From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from acsinet15.oracle.com ([141.146.126.227]:20516 "EHLO acsinet15.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751274Ab2H1RAV (ORCPT ); Tue, 28 Aug 2012 13:00:21 -0400 Date: Tue, 28 Aug 2012 12:59:59 -0400 From: Konrad Rzeszutek Wilk To: Jiang Liu Cc: Bjorn Helgaas , Jiang Liu , Don Dutile , Yinghai Lu , Kenji Kaneshige , Yijing Wang , linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org Subject: Re: [PATCH 5/5] PCI/xen-pcifront: simplify code by hotplug safe pci_get_domain_bus_and_slot() Message-ID: <20120828165959.GA23312@localhost.localdomain> References: <1346168638-32724-1-git-send-email-jiang.liu@huawei.com> <1346168638-32724-6-git-send-email-jiang.liu@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1346168638-32724-6-git-send-email-jiang.liu@huawei.com> Sender: linux-pci-owner@vger.kernel.org List-ID: On Tue, Aug 28, 2012 at 11:43:58PM +0800, Jiang Liu wrote: > Following code has a race window between pci_find_bus() and pci_get_slot() > if PCI hotplug operation happens between them which removes the pci_bus. > So use PCI hotplug safe interface pci_get_domain_bus_and_slot() instead, > which also reduces code complexity. Has this happend in practice? Is this something one can reproduce by manipulating SysFS and at the same time unplugging the PCI devices? > > struct pci_bus *pci_bus = pci_find_bus(domain, busno); > struct pci_dev *pci_dev = pci_get_slot(pci_bus, devfn); > > Signed-off-by: Jiang Liu > --- > drivers/pci/xen-pcifront.c | 10 ++-------- > 1 file changed, 2 insertions(+), 8 deletions(-) > > diff --git a/drivers/pci/xen-pcifront.c b/drivers/pci/xen-pcifront.c > index d6cc62c..def8d0b 100644 > --- a/drivers/pci/xen-pcifront.c > +++ b/drivers/pci/xen-pcifront.c > @@ -982,7 +982,6 @@ static int pcifront_detach_devices(struct pcifront_device *pdev) > int err = 0; > int i, num_devs; > unsigned int domain, bus, slot, func; > - struct pci_bus *pci_bus; > struct pci_dev *pci_dev; > char str[64]; > > @@ -1032,13 +1031,8 @@ static int pcifront_detach_devices(struct pcifront_device *pdev) > goto out; > } > > - pci_bus = pci_find_bus(domain, bus); > - if (!pci_bus) { > - dev_dbg(&pdev->xdev->dev, "Cannot get bus %04x:%02x\n", > - domain, bus); > - continue; > - } > - pci_dev = pci_get_slot(pci_bus, PCI_DEVFN(slot, func)); > + pci_dev = pci_get_domain_bus_and_slot(domain, bus, > + PCI_DEVFN(slot, func)); > if (!pci_dev) { > dev_dbg(&pdev->xdev->dev, > "Cannot get PCI device %04x:%02x:%02x.%d\n", > -- > 1.7.9.5 >