LoongArch: KVM: remove unused returns.

[PATCH] LoongArch: KVM: remove unused returns.

Posted by cuitao 4 weeks, 1 day ago

The default branch has already handled all undefined cases,
so the final return statement is redundant.

Signed-off-by: cuitao <cuitao@kylinos.cn>
---
 arch/loongarch/kvm/exit.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/arch/loongarch/kvm/exit.c b/arch/loongarch/kvm/exit.c
index 2ce41f93b2a4..e501867740b1 100644
--- a/arch/loongarch/kvm/exit.c
+++ b/arch/loongarch/kvm/exit.c
@@ -778,9 +778,7 @@ static long kvm_save_notify(struct kvm_vcpu *vcpu)
 		return 0;
 	default:
 		return KVM_HCALL_INVALID_CODE;
-	};
-
-	return KVM_HCALL_INVALID_CODE;
+	}
 };
 
 /*
-- 
2.48.1

Re: [PATCH] LoongArch: KVM: remove unused returns.

Posted by Tiezhu Yang 4 weeks ago

On 2025/9/4 下午12:26, cuitao wrote:
> The default branch has already handled all undefined cases,
> so the final return statement is redundant.
> 
> Signed-off-by: cuitao <cuitao@kylinos.cn>
> ---
>   arch/loongarch/kvm/exit.c | 4 +---
>   1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/arch/loongarch/kvm/exit.c b/arch/loongarch/kvm/exit.c
> index 2ce41f93b2a4..e501867740b1 100644
> --- a/arch/loongarch/kvm/exit.c
> +++ b/arch/loongarch/kvm/exit.c
> @@ -778,9 +778,7 @@ static long kvm_save_notify(struct kvm_vcpu *vcpu)
>   		return 0;
>   	default:
>   		return KVM_HCALL_INVALID_CODE;
> -	};
> -
> -	return KVM_HCALL_INVALID_CODE;
> +	}
>   };
>   
>   /*

In my opinion, there is only one case, no need to use switch case,
the ";" at the end can be removed, the code can be like this:

static long kvm_save_notify(struct kvm_vcpu *vcpu)
{
         unsigned long id, data;

         id   = kvm_read_reg(vcpu, LOONGARCH_GPR_A1);
         data = kvm_read_reg(vcpu, LOONGARCH_GPR_A2);
         if (id == BIT(KVM_FEATURE_STEAL_TIME)) {
                 if (data & ~(KVM_STEAL_PHYS_MASK | KVM_STEAL_PHYS_VALID))
                         return KVM_HCALL_INVALID_PARAMETER;

                 vcpu->arch.st.guest_addr = data;
                 if (!(data & KVM_STEAL_PHYS_VALID))
                         return 0;

                 vcpu->arch.st.last_steal = current->sched_info.run_delay;
                 kvm_make_request(KVM_REQ_STEAL_UPDATE, vcpu);
                 return 0;
         }

         return KVM_HCALL_INVALID_CODE;
}

The following is the diff:

diff --git a/arch/loongarch/kvm/exit.c b/arch/loongarch/kvm/exit.c
index 2ce41f93b2a4..0c18761539fc 100644
--- a/arch/loongarch/kvm/exit.c
+++ b/arch/loongarch/kvm/exit.c
@@ -764,8 +764,7 @@ static long kvm_save_notify(struct kvm_vcpu *vcpu)

         id   = kvm_read_reg(vcpu, LOONGARCH_GPR_A1);
         data = kvm_read_reg(vcpu, LOONGARCH_GPR_A2);
-       switch (id) {
-       case BIT(KVM_FEATURE_STEAL_TIME):
+       if (id == BIT(KVM_FEATURE_STEAL_TIME)) {
                 if (data & ~(KVM_STEAL_PHYS_MASK | KVM_STEAL_PHYS_VALID))
                         return KVM_HCALL_INVALID_PARAMETER;

@@ -776,12 +775,10 @@ static long kvm_save_notify(struct kvm_vcpu *vcpu)
                 vcpu->arch.st.last_steal = current->sched_info.run_delay;
                 kvm_make_request(KVM_REQ_STEAL_UPDATE, vcpu);
                 return 0;
-       default:
-               return KVM_HCALL_INVALID_CODE;
-       };
+       }

         return KVM_HCALL_INVALID_CODE;
-};
+}

  /*
   * kvm_handle_lsx_disabled() - Guest used LSX while disabled in root.

Thanks,
Tiezhu

Re: [PATCH] LoongArch: KVM: remove unused returns.

Posted by cuitao 4 weeks ago

Thanks for the review.

My initial idea was to remove the switch-case structure. 
However, after checking the case value KVM_FEATURE_STEAL_TIME, 
I found there are 13 parallel definitions—and it is unclear when 
this part of the development will be completed later. Therefore, 
I temporarily retained the switch-case structure. 

