Re: [RFC PATCH v2, part 2 16/18] PCI, iommu: use hotplug-safe iterators to walk PCI buses

[Don Dutile]

On 05/14/2013 12:52 PM, Jiang Liu wrote:

Enhance iommu drviers to use hotplug-safe iterators to walk
PCI buses.

Signed-off-by: Jiang Liu<jiang....@huawei.com>
Cc: Joerg Roedel<j...@8bytes.org>
Cc: Ingo Molnar<mi...@kernel.org>
Cc: Donald Dutile<ddut...@redhat.com>
Cc: Hannes Reinecke<h...@suse.de>
Cc: "Li, Zhen-Hua"<zhen-h...@hp.com>
Cc: iommu@lists.linux-foundation.org
Cc: linux-ker...@vger.kernel.org
---
  drivers/iommu/amd_iommu.c | 4 +++-
  drivers/iommu/dmar.c      | 6 ++++--
  2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index e046d7a..d6fdf94 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -357,6 +357,7 @@ 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);
@@ -393,7 +394,7 @@ 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_find_bus(0, alias>>  8);
                if (!bus)
                        goto use_group;

@@ -413,6 +414,7 @@ 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_find_bus() does a pci_bus_put() after the pci_get_bus();
is this needed, or did you mean to make the above patch pci_get_bus() ?

        pci_dev_put(dma_pdev);
        return ret;
  use_group:
diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
index e5cdaf8..5bb3cdc 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_find_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);

ditto.

+
        if (!pdev) {
                pr_warn("Device scope device [%04x:%02x:%02x.%02x] not found\n",
                        segment, scope->bus, path->dev, path->fn);

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