[Intel-gfx] [PATCH 1/6] drm/i915: Update dma_fence_work

Daniel Vetter daniel at ffwll.ch
Wed Oct 13 12:41:34 UTC 2021


On Fri, Oct 08, 2021 at 03:35:25PM +0200, Thomas Hellström wrote:
> Move the release callback to after fence signaling to align with
> what's done for upcoming VM_BIND user-fence signaling.
> 
> Finally call the work callback regardless of whether we have a fence
> error or not and update the existing callbacks accordingly. We will
> need this to intercept the error for failsafe migration.
> 
> Signed-off-by: Thomas Hellström <thomas.hellstrom at linux.intel.com>

I think before we make this thing more complex we really should either
move this into dma-buf/ as a proper thing, or just open-code.

Minimally at least any new async dma_fence worker needs to have
dma_fence_begin/end_signalling annotations, or we're just digging a grave
here.

I'm also not seeing the point in building everything on top of this, for
many cases just an open-coded work_struct should be a lot simpler. It's
just more to clean up later on, that part is for sure.
-Daniel

> ---
>  drivers/gpu/drm/i915/gem/i915_gem_clflush.c |  5 +++
>  drivers/gpu/drm/i915/i915_sw_fence_work.c   | 36 ++++++++++-----------
>  drivers/gpu/drm/i915/i915_sw_fence_work.h   |  1 +
>  drivers/gpu/drm/i915/i915_vma.c             | 12 +++++--
>  4 files changed, 33 insertions(+), 21 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_clflush.c b/drivers/gpu/drm/i915/gem/i915_gem_clflush.c
> index f0435c6feb68..2143ebaf5b6f 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_clflush.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_clflush.c
> @@ -28,6 +28,11 @@ static void clflush_work(struct dma_fence_work *base)
>  {
>  	struct clflush *clflush = container_of(base, typeof(*clflush), base);
>  
> +	if (base->error) {
> +		dma_fence_set_error(&base->dma, base->error);
> +		return;
> +	}
> +
>  	__do_clflush(clflush->obj);
>  }
>  
> diff --git a/drivers/gpu/drm/i915/i915_sw_fence_work.c b/drivers/gpu/drm/i915/i915_sw_fence_work.c
> index 5b33ef23d54c..5b55cddafc9b 100644
> --- a/drivers/gpu/drm/i915/i915_sw_fence_work.c
> +++ b/drivers/gpu/drm/i915/i915_sw_fence_work.c
> @@ -6,21 +6,24 @@
>  
>  #include "i915_sw_fence_work.h"
>  
> -static void fence_complete(struct dma_fence_work *f)
> +static void dma_fence_work_complete(struct dma_fence_work *f)
>  {
> +	dma_fence_signal(&f->dma);
> +
>  	if (f->ops->release)
>  		f->ops->release(f);
> -	dma_fence_signal(&f->dma);
> +
> +	dma_fence_put(&f->dma);
>  }
>  
> -static void fence_work(struct work_struct *work)
> +static void dma_fence_work_work(struct work_struct *work)
>  {
>  	struct dma_fence_work *f = container_of(work, typeof(*f), work);
>  
> -	f->ops->work(f);
> +	if (f->ops->work)
> +		f->ops->work(f);
>  
> -	fence_complete(f);
> -	dma_fence_put(&f->dma);
> +	dma_fence_work_complete(f);
>  }
>  
>  static int __i915_sw_fence_call
> @@ -31,17 +34,13 @@ fence_notify(struct i915_sw_fence *fence, enum i915_sw_fence_notify state)
>  	switch (state) {
>  	case FENCE_COMPLETE:
>  		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);
> -		}
> +			cmpxchg(&f->error, 0, fence->error);
> +
> +		dma_fence_get(&f->dma);
> +		if (test_bit(DMA_FENCE_WORK_IMM, &f->dma.flags))
> +			dma_fence_work_work(&f->work);
> +		else
> +			queue_work(system_unbound_wq, &f->work);
>  		break;
>  
>  	case FENCE_FREE:
> @@ -84,10 +83,11 @@ void dma_fence_work_init(struct dma_fence_work *f,
>  			 const struct dma_fence_work_ops *ops)
>  {
>  	f->ops = ops;
> +	f->error = 0;
>  	spin_lock_init(&f->lock);
>  	dma_fence_init(&f->dma, &fence_ops, &f->lock, 0, 0);
>  	i915_sw_fence_init(&f->chain, fence_notify);
> -	INIT_WORK(&f->work, fence_work);
> +	INIT_WORK(&f->work, dma_fence_work_work);
>  }
>  
>  int dma_fence_work_chain(struct dma_fence_work *f, struct dma_fence *signal)
> diff --git a/drivers/gpu/drm/i915/i915_sw_fence_work.h b/drivers/gpu/drm/i915/i915_sw_fence_work.h
> index d56806918d13..caa59fb5252b 100644
> --- a/drivers/gpu/drm/i915/i915_sw_fence_work.h
> +++ b/drivers/gpu/drm/i915/i915_sw_fence_work.h
> @@ -24,6 +24,7 @@ struct dma_fence_work_ops {
>  struct dma_fence_work {
>  	struct dma_fence dma;
>  	spinlock_t lock;
> +	int error;
>  
>  	struct i915_sw_fence chain;
>  	struct i915_sw_dma_fence_cb cb;
> diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c
> index 4b7fc4647e46..5123ac28ad9a 100644
> --- a/drivers/gpu/drm/i915/i915_vma.c
> +++ b/drivers/gpu/drm/i915/i915_vma.c
> @@ -301,6 +301,11 @@ static void __vma_bind(struct dma_fence_work *work)
>  	struct i915_vma_work *vw = container_of(work, typeof(*vw), base);
>  	struct i915_vma *vma = vw->vma;
>  
> +	if (work->error) {
> +		dma_fence_set_error(&work->dma, work->error);
> +		return;
> +	}
> +
>  	vma->ops->bind_vma(vw->vm, &vw->stash,
>  			   vma, vw->cache_level, vw->flags);
>  }
> @@ -333,7 +338,7 @@ struct i915_vma_work *i915_vma_work(void)
>  		return NULL;
>  
>  	dma_fence_work_init(&vw->base, &bind_ops);
> -	vw->base.dma.error = -EAGAIN; /* disable the worker by default */
> +	vw->base.error = -EAGAIN; /* disable the worker by default */
>  
>  	return vw;
>  }
> @@ -416,6 +421,9 @@ int i915_vma_bind(struct i915_vma *vma,
>  		 * part of the obj->resv->excl_fence as it only affects
>  		 * execution and not content or object's backing store lifetime.
>  		 */
> +
> +		work->base.error = 0; /* enable the queue_work() */
> +
>  		prev = i915_active_set_exclusive(&vma->active, &work->base.dma);
>  		if (prev) {
>  			__i915_sw_fence_await_dma_fence(&work->base.chain,
> @@ -424,8 +432,6 @@ int i915_vma_bind(struct i915_vma *vma,
>  			dma_fence_put(prev);
>  		}
>  
> -		work->base.dma.error = 0; /* enable the queue_work() */
> -
>  		if (vma->obj) {
>  			__i915_gem_object_pin_pages(vma->obj);
>  			work->pinned = i915_gem_object_get(vma->obj);
> -- 
> 2.31.1
> 

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


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