Re: [PATCH v6 21/30] PCI: Introduce pci_bus_child_max_busnr()

[Bjorn Helgaas]

On Mon, Mar 09, 2015 at 10:34:18AM +0800, Yijing Wang wrote:
> Sometimes, we need to know the highest reserved
> busnr for children bus. Because parent's
> bus->busn_res could have padding in it.
> This function return the max child busnr as
> pci_scan_child_bus().

I'm not convinced about this one.  The fact that it's only used by parisc
lba_pci.c and acpiphp makes me suspicious that either they're doing
something funny, or other drivers *should* be using it, too.

> Signed-off-by: Yijing Wang <wangyijing@xxxxxxxxxx>
> Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> Signed-off-by: Fengguang Wu <fengguang.wu@xxxxxxxxx>
> ---
>  drivers/pci/hotplug/acpiphp_glue.c |   29 +----------------------------
>  drivers/pci/pci.c                  |   27 +++++++++++++++++++++++++--
>  include/linux/pci.h                |    2 +-
>  3 files changed, 27 insertions(+), 31 deletions(-)
> 
> diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c
> index bcb90e4..84f2584 100644
> --- a/drivers/pci/hotplug/acpiphp_glue.c
> +++ b/drivers/pci/hotplug/acpiphp_glue.c
> @@ -397,33 +397,6 @@ static void cleanup_bridge(struct acpiphp_bridge *bridge)
>  	acpi_unlock_hp_context();
>  }
>  
> -/**
> - * acpiphp_max_busnr - return the highest reserved bus number under the given bus.
> - * @bus: bus to start search with
> - */
> -static unsigned char acpiphp_max_busnr(struct pci_bus *bus)
> -{
> -	struct pci_bus *tmp;
> -	unsigned char max, n;
> -
> -	/*
> -	 * pci_bus_max_busnr will return the highest
> -	 * reserved busnr for all these children.
> -	 * that is equivalent to the bus->subordinate
> -	 * value.  We don't want to use the parent's
> -	 * bus->subordinate value because it could have
> -	 * padding in it.
> -	 */
> -	max = bus->busn_res.start;
> -
> -	list_for_each_entry(tmp, &bus->children, node) {
> -		n = pci_bus_max_busnr(tmp);
> -		if (n > max)
> -			max = n;
> -	}
> -	return max;
> -}
> -
>  static void acpiphp_set_acpi_region(struct acpiphp_slot *slot)
>  {
>  	struct acpiphp_func *func;
> @@ -489,7 +462,7 @@ static void enable_slot(struct acpiphp_slot *slot)
>  	LIST_HEAD(add_list);
>  
>  	acpiphp_rescan_slot(slot);
> -	max = acpiphp_max_busnr(bus);
> +	max = pci_bus_child_max_busnr(bus);
>  	for (pass = 0; pass < 2; pass++) {
>  		list_for_each_entry(dev, &bus->devices, bus_list) {
>  			if (PCI_SLOT(dev->devfn) != slot->device)
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index c49eec1..0001896 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -108,7 +108,7 @@ static bool pcie_ari_disabled;
>   * Given a PCI bus, returns the highest PCI bus number present in the set
>   * including the given PCI bus and its list of child PCI buses.
>   */
> -unsigned char pci_bus_max_busnr(struct pci_bus *bus)
> +static unsigned char pci_bus_max_busnr(struct pci_bus *bus)
>  {
>  	struct pci_bus *tmp;
>  	unsigned char max, n;
> @@ -121,7 +121,30 @@ unsigned char pci_bus_max_busnr(struct pci_bus *bus)
>  	}
>  	return max;
>  }
> -EXPORT_SYMBOL_GPL(pci_bus_max_busnr);
> +
> +unsigned char pci_bus_child_max_busnr(struct pci_bus *bus)
> +{
> +	struct pci_bus *tmp;
> +	unsigned char max, n;
> +
> +	/*
> +	 * pci_bus_max_busnr will return the highest
> +	 * reserved busnr for all these children.
> +	 * that is equivalent to the bus->subordinate
> +	 * value.  We don't want to use the parent's
> +	 * bus->subordinate value because it could have
> +	 * padding in it.
> +	 */
> +	max = bus->busn_res.start;
> +
> +	list_for_each_entry(tmp, &bus->children, node) {
> +		n = pci_bus_max_busnr(tmp);
> +		if (n > max)
> +			max = n;
> +	}
> +	return max;
> +}
> +EXPORT_SYMBOL_GPL(pci_bus_child_max_busnr);
>  
>  #ifdef CONFIG_HAS_IOMEM
>  void __iomem *pci_ioremap_bar(struct pci_dev *pdev, int bar)
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index cfaf217..261b8de 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1181,7 +1181,7 @@ int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max,
>  void pci_walk_bus(struct pci_bus *top, int (*cb)(struct pci_dev *, void *),
>  		  void *userdata);
>  int pci_cfg_space_size(struct pci_dev *dev);
> -unsigned char pci_bus_max_busnr(struct pci_bus *bus);
> +unsigned char pci_bus_child_max_busnr(struct pci_bus *bus);
>  void pci_setup_bridge(struct pci_bus *bus);
>  resource_size_t pcibios_window_alignment(struct pci_bus *bus,
>  					 unsigned long type);
> -- 
> 1.7.1
> 
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