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From: Daniel Vetter <daniel@ffwll.ch>
To: "Christian König" <ckoenig.leichtzumerken@gmail.com>
Cc: linaro-mm-sig@lists.linaro.org, dri-devel@lists.freedesktop.org,
	linux-media@vger.kernel.org, intel-gfx@lists.freedesktop.org,
	daniel@ffwll.ch
Subject: Re: [PATCH 07/26] drm/ttm: use the new iterator in ttm_bo_flush_all_fences
Date: Fri, 17 Sep 2021 16:50:17 +0200	[thread overview]
Message-ID: <YUSrKdHwcK+us4XG@phenom.ffwll.local> (raw)
In-Reply-To: <20210917123513.1106-8-christian.koenig@amd.com>

On Fri, Sep 17, 2021 at 02:34:54PM +0200, Christian König wrote:
> This is probably a fix since we didn't even grabed a reference to the
> fences.

It's rcu protected, and we only care about speeding things up a bit. I
think this wont have any impact on correctness, and I don't think any
driver could blow up?

But yeah maybe we should have a few assert sprinkled into various
dma_fence functions to make sure we never call them when the refcount has
dropped to 0. That would catch stuff like this, and help lock down the
dma-fence api quite a bit.
> 
> Signed-off-by: Christian König <christian.koenig@amd.com>
> ---
>  drivers/gpu/drm/ttm/ttm_bo.c | 14 ++++----------
>  1 file changed, 4 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
> index 3b22c0013dbf..7d804c0c69b0 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo.c
> @@ -269,22 +269,16 @@ static int ttm_bo_individualize_resv(struct ttm_buffer_object *bo)
>  static void ttm_bo_flush_all_fences(struct ttm_buffer_object *bo)
>  {
>  	struct dma_resv *resv = &bo->base._resv;
> -	struct dma_resv_list *fobj;
> +	struct dma_resv_iter cursor;
>  	struct dma_fence *fence;
> -	int i;
>  
>  	rcu_read_lock();
> -	fobj = dma_resv_shared_list(resv);
> -	fence = dma_resv_excl_fence(resv);
> -	if (fence && !fence->ops->signaled)
> -		dma_fence_enable_sw_signaling(fence);
> -
> -	for (i = 0; fobj && i < fobj->shared_count; ++i) {
> -		fence = rcu_dereference(fobj->shared[i]);
> -
> +	dma_resv_iter_begin(&cursor, resv, true);
> +	dma_resv_for_each_fence_unlocked(&cursor, fence) {
>  		if (!fence->ops->signaled)

Imo delete this check here. If that really matters for performance we
should have it in the core dma_fence function, not replicated all over the
place like this. Noodling around in dma_fence internals like this isn't
cool.

With that removal included:

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

>  			dma_fence_enable_sw_signaling(fence);
>  	}
> +	dma_resv_iter_end(&cursor);
>  	rcu_read_unlock();
>  }
>  
> -- 
> 2.25.1
> 

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

WARNING: multiple messages have this Message-ID
From: Daniel Vetter <daniel@ffwll.ch>
To: "Christian König" <ckoenig.leichtzumerken@gmail.com>
Cc: linaro-mm-sig@lists.linaro.org, dri-devel@lists.freedesktop.org,
	linux-media@vger.kernel.org, intel-gfx@lists.freedesktop.org,
	daniel@ffwll.ch
Subject: Re: [Intel-gfx] [PATCH 07/26] drm/ttm: use the new iterator in ttm_bo_flush_all_fences
Date: Fri, 17 Sep 2021 16:50:17 +0200	[thread overview]
Message-ID: <YUSrKdHwcK+us4XG@phenom.ffwll.local> (raw)
In-Reply-To: <20210917123513.1106-8-christian.koenig@amd.com>

On Fri, Sep 17, 2021 at 02:34:54PM +0200, Christian König wrote:
> This is probably a fix since we didn't even grabed a reference to the
> fences.

It's rcu protected, and we only care about speeding things up a bit. I
think this wont have any impact on correctness, and I don't think any
driver could blow up?

