From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sheng Yang Subject: Re: [PATCH 2/3] KVM: Use kvm_free_assigned_irq() for free irq Date: Tue, 30 Dec 2008 19:11:10 +0800 Message-ID: <200812301911.10975.sheng@linux.intel.com> References: <1230616173-17723-1-git-send-email-sheng@linux.intel.com> <1230616173-17723-3-git-send-email-sheng@linux.intel.com> <4959F7C5.101@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org To: Avi Kivity Return-path: Received: from mga06.intel.com ([134.134.136.21]:62061 "EHLO orsmga101.jf.intel.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752524AbYL3LLO (ORCPT ); Tue, 30 Dec 2008 06:11:14 -0500 In-Reply-To: <4959F7C5.101@redhat.com> Content-Disposition: inline Sender: kvm-owner@vger.kernel.org List-ID: On Tuesday 30 December 2008 18:28:21 Avi Kivity wrote: > Sheng Yang wrote: > > Which is more convenient... > > > > Signed-off-by: Sheng Yang > > --- > > virt/kvm/kvm_main.c | 10 ++-------- > > 1 files changed, 2 insertions(+), 8 deletions(-) > > > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > > index ffd261d..cd84b3e 100644 > > --- a/virt/kvm/kvm_main.c > > +++ b/virt/kvm/kvm_main.c > > @@ -284,11 +284,7 @@ static int assigned_device_update_intx(struct kvm > > *kvm, return 0; > > > > if (irqchip_in_kernel(kvm)) { > > - if (!msi2intx && > > - adev->irq_requested_type & KVM_ASSIGNED_DEV_HOST_MSI) { > > - free_irq(adev->host_irq, (void *)kvm); > > - pci_disable_msi(adev->dev); > > - } > > + kvm_free_assigned_irq(kvm, adev); > > This will call cancel_work_sync(), which may wait upon kvm->lock, which > I think we hold here -> deadlock. > > I think that the current code has even bigger problems (races), since a > scheduled work can arrive after the interrupt has been freed and > reallocated. For the race problem, how about put a cancel_work_sync() for all devices at the beginning of kvm_destroy_vm? Something named kvm_arch_cancel_work_sync... -- regards Yang, Sheng