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Date: Wed, 10 May 2017 12:44:53 -0400
From: Keith Busch <keith.busch@intel.com>
To: Wei Zhang <wzhang@fb.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>,
        "linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
        Wesley Yung <wesley.yung@microsemi.com>,
        Sammy Hui <sammy.hui@intel.com>,
        Joseph Gruher <joseph.r.gruher@intel.com>,
        Krishna Dhulipala <krishnad@fb.com>
Subject: Re: [PATCH 1/2] pcie/dpc: Skip DPC event if device is not present
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On Wed, May 10, 2017 at 04:35:06PM +0000, Wei Zhang wrote:
> Hi Keith,
> 
> I see.  I thought the current CPU root complex does not support such a use case, ie removing the DPC switch device itself and might result in kernel panic.  But I agree this will make the code future-proof when CPU does support such a case in the future.

What do you mean in the future? I do this today (hotplug enclosures),
but I need this fix in place otherwise we get a use-after-free when
the DPC work queue runs after the hotplug code freed the topology that
includes the DPC parts.