Re: [PATCH 2/3] KVM: Centralize slots_lock aquisition during KVM_CREATE_IRQCHIP

[Avi Kivity <avi@redhat.com>]

On 12/15/2010 06:43 PM, Takuya Yoshikawa wrote:
> From: Takuya Yoshikawa<yoshikawa.takuya@oss.ntt.co.jp>
>
> Move slots_lock aquisition from kvm_ioapic_init() and kvm_create_pic()
> to their caller.
>
> As a result, x86's KVM_CREATE_IRQCHIP is now covered by a unified slots_lock
> section, including kvm_setup_default_irq_routing().
>
>

I'm not sure about this...

> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -3300,6 +3300,7 @@ long kvm_arch_vm_ioctl(struct file *filp,
>   		struct kvm_pic *vpic;
>
>   		mutex_lock(&kvm->lock);
> +		mutex_lock(&kvm->slots_lock);

here, the reader might wonder why we take slots_lock, since we aren't 
manipulating anything covered by the lock directly.

>   		r = -EEXIST;
>   		if (kvm->arch.vpic)
>   			goto create_irqchip_unlock;
> @@ -3308,10 +3309,8 @@ long kvm_arch_vm_ioctl(struct file *filp,
>   		if (vpic) {
>   			r = kvm_ioapic_init(kvm);
>   			if (r) {
> -				mutex_lock(&kvm->slots_lock);

and here, the reader might wonder why we don't take slots_lock, which 
protects io_bus.

Maybe we ought to move slots_lock acquisition to kvm_io_bus_register() 
and friends.

-- 
error compiling committee.c: too many arguments to function