Re: [Qemu-devel] [PATCH 1/9] s390x/css: fix cc handling for XSCH

[Thomas Huth]

On 31.08.2017 08:38, Cornelia Huck wrote:
> On Thu, 31 Aug 2017 07:51:17 +0200
> Thomas Huth <address@hidden> wrote:
> 
>> On 30.08.2017 18:36, Halil Pasic wrote:
>>> The function ioinst_handle_xsch is presenting cc 2 when it's supposed to
>>> present cc 1 and the other way around, because css_do_xsch has the error
>>> codes mixed up. Fixing the error codes also fixes the priority.
>>>
>>> Let us fix this.  
>>
>> (Nit: In case you respin, I'd suggest to remove the last sentence. You
>> already used "fix" two times in the previous one)
> 
> I can also remove it on applying, if Halil agrees (I have not yet
> reviewed it, though).
> 
>>
>>> Signed-off-by: Halil Pasic <address@hidden>
>>> Reported-by: Pierre Morel<address@hidden>  
>>
>> Space missing -------------^
> 
> And I can also add that space on applying :)
> 
>>
>>> ---
>>>  hw/s390x/css.c | 4 ++--
>>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/hw/s390x/css.c b/hw/s390x/css.c
>>> index 1880b1a0ff..a50fb0727e 100644
>>> --- a/hw/s390x/css.c
>>> +++ b/hw/s390x/css.c
>>> @@ -1281,12 +1281,12 @@ int css_do_xsch(SubchDev *sch)
>>>          (!(s->ctrl &
>>>             (SCSW_ACTL_RESUME_PEND | SCSW_ACTL_START_PEND | 
>>> SCSW_ACTL_SUSP))) ||
>>>          (s->ctrl & SCSW_ACTL_SUBCH_ACTIVE)) {
>>> -        ret = -EINPROGRESS;
>>> +        ret = -EBUSY;
>>>          goto out;
>>>      }
>>>  
>>>      if (s->ctrl & SCSW_CTRL_MASK_STCTL) {
>>> -        ret = -EBUSY;
>>> +        ret = -EINPROGRESS;
>>>          goto out;
>>>      }  
>>
>> Using both, EBUSY and EINPROGRESS as error codes sounds very confusing
>> to me here ... what's the difference between busy and in-progress? So
>> while you're at it, maybe you could replace the code for CC 2 ("CANCEL
>> SUBCHANNEL not applicable") with a different error code?
> 
> IIRC, I used these two as they matched my idea of what happens best
> (there's a difference between "subchannel is busy" and "the I/O is
> already in progress, too late to cancel"). "xsch not applicable" is
> very hard to translate to an Unix error code :/

OK, the codes make more sense with your description ==> Maybe simply add
a proper comment for each of the return codes?

 Thomas