linux-kernel - Re: [PATCH v5 09/12] iommu: Make iommu_queue

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Date:   Fri, 22 Sep 2023 20:47:35 +0800
From:   Baolu Lu <baolu.lu@...ux.intel.com>
To:     Jason Gunthorpe <jgg@...pe.ca>
Cc:     baolu.lu@...ux.intel.com, "Liu, Jingqi" <jingqi.liu@...el.com>,
        Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Kevin Tian <kevin.tian@...el.com>,
        Jean-Philippe Brucker <jean-philippe@...aro.org>,
        Nicolin Chen <nicolinc@...dia.com>,
        Yi Liu <yi.l.liu@...el.com>,
        Jacob Pan <jacob.jun.pan@...ux.intel.com>,
        iommu@...ts.linux.dev, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 09/12] iommu: Make iommu_queue_iopf() more generic

On 2023/9/22 20:43, Jason Gunthorpe wrote:
> On Fri, Sep 22, 2023 at 10:44:45AM +0800, Baolu Lu wrote:
> 
>>>>> @@ -112,6 +110,7 @@ int iommu_queue_iopf(struct iommu_fault *fault, struct device *dev)
>>>>>     {
>>>>>     	int ret;
>>>>>     	struct iopf_group *group;
>>>>> +	struct iommu_domain *domain;
>>>>>     	struct iopf_fault *iopf, *next;
>>>>>     	struct iommu_fault_param *iopf_param;
>>>>>     	struct dev_iommu *param = dev->iommu;
>>>>> @@ -143,6 +142,19 @@ int iommu_queue_iopf(struct iommu_fault *fault, struct device *dev)
>>>>>     		return 0;
>>>>>     	}
>>>>> +	if (fault->prm.flags & IOMMU_FAULT_PAGE_REQUEST_PASID_VALID)
>>>>> +		domain = iommu_get_domain_for_dev_pasid(dev, fault->prm.pasid, 0);
>>>>> +	else
>>>>> +		domain = iommu_get_domain_for_dev(dev);
>>>>> +
>>>>> +	if (!domain || !domain->iopf_handler) {
>>>> Does it need to check if 'domain' is error ?  Like below:
>>>>
>>>>            if (!domain || IS_ERR(domain) || !domain->iopf_handler)
>>> Urk, yes, but not like that
>>>
>>> The IF needs to be moved into the else block as each individual
>>> function has its own return convention.
>> iommu_get_domain_for_dev_pasid() returns an ERR_PTR only if the matching
>> domain type is specified (non-zero).
>>
>> Adding IS_ERR(domain) in the else block will make the code more
>> readable. Alternatively we can put a comment around above code to
>> explain that ERR_PTR is not a case here.
> You should check it because you'll probably get a static tool
> complaint otherwise

Okay, got you.

Best regards,
baolu