From: Sheng Yang <sheng@linux.intel.com>
Date: Tue, 15 Dec 2009 02:28:07 +0000 (+0800)
Subject: KVM: Fix possible circular locking in kvm_vm_ioctl_assign_device()
X-Git-Tag: v2.6.33-rc3~37^2~5
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=fae3a3536a6fecedebd49fa847f810e599bfb132;p=pandora-kernel.git

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>
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