Re: [PATCH v2 7/9] iommu/arm-smmu: remove arm_smmu_devices

[leizhen <thunder.leizhen-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>]

On 2015/7/8 21:13, Robin Murphy wrote:
> On 07/07/15 04:30, Zhen Lei wrote:
>> It can be replaced by of_iommu_list(in of_iommu.c).
>>
>> Signed-off-by: Zhen Lei <thunder.leizhen-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
>> ---
>>   drivers/iommu/arm-smmu-v3.c | 22 ++--------------------
>>   1 file changed, 2 insertions(+), 20 deletions(-)
>>
>> diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
>> index c569539..39c55f6 100644
>> --- a/drivers/iommu/arm-smmu-v3.c
>> +++ b/drivers/iommu/arm-smmu-v3.c
>> @@ -604,10 +604,6 @@ struct arm_smmu_domain {
>>       struct iommu_domain        domain;
>>   };
>>
>> -/* Our list of SMMU instances */
>> -static DEFINE_SPINLOCK(arm_smmu_devices_lock);
>> -static LIST_HEAD(arm_smmu_devices);
>> -
>>   struct arm_smmu_option_prop {
>>       u32 opt;
>>       const char *prop;
>> @@ -2675,11 +2671,6 @@ static int arm_smmu_device_dt_probe(struct platform_device *pdev)
>>       if (ret)
>>           goto out_free_structures;
>>
>> -    /* Record our private device structure */
>> -    INIT_LIST_HEAD(&smmu->list);
>> -    spin_lock(&arm_smmu_devices_lock);
>> -    list_add(&smmu->list, &arm_smmu_devices);
>> -    spin_unlock(&arm_smmu_devices_lock);
>>       platform_set_drvdata(pdev, smmu);
>>       of_iommu_set_ops(smmu->dev->of_node, &arm_smmu_ops);
>>
>> @@ -2692,19 +2683,10 @@ out_free_structures:
>>
>>   static int arm_smmu_device_remove(struct platform_device *pdev)
>>   {
>> -    struct arm_smmu_device *curr, *smmu = NULL;
>> +    struct arm_smmu_device *smmu;
>>       struct device *dev = &pdev->dev;
>>
>> -    spin_lock(&arm_smmu_devices_lock);
>> -    list_for_each_entry(curr, &arm_smmu_devices, list) {
>> -        if (curr->dev == dev) {
>> -            smmu = curr;
>> -            list_del(&smmu->list);
>> -            break;
>> -        }
>> -    }
>> -    spin_unlock(&arm_smmu_devices_lock);
>> -
>> +    smmu = find_smmu_by_node(dev->of_node);
> 
> Isn't that just a really long round-trip to platform_get_drvdata(pdev)?

But we should first check that pdev is a real smmu device, not others. So we can not omit:
if (!of_iommu_get_ops(np))

I think arm_smmu_device_remove will rarely be called, so it will not impact performance.

> 
>>       if (!smmu)
>>           return -ENODEV;
>>
>> -- 
>> 1.8.0
>>
>>
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>>
> 
> 
> .
>