[PATCH 4/4] Convert irq notifiers lists to RCU locking.

[Gleb Natapov <gleb@redhat.com>]

Use RCU locking for mask/ack notifiers lists.

Signed-off-by: Gleb Natapov <gleb@redhat.com>
---
 virt/kvm/irq_comm.c |   20 +++++++++++---------
 1 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/virt/kvm/irq_comm.c b/virt/kvm/irq_comm.c
index 5dde1ef..ba3a115 100644
--- a/virt/kvm/irq_comm.c
+++ b/virt/kvm/irq_comm.c
@@ -179,18 +179,18 @@ void kvm_notify_acked_irq(struct kvm *kvm, unsigned irqchip, unsigned pin)
 			break;
 		}
 	}
-	rcu_read_unlock();
 
-	hlist_for_each_entry(kian, n, &kvm->irq_ack_notifier_list, link)
+	hlist_for_each_entry_rcu(kian, n, &kvm->irq_ack_notifier_list, link)
 		if (kian->gsi == gsi)
 			kian->irq_acked(kian);
+	rcu_read_unlock();
 }
 
 void kvm_register_irq_ack_notifier(struct kvm *kvm,
 				   struct kvm_irq_ack_notifier *kian)
 {
 	mutex_lock(&kvm->irq_lock);
-	hlist_add_head(&kian->link, &kvm->irq_ack_notifier_list);
+	hlist_add_head_rcu(&kian->link, &kvm->irq_ack_notifier_list);
 	mutex_unlock(&kvm->irq_lock);
 }
 
@@ -198,8 +198,9 @@ void kvm_unregister_irq_ack_notifier(struct kvm *kvm,
 				    struct kvm_irq_ack_notifier *kian)
 {
 	mutex_lock(&kvm->irq_lock);
-	hlist_del_init(&kian->link);
+	hlist_del_init_rcu(&kian->link);
 	mutex_unlock(&kvm->irq_lock);
+	synchronize_rcu();
 }
 
 int kvm_request_irq_source_id(struct kvm *kvm)
@@ -246,7 +247,7 @@ void kvm_register_irq_mask_notifier(struct kvm *kvm, int irq,
 {
 	mutex_lock(&kvm->irq_lock);
 	kimn->irq = irq;
-	hlist_add_head(&kimn->link, &kvm->mask_notifier_list);
+	hlist_add_head_rcu(&kimn->link, &kvm->mask_notifier_list);
 	mutex_unlock(&kvm->irq_lock);
 }
 
@@ -254,8 +255,9 @@ void kvm_unregister_irq_mask_notifier(struct kvm *kvm, int irq,
 				      struct kvm_irq_mask_notifier *kimn)
 {
 	mutex_lock(&kvm->irq_lock);
-	hlist_del(&kimn->link);
+	hlist_del_rcu(&kimn->link);
 	mutex_unlock(&kvm->irq_lock);
+	synchronize_rcu();
 }
 
 void kvm_fire_mask_notifiers(struct kvm *kvm, int irq, bool mask)
@@ -263,11 +265,11 @@ void kvm_fire_mask_notifiers(struct kvm *kvm, int irq, bool mask)
 	struct kvm_irq_mask_notifier *kimn;
 	struct hlist_node *n;
 
-	WARN_ON(!mutex_is_locked(&kvm->irq_lock));
-
-	hlist_for_each_entry(kimn, n, &kvm->mask_notifier_list, link)
+	rcu_read_lock();
+	hlist_for_each_entry_rcu(kimn, n, &kvm->mask_notifier_list, link)
 		if (kimn->irq == irq)
 			kimn->func(kimn, mask);
+	rcu_read_unlock();
 }
 
 void kvm_free_irq_routing(struct kvm *kvm)
-- 
1.6.2.1