Re: [Qemu-devel] [PATCH v3 7/7] s390x: refactor error handling for MSCH handler

[Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>]

* Halil Pasic <pasic@linux.vnet.ibm.com> [2017-10-18 13:01:03 +0200]:

> 
> 
> On 10/18/2017 12:02 PM, Cornelia Huck wrote:
> > On Wed, 18 Oct 2017 12:00:05 +0200
> > Thomas Huth <thuth@redhat.com> wrote:
> > 
> >> On 17.10.2017 16:04, Halil Pasic wrote:
> >>> Simplify the error handling of the MSCH.  Let the code detecting the
> >>> condition tell (in a less ambiguous way) how it's to be handled. No
> >>> changes in behavior.  
> >>
> >> ok, so you claim no changes in behavior ...
> >>
> >>> Signed-off-by: Halil Pasic <pasic@linux.vnet.ibm.com>
> >>> ---
> >>>  hw/s390x/css.c         | 18 +++++-------------
> >>>  include/hw/s390x/css.h |  2 +-
> >>>  target/s390x/ioinst.c  | 23 ++++-------------------
> >>>  3 files changed, 10 insertions(+), 33 deletions(-)
> >>>
> >>> diff --git a/hw/s390x/css.c b/hw/s390x/css.c
> >>> index b9e0329825..30fc236946 100644
> >>> --- a/hw/s390x/css.c
> >>> +++ b/hw/s390x/css.c
> >>> @@ -1347,28 +1347,24 @@ static void copy_schib_from_guest(SCHIB *dest, const SCHIB *src)
> >>>      }
> >>>  }
> >>>  
> >>> -int css_do_msch(SubchDev *sch, const SCHIB *orig_schib)
> >>> +IOInstEnding css_do_msch(SubchDev *sch, const SCHIB *orig_schib)
> >>>  {
> >>>      SCSW *s = &sch->curr_status.scsw;
> >>>      PMCW *p = &sch->curr_status.pmcw;
> >>>      uint16_t oldflags;
> >>> -    int ret;
> >>>      SCHIB schib;
> >>>  
> >>>      if (!(sch->curr_status.pmcw.flags & PMCW_FLAGS_MASK_DNV)) {
> >>> -        ret = 0;
> >>> -        goto out;
> >>> +        return IOINST_CC_EXPECTED;
> >>>      }
> >>>  
> >>>      if (s->ctrl & SCSW_STCTL_STATUS_PEND) {
> >>> -        ret = -EINPROGRESS;
> >>> -        goto out;
> >>> +        return IOINST_CC_STATUS_PRESENT;
> >>>      }
> >>>  
> >>>      if (s->ctrl &
> >>>          (SCSW_FCTL_START_FUNC|SCSW_FCTL_HALT_FUNC|SCSW_FCTL_CLEAR_FUNC)) {
> >>> -        ret = -EBUSY;
> >>> -        goto out;
> >>> +        return IOINST_CC_STATUS_PRESENT;
> >>>      }  
> >>
> >> ... but here you change -EBUSY (which got mapped to CC=2) to
> >> CC_STATUS_PRESENT which means CC=1. So that's a change in behavior. i.e.
> >> this is either a bug, or you should update the patch description with a
> >> justification for this change in behavior.
> > 
> > Indeed, that's a bug. We still want cc 2.
> > 
> 
> Agree, it is a bug. It was OK in v1 but was already buggy in
> v2.
> 
> Conny can you fix this up as well please?
> 
> Thanks in advance!
> 
I saw Conny fixed this in her branch. So:
Reviewed-by: Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>

-- 
Dong Jia Shi