On Thu, 31 Aug 2017 09:32:49 +0200 Thomas Huth <th...@redhat.com> wrote:
> On 31.08.2017 08:38, Cornelia Huck wrote: > > On Thu, 31 Aug 2017 07:51:17 +0200 > > Thomas Huth <th...@redhat.com> 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 <pa...@linux.vnet.ibm.com> > >>> Reported-by: Pierre Morel<pmo...@linux.vnet.ibm.com> > >> > >> 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? Taking a step back and looking at the other I/O instructions and their implementation in qemu: - For those instructions that can set it, cc 1 is set when the subchannel is status pending. That's usually the "default" branch in ioinst.c. - cc 2 is set when the subchannel is "busy" (or, in the case of xsch, "not applicable for xsch"... sigh) This is supposed to be handled via -EBUSY. So, there are actually two problems with the current implementation of xsch: - The return codes are switched around, which this patch fixes. - But "status pending" should also take precedence over "not applicable", if I read the PoP correctly, so the second if needs to be moved up. And yes, it makes sense do add some comments...