linux-kernel - Re: [PATCH] iommu: Fix group refcount in iommu_alloc_default

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Date:   Mon, 25 May 2020 18:40:19 +0530
From:   Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>
To:     Joerg Roedel <jroedel@...e.de>
Cc:     Will Deacon <will@...nel.org>, Joerg Roedel <joro@...tes.org>,
        linux-kernel@...r.kernel.org, Evan Green <evgreen@...omium.org>,
        Douglas Anderson <dianders@...omium.org>,
        iommu@...ts.linux-foundation.org, linux-arm-msm@...r.kernel.org,
        Robin Murphy <robin.murphy@....com>,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] iommu: Fix group refcount in iommu_alloc_default_domain()

Hi Joerg,

On 2020-05-25 18:32, Joerg Roedel wrote:
> Hi,
> 
> On Fri, May 22, 2020 at 06:31:45PM +0530, Sai Prakash Ranjan wrote:
>> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
>> index a4c2f122eb8b..05f7b77c432f 100644
>> --- a/drivers/iommu/iommu.c
>> +++ b/drivers/iommu/iommu.c
>> @@ -1491,6 +1491,7 @@ static int iommu_alloc_default_domain(struct 
>> device *dev)
>>  {
>>  	struct iommu_group *group;
>>  	unsigned int type;
>> +	int ret;
>> 
>>  	group = iommu_group_get(dev);
>>  	if (!group)
>> @@ -1501,7 +1502,11 @@ static int iommu_alloc_default_domain(struct 
>> device *dev)
>> 
>>  	type = iommu_get_def_domain_type(dev);
>> 
>> -	return iommu_group_alloc_default_domain(dev->bus, group, type);
>> +	ret = iommu_group_alloc_default_domain(dev->bus, group, type);
>> +
>> +	iommu_group_put(group);
>> +
>> +	return ret;
>>  }
>> 
>>  /**
> 
> Thanks for the report and the fix. I think it is better to fix this by
> not taking a group reference in iommu_alloc_default_domain() at all and
> pass group as a parameter. Please see the patch I just sent out.
> 

Thanks for the patch, it looks like the right thing to do. Testing it
out now.

Thanks,
Sai

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