > add_dev_err: > > @@ -220,6 +223,8 @@ EXPORT_SYMBOL(mdev_register_device); > > void mdev_unregister_device(struct device *dev) > > { > > struct mdev_parent *parent; > > + char *env_string = "MDEV_STATE=unregistered"; > > Ok. > > > + char *envp[] = { env_string, NULL }; > > > > mutex_lock(&parent_list_lock); > > parent = __find_parent_device(dev); > > @@ -228,7 +233,6 @@ void mdev_unregister_device(struct device *dev) > > mutex_unlock(&parent_list_lock); > > return; > > } > > - dev_info(dev, "MDEV: Unregistering\n"); > > > > list_del(&parent->next); > > mutex_unlock(&parent_list_lock); > > @@ -243,6 +247,8 @@ void mdev_unregister_device(struct device *dev) > > up_write(&parent->unreg_sem); > > > > mdev_put_parent(parent); > > + > > + kobject_uevent_env(&dev->kobj, KOBJ_CHANGE, envp); > > I'm wondering whether we should indicate this uevent earlier: Once we > have detached from the parent list, we're basically done for all > practical purposes. So maybe move this right before we grab the > unreg_sem? That would make it a "this thing is about to go away" (ie. "unregistering") rather than "this thing is gone" ("unregistered"). I was aiming for the latter as the former just seems like it might make userspace race to remove devices. Note that I don't actually make use of this event in mdevctl currently, so we could maybe save it for later, but the symmetry seemed preferable. Thanks, Alex