Michael S. Tsirkin wrote: > On Sun, Jul 12, 2009 at 03:03:53PM +0300, Gleb Natapov wrote: > >> Use RCU locking for mask/ack notifiers lists. >> >> Signed-off-by: Gleb Natapov <[email protected]> >> --- >> 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); >> > > I think we need synchronize_rcu here as well. If the user adds a > notifier, he expects to get notified of irqs immediately > after the function returns, not after the next rcu grace period. >
Agreed.
>
>> }
>>
>> @@ -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
>>
>> --
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>>
> --
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