Re: [Xen-devel] [PATCH v7 2/2] VT-d: Fix vt-d Device-TLB flush timeout issue

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 17.03.16 at 09:17, <kevin.tian@xxxxxxxxx> wrote:
>>  From: Xu, Quan
>> Sent: Thursday, March 17, 2016 3:13 PM
>> --- a/xen/drivers/passthrough/vtd/qinval.c
>> +++ b/xen/drivers/passthrough/vtd/qinval.c
>> @@ -233,6 +233,57 @@ int qinval_device_iotlb(struct iommu *iommu,
>>      return 0;
>>  }
>> 
>> +static void dev_invalidate_iotlb_timeout(struct iommu *iommu, u16 did,
>> +                                         u16 seg, u8 bus, u8 devfn)
>> +{
>> +    struct domain *d = NULL;
>> +    struct pci_dev *pdev;
>> +
>> +    if ( test_bit(did, iommu->domid_bitmap) )
>> +        d = rcu_lock_domain_by_id(iommu->domid_map[did]);
>> +
>> +    if ( d == NULL )
>> +        return;
>> +
>> +    pcidevs_lock();
>> +    for_each_pdev(d, pdev)
> 
> we need a 'safe' version here since you're deleting nodes
> when walking list. for_each_pdev today is based on 
> list_for_each_entry. Or if it's sure that only one pdev
> can match, we can break out of the loop to do removal.

But breaking out of the loop is what is already being done ...

>> +    {
>> +        if ( ( pdev->seg == seg ) &&
>> +             ( pdev->bus == bus ) &&
>> +             ( pdev->devfn == devfn ) )
>> +        {
>> +            ASSERT ( pdev->domain );
>> +            list_del(&pdev->domain_list);
>> +            pdev->domain = NULL;
>> +            pci_hide_existing_device(pdev);
>> +            break;

... here.

>> +        }
>> +    }
>> +
>> +    pcidevs_unlock();

No need for using "safe" list traversal afaict.

Jan


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