Date:   Wed, 16 Nov 2016 14:39:40 +0100
From:   Daniel Vetter <daniel@...ll.ch>
To:     Gustavo Padovan <gustavo@...ovan.org>
Cc:     dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Daniel Stone <daniels@...labora.com>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        Rob Clark <robdclark@...il.com>,
        Greg Hackmann <ghackmann@...gle.com>,
        John Harrison <John.C.Harrison@...el.com>,
        laurent.pinchart@...asonboard.com, seanpaul@...gle.com,
        marcheu@...gle.com, m.chehab@...sung.com,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Brian Starkey <brian.starkey@....com>,
        Gustavo Padovan <gustavo.padovan@...labora.co.uk>
Subject: Re: [PATCH v13] drm/fence: add out-fences support

On Wed, Nov 16, 2016 at 10:00:21PM +0900, Gustavo Padovan wrote:
> From: Gustavo Padovan <gustavo.padovan@...labora.co.uk>
> 
> Support DRM out-fences by creating a sync_file with a fence for each CRTC
> that sets the OUT_FENCE_PTR property.
> 
> We use the out_fence pointer received in the OUT_FENCE_PTR prop to send
> the sync_file fd back to userspace.
> 
> The sync_file and fd are allocated/created before commit, but the
> fd_install operation only happens after we know that commit succeed.
> 
> v2: Comment by Rob Clark:
> 	- Squash commit that adds DRM_MODE_ATOMIC_OUT_FENCE flag here.
> 
>     Comment by Daniel Vetter:
> 	- Add clean up code for out_fences
> 
> v3: Comments by Daniel Vetter:
> 	- create DRM_MODE_ATOMIC_EVENT_MASK
> 	- userspace should fill out_fences_ptr with the crtc_ids for which
> 	it wants fences back.
> 
> v4: Create OUT_FENCE_PTR properties and remove old approach.
> 
> v5: Comments by Brian Starkey:
> 	- Remove extra fence_get() in atomic_ioctl()
> 	- Check ret before iterating on the crtc_state
> 	- check ret before fd_install
> 	- set fence_state to NULL at the beginning
> 	- check fence_state->out_fence_ptr before put_user()
> 	- change order of fput() and put_unused_fd() on failure
> 
>      - Add access_ok() check to the out_fence_ptr received
>      - Rebase after fence -> dma_fence rename
>      - Store out_fence_ptr in the drm_atomic_state
>      - Split crtc_setup_out_fence()
>      - return -1 as out_fence with TEST_ONLY flag
> 
> v6: Comments by Daniel Vetter
> 	- Add prepare/unprepare_crtc_signaling()
> 	- move struct drm_out_fence_state to drm_atomic.c
> 	- mark get_crtc_fence() as static
> 
>     Comments by Brian Starkey
> 	- proper set fence_ptr fence_state array
> 	- isolate fence_idx increment
> 
>     - improve error handling
> 
> v7: Comments by Daniel Vetter
> 	- remove prefix from internal functions
> 	- make out_fence_ptr an s64 pointer
> 	- degrade DRM_INFO to DRM_DEBUG_ATOMIC when put_user fail
> 	- fix doc issues
> 	- filter out OUT_FENCE_PTR == NULL and do not fail in this case
> 	- add complete_crtc_signalling()
> 	- krealloc fence_state on demand
> 
>     Comment by Brian Starkey
> 	- remove unused crtc_state arg from get_out_fence()
> 
> v8: Comment by Brian Starkey
> 	- cancel events before check for !fence_state
> 	- convert a few lefovers u64 types for out_fence_ptr
> 	- fix memleak by assign fence_state earlier after realloc
> 	- proper accout num_fences in case of error
> 
> v9: Comment by Brian Starkey
> 	- memset last position of fence_state after krealloc
>     Comments by Sean Paul
> 	- pass install_fds in complete_crtc_signaling() instead of ret
> 
>      - put_user(-1, fence_ptr) when decoding props
> 
> v10: Comment by Brian Starkey
> 	- remove unneeded num_fences increment on error path
> 	- kfree fence_state after installing fences fd
> 
> v11: rebase against latest drm-misc
> 
> v12: rebase again against latest drm-misc
> 
> Signed-off-by: Gustavo Padovan <gustavo.padovan@...labora.co.uk>
> Reviewed-by: Brian Starkey <brian.starkey@....com> (v10)
> Tested-by: Robert Foss <robert.foss@...labora.com> (v10)

Appeased checkpatch a bit and applied.

