linux-kernel - Re: [PATCH 1/2] pciehp: remove redundancy in bridge resource allocation

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Message-ID: <4B0D6B62.6080500@kernel.org>
Date:	Wed, 25 Nov 2009 09:37:38 -0800
From:	Yinghai Lu <yinghai@...nel.org>
To:	Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>
CC:	Jesse Barnes <jbarnes@...tuousgeek.org>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Alex Chiang <achiang@...com>,
	Bjorn Helgaas <bjorn.helgaas@...com>,
	Ingo Molnar <mingo@...e.hu>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	Ivan Kokshaysky <ink@...assic.park.msu.ru>
Subject: Re: [PATCH 1/2] pciehp: remove redundancy in bridge resource allocation

Kenji Kaneshige wrote:
> Current pciehp driver configures bridge's child bus each time the
> bridge is found on the hot-added PCIe adapter card. It is redundant
> and strange because pciehp tryies to add devices on the child bus
> before adding its parent bridge. It should be done at one time on the
> slot's parent bus.
> 
> Signed-off-by: Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>
> 
> ---
>  drivers/pci/hotplug/pciehp_pci.c |   28 +++++++++++++---------------
>  1 file changed, 13 insertions(+), 15 deletions(-)
> 
> Index: 20091125/drivers/pci/hotplug/pciehp_pci.c
> ===================================================================
> --- 20091125.orig/drivers/pci/hotplug/pciehp_pci.c
> +++ 20091125/drivers/pci/hotplug/pciehp_pci.c
> @@ -34,30 +34,26 @@
>  #include "../pci.h"
>  #include "pciehp.h"
>  
> -static int __ref pciehp_add_bridge(struct pci_dev *dev)
> +static void __ref pciehp_scan_bridge(struct pci_dev *dev)
>  {
>  	struct pci_bus *parent = dev->bus;
> -	int pass, busnr, start = parent->secondary;
> -	int end = parent->subordinate;
> +	int pass, busnr, start, end;
>  
> +	start = parent->secondary;
> +	end = parent->subordinate;
>  	for (busnr = start; busnr <= end; busnr++) {
>  		if (!pci_find_bus(pci_domain_nr(parent), busnr))
>  			break;
>  	}
> +
>  	if (busnr-- > end) {
>  		err("No bus number available for hot-added bridge %s\n",
> -				pci_name(dev));
> -		return -1;
> +		    pci_name(dev));
> +		return;
>  	}
> +
>  	for (pass = 0; pass < 2; pass++)
>  		busnr = pci_scan_bridge(parent, dev, busnr, pass);
> -	if (!dev->subordinate)
> -		return -1;
> -	pci_bus_size_bridges(dev->subordinate);
> -	pci_bus_assign_resources(parent);
> -	pci_enable_bridges(parent);
> -	pci_bus_add_devices(parent);
> -	return 0;
>  }
>  
>  int pciehp_configure_device(struct slot *p_slot)
> @@ -93,14 +89,16 @@ int pciehp_configure_device(struct slot 
>  			continue;
>  		}
>  		if ((dev->hdr_type == PCI_HEADER_TYPE_BRIDGE) ||
> -				(dev->hdr_type == PCI_HEADER_TYPE_CARDBUS)) {
> -			pciehp_add_bridge(dev);
> -		}
> +		    (dev->hdr_type == PCI_HEADER_TYPE_CARDBUS))
> +			pciehp_scan_bridge(dev);
> +
>  		pci_configure_slot(dev);
>  		pci_dev_put(dev);
>  	}
>  
> +	pci_bus_size_bridges(parent);
>  	pci_bus_assign_resources(parent);
> +	pci_enable_bridges(parent);
>  	pci_bus_add_devices(parent);
>  	return 0;
>  }

you comment on my patch2, that we should move pci_configure_slot later?


YH
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