[PATCH 28/42] KVM: fix lock imbalance in kvm_*_irq_source_id()

Avi Kivity
2009-11-16T12:27:31Z

From: Jiri Slaby <jirislaby@gmail.com>

Stanse found 2 lock imbalances in kvm_request_irq_source_id and
kvm_free_irq_source_id. They omit to unlock kvm->irq_lock on fail paths.

Fix that by adding unlock labels at the end of the functions and jump
there from the fail paths.

Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
---
virt/kvm/irq_comm.c | 7 +++++--
1 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/virt/kvm/irq_comm.c b/virt/kvm/irq_comm.c
index 15a83b9..00c68d2 100644
--- a/virt/kvm/irq_comm.c
+++ b/virt/kvm/irq_comm.c
@@ -220,11 +220,13 @@ int kvm_request_irq_source_id(struct kvm *kvm)

if (irq_source_id >= sizeof(kvm->arch.irq_sources_bitmap)) {
printk(KERN_WARNING "kvm: exhaust allocatable IRQ sources!\n");
- return -EFAULT;
+ irq_source_id = -EFAULT;
+ goto unlock;
}

ASSERT(irq_source_id != KVM_USERSPACE_IRQ_SOURCE_ID);
set_bit(irq_source_id, bitmap);
+unlock:
mutex_unlock(&kvm->irq_lock);

return irq_source_id;
@@ -240,7 +242,7 @@ void kvm_free_irq_source_id(struct kvm *kvm, int irq_source_id)
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");
- return;
+ goto unlock;
}
for (i = 0; i < KVM_IOAPIC_NUM_PINS; i++) {
clear_bit(irq_source_id, &kvm->arch.vioapic->irq_states[i]);
@@ -251,6 +253,7 @@ void kvm_free_irq_source_id(struct kvm *kvm, int irq_source_id)
#endif
}
clear_bit(irq_source_id, &kvm->arch.irq_sources_bitmap);
+unlock:
mutex_unlock(&kvm->irq_lock);
}

--
1.6.5.2