Re: [PATCH Trivial] intel-iommu: check return value ofdevice_to_iommu() before using it

[Ethan Zhao]

On Thu, Jan 9, 2014 at 8:01 PM, Joerg Roedel <joro@xxxxxxxxxx> wrote:
> On Thu, Jan 09, 2014 at 09:58:42AM +0800, ethan zhao wrote:
>>  drivers/iommu/intel-iommu.c |    2 ++
>>  1 files changed, 2 insertions(+), 0 deletions(-)
>>
>> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
>> index 40203ad..5b4531a 100644
>> --- a/drivers/iommu/intel-iommu.c
>> +++ b/drivers/iommu/intel-iommu.c
>> @@ -1105,6 +1105,8 @@ static struct device_domain_info
>> *iommu_support_dev_iotlb(
>>      struct device_domain_info *info;
>>      struct intel_iommu *iommu = device_to_iommu(segment, bus, devfn);
>>
>> +    if (!iommu)
>> +        return NULL;
>>      if (!ecap_dev_iotlb_support(iommu->ecap))
>>          return NULL;
>
> This call can not fail, iommu_support_dev_iotlb() is only called from
> domain_context_mapping_one() which does the iommu==NULL check on its
> own before the call.
>
Agree, till now, was checked in domain_context_mapping_one(), but how
about if we query information with iommu_support_dev_iotlb() in other
code ?

Thanks,
Ethan
>
>         Joerg
>
>
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