Re: [PATCH v3, part2 17/20] PCI, iommu: use hotplug-safe iterators to walk PCI buses

[Bjorn Helgaas <bhelgaas-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>]

On Sun, May 26, 2013 at 11:53:14PM +0800, Jiang Liu wrote:
> Enhance iommu drviers to use hotplug-safe iterators to walk
> PCI buses.
> 
> Signed-off-by: Jiang Liu <jiang.liu-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
> Cc: Joerg Roedel <joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
> Cc: Ingo Molnar <mingo-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
> Cc: Donald Dutile <ddutile-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
> Cc: Hannes Reinecke <hare-l3A5Bk7waGM@public.gmane.org>
> Cc: "Li, Zhen-Hua" <zhen-hual-VXdhtT5mjnY@public.gmane.org>
> Cc: iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org
> Cc: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> ---
>  drivers/iommu/amd_iommu.c | 4 +++-
>  drivers/iommu/dmar.c      | 6 ++++--

The AMD and Intel IOMMU drivers are very different, and I would
split this into a patch for each.

>  2 files changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
> index 21d02b0..eef7a7e 100644
> --- a/drivers/iommu/amd_iommu.c
> +++ b/drivers/iommu/amd_iommu.c
> @@ -352,6 +352,7 @@ static int init_iommu_group(struct device *dev)
>  	struct iommu_dev_data *dev_data;
>  	struct iommu_group *group;
>  	struct pci_dev *dma_pdev;
> +	struct pci_bus *b = NULL;
>  	int ret;
>  
>  	group = iommu_group_get(dev);
> @@ -388,7 +389,7 @@ static int init_iommu_group(struct device *dev)
>  		 * the alias.  Be careful to also test the parent device if
>  		 * we think the alias is the root of the group.
>  		 */
> -		bus = pci_find_bus(0, alias >> 8);
> +		b = bus = pci_get_bus(0, alias >> 8);
>  		if (!bus)
>  			goto use_group;
>  
> @@ -408,6 +409,7 @@ static int init_iommu_group(struct device *dev)
>  	dma_pdev = get_isolation_root(pci_dev_get(to_pci_dev(dev)));
>  use_pdev:
>  	ret = use_pdev_iommu_group(dma_pdev, dev);
> +	pci_bus_put(b);
>  	pci_dev_put(dma_pdev);
>  	return ret;
>  use_group:
> diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
> index a7967ce..7162787 100644
> --- a/drivers/iommu/dmar.c
> +++ b/drivers/iommu/dmar.c
> @@ -67,12 +67,12 @@ static void __init dmar_register_drhd_unit(struct dmar_drhd_unit *drhd)
>  static int __init dmar_parse_one_dev_scope(struct acpi_dmar_device_scope *scope,
>  					   struct pci_dev **dev, u16 segment)
>  {
> -	struct pci_bus *bus;
> +	struct pci_bus *b, *bus;
>  	struct pci_dev *pdev = NULL;
>  	struct acpi_dmar_pci_path *path;
>  	int count;
>  
> -	bus = pci_find_bus(segment, scope->bus);
> +	b = bus = pci_get_bus(segment, scope->bus);
>  	path = (struct acpi_dmar_pci_path *)(scope + 1);
>  	count = (scope->length - sizeof(struct acpi_dmar_device_scope))
>  		/ sizeof(struct acpi_dmar_pci_path);
> @@ -97,6 +97,8 @@ static int __init dmar_parse_one_dev_scope(struct acpi_dmar_device_scope *scope,
>  		count --;
>  		bus = pdev->subordinate;
>  	}
> +	pci_bus_put(b);
> +
>  	if (!pdev) {
>  		pr_warn("Device scope device [%04x:%02x:%02x.%02x] not found\n",
>  			segment, scope->bus, path->dev, path->fn);
> -- 
> 1.8.1.2
>