But yeah maybe we should have a few assert sprinkled into various
dma_fence functions to make sure we never call them when the refcount has
dropped to 0. That would catch stuff like this, and help lock down the
dma-fence api quite a bit.
> 
> Signed-off-by: Christian König <christian.koenig@amd.com>
> ---
>  drivers/gpu/drm/ttm/ttm_bo.c | 14 ++++----------
>  1 file changed, 4 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
> index 3b22c0013dbf..7d804c0c69b0 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo.c
> @@ -269,22 +269,16 @@ static int ttm_bo_individualize_resv(struct ttm_buffer_object *bo)
>  static void ttm_bo_flush_all_fences(struct ttm_buffer_object *bo)
>  {
>  	struct dma_resv *resv = &bo->base._resv;
> -	struct dma_resv_list *fobj;
> +	struct dma_resv_iter cursor;
>  	struct dma_fence *fence;
> -	int i;
>  
>  	rcu_read_lock();
> -	fobj = dma_resv_shared_list(resv);
> -	fence = dma_resv_excl_fence(resv);
> -	if (fence && !fence->ops->signaled)
> -		dma_fence_enable_sw_signaling(fence);
> -
> -	for (i = 0; fobj && i < fobj->shared_count; ++i) {
> -		fence = rcu_dereference(fobj->shared[i]);
> -
> +	dma_resv_iter_begin(&cursor, resv, true);
> +	dma_resv_for_each_fence_unlocked(&cursor, fence) {
>  		if (!fence->ops->signaled)

Imo delete this check here. If that really matters for performance we
should have it in the core dma_fence function, not replicated all over the
place like this. Noodling around in dma_fence internals like this isn't
cool.

With that removal included:

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

>  			dma_fence_enable_sw_signaling(fence);
>  	}
> +	dma_resv_iter_end(&cursor);
>  	rcu_read_unlock();
>  }
>  
> -- 
> 2.25.1
> 

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

  reply	other threads:[~2021-09-17 14:50 UTC|newest]

