[Qemu-devel] [PATCH v6 2/2] PCI: acpiphp: remove all functions in slot, even without ACPI _EJx

[Bjorn Helgaas]

From: Amos Kong <address@hidden>

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 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 <address@hidden>
Signed-off-by: Bjorn Helgaas <address@hidden>
---
 drivers/pci/hotplug/acpiphp_glue.c |   39 +++++++++++++++++++++++++++---------
 1 files changed, 29 insertions(+), 10 deletions(-)

diff --git a/drivers/pci/hotplug/acpiphp_glue.c 
b/drivers/pci/hotplug/acpiphp_glue.c
index c8f9991..9aff4f0 100644
--- a/drivers/pci/hotplug/acpiphp_glue.c
+++ b/drivers/pci/hotplug/acpiphp_glue.c
@@ -878,6 +878,21 @@ 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;
+
+       down_read(&pci_bus_sem);
+       list_for_each_entry(dev, &bus->devices, bus_list)
+               if (PCI_SLOT(dev->devfn) == slot->device)
+                       return pci_dev_get(dev);
+       up_read(&pci_bus_sem);
+
+       return NULL;
+}
+
 /**
  * disable_device - disable a slot
  * @slot: ACPI PHP slot
@@ -902,18 +917,22 @@ 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) {