On Sat 08 Jun 2013 01:07:06 AM CST, Konrad Rzeszutek Wilk wrote: > On Sat, Jun 08, 2013 at 12:50:31AM +0800, Jiang Liu wrote: >> On 06/07/2013 11:38 PM, Konrad Rzeszutek Wilk wrote: >>> On Fri, Jun 07, 2013 at 10:50:24AM -0400, Konrad Rzeszutek Wilk wrote: >>>> On Thu, May 16, 2013 at 11:50:55PM +0800, Jiang Liu wrote: >>>>> Use new PCI interfaces to simplify xen-pcifront implementation: >>>>> 1) Use pci_create_root_bus() instead of pci_scan_bus_parented() >>>>> because pci_scan_bus_parented() is marked as __deprecated.This >>>>> also gets rid of a duplicated call of pci_bus_start_devices(). >>>>> 2) Use pci_stop_root_bus() and pci_remove_root_bus() instead of >>>>> open-coded private implementation. >>>>> 3) Use pci_set_host_bridge_release() to release data structures >>>>> associated with PCI root buses. >>>>> 4) Use pci_bus_get()/pci_bus_put() to manage PCI root bus reference >>>>> count. >>>>> >>>>> This is also a preparation for coming PCI bus lock enhancement. >>> >>> With this patch from : >>> >>> Merge branch 'pci_lock_v3' of https://github.com/jiangliu/linux into testing >>> >>> >>> it blows up when detaching the device. >> Hi Konrad, >> Thanks for testing! According to the log messages, this issue should >> be related to pci bus reference counter management. Seems we have done >> an extra(unbalanced) release of pci bus device. >> Will investigate it tomorrow! > > That is quite commendable that you are willing to look over this on > the weekend but I am not going to be able to rerun this test until > some time in the week. You could enjoy the weekend and just look at > this during the week. Hi Konrad, We should have root-caused this bug, which is caused by for_each_pci_root_bus(). Current implementation doesn't support root bus deletion when walking PCI root buses by for_each_pci_root_bus(). The reference counter (pci_bus->dev.knode_class.n_ref) becomes zero after returning from pci_remove_root_bus(), so it triggers kref warnings and double-free of klist_node object when we call pci_get_next_root_bus() to get the next PCI root bus. So we will first revert to list_for_each_entry_safe(bus, temp, &pci_root_buses, node) and solve this issue in next version of for_each_pci_root_bus(). Regards! Gerry --- diff --git a/drivers/pci/xen-pcifront.c b/drivers/pci/xen-pcifront.c index 6aa2c0f..6e577db 100644 --- a/drivers/pci/xen-pcifront.c +++ b/drivers/pci/xen-pcifront.c @@ -553,11 +553,11 @@ static int pcifront_rescan_root(struct pcifront_device *pdev, static void pcifront_free_roots(struct pcifront_device *pdev) { struct pcifront_sd *sd; - struct pci_bus *bus; + struct pci_bus *bus, *temp; dev_dbg(&pdev->xdev->dev, "cleaning up root buses\n"); - for_each_pci_root_bus(bus) { + list_for_each_entry_safe(bus, temp, &pci_root_buses, node) { sd = bus->sysdata; if (sd->pdev == pdev) { pci_stop_root_bus(bus); --- _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
