Re: [Qemu-ppc] [PATCH v2 2/4] spapr: fix error reporting in xics_system_init()

[David Gibson]

On Fri, May 19, 2017 at 12:32:12PM +0200, Greg Kurz wrote:
> If the user explicitely asked for kernel-irqchip support and "xics-kvm"
> initialization fails, we shouldn't fallback to emulated "xics" as we
> do now. It is also awkward to print an error message when we have an
> errp pointer argument.
> 
> Let's use the errp argument to report the error and let the caller decide.
> This simplifies the code as we don't need a local Error * here.
> 
> Signed-off-by: Greg Kurz <address@hidden>

Concept looks good, but..

> ---
> v2: - total rewrite
> ---
>  hw/ppc/spapr.c |   13 ++++++-------
>  1 file changed, 6 insertions(+), 7 deletions(-)
> 
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 91f7434861a8..75e298b4c6be 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -128,18 +128,14 @@ static void xics_system_init(MachineState *machine, int 
> nr_irqs, Error **errp)
>      sPAPRMachineState *spapr = SPAPR_MACHINE(machine);
>  
>      if (kvm_enabled()) {
> -        Error *err = NULL;
> -
>          if (machine_kernel_irqchip_allowed(machine) &&
>              !xics_kvm_init(spapr, errp)) {
>              spapr->icp_type = TYPE_KVM_ICP;
> -            spapr->ics = spapr_ics_create(spapr, TYPE_ICS_KVM, nr_irqs, 
> &err);
> +            spapr->ics = spapr_ics_create(spapr, TYPE_ICS_KVM, nr_irqs, 
> errp);

I believe there are reasons you're not supposed to just pass an errp
through to a subordinate function.  Instead you're supposed to have a
local Error * and use error_propagate().

>          }
>          if (machine_kernel_irqchip_required(machine) && !spapr->ics) {
> -            error_reportf_err(err,
> -                              "kernel_irqchip requested but unavailable: ");
> -        } else {
> -            error_free(err);
> +            error_prepend(errp, "kernel_irqchip requested but unavailable: 
> ");
> +            return;
>          }
>      }
>  
> @@ -147,6 +143,9 @@ static void xics_system_init(MachineState *machine, int 
> nr_irqs, Error **errp)
>          xics_spapr_init(spapr);
>          spapr->icp_type = TYPE_ICP;
>          spapr->ics = spapr_ics_create(spapr, TYPE_ICS_SIMPLE, nr_irqs, errp);
> +        if (!spapr->ics) {

It would also be more standard to check the returned error, rather
than the other result.

> +            return;
> +        }
>      }
>  }
>  
> 

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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