Re: [PATCH 3/5] Move irq notifiers lists to its own locking.

[Gleb Natapov <gleb@redhat.com>]

On Mon, Jul 13, 2009 at 02:45:51PM +0300, Michael S. Tsirkin wrote:
> On Mon, Jul 13, 2009 at 12:12:33PM +0300, Gleb Natapov wrote:
> > 
> > Signed-off-by: Gleb Natapov <gleb@redhat.com>
> 
> This one is probably better off left as is,
What do you mean "as is"?

> with RCU in place list modifications are slow anyway.
> 
> > ---
> >  include/linux/kvm_host.h |    1 +
> >  virt/kvm/irq_comm.c      |   16 ++++++++--------
> >  virt/kvm/kvm_main.c      |    1 +
> >  3 files changed, 10 insertions(+), 8 deletions(-)
> > 
> > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> > index 3f2a4fc..12f4ee2 100644
> > --- a/include/linux/kvm_host.h
> > +++ b/include/linux/kvm_host.h
> > @@ -165,6 +165,7 @@ struct kvm {
> >  	spinlock_t irq_routing_lock;
> >  	struct hlist_head mask_notifier_list;
> >  	struct hlist_head irq_ack_notifier_list;
> > +	spinlock_t irq_notifier_list_lock;
> >  #endif
> >  
> >  #ifdef KVM_ARCH_WANT_MMU_NOTIFIER
> > diff --git a/virt/kvm/irq_comm.c b/virt/kvm/irq_comm.c
> > index 3dbba41..59c1cde 100644
> > --- a/virt/kvm/irq_comm.c
> > +++ b/virt/kvm/irq_comm.c
> > @@ -191,17 +191,17 @@ void kvm_notify_acked_irq(struct kvm *kvm, unsigned irqchip, unsigned pin)
> >  void kvm_register_irq_ack_notifier(struct kvm *kvm,
> >  				   struct kvm_irq_ack_notifier *kian)
> >  {
> > -	mutex_lock(&kvm->irq_lock);
> > +	spin_lock(&kvm->irq_notifier_list_lock);
> >  	hlist_add_head_rcu(&kian->link, &kvm->irq_ack_notifier_list);
> > -	mutex_unlock(&kvm->irq_lock);
> > +	spin_unlock(&kvm->irq_notifier_list_lock);
> >  }
> >  
> >  void kvm_unregister_irq_ack_notifier(struct kvm *kvm,
> >  				    struct kvm_irq_ack_notifier *kian)
> >  {
> > -	mutex_lock(&kvm->irq_lock);
> > +	spin_lock(&kvm->irq_notifier_list_lock);
> >  	hlist_del_init_rcu(&kian->link);
> > -	mutex_unlock(&kvm->irq_lock);
> > +	spin_unlock(&kvm->irq_notifier_list_lock);
> >  	synchronize_rcu();
> >  }
> >  
> > @@ -247,18 +247,18 @@ void kvm_free_irq_source_id(struct kvm *kvm, int irq_source_id)
> >  void kvm_register_irq_mask_notifier(struct kvm *kvm, int irq,
> >  				    struct kvm_irq_mask_notifier *kimn)
> >  {
> > -	mutex_lock(&kvm->irq_lock);
> > +	spin_lock(&kvm->irq_notifier_list_lock);
> >  	kimn->irq = irq;
> >  	hlist_add_head_rcu(&kimn->link, &kvm->mask_notifier_list);
> > -	mutex_unlock(&kvm->irq_lock);
> > +	spin_unlock(&kvm->irq_notifier_list_lock);
> >  }
> >  
> >  void kvm_unregister_irq_mask_notifier(struct kvm *kvm, int irq,
> >  				      struct kvm_irq_mask_notifier *kimn)
> >  {
> > -	mutex_lock(&kvm->irq_lock);
> > +	spin_lock(&kvm->irq_notifier_list_lock);
> >  	hlist_del_rcu(&kimn->link);
> > -	mutex_unlock(&kvm->irq_lock);
> > +	spin_unlock(&kvm->irq_notifier_list_lock);
> >  	synchronize_rcu();
> >  }
> >  
> > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> > index 4e31634..018bde8 100644
> > --- a/virt/kvm/kvm_main.c
> > +++ b/virt/kvm/kvm_main.c
> > @@ -948,6 +948,7 @@ static struct kvm *kvm_create_vm(void)
> >  	spin_lock_init(&kvm->irq_routing_lock);
> >  	INIT_HLIST_HEAD(&kvm->mask_notifier_list);
> >  	INIT_HLIST_HEAD(&kvm->irq_ack_notifier_list);
> > +	spin_lock_init(&kvm->irq_notifier_list_lock);
> >  #endif
> >  
> >  #ifdef KVM_COALESCED_MMIO_PAGE_OFFSET
> > -- 
> > 1.6.2.1
> > 
> > --
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--
			Gleb.