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* [PATCH] drm/amdgpu: avoid null dereference of fence when using cpu to update page tables
@ 2023-05-05  9:10 Lang Yu
  2023-05-05 11:13 ` Christian König
  0 siblings, 1 reply; 3+ messages in thread
From: Lang Yu @ 2023-05-05  9:10 UTC (permalink / raw)
  To: amd-gfx; +Cc: Jack Xiao, Lang Yu, Christian Koenig

Using cpu to update page tables is sychronous, no need to wait fence
and it is NULL in such a case.

Signed-off-by: Lang Yu <Lang.Yu@amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_mes.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_mes.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_mes.c
index f0f00466b59f..197981c4ac7d 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_mes.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_mes.c
@@ -1043,8 +1043,11 @@ int amdgpu_mes_add_ring(struct amdgpu_device *adev, int gang_id,
 
 	amdgpu_mes_ring_to_queue_props(adev, ring, &qprops);
 
-	dma_fence_wait(gang->process->vm->last_update, false);
-	dma_fence_wait(ctx_data->meta_data_va->last_pt_update, false);
+	if (gang->process->vm->last_update)
+		dma_fence_wait(gang->process->vm->last_update, false);
+	if (ctx_data->meta_data_va->last_pt_update)
+		dma_fence_wait(ctx_data->meta_data_va->last_pt_update, false);
+
 	amdgpu_mes_unlock(&adev->mes);
 
 	r = amdgpu_mes_add_hw_queue(adev, gang_id, &qprops, &queue_id);
-- 
2.25.1


^ permalink raw reply related	[flat|nested] 3+ messages in thread

* Re: [PATCH] drm/amdgpu: avoid null dereference of fence when using cpu to update page tables
  2023-05-05  9:10 [PATCH] drm/amdgpu: avoid null dereference of fence when using cpu to update page tables Lang Yu
@ 2023-05-05 11:13 ` Christian König
  2023-05-05 12:42   ` Lang Yu
  0 siblings, 1 reply; 3+ messages in thread
From: Christian König @ 2023-05-05 11:13 UTC (permalink / raw)
  To: Lang Yu, amd-gfx; +Cc: Jack Xiao, Christian Koenig

Am 05.05.23 um 11:10 schrieb Lang Yu:
> Using cpu to update page tables is sychronous, no need to wait fence
> and it is NULL in such a case.

Good catch, be we usually install the stub into fence pointers when they 
are unused. See dma_fence_get_stub().

Christian.

>
> Signed-off-by: Lang Yu <Lang.Yu@amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_mes.c | 7 +++++--
>   1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_mes.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_mes.c
> index f0f00466b59f..197981c4ac7d 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_mes.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_mes.c
> @@ -1043,8 +1043,11 @@ int amdgpu_mes_add_ring(struct amdgpu_device *adev, int gang_id,
>   
>   	amdgpu_mes_ring_to_queue_props(adev, ring, &qprops);
>   
> -	dma_fence_wait(gang->process->vm->last_update, false);
> -	dma_fence_wait(ctx_data->meta_data_va->last_pt_update, false);
> +	if (gang->process->vm->last_update)
> +		dma_fence_wait(gang->process->vm->last_update, false);
> +	if (ctx_data->meta_data_va->last_pt_update)
> +		dma_fence_wait(ctx_data->meta_data_va->last_pt_update, false);
> +
>   	amdgpu_mes_unlock(&adev->mes);
>   
>   	r = amdgpu_mes_add_hw_queue(adev, gang_id, &qprops, &queue_id);


^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH] drm/amdgpu: avoid null dereference of fence when using cpu to update page tables
  2023-05-05 11:13 ` Christian König
@ 2023-05-05 12:42   ` Lang Yu
  0 siblings, 0 replies; 3+ messages in thread
From: Lang Yu @ 2023-05-05 12:42 UTC (permalink / raw)
  To: Christian König; +Cc: Jack Xiao, Christian Koenig, amd-gfx

On 05/05/ , Christian König wrote:
> Am 05.05.23 um 11:10 schrieb Lang Yu:
> > Using cpu to update page tables is sychronous, no need to wait fence
> > and it is NULL in such a case.
> 
> Good catch, be we usually install the stub into fence pointers when they are
> unused. See dma_fence_get_stub().

Got it. Thanks for your suggestions.

Regards,
Lang

> Christian.
> 
> > 
> > Signed-off-by: Lang Yu <Lang.Yu@amd.com>
> > ---
> >   drivers/gpu/drm/amd/amdgpu/amdgpu_mes.c | 7 +++++--
> >   1 file changed, 5 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_mes.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_mes.c
> > index f0f00466b59f..197981c4ac7d 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_mes.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_mes.c
> > @@ -1043,8 +1043,11 @@ int amdgpu_mes_add_ring(struct amdgpu_device *adev, int gang_id,
> >   	amdgpu_mes_ring_to_queue_props(adev, ring, &qprops);
> > -	dma_fence_wait(gang->process->vm->last_update, false);
> > -	dma_fence_wait(ctx_data->meta_data_va->last_pt_update, false);
> > +	if (gang->process->vm->last_update)
> > +		dma_fence_wait(gang->process->vm->last_update, false);
> > +	if (ctx_data->meta_data_va->last_pt_update)
> > +		dma_fence_wait(ctx_data->meta_data_va->last_pt_update, false);
> > +
> >   	amdgpu_mes_unlock(&adev->mes);
> >   	r = amdgpu_mes_add_hw_queue(adev, gang_id, &qprops, &queue_id);
> 

^ permalink raw reply	[flat|nested] 3+ messages in thread

end of thread, other threads:[~2023-05-05 12:42 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
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2023-05-05  9:10 [PATCH] drm/amdgpu: avoid null dereference of fence when using cpu to update page tables Lang Yu
2023-05-05 11:13 ` Christian König
2023-05-05 12:42   ` Lang Yu

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