PCI: acpiphp: remove all functions in slot, even without ACPI _EJx

When we add a device with acpiphp, we enumerate all functions in the
slot with pci_scan_slot(), regardless of whether they have associated
ACPI methods such as _EJ0.

When removing the device, we previously removed only the functions
with those ACPI methods.  This patch makes the remove symmetric with the
add: we remove all functions in the slot, whether they have associated
ACPI methods or not.

With qemu-kvm and SeaBIOS, we can build a multi-function device where
only function 0 has _EJ0 and _ADR (see bugzilla below).  Removing and
re-adding that slot (including all functions of the device) works correctly
with Windows guests.  This patch makes it also work in Linux guests.

[bhelgaas: restructure loop iteration, pull out of slot->funcs loop]
Reference: https://bugzilla.kernel.org/show_bug.cgi?id=43219
Signed-off-by: Amos Kong <kongjianjun@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

1 files changed, 32 insertions, 10 deletions

diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c
index c8f99910276..73af3374e91 100644
--- a/drivers/pci/hotplug/acpiphp_glue.c
+++ b/drivers/pci/hotplug/acpiphp_glue.c
@@ -878,6 +878,24 @@ static void disable_bridges(struct pci_bus *bus)
         }
 }
 
+/* return first device in slot, acquiring a reference on it */
+static struct pci_dev *dev_in_slot(struct acpiphp_slot *slot)
+{
+        struct pci_bus *bus = slot->bridge->pci_bus;
+        struct pci_dev *dev;
+        struct pci_dev *ret = NULL;
+
+        down_read(&pci_bus_sem);
+        list_for_each_entry(dev, &bus->devices, bus_list)
+                if (PCI_SLOT(dev->devfn) == slot->device) {
+                        ret = pci_dev_get(dev);
+                        break;
+                }
+        up_read(&pci_bus_sem);
+
+        return ret;
+}
+
 /**
  * disable_device - disable a slot
  * @slot: ACPI PHP slot
@@ -902,18 +920,22 @@ static int disable_device(struct acpiphp_slot *slot)
                                                 (u32)1, NULL, NULL);
                         func->bridge = NULL;
                 }
+        }
 
-                pdev = pci_get_slot(slot->bridge->pci_bus,
-                                    PCI_DEVFN(slot->device, func->function));
-                if (pdev) {
-                        pci_stop_bus_device(pdev);
-                        if (pdev->subordinate) {
-                                disable_bridges(pdev->subordinate);
-                                pci_disable_device(pdev);
-                        }
-                        __pci_remove_bus_device(pdev);
-                        pci_dev_put(pdev);
+        /*
+         * enable_device() enumerates all functions in this device via
+         * pci_scan_slot(), whether they have associated ACPI hotplug
+         * methods (_EJ0, etc.) or not.  Therefore, we remove all functions
+         * here.
+         */
+        while ((pdev = dev_in_slot(slot))) {
+                pci_stop_bus_device(pdev);
+                if (pdev->subordinate) {
+                        disable_bridges(pdev->subordinate);
+                        pci_disable_device(pdev);
                 }
+                __pci_remove_bus_device(pdev);
+                pci_dev_put(pdev);
         }
 
         list_for_each_entry(func, &slot->funcs, sibling) {