Thanks, Daniel

> ---
>  drivers/gpu/drm/drm_atomic.c      | 241 +++++++++++++++++++++++++++++++-------
>  drivers/gpu/drm/drm_crtc.c        |   2 +
>  drivers/gpu/drm/drm_mode_config.c |   6 +
>  include/drm/drm_atomic.h          |   1 +
>  include/drm/drm_mode_config.h     |   6 +
>  5 files changed, 211 insertions(+), 45 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
> index 3ad780a..d4a92a9 100644
> --- a/drivers/gpu/drm/drm_atomic.c
> +++ b/drivers/gpu/drm/drm_atomic.c
> @@ -290,6 +290,23 @@ drm_atomic_get_crtc_state(struct drm_atomic_state *state,
>  }
>  EXPORT_SYMBOL(drm_atomic_get_crtc_state);
>  
> +static void set_out_fence_for_crtc(struct drm_atomic_state *state,
> +				   struct drm_crtc *crtc, s64 __user *fence_ptr)
> +{
> +	state->crtcs[drm_crtc_index(crtc)].out_fence_ptr = fence_ptr;
> +}
> +
> +static s64 __user * get_out_fence_for_crtc(struct drm_atomic_state *state,
> +					   struct drm_crtc *crtc)
> +{
> +	s64 __user *fence_ptr;
> +
> +	fence_ptr = state->crtcs[drm_crtc_index(crtc)].out_fence_ptr;
> +	state->crtcs[drm_crtc_index(crtc)].out_fence_ptr = NULL;
> +
> +	return fence_ptr;
> +}
> +
>  /**
>   * drm_atomic_set_mode_for_crtc - set mode for CRTC
>   * @state: the CRTC whose incoming state to update
> @@ -494,6 +511,16 @@ int drm_atomic_crtc_set_property(struct drm_crtc *crtc,
>  					&replaced);
>  		state->color_mgmt_changed |= replaced;
>  		return ret;
> +	} else if (property == config->prop_out_fence_ptr) {
> +		s64 __user *fence_ptr = u64_to_user_ptr(val);
> +
> +		if (!fence_ptr)
> +			return 0;
> +
> +		if (put_user(-1, fence_ptr))
> +			return -EFAULT;
> +
> +		set_out_fence_for_crtc(state->state, crtc, fence_ptr);
>  	} else if (crtc->funcs->atomic_set_property)
>  		return crtc->funcs->atomic_set_property(crtc, state, property, val);
>  	else
> @@ -536,6 +563,8 @@ drm_atomic_crtc_get_property(struct drm_crtc *crtc,
>  		*val = (state->ctm) ? state->ctm->base.id : 0;
>  	else if (property == config->gamma_lut_property)
>  		*val = (state->gamma_lut) ? state->gamma_lut->base.id : 0;
> +	else if (property == config->prop_out_fence_ptr)
> +		*val = 0;
>  	else if (crtc->funcs->atomic_get_property)
>  		return crtc->funcs->atomic_get_property(crtc, state, property, val);
>  	else
> @@ -1664,11 +1693,9 @@ int drm_atomic_debugfs_init(struct drm_minor *minor)
>   */
>  
>  static struct drm_pending_vblank_event *create_vblank_event(
> -		struct drm_device *dev, struct drm_file *file_priv,
> -		struct dma_fence *fence, uint64_t user_data)
> +		struct drm_device *dev, uint64_t user_data)
>  {
>  	struct drm_pending_vblank_event *e = NULL;
> -	int ret;
>  
>  	e = kzalloc(sizeof *e, GFP_KERNEL);
>  	if (!e)
> @@ -1678,17 +1705,6 @@ static struct drm_pending_vblank_event *create_vblank_event(
>  	e->event.base.length = sizeof(e->event);
>  	e->event.user_data = user_data;
>  
> -	if (file_priv) {
> -		ret = drm_event_reserve_init(dev, file_priv, &e->base,
> -					     &e->event.base);
