[v8,07/21] ppc: well form kvmppc_hint_smt_possible error hint helper

Make kvmppc_hint_smt_possible hint append helper well formed:
switch errp paramter to Error *const * type, as it has uncommon
behavior: not change the pointer to return error, but operate on
already existent error object.
Rename function to be kvmppc_error_append_*_hint.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
---
 target/ppc/kvm_ppc.h | 4 ++--
 hw/ppc/spapr.c       | 2 +-
 target/ppc/kvm.c     | 2 +-
 3 files changed, 4 insertions(+), 4 deletions(-)

On Thu, Dec 05, 2019 at 08:46:21PM +0300, Vladimir Sementsov-Ogievskiy wrote:
> Make kvmppc_hint_smt_possible hint append helper well formed:
> switch errp paramter to Error *const * type, as it has uncommon
> behavior: not change the pointer to return error, but operate on
> already existent error object.
> Rename function to be kvmppc_error_append_*_hint.
> 
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> Reviewed-by: Greg Kurz <groug@kaod.org>

Acked-by: David Gibson <david@gibson.dropbear.id.au>

> ---
>  target/ppc/kvm_ppc.h | 4 ++--
>  hw/ppc/spapr.c       | 2 +-
>  target/ppc/kvm.c     | 2 +-
>  3 files changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/target/ppc/kvm_ppc.h b/target/ppc/kvm_ppc.h
> index 98bd7d5da6..f22daabf51 100644
> --- a/target/ppc/kvm_ppc.h
> +++ b/target/ppc/kvm_ppc.h
> @@ -28,7 +28,7 @@ void kvmppc_set_papr(PowerPCCPU *cpu);
>  int kvmppc_set_compat(PowerPCCPU *cpu, uint32_t compat_pvr);
>  void kvmppc_set_mpic_proxy(PowerPCCPU *cpu, int mpic_proxy);
>  int kvmppc_smt_threads(void);
> -void kvmppc_hint_smt_possible(Error **errp);
> +void kvmppc_error_append_smt_possible_hint(Error *const *errp);
>  int kvmppc_set_smt_threads(int smt);
>  int kvmppc_clear_tsr_bits(PowerPCCPU *cpu, uint32_t tsr_bits);
>  int kvmppc_or_tsr_bits(PowerPCCPU *cpu, uint32_t tsr_bits);
> @@ -164,7 +164,7 @@ static inline int kvmppc_smt_threads(void)
>      return 1;
>  }
>  
> -static inline void kvmppc_hint_smt_possible(Error **errp)
> +static inline void kvmppc_error_append_smt_possible_hint(Error *const *errp)
>  {
>      return;
>  }
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index e076f6023c..1b87eb0ffd 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -2564,7 +2564,7 @@ static void spapr_set_vsmt_mode(SpaprMachineState *spapr, Error **errp)
>                                        " requires the use of VSMT mode %d.\n",
>                                        smp_threads, kvm_smt, spapr->vsmt);
>                  }
> -                kvmppc_hint_smt_possible(&local_err);
> +                kvmppc_error_append_smt_possible_hint(&local_err);
>                  goto out;
>              }
>          }
> diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c
> index c77f9848ec..27ea3ce535 100644
> --- a/target/ppc/kvm.c
> +++ b/target/ppc/kvm.c
> @@ -2076,7 +2076,7 @@ int kvmppc_set_smt_threads(int smt)
>      return ret;
>  }
>  
> -void kvmppc_hint_smt_possible(Error **errp)
> +void kvmppc_error_append_smt_possible_hint(Error *const *errp)
>  {
>      int i;
>      GString *g;

Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> writes:

> Make kvmppc_hint_smt_possible hint append helper well formed:
> switch errp paramter to Error *const * type, as it has uncommon
> behavior: not change the pointer to return error, but operate on
> already existent error object.
> Rename function to be kvmppc_error_append_*_hint.
>
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> Reviewed-by: Greg Kurz <groug@kaod.org>

Let's adapt PATCH 03's commit message, like this:

  ppc: make Error **errp const where it is appropriate

  Mostly, Error ** is for returning error from the function, so the
  callee sets it. However kvmppc_hint_smt_possible gets already filled
  errp parameter. It doesn't change the pointer itself, only change the
  internal state of referenced Error object. So we can make it Error
  *const * errp, to stress the behavior. It will also help coccinelle
  script (in future) to distinguish such cases from common errp usage.

  While there, rename the function to
  kvmppc_error_append_smt_possible_hint().

With something like that:
Reviewed-by: Markus Armbruster <armbru@redhat.com>