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


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