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

[Liu Jiang]

On 05/15/2013 06:13 AM, Don Dutile wrote:
> 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.liu@xxxxxxxxxx>
> > Cc: Joerg Roedel<joro@xxxxxxxxxx>
> > Cc: Ingo Molnar<mingo@xxxxxxxxxx>
> > Cc: Donald Dutile<ddutile@xxxxxxxxxx>
> > Cc: Hannes Reinecke<hare@xxxxxxx>
> > Cc: "Li, Zhen-Hua"<zhen-hual@xxxxxx>
> > Cc: iommu@xxxxxxxxxxxxxxxxxxxxxxxxxx
> > Cc: linux-kernel@xxxxxxxxxxxxxxx
> > ---
> >   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() ?
Hi Don,
    Thanks for review!
    My fault, I should use pci_get_bus() instead, will fix it in next 
version.
Regards!
Gerry


> >       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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