Re: [PATCH -v2 2/2] x86,pci, acpi: Inherent BUSY flag when setup_resource for root bus

[Bjorn Helgaas <bjorn.helgaas@hp.com>]

On Mon, 2010-04-12 at 15:33 -0700, Yinghai wrote:
> So make pci root resource from _CRS honor the range We reserve in e820 below 1M
> then  will not assign them to unsigned pci BAR
> 
> -v2: let pci_bus_alloc_resource() honor IORESOURCE_BUSY
>      driver can not use those range, so skip it

This -v2 text doesn't belong in the changelog.  If you need it, it
should be in a cover message so it doesn't clutter the permanent git
logs.

> Index: linux-2.6/arch/x86/pci/acpi.c
> ===================================================================
> --- linux-2.6.orig/arch/x86/pci/acpi.c
> +++ linux-2.6/arch/x86/pci/acpi.c
> @@ -175,6 +175,10 @@ setup_resource(struct acpi_resource *acp
>  			"conflicts with %s %pR\n",
>  			res, conflict->name, conflict);
>  	} else {
> +		/* In case it falls in big reserved region */
> +		if (res->parent->flags & IORESOURCE_BUSY)
> +			res->flags |= IORESOURCE_BUSY;
> +
>  		pci_bus_add_resource(info->bus, res, 0);
>  		info->res_num++;
>  		if (addr.translation_offset)
> Index: linux-2.6/drivers/pci/bus.c
> ===================================================================
> --- linux-2.6.orig/drivers/pci/bus.c
> +++ linux-2.6/drivers/pci/bus.c
> @@ -103,6 +103,10 @@ pci_bus_alloc_resource(struct pci_bus *b
>  		if (!r)
>  			continue;
>  
> +		/* Driver can not reserve it later, so don't use it */
> +		if (r->flags & IORESOURCE_BUSY)
> +			continue;
> +
>  		/* type_mask must match */
>  		if ((res->flags ^ r->flags) & type_mask)
>  			continue;

I think this makes sense, but I think it should be in two separate
patches.  The first would be the pci_bus_alloc_resource() change, which
is of interest to all architectures, with a changelog like this:

  PCI: don't allocate from a BUSY bus resource

  Drivers typically use pci_request_regions() to reserve the resources
  they use, but that fails if the resource is already busy.  Therefore,
  we should ignore busy resources when we're assigning resources to a
  device.

and the second would be:

  x86/PCI: host bridge windows inherit BUSY flag from parent

  If a host bridge window falls inside a region the architecture has
  marked busy, the window should inherit the busy flag so we don't
  try to assign that region to a device.

Acked-by: Bjorn Helgaas <bjorn.helgaas@hp.com>