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

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Date:	Wed, 15 May 2013 23:36:44 +0800
From:	Liu Jiang <liuj97@...il.com>
To:	Don Dutile <ddutile@...hat.com>
CC:	Bjorn Helgaas <bhelgaas@...gle.com>,
	Yinghai Lu <yinghai@...nel.org>,
	Jiang Liu <jiang.liu@...wei.com>,
	"Rafael J . Wysocki" <rjw@...k.pl>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Gu Zheng <guz.fnst@...fujitsu.com>,
	Toshi Kani <toshi.kani@...com>,
	Myron Stowe <myron.stowe@...hat.com>,
	Yijing Wang <wangyijing@...wei.com>, linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org, Joerg Roedel <joro@...tes.org>,
	Ingo Molnar <mingo@...nel.org>, Hannes Reinecke <hare@...e.de>,
	"Li, Zhen-Hua" <zhen-hual@...com>, iommu@...ts.linux-foundation.org
Subject: Re: [RFC PATCH v2, part 2 16/18] PCI, iommu: use hotplug-safe iterators
 to walk PCI buses

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@...wei.com>
>> Cc: Joerg Roedel<joro@...tes.org>
>> Cc: Ingo Molnar<mingo@...nel.org>
>> Cc: Donald Dutile<ddutile@...hat.com>
>> Cc: Hannes Reinecke<hare@...e.de>
>> Cc: "Li, Zhen-Hua"<zhen-hual@...com>
>> Cc: iommu@...ts.linux-foundation.org
>> Cc: linux-kernel@...r.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() ?
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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