On Thu, Feb 9, 2012 at 6:36 PM, Bjorn Helgaas <bhelgaas@xxxxxxxxxx> wrote:
> This adds a list of all PCI host bridges we find and a way to look up
> the host bridge from a pci_dev.
>
> Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> ---
> drivers/pci/probe.c | 39 ++++++++++++++++++++++++++++++++++-----
> include/linux/pci.h | 5 +++++
> 2 files changed, 39 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index da0d655..2ffe8a3 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -15,6 +15,8 @@
> #define CARDBUS_LATENCY_TIMER 176 /* secondary latency timer */
> #define CARDBUS_RESERVE_BUSNR 3
>
> +static LIST_HEAD(pci_host_bridges);
> +
> /* Ugh. Need to stop exporting this to modules. */
> LIST_HEAD(pci_root_buses);
> EXPORT_SYMBOL(pci_root_buses);
> @@ -42,6 +44,23 @@ int no_pci_devices(void)
> }
> EXPORT_SYMBOL(no_pci_devices);
>
> +static struct pci_host_bridge *pci_host_bridge(struct pci_dev *dev)
> +{
> + struct pci_bus *bus;
> + struct pci_host_bridge *bridge;
> +
> + bus = dev->bus;
> + while (bus->parent)
> + bus = bus->parent;
> +
> + list_for_each_entry(bridge, &pci_host_bridges, list) {
> + if (bridge->bus == bus)
> + return bridge;
> + }
> +
> + return NULL;
> +}
> +
so pci_host_bridge(dev) still is expensive.
> /*
> * PCI Bus Class
> */
> @@ -1526,20 +1545,23 @@ struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
> struct pci_ops *ops, void *sysdata, struct list_head *resources)
> {
> int error, i;
> + struct pci_host_bridge *bridge;
> struct pci_bus *b, *b2;
> struct device *dev;
> struct pci_bus_resource *bus_res, *n;
> struct resource *res;
>
> + bridge = kzalloc(sizeof(*bridge), GFP_KERNEL);
> + if (!bridge)
> + return NULL;
> +
> b = pci_alloc_bus();
> if (!b)
> - return NULL;
> + goto err_bus;
>
> dev = kzalloc(sizeof(*dev), GFP_KERNEL);
> - if (!dev) {
> - kfree(b);
> - return NULL;
> - }
> + if (!dev)
> + goto err_dev;
>
> b->sysdata = sysdata;
> b->ops = ops;
> @@ -1576,6 +1598,8 @@ struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
>
> b->number = b->secondary = bus;
>
> + bridge->bus = b;
> +
> /* Add initial resources to the bus */
> list_for_each_entry_safe(bus_res, n, resources, list)
> list_move_tail(&bus_res->list, &b->resources);
> @@ -1591,6 +1615,7 @@ struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
> }
>
> down_write(&pci_bus_sem);
> + list_add_tail(&bridge->list, &pci_host_bridges);
> list_add_tail(&b->node, &pci_root_buses);
> up_write(&pci_bus_sem);
>
> @@ -1600,11 +1625,15 @@ class_dev_reg_err:
> device_unregister(dev);
> dev_reg_err:
> down_write(&pci_bus_sem);
> + list_del(&bridge->list);
> list_del(&b->node);
> up_write(&pci_bus_sem);
> err_out:
> kfree(dev);
> +err_dev:
> kfree(b);
> +err_bus:
> + kfree(bridge);
> return NULL;
> }
>
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index a16b1df..dfb2b64 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -388,6 +388,11 @@ static inline void pci_add_saved_cap(struct pci_dev *pci_dev,
> hlist_add_head(&new_cap->next, &pci_dev->saved_cap_space);
> }
>
> +struct pci_host_bridge {
> + struct list_head list;
> + struct pci_bus *bus; /* root bus */
> +};
> +
also still have two list: one for host bridges and one for root buses.
Yinghai
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