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Message-ID: <d95e9104-e518-4aa5-8dd8-b6b7fd2294b6@linux.intel.com>
Date:   Tue, 12 Dec 2023 13:23:28 +0800
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Cc:     baolu.lu@linux.intel.com, Joerg Roedel <joro@8bytes.org>,
        Will Deacon <will@kernel.org>,
        Robin Murphy <robin.murphy@arm.com>,
        Kevin Tian <kevin.tian@intel.com>,
        Jean-Philippe Brucker <jean-philippe@linaro.org>,
        Nicolin Chen <nicolinc@nvidia.com>,
        Yi Liu <yi.l.liu@intel.com>,
        Jacob Pan <jacob.jun.pan@linux.intel.com>,
        Longfang Liu <liulongfang@huawei.com>,
        Yan Zhao <yan.y.zhao@intel.com>, iommu@lists.linux.dev,
        kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v8 12/12] iommu: Use refcount for fault data access
Content-Language: en-US
To:     Jason Gunthorpe <jgg@ziepe.ca>
References: <20231207064308.313316-1-baolu.lu@linux.intel.com>
 <20231207064308.313316-13-baolu.lu@linux.intel.com>
 <20231211152456.GB1489931@ziepe.ca>
From:   Baolu Lu <baolu.lu@linux.intel.com>
In-Reply-To: <20231211152456.GB1489931@ziepe.ca>
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On 12/11/23 11:24 PM, Jason Gunthorpe wrote:
>> @@ -282,22 +313,15 @@ EXPORT_SYMBOL_GPL(iommu_page_response);
>>    */
>>   int iopf_queue_flush_dev(struct device *dev)
>>   {
>> -	int ret = 0;
>> -	struct iommu_fault_param *iopf_param;
>> -	struct dev_iommu *param = dev->iommu;
>> +	struct iommu_fault_param *iopf_param = iopf_get_dev_fault_param(dev);
>>   
>> -	if (!param)
>> +	if (!iopf_param)
>>   		return -ENODEV;
> And this also seems unnecessary, it is a bug to call this after
> iopf_queue_remove_device() right? Just

Yes. They both are called from the iommu driver. The iommu driver should
guarantee this.

> rcu_derefernce(param->fault_param, true) and WARN_ON NULL.

Okay, sure.

Best regards,
baolu