[Intel-gfx] [PATCH 25/28] drm/nouveau: use the new iterator in nouveau_fence_sync

[Daniel Vetter]

On Tue, Oct 05, 2021 at 01:37:39PM +0200, Christian König wrote:
> Simplifying the code a bit.
> 
> Signed-off-by: Christian König <christian.koenig at amd.com>

A bit a trick conversion since the previous code was clever with the ret
handling in the loop, but looks correct.

Please mention in the commit message that this code now also waits for all
shared fences in all cases. Previously if we found an exclusive fence, we
bailed out. That needs to be recorded in the commit message, together with
an explainer that defacto too many other drivers have broken this rule
already, and so you have to always iterate all fences.

With that added:

Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>


> ---
>  drivers/gpu/drm/nouveau/nouveau_fence.c | 48 +++++++------------------
>  1 file changed, 12 insertions(+), 36 deletions(-)
> 
> diff --git a/drivers/gpu/drm/nouveau/nouveau_fence.c b/drivers/gpu/drm/nouveau/nouveau_fence.c
> index 05d0b3eb3690..26f9299df881 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_fence.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_fence.c
> @@ -339,14 +339,15 @@ nouveau_fence_wait(struct nouveau_fence *fence, bool lazy, bool intr)
>  }
>  
>  int
> -nouveau_fence_sync(struct nouveau_bo *nvbo, struct nouveau_channel *chan, bool exclusive, bool intr)
> +nouveau_fence_sync(struct nouveau_bo *nvbo, struct nouveau_channel *chan,
> +		   bool exclusive, bool intr)
>  {
>  	struct nouveau_fence_chan *fctx = chan->fence;
> -	struct dma_fence *fence;
>  	struct dma_resv *resv = nvbo->bo.base.resv;
> -	struct dma_resv_list *fobj;
> +	struct dma_resv_iter cursor;
> +	struct dma_fence *fence;
>  	struct nouveau_fence *f;
> -	int ret = 0, i;
> +	int ret;
>  
>  	if (!exclusive) {
>  		ret = dma_resv_reserve_shared(resv, 1);
> @@ -355,10 +356,7 @@ nouveau_fence_sync(struct nouveau_bo *nvbo, struct nouveau_channel *chan, bool e
>  			return ret;
>  	}
>  
> -	fobj = dma_resv_shared_list(resv);
> -	fence = dma_resv_excl_fence(resv);
> -
> -	if (fence) {
> +	dma_resv_for_each_fence(&cursor, resv, exclusive, fence) {
>  		struct nouveau_channel *prev = NULL;
>  		bool must_wait = true;
>  
> @@ -366,41 +364,19 @@ nouveau_fence_sync(struct nouveau_bo *nvbo, struct nouveau_channel *chan, bool e
>  		if (f) {
>  			rcu_read_lock();
>  			prev = rcu_dereference(f->channel);
> -			if (prev && (prev == chan || fctx->sync(f, prev, chan) == 0))
> +			if (prev && (prev == chan ||
> +				     fctx->sync(f, prev, chan) == 0))
>  				must_wait = false;
>  			rcu_read_unlock();
>  		}
>  
> -		if (must_wait)
> +		if (must_wait) {
>  			ret = dma_fence_wait(fence, intr);
> -
> -		return ret;
> -	}
> -
> -	if (!exclusive || !fobj)
> -		return ret;
> -
> -	for (i = 0; i < fobj->shared_count && !ret; ++i) {
> -		struct nouveau_channel *prev = NULL;
> -		bool must_wait = true;
> -
> -		fence = rcu_dereference_protected(fobj->shared[i],
> -						dma_resv_held(resv));
> -
> -		f = nouveau_local_fence(fence, chan->drm);
> -		if (f) {
> -			rcu_read_lock();
> -			prev = rcu_dereference(f->channel);
> -			if (prev && (prev == chan || fctx->sync(f, prev, chan) == 0))
> -				must_wait = false;
> -			rcu_read_unlock();
> +			if (ret)
> +				return ret;
>  		}
> -
> -		if (must_wait)
> -			ret = dma_fence_wait(fence, intr);
>  	}
> -
> -	return ret;
> +	return 0;
>  }
>  
>  void
> -- 
> 2.25.1
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch