From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg Kroah-Hartman Subject: Re: [RFC PATCH 1/6] driver core: add a bus notification to temporarily reject driver binding Date: Sun, 11 Nov 2012 06:21:52 +0100 Message-ID: <20121111052152.GA5795@kroah.com> References: <1352555839-18961-1-git-send-email-jiang.liu@huawei.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Alex Williamson , Yinghai Lu , Jiang Liu , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Hanjun Guo To: Jiang Liu Return-path: Content-Disposition: inline In-Reply-To: <1352555839-18961-1-git-send-email-jiang.liu@huawei.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On Sat, Nov 10, 2012 at 09:57:14PM +0800, Jiang Liu wrote: > From: Jiang Liu > > There are several requirements to temporarily reject device driver > binding. Possible usage cases as below: > 1) We should avoid binding an unsafe driver to a device belonging to > an active VFIO group, otherwise it will break the DMA isolation > property of VFIO. > 2) When hot-removing a PCI hierachy, we should avoid binding device > drivers to PCI devices going to be removed during the window > between unbinding of device driver and destroying of device nodes. > 3) When hot-adding a PCI host bridge, we should temporarily disable > driver binding before setting up corresponding IOMMU and IOAPIC. > > We may add a flag into struct device to temporarily disable driver > binding as in this thread https://patchwork.kernel.org/patch/1535721/. I totally do not understand. The bus controls this, if it does not want to bind a device to a driver, then don't do it. It's really quite simple to just block the probe callback the bus gets, right? Why create all of this extra, and confusing, interface instead? > This patch proposes another solution to temporarily disable driver > binding by using bus notification mechanisms. It adds an notification > event to solicit if anybody has objections when binding a driver to a > device. Sorry, but no, don't do this, it's way more confusing. greg k-h