xen-pcifront: Use hotplug-safe pci_get_domain_bus_and_slot()

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.

    struct pci_bus *pci_bus = pci_find_bus(domain, busno);
    struct pci_dev *pci_dev = pci_get_slot(pci_bus, devfn);

Tested-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

1 files changed, 2 insertions, 8 deletions

diff --git a/drivers/pci/xen-pcifront.c b/drivers/pci/xen-pcifront.c
index d6cc62cb4cf7..def8d0b5620c 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",