diff mbox series

[v3,6/9] dma-buf/fence-array: Add fence deadline support

Message ID 20210903184806.1680887-7-robdclark@gmail.com (mailing list archive)
State Not Applicable, archived
Headers
Series dma-fence: Deadline awareness |

Commit Message

Rob Clark Sept. 3, 2021, 6:47 p.m. UTC 
  From: Rob Clark <robdclark@chromium.org>

Signed-off-by: Rob Clark <robdclark@chromium.org>
---
 drivers/dma-buf/dma-fence-array.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

Comments

Daniel Vetter Sept. 8, 2021, 6 p.m. UTC | #1 
On Fri, Sep 03, 2021 at 11:47:57AM -0700, Rob Clark wrote:
> From: Rob Clark <robdclark@chromium.org>
> 
> Signed-off-by: Rob Clark <robdclark@chromium.org>
> ---
>  drivers/dma-buf/dma-fence-array.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/drivers/dma-buf/dma-fence-array.c b/drivers/dma-buf/dma-fence-array.c
> index d3fbd950be94..8d194b09ee3d 100644
> --- a/drivers/dma-buf/dma-fence-array.c
> +++ b/drivers/dma-buf/dma-fence-array.c
> @@ -119,12 +119,23 @@ static void dma_fence_array_release(struct dma_fence *fence)
>  	dma_fence_free(fence);
>  }
>  
> +static void dma_fence_array_set_deadline(struct dma_fence *fence,
> +					 ktime_t deadline)
> +{
> +	struct dma_fence_array *array = to_dma_fence_array(fence);
> +	unsigned i;
> +
> +	for (i = 0; i < array->num_fences; ++i)
> +		dma_fence_set_deadline(array->fences[i], deadline);

Hm I wonder whether this can go wrong, and whether we need Christian's
massive fence iterator that I've seen flying around. If you nest these
things too much it could all go wrong I think. I looked at other users
which inspect dma_fence_array and none of them have a risk for unbounded
recursion.

Maybe check with Christian.
-Daniel


> +}
> +
>  const struct dma_fence_ops dma_fence_array_ops = {
>  	.get_driver_name = dma_fence_array_get_driver_name,
>  	.get_timeline_name = dma_fence_array_get_timeline_name,
>  	.enable_signaling = dma_fence_array_enable_signaling,
>  	.signaled = dma_fence_array_signaled,
>  	.release = dma_fence_array_release,
> +	.set_deadline = dma_fence_array_set_deadline,
>  };
>  EXPORT_SYMBOL(dma_fence_array_ops);
>  
> -- 
> 2.31.1
>
Christian König Sept. 9, 2021, 6:55 a.m. UTC | #2 
Am 08.09.21 um 20:00 schrieb Daniel Vetter:
> On Fri, Sep 03, 2021 at 11:47:57AM -0700, Rob Clark wrote:
>> From: Rob Clark <robdclark@chromium.org>
>>
>> Signed-off-by: Rob Clark <robdclark@chromium.org>
>> ---
>>   drivers/dma-buf/dma-fence-array.c | 11 +++++++++++
>>   1 file changed, 11 insertions(+)
>>
>> diff --git a/drivers/dma-buf/dma-fence-array.c b/drivers/dma-buf/dma-fence-array.c
>> index d3fbd950be94..8d194b09ee3d 100644
>> --- a/drivers/dma-buf/dma-fence-array.c
>> +++ b/drivers/dma-buf/dma-fence-array.c
>> @@ -119,12 +119,23 @@ static void dma_fence_array_release(struct dma_fence *fence)
>>   	dma_fence_free(fence);
>>   }
>>   
>> +static void dma_fence_array_set_deadline(struct dma_fence *fence,
>> +					 ktime_t deadline)
>> +{
>> +	struct dma_fence_array *array = to_dma_fence_array(fence);
>> +	unsigned i;
>> +
>> +	for (i = 0; i < array->num_fences; ++i)
>> +		dma_fence_set_deadline(array->fences[i], deadline);
> Hm I wonder whether this can go wrong, and whether we need Christian's
> massive fence iterator that I've seen flying around. If you nest these
> things too much it could all go wrong I think. I looked at other users
> which inspect dma_fence_array and none of them have a risk for unbounded
> recursion.

That should work fine or at least doesn't add anything new which could 
go boom.

The dma_fence_array() can't contain other dma_fence_array or 
dma_fence_chain objects or it could end up in a recursion and corrupt 
the kernel stack.

That's a well known limitation for other code paths as well.

So Reviewed-by: Christian König <christian.koenig@amd.com> for this one.

Regards,
Christian.

>
> Maybe check with Christian.
> -Daniel
>
>
>> +}
>> +
>>   const struct dma_fence_ops dma_fence_array_ops = {
>>   	.get_driver_name = dma_fence_array_get_driver_name,
>>   	.get_timeline_name = dma_fence_array_get_timeline_name,
>>   	.enable_signaling = dma_fence_array_enable_signaling,
>>   	.signaled = dma_fence_array_signaled,
>>   	.release = dma_fence_array_release,
>> +	.set_deadline = dma_fence_array_set_deadline,
>>   };
>>   EXPORT_SYMBOL(dma_fence_array_ops);
>>   
>> -- 
>> 2.31.1
>>
diff mbox series

Patch

diff --git a/drivers/dma-buf/dma-fence-array.c b/drivers/dma-buf/dma-fence-array.c
index d3fbd950be94..8d194b09ee3d 100644
--- a/drivers/dma-buf/dma-fence-array.c
+++ b/drivers/dma-buf/dma-fence-array.c
@@ -119,12 +119,23 @@  static void dma_fence_array_release(struct dma_fence *fence)
 	dma_fence_free(fence);
 }
 
+static void dma_fence_array_set_deadline(struct dma_fence *fence,
+					 ktime_t deadline)
+{
+	struct dma_fence_array *array = to_dma_fence_array(fence);
+	unsigned i;
+
+	for (i = 0; i < array->num_fences; ++i)
+		dma_fence_set_deadline(array->fences[i], deadline);
+}
+
 const struct dma_fence_ops dma_fence_array_ops = {
 	.get_driver_name = dma_fence_array_get_driver_name,
 	.get_timeline_name = dma_fence_array_get_timeline_name,
 	.enable_signaling = dma_fence_array_enable_signaling,
 	.signaled = dma_fence_array_signaled,
 	.release = dma_fence_array_release,
+	.set_deadline = dma_fence_array_set_deadline,
 };
 EXPORT_SYMBOL(dma_fence_array_ops);