Re: [PATCH] Xen/PCI: correct notifier used for device removal

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From	David Vrabel <david.vrabel@citrix.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH] Xen/PCI: correct notifier used for device removal
Date	Mon, 01 Feb 2016 14:20:02 +0100
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On 01/02/16 12:16, Jan Beulich wrote:
>>>> On 01.02.16 at 13:01, <david.vrabel@citrix.com> wrote:
>> On 01/02/16 11:58, Jan Beulich wrote:
>>> Commit 599bad38cf added BUS_NOTIFY_REMOVED_DEVICE in order to allow
>>> avoiding removal of IOMMU mappings before the driver actually got
>>> unbound from the device. Naturally we should be using this too.
>>
>> Because otherwise...?  What happens if we don't make this change?
>>
>> Removing IOMMU mappings for a device when the driver is still bound to
>> the device looks wrong to me. Surely the device is still active and may
>> still be performing DMA at this point?
> 
> Exactly - you answered your own question (as does the commit
> referred to).

I misread, sorry.  I think I will reword this as:

"Commit 599bad38cf added BUS_NOTIFY_REMOVED_DEVICE to defer the removal
of IOMMU mappings until the driver has been unbound from the device
(i.e., until it is guaranteed that there are no outstanding DMA
transactions).

Naturally we should be using this too."

David

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Thread

[PATCH] Xen/PCI: correct notifier used for device removal "Jan Beulich" <JBeulich@suse.com> - 2016-02-01 13:00 +0100
  Re: [PATCH] Xen/PCI: correct notifier used for device removal David Vrabel <david.vrabel@citrix.com> - 2016-02-01 13:10 +0100
    Re: [PATCH] Xen/PCI: correct notifier used for device removal "Jan Beulich" <JBeulich@suse.com> - 2016-02-01 13:20 +0100
      Re: [PATCH] Xen/PCI: correct notifier used for device removal "Jan Beulich" <JBeulich@suse.com> - 2016-02-01 14:10 +0100
      Re: [PATCH] Xen/PCI: correct notifier used for device removal David Vrabel <david.vrabel@citrix.com> - 2016-02-01 14:20 +0100

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