From fae3a3536a6fecedebd49fa847f810e599bfb132 Mon Sep 17 00:00:00 2001 From: Sheng Yang Date: Tue, 15 Dec 2009 10:28:07 +0800 Subject: KVM: Fix possible circular locking in kvm_vm_ioctl_assign_device() One possible order is: KVM_CREATE_IRQCHIP ioctl(took kvm->lock) -> kvm_iobus_register_dev() -> down_write(kvm->slots_lock). The other one is in kvm_vm_ioctl_assign_device(), which take kvm->slots_lock first, then kvm->lock. Update the comment of lock order as well. Observe it due to kernel locking debug warnings. Cc: stable@kernel.org Signed-off-by: Sheng Yang Signed-off-by: Avi Kivity --- virt/kvm/assigned-dev.c | 6 +++--- virt/kvm/kvm_main.c | 2 +- 2 files changed, 4 insertions(+), 4 deletions(-) diff --git a/virt/kvm/assigned-dev.c b/virt/kvm/assigned-dev.c index fd9c097b760..f73de631e3e 100644 --- a/virt/kvm/assigned-dev.c +++ b/virt/kvm/assigned-dev.c @@ -508,8 +508,8 @@ static int kvm_vm_ioctl_assign_device(struct kvm *kvm, struct kvm_assigned_dev_kernel *match; struct pci_dev *dev; - down_read(&kvm->slots_lock); mutex_lock(&kvm->lock); + down_read(&kvm->slots_lock); match = kvm_find_assigned_dev(&kvm->arch.assigned_dev_head, assigned_dev->assigned_dev_id); @@ -573,8 +573,8 @@ static int kvm_vm_ioctl_assign_device(struct kvm *kvm, } out: - mutex_unlock(&kvm->lock); up_read(&kvm->slots_lock); + mutex_unlock(&kvm->lock); return r; out_list_del: list_del(&match->list); @@ -585,8 +585,8 @@ out_put: pci_dev_put(dev); out_free: kfree(match); - mutex_unlock(&kvm->lock); up_read(&kvm->slots_lock); + mutex_unlock(&kvm->lock); return r; } diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index b5af8816761..7db071ba466 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -64,7 +64,7 @@ MODULE_LICENSE("GPL"); /* * Ordering of locks: * - * kvm->slots_lock --> kvm->lock --> kvm->irq_lock + * kvm->lock --> kvm->slots_lock --> kvm->irq_lock */ DEFINE_SPINLOCK(kvm_lock); -- cgit v1.2.3-18-g5258