> -		if (ret) {
> -			kfree(e);
> -			return NULL;
> -		}
> -	}
> -
> -	e->base.fence = fence;
> -
>  	return e;
>  }
>  
> @@ -1793,6 +1809,165 @@ void drm_atomic_clean_old_fb(struct drm_device *dev,
>  }
>  EXPORT_SYMBOL(drm_atomic_clean_old_fb);
>  
> +static struct dma_fence *get_crtc_fence(struct drm_crtc *crtc)
> +{
> +	struct dma_fence *fence;
> +
> +	fence = kzalloc(sizeof(*fence), GFP_KERNEL);
> +	if (!fence)
> +		return NULL;
> +
> +	dma_fence_init(fence, &drm_crtc_fence_ops, &crtc->fence_lock,
> +		       crtc->fence_context, ++crtc->fence_seqno);
> +
> +	return fence;
> +}
> +
> +struct drm_out_fence_state {
> +	s64 __user *out_fence_ptr;
> +	struct sync_file *sync_file;
> +	int fd;
> +};
> +
> +static int setup_out_fence(struct drm_out_fence_state *fence_state,
> +			   struct dma_fence *fence)
> +{
> +	fence_state->fd = get_unused_fd_flags(O_CLOEXEC);
> +	if (fence_state->fd < 0)
> +		return fence_state->fd;
> +
> +	if (put_user(fence_state->fd, fence_state->out_fence_ptr))
> +		return -EFAULT;
> +
> +	fence_state->sync_file = sync_file_create(fence);
> +	if(!fence_state->sync_file)
> +		return -ENOMEM;
> +
> +	return 0;
> +}
> +
> +static int prepare_crtc_signaling(struct drm_device *dev,
> +				  struct drm_atomic_state *state,
> +				  struct drm_mode_atomic *arg,
> +				  struct drm_file *file_priv,
> +				  struct drm_out_fence_state **fence_state,
> +				  unsigned int *num_fences)
> +{
> +	struct drm_crtc *crtc;
> +	struct drm_crtc_state *crtc_state;
> +	int i, ret;
> +
> +	if (arg->flags & DRM_MODE_ATOMIC_TEST_ONLY)
> +		return 0;
> +
> +	for_each_crtc_in_state(state, crtc, crtc_state, i) {
> +		u64 __user *fence_ptr;
> +
> +		fence_ptr = get_out_fence_for_crtc(crtc_state->state, crtc);
> +
> +		if (arg->flags & DRM_MODE_PAGE_FLIP_EVENT || fence_ptr) {
> +			struct drm_pending_vblank_event *e;
> +
> +			e = create_vblank_event(dev, arg->user_data);
> +			if (!e)
> +				return -ENOMEM;
> +
> +			crtc_state->event = e;
> +		}
> +
> +		if (arg->flags & DRM_MODE_PAGE_FLIP_EVENT) {
> +			struct drm_pending_vblank_event *e = crtc_state->event;
> +
> +			if (!file_priv)
> +				continue;
> +
> +			ret = drm_event_reserve_init(dev, file_priv, &e->base,
> +						     &e->event.base);
> +			if (ret) {
> +				kfree(e);
> +				crtc_state->event = NULL;
> +				return ret;
> +			}
> +		}
> +
> +		if (fence_ptr) {
> +			struct dma_fence *fence;
> +			struct drm_out_fence_state *f;
> +
> +			f = krealloc(*fence_state, sizeof(**fence_state) *
> +				     (*num_fences + 1), GFP_KERNEL);
> +			if (!f)
> +				return -ENOMEM;
> +
> +			memset(&f[*num_fences], 0, sizeof(*f));
> +
> +			f[*num_fences].out_fence_ptr = fence_ptr;
> +			*fence_state = f;
> +
> +			fence = get_crtc_fence(crtc);
> +			if (!fence)
> +				return -ENOMEM;
> +
> +			ret = setup_out_fence(&f[(*num_fences)++], fence);
> +			if (ret) {
> +				dma_fence_put(fence);
> +				return ret;
> +			}
> +
