On Fri, Sep 14, 2012 at 8:05 PM, Jiang Liu <liuj97@xxxxxxxxx> wrote:
> When handling BUS_NOTIFY_ADD_DEVICE event for a PCI bridge device,
> the notification handler can't hold reference count to the new PCI bus
> because the device object for the new bus (pci_dev->subordinate->dev)
> hasn't been initialized yet.
>
> Split the registration of PCI bus device into two stages as below,
> so that the event handler could hold reference count to the new PCI bus
> when handling BUS_NOTIFY_ADD_DEVICE event.
>
> 1) device_initialize(&pci_dev->dev)
> 2) device_initialize(&pci_dev->subordinate->dev)
> 3) notify BUS_NOTIFY_ADD_DEVICE event for pci_dev
> 4) device_add(&pci_dev->dev)
> 5) device_add(&pci_dev->subordinate->dev)
>
> Signed-off-by: Jiang Liu <jiang.liu@xxxxxxxxxx>
> ---
> drivers/pci/bus.c | 2 +-
> drivers/pci/probe.c | 3 ++-
> drivers/pci/remove.c | 10 +++++-----
> 3 files changed, 8 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c
> index 4b0970b..11a5c28 100644
> --- a/drivers/pci/bus.c
> +++ b/drivers/pci/bus.c
> @@ -189,7 +189,7 @@ int pci_bus_add_child(struct pci_bus *bus)
> if (bus->bridge)
> bus->dev.parent = bus->bridge;
>
> - retval = device_register(&bus->dev);
> + retval = device_add(&bus->dev);
> if (retval)
> return retval;
>
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index 5dbad03..ddc8f7f 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -464,6 +464,7 @@ static struct pci_bus * pci_alloc_bus(void)
> INIT_LIST_HEAD(&b->resources);
> b->max_bus_speed = PCI_SPEED_UNKNOWN;
> b->cur_bus_speed = PCI_SPEED_UNKNOWN;
> + device_initialize(&b->dev);
> }
> return b;
> }
> @@ -1672,7 +1673,7 @@ struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
> b->dev.class = &pcibus_class;
> b->dev.parent = b->bridge;
> dev_set_name(&b->dev, "%04x:%02x", pci_domain_nr(b), bus);
> - error = device_register(&b->dev);
> + error = device_add(&b->dev);
> if (error)
> goto class_dev_reg_err;
failing path in pci_create_root_bus is not handled.
you could try to move
device_initialize(&b->dev);
to
pci_add_new_bus and pci_create_root_bus instead.
>
> diff --git a/drivers/pci/remove.c b/drivers/pci/remove.c
> index 37b9407..86a4636 100644
> --- a/drivers/pci/remove.c
> +++ b/drivers/pci/remove.c
> @@ -48,11 +48,11 @@ void pci_remove_bus(struct pci_bus *bus)
> list_del(&bus->node);
> pci_bus_release_busn_res(bus);
> up_write(&pci_bus_sem);
> - if (!bus->is_added)
> - return;
> -
> - pci_remove_legacy_files(bus);
> - device_unregister(&bus->dev);
> + if (bus->is_added) {
> + pci_remove_legacy_files(bus);
> + device_del(&bus->dev);
> + }
> + put_device(&bus->dev);
> }
> EXPORT_SYMBOL(pci_remove_bus);
>
> --
> 1.7.9.5
>
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