[v2,2/9] PCI: split registration of PCI bus devices into two stages

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@huawei.com>
---
 drivers/pci/bus.c    |    2 +-
 drivers/pci/probe.c  |    3 ++-
 drivers/pci/remove.c |   10 +++++-----
 3 files changed, 8 insertions(+), 7 deletions(-)

On Fri, Sep 14, 2012 at 8:05 PM, Jiang Liu <liuj97@gmail.com> 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@huawei.com>
> ---
>  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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On Sat, Sep 15, 2012 at 1:03 AM, Yinghai Lu <yinghai@kernel.org> wrote:
> On Fri, Sep 14, 2012 at 8:05 PM, Jiang Liu <liuj97@gmail.com> wrote:
>
> 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.

sth like attached...