Now, I have updated the patch according to your suggestion:
- Replaced `switch` with `if` since there is only one case.
- Removed the redundant semicolon after the block.

Please see the updated patch below.

Thanks,
Tiezhu

Re: [PATCH] LoongArch: KVM: remove unused returns.

Posted by Huacai Chen 4 weeks ago

On Thu, Sep 4, 2025 at 4:14 PM cuitao <cuitao@kylinos.cn> wrote:
>
> Thanks for the review.
>
> My initial idea was to remove the switch-case structure.
> However, after checking the case value KVM_FEATURE_STEAL_TIME,
> I found there are 13 parallel definitions—and it is unclear when
> this part of the development will be completed later. Therefore,
> I temporarily retained the switch-case structure.
>
> Now, I have updated the patch according to your suggestion:
> - Replaced `switch` with `if` since there is only one case.
> - Removed the redundant semicolon after the block.
>
> Please see the updated patch below.
It has been applied, don't make useless effort.
https://github.com/chenhuacai/linux/commit/f5d35375a6546bcc5d0993e3a48cdbc3a7217544

Huacai

>
> Thanks,
> Tiezhu

Re: [PATCH] LoongArch: KVM: remove unused returns.

Posted by Bibo Mao 4 weeks ago


On 2025/9/4 下午4:20, Huacai Chen wrote:
> On Thu, Sep 4, 2025 at 4:14 PM cuitao <cuitao@kylinos.cn> wrote:
>>
>> Thanks for the review.
>>
>> My initial idea was to remove the switch-case structure.
>> However, after checking the case value KVM_FEATURE_STEAL_TIME,
>> I found there are 13 parallel definitions—and it is unclear when
>> this part of the development will be completed later. Therefore,
>> I temporarily retained the switch-case structure.
>>
>> Now, I have updated the patch according to your suggestion:
>> - Replaced `switch` with `if` since there is only one case.
>> - Removed the redundant semicolon after the block.
>>
>> Please see the updated patch below.
> It has been applied, don't make useless effort.
> https://github.com/chenhuacai/linux/commit/f5d35375a6546bcc5d0993e3a48cdbc3a7217544
I think that it is unnecessary to replace `switch` with `if` here:)

One thing is that the change is big for such thing, and also there may 
be new case condition in future, just maybe.

Regards
Bibo Mao
> 
> Huacai
> 
>>
>> Thanks,
>> Tiezhu

Re: [PATCH] LoongArch: KVM: remove unused returns.

Posted by Bibo Mao 4 weeks ago


On 2025/9/4 下午12:26, cuitao wrote:
> The default branch has already handled all undefined cases,
> so the final return statement is redundant.
> 
> Signed-off-by: cuitao <cuitao@kylinos.cn>
> ---
>   arch/loongarch/kvm/exit.c | 4 +---
>   1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/arch/loongarch/kvm/exit.c b/arch/loongarch/kvm/exit.c
> index 2ce41f93b2a4..e501867740b1 100644
> --- a/arch/loongarch/kvm/exit.c
> +++ b/arch/loongarch/kvm/exit.c
> @@ -778,9 +778,7 @@ static long kvm_save_notify(struct kvm_vcpu *vcpu)
>   		return 0;
>   	default:
>   		return KVM_HCALL_INVALID_CODE;
> -	};
> -
> -	return KVM_HCALL_INVALID_CODE;
> +	}
>   };
>   
>   /*
> 
Reviewed-by: Bibo Mao <maobibo@loongson.cn>

Re: [PATCH] LoongArch: KVM: remove unused returns.

Posted by Huacai Chen 4 weeks ago

On Thu, Sep 4, 2025 at 2:17 PM Bibo Mao <maobibo@loongson.cn> wrote:
>
>
>
> On 2025/9/4 下午12:26, cuitao wrote:
> > The default branch has already handled all undefined cases,
> > so the final return statement is redundant.
> >
> > Signed-off-by: cuitao <cuitao@kylinos.cn>
> > ---
> >   arch/loongarch/kvm/exit.c | 4 +---
> >   1 file changed, 1 insertion(+), 3 deletions(-)
> >
> > diff --git a/arch/loongarch/kvm/exit.c b/arch/loongarch/kvm/exit.c
> > index 2ce41f93b2a4..e501867740b1 100644
> > --- a/arch/loongarch/kvm/exit.c
> > +++ b/arch/loongarch/kvm/exit.c
> > @@ -778,9 +778,7 @@ static long kvm_save_notify(struct kvm_vcpu *vcpu)
> >               return 0;
> >       default:
> >               return KVM_HCALL_INVALID_CODE;
> > -     };
> > -
> > -     return KVM_HCALL_INVALID_CODE;
> > +     }
> >   };
> >
> >   /*
> >
> Reviewed-by: Bibo Mao <maobibo@loongson.cn>
Applied, thanks.

Huacai

>
>