| Message ID | 1249821671-32356-8-git-send-email-gleb@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Sun, Aug 09, 2009 at 05:52:30PM +0300, Avi Kivity wrote: > On 08/09/2009 03:41 PM, Gleb Natapov wrote: >> Signed-off-by: Gleb Natapov<gleb@redhat.com> >> --- >> 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 ce28cb7..8791ce8 100644 >> --- a/include/linux/kvm_host.h >> +++ b/include/linux/kvm_host.h >> @@ -178,6 +178,7 @@ 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; >> > > Again, why? > Because later patches remove irq_lock entirely and lock is need for write even with rcu. So instead of reusing irq_lock to protect those structures on write I introduce locks with self descriptive names. -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 08/09/2009 03:41 PM, Gleb Natapov wrote: > Signed-off-by: Gleb Natapov<gleb@redhat.com> > --- > 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 ce28cb7..8791ce8 100644 > --- a/include/linux/kvm_host.h > +++ b/include/linux/kvm_host.h > @@ -178,6 +178,7 @@ 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; > Again, why?
On 08/09/2009 05:49 PM, Gleb Natapov wrote: > On Sun, Aug 09, 2009 at 05:52:30PM +0300, Avi Kivity wrote: > >> On 08/09/2009 03:41 PM, Gleb Natapov wrote: >> >>> Signed-off-by: Gleb Natapov<gleb@redhat.com> >>> --- >>> 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 ce28cb7..8791ce8 100644 >>> --- a/include/linux/kvm_host.h >>> +++ b/include/linux/kvm_host.h >>> @@ -178,6 +178,7 @@ 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; >>> >>> >> Again, why? >> >> > Because later patches remove irq_lock entirely and lock is need for > write even with rcu. So instead of reusing irq_lock to protect those > structures on write I introduce locks with self descriptive names. > I prefer a /* protected by irq_lock */ rather than lock proliferation. Locks should be split only if they are contended, and your rcu work removes any possible contention.
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index ce28cb7..8791ce8 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -178,6 +178,7 @@ 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 55eb6f6..65f66f1 100644 --- a/virt/kvm/irq_comm.c +++ b/virt/kvm/irq_comm.c @@ -188,17 +188,17 @@ 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(); } @@ -244,18 +244,18 @@ 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 2f4a47e..c108edc 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -947,6 +947,7 @@ 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
Signed-off-by: Gleb Natapov <gleb@redhat.com> --- 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(-)