[PATCH v12 3/3] drm/fence: add out-fences support

[Gustavo Padovan]

From: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxxxx>

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

Signed-off-by: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxxxx>
Reviewed-by: Brian Starkey <brian.starkey@xxxxxxx>
Tested-by: Robert Foss <robert.foss@xxxxxxxxxxxxx>
---
 drivers/gpu/drm/drm_atomic.c | 241 +++++++++++++++++++++++++++++++++++--------
 drivers/gpu/drm/drm_crtc.c   |   8 ++
 include/drm/drm_atomic.h     |   1 +
 include/drm/drm_crtc.h       |   6 ++
 4 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 02e9451..e16651c 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -279,6 +279,8 @@ 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;
@@ -439,6 +441,12 @@ 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_crtc.h b/include/drm/drm_crtc.h
index edd2d83..5f4e91b 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -1248,6 +1248,12 @@ 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