From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sheng Yang Subject: Re: [PATCH 2/8] KVM: Use kvm_free_assigned_irq() for free irq Date: Thu, 25 Dec 2008 16:42:21 +0800 Message-ID: <200812251642.22294.sheng@linux.intel.com> References: <1230019231-16543-1-git-send-email-sheng@linux.intel.com> <1230019231-16543-3-git-send-email-sheng@linux.intel.com> <20081223151843.GA4077@amt.cnet> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Cc: Avi Kivity , kvm@vger.kernel.org To: Marcelo Tosatti Return-path: Received: from mga10.intel.com ([192.55.52.92]:6467 "EHLO fmsmga102.fm.intel.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750912AbYLYImp (ORCPT ); Thu, 25 Dec 2008 03:42:45 -0500 In-Reply-To: <20081223151843.GA4077@amt.cnet> Content-Disposition: inline Sender: kvm-owner@vger.kernel.org List-ID: On Tuesday 23 December 2008 23:18:43 Marcelo Tosatti wrote: > Hi Sheng, > > On Tue, Dec 23, 2008 at 04:00:25PM +0800, 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); > > > > if (!capable(CAP_SYS_RAWIO)) > > return -EPERM; > > @@ -339,9 +335,7 @@ static int assigned_device_update_msi(struct kvm > > *kvm, > > > > if (irqchip_in_kernel(kvm)) { > > if (!msi2intx) { > > - if (adev->irq_requested_type & > > - KVM_ASSIGNED_DEV_HOST_INTX) > > - free_irq(adev->host_irq, (void *)adev); > > + kvm_free_assigned_irq(kvm, adev); > > > > r = pci_enable_msi(adev->dev); > > if (r) > > Regarding kvm_free_assigned_irq and > assigned_device_update_msi/update_intx: > > if (cancel_work_sync(&assigned_dev->interrupt_work)) > /* We had pending work. That means we will have to take > * care of kvm_put_kvm. > */ > kvm_put_kvm(kvm); > > free_irq(assigned_dev->host_irq, (void *)assigned_dev); > > What prevents the host IRQ from being triggered between kvm_put_kvm and > free_irq? > > Also, if the kvm_put_kvm(kvm) from > kvm_assigned_dev_interrupt_work_handler happens to be the last one, > can't this happen: > > - kvm_assigned_dev_interrupt_work_handler > - kvm_put_kvm > - kvm_destroy_vm > - kvm_arch_destroy_vm > - kvm_free_all_assigned_devices > - kvm_free_assigned_device > - kvm_free_assigned_irq > - cancel_work_sync(&assigned_dev->interrupt_work) > > deadlock. > Nice catch! I've updated the patchset to address this, take a look? :) -- regards Yang, Sheng