> +			crtc_state->event->base.fence = fence;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static void complete_crtc_signaling(struct drm_device *dev,
> +				     struct drm_atomic_state *state,
> +				     struct drm_out_fence_state *fence_state,
> +				     unsigned int num_fences,
> +				     bool install_fds)
> +{
> +	struct drm_crtc *crtc;
> +	struct drm_crtc_state *crtc_state;
> +	int i;
> +
> +	if (install_fds) {
> +		for (i = 0; i < num_fences; i++)
> +			fd_install(fence_state[i].fd,
> +				   fence_state[i].sync_file->file);
> +
> +		kfree(fence_state);
> +		return;
> +	}
> +
> +	for_each_crtc_in_state(state, crtc, crtc_state, i) {
> +		/*
> +		 * TEST_ONLY and PAGE_FLIP_EVENT are mutually
> +		 * exclusive, if they weren't, this code should be
> +		 * called on success for TEST_ONLY too.
> +		 */
> +		if (crtc_state->event)
> +			drm_event_cancel_free(dev, &crtc_state->event->base);
> +	}
> +
> +	if (!fence_state)
> +		return;
> +
> +	for (i = 0; i < num_fences; i++) {
> +		if (fence_state[i].sync_file)
> +			fput(fence_state[i].sync_file->file);
> +		if (fence_state[i].fd >= 0)
> +			put_unused_fd(fence_state[i].fd);
> +
> +		/* If this fails log error to the user */
> +		if (fence_state[i].out_fence_ptr &&
> +		    put_user(-1, fence_state[i].out_fence_ptr))
> +			DRM_DEBUG_ATOMIC("Couldn't clear out_fence_ptr\n");
> +	}
> +
> +	kfree(fence_state);
> +}
> +
>  int drm_mode_atomic_ioctl(struct drm_device *dev,
>  			  void *data, struct drm_file *file_priv)
>  {
> @@ -1805,11 +1980,10 @@ int drm_mode_atomic_ioctl(struct drm_device *dev,
>  	struct drm_atomic_state *state;
>  	struct drm_modeset_acquire_ctx ctx;
>  	struct drm_plane *plane;
> -	struct drm_crtc *crtc;
> -	struct drm_crtc_state *crtc_state;
> +	struct drm_out_fence_state *fence_state = NULL;
>  	unsigned plane_mask;
>  	int ret = 0;
> -	unsigned int i, j;
> +	unsigned int i, j, num_fences = 0;
>  
>  	/* disallow for drivers not supporting atomic: */
>  	if (!drm_core_check_feature(dev, DRIVER_ATOMIC))
> @@ -1924,20 +2098,10 @@ int drm_mode_atomic_ioctl(struct drm_device *dev,
>  		drm_mode_object_unreference(obj);
>  	}
>  
> -	if (arg->flags & DRM_MODE_PAGE_FLIP_EVENT) {
> -		for_each_crtc_in_state(state, crtc, crtc_state, i) {
> -			struct drm_pending_vblank_event *e;
> -
> -			e = create_vblank_event(dev, file_priv, NULL,
> -						arg->user_data);
> -			if (!e) {
> -				ret = -ENOMEM;
> -				goto out;
> -			}
> -
> -			crtc_state->event = e;
> -		}
> -	}
> +	ret = prepare_crtc_signaling(dev, state, arg, file_priv, &fence_state,
> +				     &num_fences);
> +	if (ret)
> +		goto out;
>  
>  	if (arg->flags & DRM_MODE_ATOMIC_TEST_ONLY) {
>  		/*
> @@ -1957,20 +2121,7 @@ int drm_mode_atomic_ioctl(struct drm_device *dev,
>  out:
>  	drm_atomic_clean_old_fb(dev, plane_mask, ret);
>  
> -	if (ret && arg->flags & DRM_MODE_PAGE_FLIP_EVENT) {
> -		/*
> -		 * TEST_ONLY and PAGE_FLIP_EVENT are mutually exclusive,
> -		 * if they weren't, this code should be called on success
> -		 * for TEST_ONLY too.
