Re: [PATCH 03/13] PCI: Add busn_res tracking in core

[Bjorn Helgaas <bhelgaas@google.com>]

On Fri, Jan 27, 2012 at 6:49 PM, Yinghai Lu <yinghai@kernel.org> wrote:
> update pci_scan_root_bus, and pci_scan_bus to insert root bus busn into
> iobusn_resource tree.
>
> Signed-off-by: Yinghai Lu <yinghai@kernel.org>
> ---
>  drivers/pci/probe.c  |   30 ++++++++++++++++++++++++++----
>  drivers/pci/remove.c |    1 +
>  include/linux/pci.h  |    4 ++++
>  3 files changed, 31 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index 71261da..55404c3 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -1666,8 +1666,9 @@ void pci_bus_release_busn_res(struct pci_bus *b)
>        release_resource(&b->busn_res);
>  }
>
> -struct pci_bus * __devinit pci_scan_root_bus(struct device *parent, int bus,
> -               struct pci_ops *ops, void *sysdata, struct list_head *resources)
> +struct pci_bus * __devinit pci_scan_root_bus_max(struct device *parent, int bus,
> +               int bus_max, struct pci_ops *ops, void *sysdata,
> +               struct list_head *resources)

We are adding "scan root bus" interfaces at an alarming rate (I'm
responsible for most of them, so I'm not blaming you :)).  Could we
get away without adding this one by just adding a bus number resource
to the "resources" list?  For example, then an arch could do:

    LIST_HEAD(resources);
    pci_add_resource(resources, bus_window);
    pci_add_resource(resources, mem_window);
    pci_add_resource(resources, io_window);
    pci_scan_root_bus(..., resources);

If pci_scan_root_bus() didn't find a bus number resource in the list,
it could fall back to a default max_bus of 255.

>  {
>        struct pci_bus *b;
>
> @@ -1675,10 +1676,26 @@ struct pci_bus * __devinit pci_scan_root_bus(struct device *parent, int bus,
>        if (!b)
>                return NULL;
>
> +       pci_bus_insert_busn_res(b, bus, bus_max);
>        b->subordinate = pci_scan_child_bus(b);
>        pci_bus_add_devices(b);
>        return b;
>  }
> +EXPORT_SYMBOL(pci_scan_root_bus_max);
> +
> +struct pci_bus * __devinit pci_scan_root_bus(struct device *parent, int bus,
> +               struct pci_ops *ops, void *sysdata,
> +               struct list_head *resources)
> +{
> +       struct pci_bus *b;
> +
> +       b = pci_scan_root_bus_max(parent, bus, 255, ops, sysdata, resources);
> +
> +       if (b)
> +               pci_bus_update_busn_res_end(b, b->subordinate);
> +
> +       return b;
> +}
>  EXPORT_SYMBOL(pci_scan_root_bus);
>
>  /* Deprecated; use pci_scan_root_bus() instead */
> @@ -1691,9 +1708,11 @@ struct pci_bus * __devinit pci_scan_bus_parented(struct device *parent,
>        pci_add_resource(&resources, &ioport_resource);
>        pci_add_resource(&resources, &iomem_resource);
>        b = pci_create_root_bus(parent, bus, ops, sysdata, &resources);
> -       if (b)
> +       if (b) {
> +               pci_bus_insert_busn_res(b, bus, 255);
>                b->subordinate = pci_scan_child_bus(b);
> -       else
> +               pci_bus_update_busn_res_end(b, b->subordinate);
> +       } else
>                pci_free_resource_list(&resources);
>        return b;
>  }
> @@ -1709,7 +1728,10 @@ struct pci_bus * __devinit pci_scan_bus(int bus, struct pci_ops *ops,
>        pci_add_resource(&resources, &iomem_resource);
>        b = pci_create_root_bus(NULL, bus, ops, sysdata, &resources);
>        if (b) {
> +               pci_bus_insert_busn_res(b, bus, 255);
>                b->subordinate = pci_scan_child_bus(b);
> +               pci_bus_update_busn_res_end(b, b->subordinate);
> +
>                pci_bus_add_devices(b);
>        } else {
>                pci_free_resource_list(&resources);
> diff --git a/drivers/pci/remove.c b/drivers/pci/remove.c
> index bd70f23..8056e6a 100644
> --- a/drivers/pci/remove.c
> +++ b/drivers/pci/remove.c
> @@ -68,6 +68,7 @@ void pci_remove_bus(struct pci_bus *pci_bus)
>
>        down_write(&pci_bus_sem);
>        list_del(&pci_bus->node);
> +       pci_bus_release_busn_res(pci_bus);
>        up_write(&pci_bus_sem);
>        if (!pci_bus->is_added)
>                return;
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 3da935c..d5b6786 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -668,6 +668,10 @@ struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
>  void pci_bus_insert_busn_res(struct pci_bus *b, int bus, int busmax);
>  void pci_bus_update_busn_res_end(struct pci_bus *b, int busmax);
>  void pci_bus_release_busn_res(struct pci_bus *b);
> +struct pci_bus * __devinit pci_scan_root_bus_max(struct device *parent, int bus,
> +                                            int busmax, struct pci_ops *ops,
> +                                            void *sysdata,
> +                                            struct list_head *resources);
>  struct pci_bus * __devinit pci_scan_root_bus(struct device *parent, int bus,
>                                             struct pci_ops *ops, void *sysdata,
>                                             struct list_head *resources);
> --
> 1.7.7
>