From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sheng Yang Subject: Re: [PATCH] KVM: Fix possible circular locking in kvm_vm_ioctl_assign_device() Date: Mon, 14 Dec 2009 15:14:00 +0800 Message-ID: <200912141514.00291.sheng@linux.intel.com> References: <1260176284-4858-1-git-send-email-sheng@linux.intel.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-15" Content-Transfer-Encoding: 7bit Cc: Avi Kivity , Marcelo Tosatti To: kvm@vger.kernel.org Return-path: Received: from mga07.intel.com ([143.182.124.22]:18599 "EHLO azsmga101.ch.intel.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754552AbZLNHOO (ORCPT ); Mon, 14 Dec 2009 02:14:14 -0500 In-Reply-To: <1260176284-4858-1-git-send-email-sheng@linux.intel.com> Sender: kvm-owner@vger.kernel.org List-ID: On Monday 07 December 2009 16:58:04 Sheng Yang wrote: > 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. > > Observe it due to kernel locking debug warnings. > > Signed-off-by: Sheng Yang Avi? Marcelo? -- regards Yang, Sheng > --- > virt/kvm/assigned-dev.c | 6 +++--- > 1 files changed, 3 insertions(+), 3 deletions(-) > > diff --git a/virt/kvm/assigned-dev.c b/virt/kvm/assigned-dev.c > index fd9c097..f73de63 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; > } >