Re: [PATCH v5 02/12] iommufd: Refactor __fault_domain_replace_dev() to be a wrapper of iommu_replace_group_handle()

[Baolu Lu <baolu.lu@linux.intel.com>]

On 2024/11/5 16:01, Yi Liu wrote:
> On 2024/11/5 13:06, Baolu Lu wrote:
>> On 11/4/24 21:25, Yi Liu wrote:
>>> There is a wrapper of iommu_attach_group_handle(), so making a 
>>> wrapper for
>>> iommu_replace_group_handle() for further code refactor. No functional 
>>> change
>>> intended.
>>
>> This patch is not a simple, non-functional refactoring. It allocates
>> attach_handle for all devices in domain attach/replace interfaces,
>> regardless of whether the domain is iopf-capable. Therefore, the commit
>> message should be rephrased to accurately reflect the patch's purpose
>> and rationale.
> 
> This patch splits the __fault_domain_replace_dev() a lot, the else 
> branch of the below code was lifted to the 
> iommufd_fault_domain_replace_dev().
> While the new __fault_domain_replace_dev() will only be called when the
> hwpt->fault is valid. So the iommu_attach_handle is still allocated only
> for the iopf-capable path. When the hwpt->fault is invalid, the
> iommufd_fault_domain_replace_dev() calls iommu_replace_group_handle() with
> a null iommu_attach_handle. What you described is done in the patch 04 of
> this series. 🙂
> 
> -    if (hwpt->fault) {
> -        handle = kzalloc(sizeof(*handle), GFP_KERNEL);
> -        if (!handle)
> -            return -ENOMEM;
> -
> -        handle->idev = idev;
> -        ret = iommu_replace_group_handle(idev->igroup->group,
> -                         hwpt->domain, &handle->handle);
> -    } else {
> -        ret = iommu_replace_group_handle(idev->igroup->group,
> -                         hwpt->domain, NULL);
> -    }

Okay, I overlooked that part.

Below change caused me to think that attach handle is always allocated
in this patch no matter ...

-	if (hwpt->fault) {
-		handle = kzalloc(sizeof(*handle), GFP_KERNEL);
-		if (!handle)
-			return -ENOMEM;
-
-		handle->idev = idev;
-		ret = iommu_replace_group_handle(idev->igroup->group,
-						 hwpt->domain, &handle->handle);
-	} else {
-		ret = iommu_replace_group_handle(idev->igroup->group,
-						 hwpt->domain, NULL);
-	}
+	handle = kzalloc(sizeof(*handle), GFP_KERNEL);
+	if (!handle)
+		return -ENOMEM;

If no functional change, please just ignore this comment.

--
baolu