Re: [PATCH 2/7] s390/cio: Set vfio-ccw FSM state before ioeventfd

[Eric Farman <farman@linux.ibm.com>]

On 5/6/19 10:51 AM, Cornelia Huck wrote:
> On Fri,  3 May 2019 15:49:07 +0200
> Eric Farman <farman@linux.ibm.com> wrote:
> 
>> Otherwise, the guest can believe it's okay to start another I/O
>> and bump into the non-idle state.  This results in a cc=3
>> (or cc=2 with the pending async CSCH/HSCH code [1]) to the guest,
> 
> I think you can now refer to cc=2, as the csch/hsch is on its way in :)

Woohoo!  :)

> 
>> which is unfortunate since everything is otherwise working normally.
>>
>> [1] https://patchwork.kernel.org/comment/22588563/
>>
>> Signed-off-by: Eric Farman <farman@linux.ibm.com>
>>
>> ---
>>
>> I think this might've been part of Pierre's FSM cleanup?
> 
> Not sure if I saw this before, but there have been quite a number of
> patches going around...

I guess I should have said his original cleanup from last year.  I 
didn't find it, but it also seems familiar to me.

> 
>> ---
>>   drivers/s390/cio/vfio_ccw_drv.c | 6 +++---
>>   1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/s390/cio/vfio_ccw_drv.c b/drivers/s390/cio/vfio_ccw_drv.c
>> index 0b3b9de45c60..ddd21b6149fd 100644
>> --- a/drivers/s390/cio/vfio_ccw_drv.c
>> +++ b/drivers/s390/cio/vfio_ccw_drv.c
>> @@ -86,11 +86,11 @@ static void vfio_ccw_sch_io_todo(struct work_struct *work)
>>   	}
>>   	memcpy(private->io_region->irb_area, irb, sizeof(*irb));
>>   
>> -	if (private->io_trigger)
>> -		eventfd_signal(private->io_trigger, 1);
>> -
>>   	if (private->mdev && is_final)
>>   		private->state = VFIO_CCW_STATE_IDLE;
>> +
>> +	if (private->io_trigger)
>> +		eventfd_signal(private->io_trigger, 1);
>>   }
>>   
>>   /*
>