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

[Yijing Wang <wangyijing@huawei.com>]

On 2015/3/12 11:33, Bjorn Helgaas wrote:
> 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.

Yes, what lba_pci.c do looks some strange, I did this patch just try to
keep the original logic, but it seems to make code more complex, I would
consider this again and try to find a better solution, thanks.

> 
>> Signed-off-by: Yijing Wang <wangyijing@huawei.com>
>> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
>> Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
>> ---
>>  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
>>
> 
> .
> 


-- 
Thanks!
Yijing