linux-kernel - Re: [PATCH linux-next] KVM: x86: Replace IS_ERR() with IS_ERR

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Date:   Mon, 7 Nov 2022 09:30:38 -0800
From:   "H. Peter Anvin" <hpa@...or.com>
To:     yexingchen116@...il.com, seanjc@...gle.com
Cc:     pbonzini@...hat.com, tglx@...utronix.de, mingo@...hat.com,
        bp@...en8.de, dave.hansen@...ux.intel.com, x86@...nel.org,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        ye xingchen <ye.xingchen@....com.cn>
Subject: Re: [PATCH linux-next] KVM: x86: Replace IS_ERR() with IS_ERR_VALUE()

On 10/20/22 04:39, yexingchen116@...il.com wrote:
> From: ye xingchen <ye.xingchen@....com.cn>
> 
> Avoid type casts that are needed for IS_ERR() and use
> IS_ERR_VALUE() instead.
> 
> Signed-off-by: ye xingchen <ye.xingchen@....com.cn>
> ---
>   arch/x86/kvm/x86.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 4bd5f8a751de..1c260f716c3b 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -12414,7 +12414,7 @@ void __user * __x86_set_memory_region(struct kvm *kvm, int id, gpa_t gpa,
>   		 */
>   		hva = vm_mmap(NULL, 0, size, PROT_READ | PROT_WRITE,
>   			      MAP_SHARED | MAP_ANONYMOUS, 0);
> -		if (IS_ERR((void *)hva))
> +		if (IS_ERR_VALUE(hva))
>   			return (void __user *)hva;
>   	} else {
>   		if (!slot || !slot->npages)

This seems to imply IS_ERR() is misdesigned.

It would be nice to have IS_ERR() contain the appropriate casts. If we 
want to enforce that the argument is a pointer, add IS_ERR_PTR()?

	-hpa