> -		 */
> -
> -		for_each_crtc_in_state(state, crtc, crtc_state, i) {
> -			if (!crtc_state->event)
> -				continue;
> -
> -			drm_event_cancel_free(dev, &crtc_state->event->base);
> -		}
> -	}
> +	complete_crtc_signaling(dev, state, fence_state, num_fences, !ret);
>  
>  	if (ret == -EDEADLK) {
>  		drm_atomic_state_clear(state);
> diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
> index dbfae42..90931e0 100644
> --- a/drivers/gpu/drm/drm_crtc.c
> +++ b/drivers/gpu/drm/drm_crtc.c
> @@ -267,6 +267,8 @@ int drm_crtc_init_with_planes(struct drm_device *dev, struct drm_crtc *crtc,
>  	if (drm_core_check_feature(dev, DRIVER_ATOMIC)) {
>  		drm_object_attach_property(&crtc->base, config->prop_active, 0);
>  		drm_object_attach_property(&crtc->base, config->prop_mode_id, 0);
> +		drm_object_attach_property(&crtc->base,
> +					   config->prop_out_fence_ptr, 0);
>  	}
>  
>  	return 0;
> diff --git a/drivers/gpu/drm/drm_mode_config.c b/drivers/gpu/drm/drm_mode_config.c
> index 8bee2ad..2735a58 100644
> --- a/drivers/gpu/drm/drm_mode_config.c
> +++ b/drivers/gpu/drm/drm_mode_config.c
> @@ -314,6 +314,12 @@ static int drm_mode_create_standard_properties(struct drm_device *dev)
>  		return -ENOMEM;
>  	dev->mode_config.prop_in_fence_fd = prop;
>  
> +	prop = drm_property_create_range(dev, DRM_MODE_PROP_ATOMIC,
> +			"OUT_FENCE_PTR", 0, U64_MAX);
> +	if (!prop)
> +		return -ENOMEM;
> +	dev->mode_config.prop_out_fence_ptr = prop;
> +
>  	prop = drm_property_create_object(dev, DRM_MODE_PROP_ATOMIC,
>  			"CRTC_ID", DRM_MODE_OBJECT_CRTC);
>  	if (!prop)
> diff --git a/include/drm/drm_atomic.h b/include/drm/drm_atomic.h
> index 331bb10..c0eaec7 100644
> --- a/include/drm/drm_atomic.h
> +++ b/include/drm/drm_atomic.h
> @@ -144,6 +144,7 @@ struct __drm_crtcs_state {
>  	struct drm_crtc *ptr;
>  	struct drm_crtc_state *state;
>  	struct drm_crtc_commit *commit;
> +	s64 __user *out_fence_ptr;
>  };
>  
>  struct __drm_connnectors_state {
> diff --git a/include/drm/drm_mode_config.h b/include/drm/drm_mode_config.h
> index c6754cc..bf9991b 100644
> --- a/include/drm/drm_mode_config.h
> +++ b/include/drm/drm_mode_config.h
> @@ -486,6 +486,12 @@ struct drm_mode_config {
>  	 */
>  	struct drm_property *prop_in_fence_fd;
>  	/**
> +	 * @prop_out_fence_ptr: Sync File fd pointer representing the
> +	 * outgoing fences for a CRTC. Userspace should provide a pointer to a
> +	 * value of type s64, and then cast that pointer to u64.
> +	 */
> +	struct drm_property *prop_out_fence_ptr;
> +	/**
>  	 * @prop_crtc_id: Default atomic plane property to specify the
>  	 * &drm_crtc.
>  	 */
> -- 
> 2.5.5
> 

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

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