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SubjectRe: [patch 2/8] [Intel IOMMU] Some generic search functions required to lookup device relationships.
On Mon, Apr 09, 2007 at 02:55:54PM -0700, Ashok Raj wrote:
> +/*
> + * find the upstream PCIE-to-PCI bridge of a PCI device
> + * if the device is PCIE, return NULL
> + * if the device isn't connected to a PCIE bridge (that is its parent is a
> + * legacy PCI bridge and the bridge is directly connected to bus 0), return its
> + * parent
> + */
> +struct pci_dev *
> +pci_find_upstream_pcie_bridge(struct pci_dev *pdev)
> +{
> + struct pci_dev *tmp = NULL;
> +
> + if (pdev->is_pcie)
> + return NULL;
> + while (1) {
> + if (!pdev->bus->self)
> + break;
> + pdev = pdev->bus->self;
> + /* a p2p bridge */
> + if (!pdev->is_pcie) {
> + tmp = pdev;
> + continue;
> + }
> + /* PCI device should connect to a PCIE bridge */
> + BUG_ON(pdev->pcie_type != PCI_EXP_TYPE_PCI_BRIDGE);
> + return pdev;
> + }
> +
> + return tmp;
> +}

No locking while you walk up the bus list?

> --- linux-2.6.21-rc5.orig/include/linux/pci.h 2007-04-03 04:30:51.000000000 -0700
> +++ linux-2.6.21-rc5/include/linux/pci.h 2007-04-03 06:58:58.000000000 -0700
> @@ -126,6 +126,7 @@
> unsigned short subsystem_device;
> unsigned int class; /* 3 bytes: (base,sub,prog-if) */
> u8 hdr_type; /* PCI header type (`multi' flag masked out) */
> + u8 pcie_type; /* PCI-E device/port type */
> u8 rom_base_reg; /* which config register controls the ROM */
> u8 pin; /* which interrupt pin this device uses */
>
> @@ -168,6 +169,7 @@
> unsigned int msi_enabled:1;
> unsigned int msix_enabled:1;
> unsigned int is_managed:1;
> + unsigned int is_pcie:1;

Do you really need both fields? Wouldn't just the pcie_type one work
(with some NOT_PCIE type being set for it if it isn't I suppose.)

thanks,

greg k-h
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