If a logical hot unplug (remove) is performed on a physical PCI slot's
parent bridge, and then pci_slot is unloaded, we will encounter an oops:
[<ffffffff803a788a>] kobject_release+0x9a/0x290
[<ffffffff803a77f0>] ? kobject_release+0x0/0x290
[<ffffffff803a8ce7>] kref_put+0x37/0x80
[<ffffffff803a76f7>] kobject_put+0x27/0x60
[<ffffffff803bebcc>] ? pci_destroy_slot+0x3c/0xc0
[<ffffffff803bebd5>] pci_destroy_slot+0x45/0xc0
[<ffffffffa000f05c>] acpi_pci_slot_remove+0x5c/0x91 [pci_slot]
[<ffffffff8040064b>] acpi_pci_unregister_driver+0x4b/0x62
[<ffffffffa000f5c8>] acpi_pci_slot_exit+0x10/0x12 [pci_slot]
[<ffffffff80276ce1>] sys_delete_module+0x161/0x250
We need to grab a reference to the parent PCI bus, which will pin
the bus and prevent it from being released until pci_slot is unloaded.
Cc: lenb@xxxxxxxxxx
Reported-by: Kenji Kaneshige <kaneshige.kenji@xxxxxxxxxxxxxx>
Signed-off-by: Alex Chiang <achiang@xxxxxx>
---
drivers/acpi/pci_slot.c | 5 +++++
1 files changed, 5 insertions(+), 0 deletions(-)
diff --git a/drivers/acpi/pci_slot.c b/drivers/acpi/pci_slot.c
index cd1f446..c7ad9f2 100644
--- a/drivers/acpi/pci_slot.c
+++ b/drivers/acpi/pci_slot.c
@@ -63,6 +63,7 @@ struct acpi_pci_slot {
acpi_handle root_handle; /* handle of the root bridge */
struct pci_slot *pci_slot; /* corresponding pci_slot */
struct list_head list; /* node in the list of slots */
+ struct pci_bus *bus; /* bus the slot is on */
};
static int acpi_pci_slot_add(acpi_handle handle);
@@ -159,11 +160,14 @@ register_slot(acpi_handle handle, u32 lvl, void *context, void **rv)
slot->root_handle = parent_context->root_handle;
slot->pci_slot = pci_slot;
+ slot->bus = pci_bus;
INIT_LIST_HEAD(&slot->list);
mutex_lock(&slot_list_lock);
list_add(&slot->list, &slot_list);
mutex_unlock(&slot_list_lock);
+ get_device(&pci_bus->dev);
+
dbg("pci_slot: %p, pci_bus: %x, device: %d, name: %s\n",
pci_slot, pci_bus->number, device, name);
@@ -316,6 +320,7 @@ acpi_pci_slot_remove(acpi_handle handle)
if (slot->root_handle == handle) {
list_del(&slot->list);
pci_destroy_slot(slot->pci_slot);
+ put_device(&slot->bus->dev);
kfree(slot);
}
}
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