Re: [PATCH] KVM: x86: move kvm_create_vcpu_debugfs after last failure point

[Emanuele Giuseppe Esposito]

On 01/04/2020 00:42, Paolo Bonzini wrote:
> The placement of kvm_create_vcpu_debugfs is more or less irrelevant, since
> it cannot fail and userspace should not care about the debugfs entries until
> it knows the vcpu has been created.  Moving it after the last failure
> point removes the need to remove the directory when unwinding the creation.
>
> Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@xxxxxxxxxx>

> ---
>   virt/kvm/kvm_main.c | 4 +---
>   1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 027259af883e..0a78e1d874ed 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -2823,8 +2823,6 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, u32 id)
>   	if (r)
>   		goto vcpu_free_run_page;
>   
> -	kvm_create_vcpu_debugfs(vcpu);
> -
>   	mutex_lock(&kvm->lock);
>   	if (kvm_get_vcpu_by_id(kvm, id)) {
>   		r = -EEXIST;
> @@ -2853,11 +2851,11 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, u32 id)
>   
>   	mutex_unlock(&kvm->lock);
>   	kvm_arch_vcpu_postcreate(vcpu);
> +	kvm_create_vcpu_debugfs(vcpu);
>   	return r;
>   
>   unlock_vcpu_destroy:
>   	mutex_unlock(&kvm->lock);
> -	debugfs_remove_recursive(vcpu->debugfs_dentry);
>   	kvm_arch_vcpu_destroy(vcpu);
>   vcpu_free_run_page:
>   	free_page((unsigned long)vcpu->run);