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

[David Vrabel <david.vrabel@citrix.com>]

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.

David