[PATCH] kvm:powerpc:Fix return statements for wrapper functions in the file book3s_64_mmu_hv.c

[PATCH] kvm:powerpc:Fix return statements for wrapper functions in the file book3s_64_mmu_hv.c

[Nicholas Krause]

This fixes the wrapper functions kvm_umap_hva_hv and the function
kvm_unmap_hav_range_hv to return the return value of the function
kvm_handle_hva or kvm_handle_hva_range that they are wrapped to
call internally rather then always making the caller of these
wrapper functions think they always run successfully by returning
the value of zero directly.

Signed-off-by: Nicholas Krause <xerofoify@gmail.com>
---
 arch/powerpc/kvm/book3s_64_mmu_hv.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c
index dab68b7..0905c8f 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_hv.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c
@@ -774,14 +774,12 @@ static int kvm_unmap_rmapp(struct kvm *kvm, unsigned long *rmapp,
 
 int kvm_unmap_hva_hv(struct kvm *kvm, unsigned long hva)
 {
-	kvm_handle_hva(kvm, hva, kvm_unmap_rmapp);
-	return 0;
+	return kvm_handle_hva(kvm, hva, kvm_unmap_rmapp);
 }
 
 int kvm_unmap_hva_range_hv(struct kvm *kvm, unsigned long start, unsigned long end)
 {
-	kvm_handle_hva_range(kvm, start, end, kvm_unmap_rmapp);
-	return 0;
+	return kvm_handle_hva_range(kvm, start, end, kvm_unmap_rmapp);
 }
 
 void kvmppc_core_flush_memslot_hv(struct kvm *kvm,
-- 
2.1.4

Re: [PATCH] kvm:powerpc:Fix return statements for wrapper functions in the file book3s_64_mmu_hv.c

[Alexander Graf]

On 10.08.15 17:27, Nicholas Krause wrote:
> This fixes the wrapper functions kvm_umap_hva_hv and the function
> kvm_unmap_hav_range_hv to return the return value of the function
> kvm_handle_hva or kvm_handle_hva_range that they are wrapped to
> call internally rather then always making the caller of these
> wrapper functions think they always run successfully by returning
> the value of zero directly.
> 
> Signed-off-by: Nicholas Krause <xerofoify@gmail.com>

Paul, could you please take on this one?

Thanks,

Alex

> ---
>  arch/powerpc/kvm/book3s_64_mmu_hv.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c
> index dab68b7..0905c8f 100644
> --- a/arch/powerpc/kvm/book3s_64_mmu_hv.c
> +++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c
> @@ -774,14 +774,12 @@ static int kvm_unmap_rmapp(struct kvm *kvm, unsigned long *rmapp,
>  
>  int kvm_unmap_hva_hv(struct kvm *kvm, unsigned long hva)
>  {
> -	kvm_handle_hva(kvm, hva, kvm_unmap_rmapp);
> -	return 0;
> +	return kvm_handle_hva(kvm, hva, kvm_unmap_rmapp);
>  }
>  
>  int kvm_unmap_hva_range_hv(struct kvm *kvm, unsigned long start, unsigned long end)
>  {
> -	kvm_handle_hva_range(kvm, start, end, kvm_unmap_rmapp);
> -	return 0;
> +	return kvm_handle_hva_range(kvm, start, end, kvm_unmap_rmapp);
>  }
>  
>  void kvmppc_core_flush_memslot_hv(struct kvm *kvm,
> 

Re: [PATCH] kvm:powerpc:Fix return statements for wrapper functions in the file book3s_64_mmu_hv.c

[Michael Ellerman]

On Wed, 2015-08-12 at 21:06 +0200, Alexander Graf wrote:
> 
> On 10.08.15 17:27, Nicholas Krause wrote:
> > This fixes the wrapper functions kvm_umap_hva_hv and the function
> > kvm_unmap_hav_range_hv to return the return value of the function
> > kvm_handle_hva or kvm_handle_hva_range that they are wrapped to
> > call internally rather then always making the caller of these
> > wrapper functions think they always run successfully by returning
> > the value of zero directly.
> > 
> > Signed-off-by: Nicholas Krause <xerofoify@gmail.com>
> 
> Paul, could you please take on this one?

Paul's away for a while can you take it directly?

cheers

Re: [PATCH] kvm:powerpc:Fix return statements for wrapper functions in the file book3s_64_mmu_hv.c

[Paul Mackerras]

On Mon, Aug 10, 2015 at 11:27:31AM -0400, Nicholas Krause wrote:
> This fixes the wrapper functions kvm_umap_hva_hv and the function
> kvm_unmap_hav_range_hv to return the return value of the function
> kvm_handle_hva or kvm_handle_hva_range that they are wrapped to
> call internally rather then always making the caller of these
> wrapper functions think they always run successfully by returning
> the value of zero directly.

In fact these functions do always run successfully, and there is no
bug fixed here (see below).

I don't object to the change per se, since it reduces the code size
very slightly, but the commit message and headline needs to be
reworded to avoid giving the impression that this fixes something.

>  int kvm_unmap_hva_hv(struct kvm *kvm, unsigned long hva)
>  {
> -	kvm_handle_hva(kvm, hva, kvm_unmap_rmapp);
> -	return 0;
> +	return kvm_handle_hva(kvm, hva, kvm_unmap_rmapp);
>  }
>  
>  int kvm_unmap_hva_range_hv(struct kvm *kvm, unsigned long start, unsigned long end)
>  {
> -	kvm_handle_hva_range(kvm, start, end, kvm_unmap_rmapp);
> -	return 0;
> +	return kvm_handle_hva_range(kvm, start, end, kvm_unmap_rmapp);

kvm_handle_hva and kvm_handle_hva_range call the handler function
(kvm_unmap_rmapp in this case) one or more times, and return the
logical OR of the return values from the handler.  Since
kvm_unmap_rmapp always returns 0, the return value from
kvm_handle_hva{,_range} will always be 0 here.

Paul.