iommu: use iommu_group_ref_get to hold group reference

[PATCH] iommu: use iommu_group_ref_get to hold group reference

Posted by Yuan Can 3 years, 7 months ago

Replace kobject_get with iommu_group_ref_get for better
readability.

Signed-off-by: Yuan Can <yuancan@huawei.com>
---
 drivers/iommu/iommu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 780fb7071577..8e7f30f7188c 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -903,7 +903,7 @@ int iommu_group_add_device(struct iommu_group *group, struct device *dev)
 		goto err_free_name;
 	}
 
-	kobject_get(group->devices_kobj);
+	iommu_group_ref_get(group);
 
 	dev->iommu_group = group;
 
-- 
2.17.1

Re: [PATCH] iommu: use iommu_group_ref_get to hold group reference

Posted by Robin Murphy 3 years, 7 months ago

On 2022-08-26 03:40, Yuan Can wrote:
> Replace kobject_get with iommu_group_ref_get for better
> readability.

I disagree, sorry. iommu_group_ref_get() is meant as a helper for 
drivers, and the core code uses the raw kobject internally everywhere 
else, including several other times within this function. Especially the 
raw kobject_put() in the cleanup path - in terms of readability I'd say 
it's actively harmful to obfuscate what that pairs with.

Thanks,
Robin.

> Signed-off-by: Yuan Can <yuancan@huawei.com>
> ---
>   drivers/iommu/iommu.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 780fb7071577..8e7f30f7188c 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -903,7 +903,7 @@ int iommu_group_add_device(struct iommu_group *group, struct device *dev)
>   		goto err_free_name;
>   	}
>   
> -	kobject_get(group->devices_kobj);
> +	iommu_group_ref_get(group);
>   
>   	dev->iommu_group = group;
>

Re: [PATCH] iommu: use iommu_group_ref_get to hold group reference

Posted by Yuan Can 3 years, 7 months ago

在 2022/8/30 17:32, Robin Murphy 写道:
> On 2022-08-26 03:40, Yuan Can wrote:
>> Replace kobject_get with iommu_group_ref_get for better
>> readability.
>
> I disagree, sorry. iommu_group_ref_get() is meant as a helper for 
> drivers, and the core code uses the raw kobject internally everywhere 
> else, including several other times within this function. Especially 
> the raw kobject_put() in the cleanup path - in terms of readability 
> I'd say it's actively harmful to obfuscate what that pairs with.
>
> Thanks,
> Robin.

Understood, thanks for your reply.

Best regards,

Yuan Can

>
>> Signed-off-by: Yuan Can <yuancan@huawei.com>
>> ---
>>   drivers/iommu/iommu.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
>> index 780fb7071577..8e7f30f7188c 100644
>> --- a/drivers/iommu/iommu.c
>> +++ b/drivers/iommu/iommu.c
>> @@ -903,7 +903,7 @@ int iommu_group_add_device(struct iommu_group 
>> *group, struct device *dev)
>>           goto err_free_name;
>>       }
>>   -    kobject_get(group->devices_kobj);
>> +    iommu_group_ref_get(group);
>>         dev->iommu_group = group;
>