Re: [Qemu-devel] [PATCH v3 4/7] s390x: refactor error handling for XSCH handler

[Cornelia Huck <cohuck@redhat.com>]

On Tue, 17 Oct 2017 16:04:50 +0200
Halil Pasic <pasic@linux.vnet.ibm.com> wrote:

> Simplify the error handling of the XSCH.  Let the code detecting the
> condition tell (in a less ambiguous way) how it's to be handled. No
> changes in behavior.
> 
> Signed-off-by: Halil Pasic <pasic@linux.vnet.ibm.com>
> ---
>  hw/s390x/css.c         | 17 +++++------------
>  include/hw/s390x/css.h |  2 +-
>  target/s390x/ioinst.c  | 23 ++++-------------------
>  3 files changed, 10 insertions(+), 32 deletions(-)

Looks sane (quoting the whole mail for the benefit of the qemu-s390x list).

> 
> diff --git a/hw/s390x/css.c b/hw/s390x/css.c
> index ff5a05c34b..1b3be7729d 100644
> --- a/hw/s390x/css.c
> +++ b/hw/s390x/css.c
> @@ -1402,20 +1402,17 @@ out:
>      return ret;
>  }
>  
> -int css_do_xsch(SubchDev *sch)
> +IOInstEnding css_do_xsch(SubchDev *sch)
>  {
>      SCSW *s = &sch->curr_status.scsw;
>      PMCW *p = &sch->curr_status.pmcw;
> -    int ret;
>  
>      if (~(p->flags) & (PMCW_FLAGS_MASK_DNV | PMCW_FLAGS_MASK_ENA)) {
> -        ret = -ENODEV;
> -        goto out;
> +        return IOINST_CC_NOT_OPERATIONAL;
>      }
>  
>      if (s->ctrl & SCSW_CTRL_MASK_STCTL) {
> -        ret = -EINPROGRESS;
> -        goto out;
> +        return IOINST_CC_STATUS_PRESENT;
>      }
>  
>      if (!(s->ctrl & SCSW_CTRL_MASK_FCTL) ||
> @@ -1423,8 +1420,7 @@ 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 = -EBUSY;
> -        goto out;
> +        return IOINST_CC_BUSY;
>      }
>  
>      /* Cancel the current operation. */
> @@ -1436,10 +1432,7 @@ int css_do_xsch(SubchDev *sch)
>      sch->last_cmd_valid = false;
>      s->dstat = 0;
>      s->cstat = 0;
> -    ret = 0;
> -
> -out:
> -    return ret;
> +    return IOINST_CC_EXPECTED;
>  }
>  
>  int css_do_csch(SubchDev *sch)
> diff --git a/include/hw/s390x/css.h b/include/hw/s390x/css.h
> index 10bde18452..3c319c9096 100644
> --- a/include/hw/s390x/css.h
> +++ b/include/hw/s390x/css.h
> @@ -240,7 +240,7 @@ void css_conditional_io_interrupt(SubchDev *sch);
>  int css_do_stsch(SubchDev *sch, SCHIB *schib);
>  bool css_schid_final(int m, uint8_t cssid, uint8_t ssid, uint16_t schid);
>  int css_do_msch(SubchDev *sch, const SCHIB *schib);
> -int css_do_xsch(SubchDev *sch);
> +IOInstEnding css_do_xsch(SubchDev *sch);
>  int css_do_csch(SubchDev *sch);
>  int css_do_hsch(SubchDev *sch);
>  IOInstEnding css_do_ssch(SubchDev *sch, ORB *orb);
> diff --git a/target/s390x/ioinst.c b/target/s390x/ioinst.c
> index 16b5cf2fed..4ad07e9181 100644
> --- a/target/s390x/ioinst.c
> +++ b/target/s390x/ioinst.c
> @@ -42,8 +42,6 @@ void ioinst_handle_xsch(S390CPU *cpu, uint64_t reg1)
>  {
>      int cssid, ssid, schid, m;
>      SubchDev *sch;
> -    int ret = -ENODEV;
> -    int cc;
>  
>      if (ioinst_disassemble_sch_ident(reg1, &m, &cssid, &ssid, &schid)) {
>          program_interrupt(&cpu->env, PGM_OPERAND, 4);
> @@ -51,24 +49,11 @@ void ioinst_handle_xsch(S390CPU *cpu, uint64_t reg1)
>      }
>      trace_ioinst_sch_id("xsch", cssid, ssid, schid);
>      sch = css_find_subch(m, cssid, ssid, schid);
> -    if (sch && css_subch_visible(sch)) {
> -        ret = css_do_xsch(sch);
> -    }
> -    switch (ret) {
> -    case -ENODEV:
> -        cc = 3;
> -        break;
> -    case -EBUSY:
> -        cc = 2;
> -        break;
> -    case 0:
> -        cc = 0;
> -        break;
> -    default:
> -        cc = 1;
> -        break;
> +    if (!sch || !css_subch_visible(sch)) {
> +        setcc(cpu, 3);
> +        return;
>      }
> -    setcc(cpu, cc);
> +    setcc(cpu, css_do_xsch(sch));
>  }
>  
>  void ioinst_handle_csch(S390CPU *cpu, uint64_t reg1)