Re: [PATCH 4/9] drm/amdgpu: add bo_va cleared flag again

["Christian König" <deathsimple-ANTagKRnAhcb1SvskN2V4Q@public.gmane.org>]

Actually that lockless access is removed again in the next patch.

I will reorder the patches, so that it never even occur.

Christian.

Am 28.08.2017 um 06:12 schrieb zhoucm1:
> I'm not sure this one, since you remove status lock for vm_status 
> list, I think we need to test this carefully.
>
> Regards,
>
> David Zhou
>
>
> On 2017年08月25日 17:38, Christian König wrote:
>> From: Christian König <christian.koenig@amd.com>
>>
>> We changed this to use an extra list a while back, but for the next
>> series I need a separate flag again.
>>
>> Signed-off-by: Christian König <christian.koenig@amd.com>
>> ---
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_object.h |  3 +++
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c     | 37 
>> ++++++++++++++----------------
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h     |  3 ---
>>   3 files changed, 20 insertions(+), 23 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.h 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.h
>> index a288fa6..e613ba4 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.h
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.h
>> @@ -55,6 +55,9 @@ struct amdgpu_bo_va {
>>       /* mappings for this bo_va */
>>       struct list_head        invalids;
>>       struct list_head        valids;
>> +
>> +    /* If the mappings are cleared or filled */
>> +    bool                cleared;
>>   };
>>     struct amdgpu_bo {
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>> index f621dba..16148ef 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>> @@ -1787,10 +1787,13 @@ int amdgpu_vm_bo_update(struct amdgpu_device 
>> *adev,
>>       else
>>           flags = 0x0;
>>   -    spin_lock(&vm->status_lock);
>> -    if (!list_empty(&bo_va->base.vm_status))
>> +    /* We access vm_status without the status lock here, but that is ok
>> +     * because when we don't clear the BO is locked and so the 
>> status can't
>> +     * change
>> +     */
>> +    if ((!clear && !list_empty(&bo_va->base.vm_status)) ||
>> +        bo_va->cleared != clear)
>>           list_splice_init(&bo_va->valids, &bo_va->invalids);
>> -    spin_unlock(&vm->status_lock);
>>         list_for_each_entry(mapping, &bo_va->invalids, list) {
>>           r = amdgpu_vm_bo_split_mapping(adev, exclusive, pages_addr, 
>> vm,
>> @@ -1800,25 +1803,22 @@ int amdgpu_vm_bo_update(struct amdgpu_device 
>> *adev,
>>               return r;
>>       }
>>   -    if (trace_amdgpu_vm_bo_mapping_enabled()) {
>> -        list_for_each_entry(mapping, &bo_va->valids, list)
>> -            trace_amdgpu_vm_bo_mapping(mapping);
>> -
>> -        list_for_each_entry(mapping, &bo_va->invalids, list)
>> -            trace_amdgpu_vm_bo_mapping(mapping);
>> +    if (vm->use_cpu_for_update) {
>> +        /* Flush HDP */
>> +        mb();
>> +        amdgpu_gart_flush_gpu_tlb(adev, 0);
>>       }
>>         spin_lock(&vm->status_lock);
>> -    list_splice_init(&bo_va->invalids, &bo_va->valids);
>>       list_del_init(&bo_va->base.vm_status);
>> -    if (clear)
>> -        list_add(&bo_va->base.vm_status, &vm->cleared);
>>       spin_unlock(&vm->status_lock);
>>   -    if (vm->use_cpu_for_update) {
>> -        /* Flush HDP */
>> -        mb();
>> -        amdgpu_gart_flush_gpu_tlb(adev, 0);
>> +    list_splice_init(&bo_va->invalids, &bo_va->valids);
>> +    bo_va->cleared = clear;
>> +
>> +    if (trace_amdgpu_vm_bo_mapping_enabled()) {
>> +        list_for_each_entry(mapping, &bo_va->valids, list)
>> +            trace_amdgpu_vm_bo_mapping(mapping);
>>       }
>>         return 0;
>> @@ -2419,9 +2419,7 @@ void amdgpu_vm_bo_invalidate(struct 
>> amdgpu_device *adev,
>>         list_for_each_entry(bo_base, &bo->va, bo_list) {
>>           spin_lock(&bo_base->vm->status_lock);
>> -        if (list_empty(&bo_base->vm_status))
>> -            list_add(&bo_base->vm_status,
>> -                 &bo_base->vm->moved);
>> +        list_move(&bo_base->vm_status, &bo_base->vm->moved);
>>           spin_unlock(&bo_base->vm->status_lock);
>>       }
>>   }
>> @@ -2508,7 +2506,6 @@ int amdgpu_vm_init(struct amdgpu_device *adev, 
>> struct amdgpu_vm *vm,
>>           vm->reserved_vmid[i] = NULL;
>>       spin_lock_init(&vm->status_lock);
>>       INIT_LIST_HEAD(&vm->moved);
>> -    INIT_LIST_HEAD(&vm->cleared);
>>       INIT_LIST_HEAD(&vm->freed);
>>         /* create scheduler entity for page table updates */
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
>> index 9347d28..e705f0f 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
>> @@ -126,9 +126,6 @@ struct amdgpu_vm {
>>       /* BOs moved, but not yet updated in the PT */
>>       struct list_head    moved;
>>   -    /* BOs cleared in the PT because of a move */
>> -    struct list_head    cleared;
>> -
>>       /* BO mappings freed, but not yet updated in the PT */
>>       struct list_head    freed;
>

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