Re: [PATCH v6 6/6] drm/fence: add out-fences support

Hi Gustavo,

On Thu, Oct 27, 2016 at 05:37:11PM -0200, Gustavo Padovan wrote:

From: Gustavo Padovan gustavo.padovan@collabora.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

Signed-off-by: Gustavo Padovan gustavo.padovan@collabora.co.uk

drivers/gpu/drm/drm_atomic.c | 199 ++++++++++++++++++++++++++++++++++++------- drivers/gpu/drm/drm_crtc.c | 8 ++ include/drm/drm_atomic.h | 1 + include/drm/drm_crtc.h | 17 ++++ 4 files changed, 196 insertions(+), 29 deletions(-)

diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c index 28d9366..9b70a27 100644 --- a/drivers/gpu/drm/drm_atomic.c +++ b/drivers/gpu/drm/drm_atomic.c @@ -290,6 +290,46 @@ drm_atomic_get_crtc_state(struct drm_atomic_state *state, EXPORT_SYMBOL(drm_atomic_get_crtc_state);

/**

• • drm_atomic_set_out_fence_for_crtc - set CRTC out fence pointer
• • @state: global atomic state object
• • @crtc: crtc to set the out fence pointer
• • @fence_ptr: the userspace pointer to user
• • This function stores the out fence pointer in the atomic state.
• */

+static void +drm_atomic_set_out_fence_for_crtc(struct drm_atomic_state *state,

• 		  struct drm_crtc *crtc, u64 __user *fence_ptr)
  

bikeshed: I'd rather these were called set/get_out_fence_ptr_for_crtc, as they don't involve struct drm_fence at all.

+{

• state->crtcs[drm_crtc_index(crtc)].out_fence_ptr = fence_ptr;

+}

+/**

• • drm_atomic_get_out_fence_for_crtc - get CRTC out fence pointer
• • @state: global atomic state object
• • @crtc: crtc to set the out fence pointer
• • Get the user pointer that should be used for to store the out fence fd.
• • This function should be called only once per atomic state as it clears
• • the out_fence_ptr store there to prevent drivers to access them.
• • Returns:
• • The out fence user pointer.
• */

+static u64 __user * +drm_atomic_get_out_fence_for_crtc(struct drm_atomic_state *state,

• 	     struct drm_crtc *crtc)
  

+{

• u64 __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
• @mode: kernel-internal mode to use for the CRTC, or NULL to disable

@@ -490,6 +530,12 @@ 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) {

• uint64_t __user *fence_ptr = u64_to_user_ptr(val);
  

• if (!access_ok(VERIFY_WRITE, fence_ptr, sizeof(*fence_ptr)))
  

• 	return -EFAULT;
  

• drm_atomic_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

@@ -532,6 +578,8 @@ 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

@@ -1506,11 +1554,9 @@ EXPORT_SYMBOL(drm_atomic_nonblocking_commit); */

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)

@@ -1520,17 +1566,6 @@ 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;

}

@@ -1635,6 +1670,38 @@ void drm_atomic_clean_old_fb(struct drm_device *dev, } EXPORT_SYMBOL(drm_atomic_clean_old_fb);

+struct dma_fence *get_crtc_fence(struct drm_crtc *crtc,

• 		 struct drm_crtc_state *crtc_state)
  

+{

• 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;

+}

+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;

+}

int drm_mode_atomic_ioctl(struct drm_device *dev, void *data, struct drm_file *file_priv) { @@ -1649,9 +1716,10 @@ int drm_mode_atomic_ioctl(struct drm_device *dev, 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, fence_idx = 0;

  /* disallow for drivers not supporting atomic: */ if (!drm_core_check_feature(dev, DRIVER_ATOMIC))

@@ -1766,13 +1834,33 @@ int drm_mode_atomic_ioctl(struct drm_device *dev, drm_mode_object_unreference(obj); }

• fence_state = kcalloc(dev->mode_config.num_crtc, sizeof(*fence_state),

• 	      GFP_KERNEL);
  

