linux-kernel - Re: [PATCH v9 04/11] iommu: Add sva iommu

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Message-ID: <31116b7f-2ce5-ba18-bcc7-97076199d745@linux.intel.com>
Date:   Tue, 28 Jun 2022 19:41:28 +0800
From:   Baolu Lu <baolu.lu@...ux.intel.com>
To:     "Tian, Kevin" <kevin.tian@...el.com>,
        Joerg Roedel <joro@...tes.org>,
        Jason Gunthorpe <jgg@...dia.com>,
        Christoph Hellwig <hch@...radead.org>,
        "Raj, Ashok" <ashok.raj@...el.com>, Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Jean-Philippe Brucker <jean-philippe@...aro.com>,
        "Jiang, Dave" <dave.jiang@...el.com>, Vinod Koul <vkoul@...nel.org>
Cc:     baolu.lu@...ux.intel.com, Eric Auger <eric.auger@...hat.com>,
        "Liu, Yi L" <yi.l.liu@...el.com>,
        "Pan, Jacob jun" <jacob.jun.pan@...el.com>,
        "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
        "iommu@...ts.linux.dev" <iommu@...ts.linux.dev>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Jean-Philippe Brucker <jean-philippe@...aro.org>
Subject: Re: [PATCH v9 04/11] iommu: Add sva iommu_domain support

On 2022/6/28 16:50, Tian, Kevin wrote:
>>>> +
>>>> +	mutex_lock(&group->mutex);
>>>> +	curr = xa_cmpxchg(&group->pasid_array, pasid, NULL, domain,
>>>> GFP_KERNEL);
>>>> +	if (curr)
>>>> +		goto out_unlock;
>>> Need check xa_is_err(old).
>> Either
>>
>> (1) old entry is a valid pointer, or
> return -EBUSY in this case
> 
>> (2) xa_is_err(curr)
> return xa_err(cur)
> 
>> are failure cases. Hence, "curr == NULL" is the only check we need. Did
>> I miss anything?
>>
> But now you always return -EBUSY for all kinds of xa errors.

Fair enough. Updated like below.

         curr = xa_cmpxchg(&group->pasid_array, pasid, NULL, domain, 
GFP_KERNEL);
         if (curr) {
                 ret = xa_err(curr) ? : -EBUSY;
                 goto out_unlock;
         }

Best regards,
baolu