Thread overview: 118+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-17 12:34 Deploying new iterator interface for dma-buf Christian König
2021-09-17 12:34 ` [Intel-gfx] " Christian König
2021-09-17 12:34 ` [PATCH 01/26] dma-buf: add dma_resv_for_each_fence_unlocked v2 Christian König
2021-09-17 12:34   ` [Intel-gfx] " Christian König
2021-09-17 13:23   ` Daniel Vetter
2021-09-17 13:23     ` [Intel-gfx] " Daniel Vetter
2021-09-20  8:43     ` Tvrtko Ursulin
2021-09-20 10:09       ` Christian König
2021-09-20 10:26         ` Tvrtko Ursulin
2021-09-17 12:34 ` [PATCH 02/26] dma-buf: add dma_resv_for_each_fence Christian König
2021-09-17 12:34   ` [Intel-gfx] " Christian König
2021-09-17 13:27   ` Daniel Vetter
2021-09-17 13:27     ` [Intel-gfx] " Daniel Vetter
2021-09-17 14:30     ` Daniel Vetter
2021-09-17 14:30       ` Daniel Vetter
2021-09-17 12:34 ` [PATCH 03/26] dma-buf: use new iterator in dma_resv_copy_fences Christian König
2021-09-17 12:34   ` [Intel-gfx] " Christian König
2021-09-17 14:35   ` Daniel Vetter
2021-09-17 14:35     ` [Intel-gfx] " Daniel Vetter
2021-09-20  7:23     ` Christian König
2021-09-20  7:23       ` [Intel-gfx] " Christian König
2021-09-17 12:34 ` [PATCH 04/26] dma-buf: use new iterator in dma_resv_get_fences v2 Christian König
2021-09-17 12:34   ` [Intel-gfx] " Christian König
2021-09-17 14:39   ` Daniel Vetter
2021-09-17 14:39     ` [Intel-gfx] " Daniel Vetter
2021-09-17 12:34 ` [PATCH 05/26] dma-buf: use new iterator in dma_resv_wait_timeout Christian König
2021-09-17 12:34   ` [Intel-gfx] " Christian König
2021-09-17 14:43   ` Daniel Vetter
2021-09-17 14:43     ` [Intel-gfx] " Daniel Vetter
2021-09-20  7:27     ` Christian König
2021-09-20  7:27       ` [Intel-gfx] " Christian König
2021-09-17 12:34 ` [PATCH 06/26] dma-buf: use new iterator in dma_resv_test_signaled Christian König
2021-09-17 12:34   ` [Intel-gfx] " Christian König
2021-09-17 14:45   ` Daniel Vetter
2021-09-17 14:45     ` [Intel-gfx] " Daniel Vetter
2021-09-17 12:34 ` [PATCH 07/26] drm/ttm: use the new iterator in ttm_bo_flush_all_fences Christian König
2021-09-17 12:34   ` [Intel-gfx] " Christian König
2021-09-17 14:50   ` Daniel Vetter [this message]
2021-09-17 14:50     ` Daniel Vetter
2021-09-17 12:34 ` [PATCH 08/26] drm/amdgpu: use the new iterator in amdgpu_sync_resv Christian König
2021-09-17 12:34   ` [Intel-gfx] " Christian König
2021-09-17 12:34 ` [PATCH 09/26] drm/amdgpu: use new iterator in amdgpu_ttm_bo_eviction_valuable Christian König
2021-09-17 12:34   ` [Intel-gfx] " Christian König
2021-09-17 12:34 ` [PATCH 10/26] drm/msm: use new iterator in msm_gem_describe Christian König
2021-09-17 12:34   ` [Intel-gfx] " Christian König
2021-09-17 12:34 ` [PATCH 11/26] drm/radeon: use new iterator in radeon_sync_resv Christian König
2021-09-17 12:34   ` [Intel-gfx] " Christian König
2021-09-17 12:34 ` [PATCH 12/26] drm/scheduler: use new iterator in drm_sched_job_add_implicit_dependencies v2 Christian König
2021-09-17 12:34   ` [Intel-gfx] " Christian König
2021-09-17 14:52   ` Daniel Vetter
2021-09-17 14:52     ` [Intel-gfx] " Daniel Vetter
2021-11-15 14:03   ` Sascha Hauer
2021-11-15 14:03     ` Sascha Hauer
2021-11-15 14:03     ` [Intel-gfx] " Sascha Hauer
2021-11-15 14:08     ` Daniel Vetter
2021-11-15 14:08       ` [Intel-gfx] " Daniel Vetter
2021-11-15 14:08       ` Daniel Vetter
2021-11-15 20:32       ` Christian König
2021-11-15 20:32         ` Christian König
2021-11-15 20:32         ` [Intel-gfx] " Christian König
2021-11-16  7:56       ` Sascha Hauer
2021-11-16  7:56         ` [Intel-gfx] " Sascha Hauer
2021-11-16  7:56         ` Sascha Hauer
2021-09-17 12:35 ` [PATCH 13/26] drm/i915: use the new iterator in i915_gem_busy_ioctl Christian König
2021-09-17 12:35   ` [Intel-gfx] " Christian König
2021-09-20  8:45   ` Tvrtko Ursulin
2021-09-20 10:13     ` Christian König
2021-09-20 10:33       ` Tvrtko Ursulin
2021-09-21  9:41         ` Christian König
