[PATCH] ARM(64): KVM: add signed type cast for comparation

[PATCH] ARM(64): KVM: add signed type cast for comparation

[Chen Gang]

'len' is 'unsigned long' which is never less than zero.

So need a related type cast for comparation.

The related warning (when building ARM64 with allmodconfig):

  arch/arm64/kvm/../../../arch/arm/kvm/mmio.c:82:2: warning: comparison of unsigned expression < 0 is always false [-Wtype-limits]


Signed-off-by: Chen Gang <gang.chen@asianux.com>
---
 arch/arm/kvm/mmio.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/arm/kvm/mmio.c b/arch/arm/kvm/mmio.c
index b8e06b7..626dfc8 100644
--- a/arch/arm/kvm/mmio.c
+++ b/arch/arm/kvm/mmio.c
@@ -79,7 +79,7 @@ static int decode_hsr(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
 	}
 
 	len = kvm_vcpu_dabt_get_as(vcpu);
-	if (unlikely(len < 0))
+	if (unlikely((long)len < 0))
 		return len;
 
 	is_write = kvm_vcpu_dabt_iswrite(vcpu);
-- 
1.7.7.6

[PATCH] ARM(64): KVM: add signed type cast for comparation

[Chen Gang]

Hello Maintainers:

Please help check the patch whether OK or not, when you have time.

Thanks.

On 07/22/2013 11:20 AM, Chen Gang wrote:
> 'len' is 'unsigned long' which is never less than zero.
> 
> So need a related type cast for comparation.
> 
> The related warning (when building ARM64 with allmodconfig):
> 
>   arch/arm64/kvm/../../../arch/arm/kvm/mmio.c:82:2: warning: comparison of unsigned expression < 0 is always false [-Wtype-limits]
> 
> 
> Signed-off-by: Chen Gang <gang.chen@asianux.com>
> ---
>  arch/arm/kvm/mmio.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/arch/arm/kvm/mmio.c b/arch/arm/kvm/mmio.c
> index b8e06b7..626dfc8 100644
> --- a/arch/arm/kvm/mmio.c
> +++ b/arch/arm/kvm/mmio.c
> @@ -79,7 +79,7 @@ static int decode_hsr(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
>  	}
>  
>  	len = kvm_vcpu_dabt_get_as(vcpu);
> -	if (unlikely(len < 0))
> +	if (unlikely((long)len < 0))
>  		return len;
>  
>  	is_write = kvm_vcpu_dabt_iswrite(vcpu);
> 


-- 
Chen Gang

[PATCH] ARM(64): KVM: add signed type cast for comparation

[Christoffer Dall]

On Mon, Jul 22, 2013 at 11:20:12AM +0800, Chen Gang wrote:
> 'len' is 'unsigned long' which is never less than zero.
> 
> So need a related type cast for comparation.
> 
> The related warning (when building ARM64 with allmodconfig):
> 
>   arch/arm64/kvm/../../../arch/arm/kvm/mmio.c:82:2: warning: comparison of unsigned expression < 0 is always false [-Wtype-limits]
> 

Hmmm, interesting, I don't get this error with my compiler.

> 
> Signed-off-by: Chen Gang <gang.chen@asianux.com>
> ---
>  arch/arm/kvm/mmio.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/arch/arm/kvm/mmio.c b/arch/arm/kvm/mmio.c
> index b8e06b7..626dfc8 100644
> --- a/arch/arm/kvm/mmio.c
> +++ b/arch/arm/kvm/mmio.c
> @@ -79,7 +79,7 @@ static int decode_hsr(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
>  	}
>  
>  	len = kvm_vcpu_dabt_get_as(vcpu);
> -	if (unlikely(len < 0))
> +	if (unlikely((long)len < 0))
>  		return len;
>  
>  	is_write = kvm_vcpu_dabt_iswrite(vcpu);
> -- 
> 1.7.7.6

I think the proper fix is to declare len as an int instead.  I'll queue
that instead.

Thanks,
-Christoffer

[PATCH] ARM(64): KVM: add signed type cast for comparation

[Chen Gang]

On 07/30/2013 11:45 AM, Christoffer Dall wrote:
> On Mon, Jul 22, 2013 at 11:20:12AM +0800, Chen Gang wrote:
>> 'len' is 'unsigned long' which is never less than zero.
>>
>> So need a related type cast for comparation.
>>
>> The related warning (when building ARM64 with allmodconfig):
>>
>>   arch/arm64/kvm/../../../arch/arm/kvm/mmio.c:82:2: warning: comparison of unsigned expression < 0 is always false [-Wtype-limits]
>>
> 
> Hmmm, interesting, I don't get this error with my compiler.
> 
>>
>> Signed-off-by: Chen Gang <gang.chen@asianux.com>
>> ---
>>  arch/arm/kvm/mmio.c |    2 +-
>>  1 files changed, 1 insertions(+), 1 deletions(-)
>>
>> diff --git a/arch/arm/kvm/mmio.c b/arch/arm/kvm/mmio.c
>> index b8e06b7..626dfc8 100644
>> --- a/arch/arm/kvm/mmio.c
>> +++ b/arch/arm/kvm/mmio.c
>> @@ -79,7 +79,7 @@ static int decode_hsr(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
>>  	}
>>  
>>  	len = kvm_vcpu_dabt_get_as(vcpu);
>> -	if (unlikely(len < 0))
>> +	if (unlikely((long)len < 0))
>>  		return len;
>>  
>>  	is_write = kvm_vcpu_dabt_iswrite(vcpu);
>> -- 
>> 1.7.7.6
> 
> I think the proper fix is to declare len as an int instead.  I'll queue
> that instead.
> 

Yeah, it is fine to me (better than my original fix).

Thanks.
-- 
Chen Gang