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>

diff --git a/drivers/pci/xen-pcifront.c b/drivers/pci/xen-pcifront.c
index d6cc62cb4cf7465fe22cb643fbde7a3f79f88a29..def8d0b5620c01bf4b8fd372a0ee0f68f57dabab 100644 (file)
--- 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",