[PATCH 8/8 v2] Change irq_lock from mutex to spinlock.

[Gleb Natapov]

Change irq_lock from mutex to spinlock. We do not sleep while holding
it.

Signed-off-by: Gleb Natapov <g...@redhat.com>
---
 include/linux/kvm_host.h |    2 +-
 virt/kvm/irq_comm.c      |   28 ++++++++++++++--------------
 virt/kvm/kvm_main.c      |    2 +-
 3 files changed, 16 insertions(+), 16 deletions(-)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 56b2a12..ccc054a 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -176,7 +176,7 @@ struct kvm {
        struct kvm_coalesced_mmio_ring *coalesced_mmio_ring;
 #endif
 
-       struct mutex irq_lock;
+       spinlock_t irq_lock;
 #ifdef CONFIG_HAVE_KVM_IRQCHIP
        struct kvm_irq_routing_table *irq_routing;
        struct hlist_head mask_notifier_list;
diff --git a/virt/kvm/irq_comm.c b/virt/kvm/irq_comm.c
index 4b36917..15eab15 100644
--- a/virt/kvm/irq_comm.c
+++ b/virt/kvm/irq_comm.c
@@ -184,17 +184,17 @@ 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_lock);
        hlist_add_head_rcu(&kian->link, &kvm->irq_ack_notifier_list);
-       mutex_unlock(&kvm->irq_lock);
+       spin_unlock(&kvm->irq_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_lock);
        hlist_del_init_rcu(&kian->link);
-       mutex_unlock(&kvm->irq_lock);
+       spin_unlock(&kvm->irq_lock);
        synchronize_rcu();
 }
 
@@ -203,7 +203,7 @@ int kvm_request_irq_source_id(struct kvm *kvm)
        unsigned long *bitmap = &kvm->arch.irq_sources_bitmap;
        int irq_source_id;
 
-       mutex_lock(&kvm->irq_lock);
+       spin_lock(&kvm->irq_lock);
        irq_source_id = find_first_zero_bit(bitmap,
                                sizeof(kvm->arch.irq_sources_bitmap));
 
@@ -214,7 +214,7 @@ int kvm_request_irq_source_id(struct kvm *kvm)
 
        ASSERT(irq_source_id != KVM_USERSPACE_IRQ_SOURCE_ID);
        set_bit(irq_source_id, bitmap);
-       mutex_unlock(&kvm->irq_lock);
+       spin_unlock(&kvm->irq_lock);
 
        return irq_source_id;
 }
@@ -225,7 +225,7 @@ void kvm_free_irq_source_id(struct kvm *kvm, int 
irq_source_id)
 
        ASSERT(irq_source_id != KVM_USERSPACE_IRQ_SOURCE_ID);
 
-       mutex_lock(&kvm->irq_lock);
+       spin_lock(&kvm->irq_lock);
        if (irq_source_id < 0 ||
            irq_source_id >= sizeof(kvm->arch.irq_sources_bitmap)) {
                printk(KERN_ERR "kvm: IRQ source ID out of range!\n");
@@ -234,24 +234,24 @@ void kvm_free_irq_source_id(struct kvm *kvm, int 
irq_source_id)
        for (i = 0; i < KVM_IOAPIC_NUM_PINS; i++)
                clear_bit(irq_source_id, &kvm->arch.irq_states[i]);
        clear_bit(irq_source_id, &kvm->arch.irq_sources_bitmap);
-       mutex_unlock(&kvm->irq_lock);
+       spin_unlock(&kvm->irq_lock);
 }
 
 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_lock);
        kimn->irq = irq;
        hlist_add_head_rcu(&kimn->link, &kvm->mask_notifier_list);
-       mutex_unlock(&kvm->irq_lock);
+       spin_unlock(&kvm->irq_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_lock);
        hlist_del_rcu(&kimn->link);
-       mutex_unlock(&kvm->irq_lock);
+       spin_unlock(&kvm->irq_lock);
        synchronize_rcu();
 }
 
@@ -364,10 +364,10 @@ int kvm_set_irq_routing(struct kvm *kvm,
                ++ue;
        }
 
-       mutex_lock(&kvm->irq_lock);
+       spin_lock(&kvm->irq_lock);
        old = kvm->irq_routing;
        rcu_assign_pointer(kvm->irq_routing, new);
-       mutex_unlock(&kvm->irq_lock);
+       spin_unlock(&kvm->irq_lock);
        synchronize_rcu();
 
        new = old;
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index ef96c04..8b60039 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -978,7 +978,7 @@ static struct kvm *kvm_create_vm(void)
        kvm_io_bus_init(&kvm->pio_bus);
        kvm_eventfd_init(kvm);
        mutex_init(&kvm->lock);
-       mutex_init(&kvm->irq_lock);
+       spin_lock_init(&kvm->irq_lock);
        kvm_io_bus_init(&kvm->mmio_bus);
        init_rwsem(&kvm->slots_lock);
        atomic_set(&kvm->users_count, 1);
-- 
1.6.3.3

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