[Intel-gfx] [PATCH 08/20] drm/i915: Always defer fenced work to the worker

[Tvrtko Ursulin]

On 06/07/2020 07:19, Chris Wilson wrote:
> Currently, if an error is raised we always call the cleanup locally
> [and skip the main work callback]. However, some future users may need
> to take a mutex to cleanup and so we cannot immediately execute the
> cleanup as we may still be in interrupt context.
> 
> With the execute-immediate flag, for most cases this should result in
> immediate cleanup of an error.
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> ---
>   drivers/gpu/drm/i915/i915_sw_fence_work.c | 25 +++++++++++------------
>   1 file changed, 12 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_sw_fence_work.c b/drivers/gpu/drm/i915/i915_sw_fence_work.c
> index a3a81bb8f2c3..29f63ebc24e8 100644
> --- a/drivers/gpu/drm/i915/i915_sw_fence_work.c
> +++ b/drivers/gpu/drm/i915/i915_sw_fence_work.c
> @@ -16,11 +16,14 @@ static void fence_complete(struct dma_fence_work *f)
>   static void fence_work(struct work_struct *work)
>   {
>   	struct dma_fence_work *f = container_of(work, typeof(*f), work);
> -	int err;
>   
> -	err = f->ops->work(f);
> -	if (err)
> -		dma_fence_set_error(&f->dma, err);
> +	if (!f->dma.error) {
> +		int err;
> +
> +		err = f->ops->work(f);
> +		if (err)
> +			dma_fence_set_error(&f->dma, err);
> +	}
>   
>   	fence_complete(f);
>   	dma_fence_put(&f->dma);
> @@ -36,15 +39,11 @@ fence_notify(struct i915_sw_fence *fence, enum i915_sw_fence_notify state)
>   		if (fence->error)
>   			dma_fence_set_error(&f->dma, fence->error);
>   
> -		if (!f->dma.error) {
> -			dma_fence_get(&f->dma);
> -			if (test_bit(DMA_FENCE_WORK_IMM, &f->dma.flags))
> -				fence_work(&f->work);
> -			else
> -				queue_work(system_unbound_wq, &f->work);
> -		} else {
> -			fence_complete(f);
> -		}
> +		dma_fence_get(&f->dma);
> +		if (test_bit(DMA_FENCE_WORK_IMM, &f->dma.flags))
> +			fence_work(&f->work);
> +		else
> +			queue_work(system_unbound_wq, &f->work);

Right the commit wording really confused me since it is obviously still 
deferring stuff to the worker. By "fenced work" I understand you 
actually mean more like "never signal non-immediate work from the notify 
callback" (even in the error case).

Regards,

Tvrtko

>   		break;
>   
>   	case FENCE_FREE:
>