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| author | Sheng Yang <sheng@linux.intel.com> | 2009-12-15 10:28:07 +0800 |
|---|---|---|
| committer | Marcelo Tosatti <mtosatti@redhat.com> | 2009-12-27 13:36:31 -0200 |
| commit | fae3a3536a6fecedebd49fa847f810e599bfb132 (patch) | |
| tree | 18b555c3f6bcc6735fd7a90db2c398a35e29c84e /virt | |
| parent | fb341f572d26e0786167cd96b90cc4febed830cf (diff) | |
| download | lwn-fae3a3536a6fecedebd49fa847f810e599bfb132.tar.gz lwn-fae3a3536a6fecedebd49fa847f810e599bfb132.zip | |
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 <sheng@linux.intel.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Diffstat (limited to 'virt')
| -rw-r--r-- | virt/kvm/assigned-dev.c | 6 | ||||
| -rw-r--r-- | 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 fd9c097b760a..f73de631e3ee 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 b5af88167613..7db071ba466c 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); |