Re: [PATCHv1] xen/events/fifo: Handle linked events when closing a PIRQ port

[Boris Ostrovsky <boris.ostrovsky@oracle.com>]

On 08/10/2015 01:16 PM, David Vrabel wrote:
> On 10/08/15 17:47, linux@eikelenboom.it wrote:
>> On 2015-08-10 16:24, David Vrabel wrote:
>>> Commit fcdf31a7c162de0c93a2bee51df4688ab0a348f8 (xen/events/fifo:
>>> Handle linked events when closing a port) did not handle closing a
>>> port bound to a PIRQ because these are closed from shutdown_pirq()
>>> which is called with interrupts disabled.
>>>
>>> Defer the close to a work queue where we can safely spin waiting for
>>> the LINKED bit to clear.  For simplicity, the close is always deferred
>>> even if it is not required (i.e., we're already in process context).
>>>
>>> Signed-off-by: David Vrabel <david.vrabel@citrix.com>
>>> Cc: Ross Lagerwall <ross.lagerwall@citrix.com>
>>> ---
>>> Cc: Sander Eikelenboom <linux@eikelenboom.it>
>> Hi David,
>>
>> Tested your patch, don't know for sure but this doesn't seem to work out.
>> I end up with this event channel error on dom0 boot.
>>
>> Which ends in state:
>> Name                                        ID   Mem VCPUs    State
>> Time(s)
>> (null)                                       0  1536     6     r-----
>>   183.8
>>
>> -- 
>> Sander
>>
>> (XEN) [2015-08-10 16:35:34.584] PCI add device 0000:0d:00.0
>> (XEN) [2015-08-10 16:35:34.891] PCI add device 0000:0c:00.0
>> (XEN) [2015-08-10 16:35:35.123] PCI add device 0000:0b:00.0
>> (XEN) [2015-08-10 16:35:35.325] PCI add device 0000:0a:00.0
>> (XEN) [2015-08-10 16:35:35.574] PCI add device 0000:09:00.0
>> (XEN) [2015-08-10 16:35:35.642] PCI add device 0000:09:00.1
>> (XEN) [2015-08-10 16:35:35.872] PCI add device 0000:05:00.0
>> (XEN) [2015-08-10 16:35:36.044] PCI add device 0000:06:01.0
>> (XEN) [2015-08-10 16:35:36.109] PCI add device 0000:06:02.0
>> (XEN) [2015-08-10 16:35:36.293] PCI add device 0000:08:00.0
>> (XEN) [2015-08-10 16:35:36.603] PCI add device 0000:07:00.0
>> (XEN) [2015-08-10 16:35:36.906] PCI add device 0000:04:00.0
>> (XEN) [2015-08-10 16:35:37.074] PCI add device 0000:03:06.0
>> (XEN) [2015-08-10 16:35:39.456] PCI: Using MCFG for segment 0000 bus 00-ff
>> (XEN) [2015-08-10 16:35:49.623] d0: Forcing read-only access to MFN fed00
>> (XEN) [2015-08-10 16:35:51.374] event_channel.c:472:d0v0 EVTCHNOP
>> failure: error -17
> This didn't happen on the test box I used but I can see it is possible
> to rebind a PIRQ whose close is still deferred.
>
> I'm going to revert fcdf31a7c162de0c93a2bee51df4688ab0a348f8
> (xen/events/fifo: Handle linked events when closing a port) for now.


Any updates on these two patches? We started seeing this problem (stale 
events) in our testing when onlining/offlining vcpus in heavily 
oversubscribed guests.

-boris