2021-09-21 13:10           ` Tvrtko Ursulin
2021-09-17 12:35 ` [PATCH 14/26] drm/i915: use the new iterator in i915_sw_fence_await_reservation v3 Christian König
2021-09-17 12:35   ` [Intel-gfx] " Christian König
2021-09-20  8:45   ` Tvrtko Ursulin
2021-09-20  8:47     ` Tvrtko Ursulin
2021-09-20 10:14       ` Christian König
2021-09-17 12:35 ` [PATCH 15/26] drm/i915: use the new iterator in i915_request_await_object v2 Christian König
2021-09-17 12:35   ` [Intel-gfx] " Christian König
2021-09-17 12:35 ` [PATCH 16/26] drm/i915: use new iterator in i915_gem_object_wait_reservation v2 Christian König
2021-09-17 12:35   ` [Intel-gfx] " Christian König
2021-09-20 10:00   ` Tvrtko Ursulin
2021-09-21 17:35     ` Christian König
2021-09-17 12:35 ` [PATCH 17/26] drm/i915: use new iterator in i915_gem_object_wait_priority v2 Christian König
2021-09-17 12:35   ` [Intel-gfx] " Christian König
2021-09-17 12:35 ` [PATCH 18/26] drm/i915: use new iterator in i915_gem_object_last_write_engine v2 Christian König
2021-09-17 12:35   ` [Intel-gfx] " Christian König
2021-09-17 12:35 ` [PATCH 19/26] drm/i915: use new cursor in intel_prepare_plane_fb v2 Christian König
2021-09-17 12:35   ` [Intel-gfx] " Christian König
2021-09-17 12:35 ` [PATCH 20/26] drm: use new iterator in drm_gem_fence_array_add_implicit v2 Christian König
2021-09-17 12:35   ` [Intel-gfx] " Christian König
2021-09-17 14:53   ` Daniel Vetter
2021-09-17 14:53     ` [Intel-gfx] " Daniel Vetter
2021-09-20  7:31     ` Christian König
2021-09-20  7:31       ` [Intel-gfx] " Christian König
2021-09-17 12:35 ` [PATCH 21/26] drm: use new iterator in drm_gem_plane_helper_prepare_fb v2 Christian König
2021-09-17 12:35   ` [Intel-gfx] " Christian König
2021-09-17 14:55   ` Daniel Vetter
2021-09-17 14:55     ` [Intel-gfx] " Daniel Vetter
2021-09-20  7:35     ` Christian König
2021-09-20  7:35       ` [Intel-gfx] " Christian König
2021-09-17 12:35 ` [PATCH 22/26] drm/nouveau: use the new iterator in nouveau_fence_sync Christian König
2021-09-17 12:35   ` [Intel-gfx] " Christian König
2021-09-17 12:35 ` [PATCH 23/26] drm/nouveau: use the new interator in nv50_wndw_prepare_fb v2 Christian König
2021-09-17 12:35   ` [Intel-gfx] " Christian König
2021-09-17 12:35 ` [PATCH 24/26] drm/etnaviv: use new iterator in etnaviv_gem_describe Christian König
2021-09-17 12:35   ` [Intel-gfx] " Christian König
2021-09-17 12:35 ` [PATCH 25/26] drm/etnaviv: replace dma_resv_get_excl_unlocked Christian König
2021-09-17 12:35   ` [Intel-gfx] " Christian König
2021-09-17 12:35 ` [PATCH 26/26] dma-buf: nuke dma_resv_get_excl_unlocked Christian König
2021-09-17 12:35   ` [Intel-gfx] " Christian König
2021-09-17 14:56   ` Daniel Vetter
2021-09-17 14:56     ` [Intel-gfx] " Daniel Vetter
2021-09-17 14:01 ` [Intel-gfx] ✗ Fi.CI.CHECKPATCH: warning for series starting with [01/26] dma-buf: add dma_resv_for_each_fence_unlocked v2 Patchwork
2021-09-17 14:29 ` [Intel-gfx] ✓ Fi.CI.BAT: success " Patchwork
2021-09-17 15:43 ` [Intel-gfx] ✗ Fi.CI.IGT: failure " Patchwork
  -- strict thread matches above, loose matches on Subject: below --
2021-09-22  9:10 Deploying new iterator interface for dma-buf Christian König
2021-09-22  9:10 ` [PATCH 07/26] drm/ttm: use the new iterator in ttm_bo_flush_all_fences Christian König
2021-09-21 17:36 [PATCH 01/26] dma-buf: add dma_resv_for_each_fence_unlocked v3 Christian König
2021-09-21 17:36 ` [PATCH 07/26] drm/ttm: use the new iterator in ttm_bo_flush_all_fences Christian König
2021-09-16 11:30 Deploying new iterator interface for dma-buf Christian König
2021-09-16 11:30 ` [PATCH 07/26] drm/ttm: use the new iterator in ttm_bo_flush_all_fences Christian König
2021-09-13 13:16 Deploying new iterator interface for dma-buf Christian König
2021-09-13 13:16 ` [PATCH 07/26] drm/ttm: use the new iterator in ttm_bo_flush_all_fences Christian König

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