From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Jiang Liu <liuj97@gmail.com>
Cc: Alex Williamson <alex.williamson@redhat.com>,
Yinghai Lu <yinghai@kernel.org>, Jiang Liu <jiang.liu@huawei.com>,
Joerg Roedel <joerg.roedel@amd.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Hanjun Guo <guohanjun@huawei.com>
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 [thread overview]
Message-ID: <20121111052152.GA5795@kroah.com> (raw)
In-Reply-To: <1352555839-18961-1-git-send-email-jiang.liu@huawei.com>
On Sat, Nov 10, 2012 at 09:57:14PM +0800, Jiang Liu wrote:
> From: Jiang Liu <jiang.liu@huawei.com>
>
> 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
next prev parent reply other threads:[~2012-11-11 5:21 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-10 13:57 [RFC PATCH 1/6] driver core: add a bus notification to temporarily reject driver binding Jiang Liu
2012-11-10 13:57 ` [RFC PATCH 2/6] iommu: pass on BUS_NOTIFY_QUERY_BINDING to iommu group notifier clients Jiang Liu
2012-11-10 13:57 ` [RFC PATCH 3/6] VFIO: unregister IOMMU notifier on error recovery path Jiang Liu
2012-11-13 18:15 ` Alex Williamson
2012-11-10 13:57 ` [RFC PATCH 4/6] VFIO: reject binding driver to devices belonging to active VFIO groups Jiang Liu
2012-11-10 13:57 ` [RFC PATCH 5/6] VFIO: simplify IOMMU group notification handler Jiang Liu
2012-11-10 13:57 ` [RFC PATCH 6/6] VFIO: use ACCESS_ONCE() to guard access to dev->driver Jiang Liu
2012-11-11 5:21 ` Greg Kroah-Hartman [this message]
2012-11-13 16:02 ` [RFC PATCH 1/6] driver core: add a bus notification to temporarily reject driver binding Jiang Liu
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