I confirmed this patch fix the kernel oops problem I reported.
Reviewed-by: Kenji Kaneshige <kaneshige.kenji@xxxxxxxxxxxxxx>
Tested-by: Kenji Kaneshige <kaneshige.kenji@xxxxxxxxxxxxxx>
By the way, /sys/bus/pci/slots/<slot> directory by pci_slot are
remaining even after the parent bridge/bus of the slots are
removed. At this point, pci_slot is working with struct pci_bus
for the already disabled pci bus. This might cause something
problem. So I think we also need something mechanism to
unregister slots by pci_slot when the parent bus is removed.
Thanks,
Kenji Kaneshige
Alex Chiang wrote:
> 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..12158e0 100644
> --- a/drivers/acpi/pci_slot.c
> +++ b/drivers/acpi/pci_slot.c
> @@ -164,6 +164,8 @@ register_slot(acpi_handle handle, u32 lvl, void *context, void **rv)
> 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);
>
> @@ -310,12 +312,15 @@ static void
> acpi_pci_slot_remove(acpi_handle handle)
> {
> struct acpi_pci_slot *slot, *tmp;
> + struct pci_bus *pbus;
>
> mutex_lock(&slot_list_lock);
> list_for_each_entry_safe(slot, tmp, &slot_list, list) {
> if (slot->root_handle == handle) {
> list_del(&slot->list);
> + pbus = slot->pci_slot->bus;
> pci_destroy_slot(slot->pci_slot);
> + put_device(&pbus->dev);
> kfree(slot);
> }
> }
>
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