• if (!fence_state) {

• ret = -ENOMEM;
  

• goto out;
  

• }

• if (arg->flags & DRM_MODE_PAGE_FLIP_EVENT) {

• for_each_crtc_in_state(state, crtc, crtc_state, i) {
  

• for_each_crtc_in_state(state, crtc, crtc_state, i) {

• fence_state->out_fence_ptr =
  

• 	drm_atomic_get_out_fence_for_crtc(crtc_state->state, crtc);
  

I think you're missing some subscripting on fence_state in this loop. Here you set fence_state->out_fence_ptr directly, whereas I guess it should be fence_state[fence_idx].out_fence_ptr;

• if (fence_state->out_fence_ptr &&
  

•     (arg->flags & DRM_MODE_ATOMIC_TEST_ONLY)) {
  

• 	if (put_user(-1, fence_state->out_fence_ptr)) {
  

• 		ret = -EFAULT;
  

• 		goto out;
  

• 	}
  

• 	continue;
  

• }
  

• if (arg->flags & DRM_MODE_PAGE_FLIP_EVENT ||
  

•     fence_state->out_fence_ptr) {
  struct drm_pending_vblank_event *e;
  
  

• 	e = create_vblank_event(dev, file_priv, NULL,
  

• 				arg->user_data);
  

• 	e = create_vblank_event(dev, arg->user_data);
  if (!e) {
  	ret = -ENOMEM;
  	goto out;
  

@@ -1780,6 +1868,39 @@ int drm_mode_atomic_ioctl(struct drm_device *dev,

	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;
  

• 		goto out;
  

• 	}
  

• }
  

• if (fence_state->out_fence_ptr) {
  

• 	struct dma_fence *fence;
  

• 	fence = get_crtc_fence(crtc, crtc_state);
  

• 	if (!fence) {
  

• 		ret = -ENOMEM;
  

• 		goto out;
  

• 	}
  

• 	ret = setup_out_fence(&fence_state[fence_idx++], fence);
  

Related to above, I think if you're going to manipulate the fence_state array outside of setup_out_fence you should drop the inline increment here, as it will be easy for a refactor to miss it and add bugs.

• 	if (ret) {
  

• 		dma_fence_put(fence);
  

• 		goto out;
  

• 	}
  

• 	crtc_state->event->base.fence = fence;
  

• }
  

  }

  if (arg->flags & DRM_MODE_ATOMIC_TEST_ONLY) {

@@ -1794,24 +1915,44 @@ int drm_mode_atomic_ioctl(struct drm_device *dev, ret = drm_atomic_commit(state); }

• if (ret)

• goto out;
  

• for (i = 0; i < fence_idx; i++)

• fd_install(fence_state[i].fd, fence_state[i].sync_file->file);
  

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.
  

•  */
  

• if (ret) { for_each_crtc_in_state(state, crtc, crtc_state, i) {

• 	if (!crtc_state->event)
  

• 		continue;
  

• 	/*
  

• 	 * 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);
  

• }
  
  

• 	drm_event_cancel_free(dev, &crtc_state->event->base);
  

• if (fence_state) {
  

• 	for (i = 0; i < fence_idx; 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_INFO("Couldn't clear out_fence_ptr\n");
  

• 	}
  

  } }

• kfree(fence_state);

• if (ret == -EDEADLK) { drm_atomic_state_clear(state); drm_modeset_backoff(&ctx);

diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c index e2a06c8..a18d81b 100644 --- a/drivers/gpu/drm/drm_crtc.c +++ b/drivers/gpu/drm/drm_crtc.c @@ -274,6 +274,8 @@ 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;

@@ -434,6 +436,12 @@ 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 2d1e9c9..ebde60e 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;

• u64 __user *out_fence_ptr;

};

struct __drm_connnectors_state { diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h index 278dbdd..2539394 100644 --- a/include/drm/drm_crtc.h +++ b/include/drm/drm_crtc.h @@ -768,6 +768,18 @@ static inline struct drm_crtc *fence_to_crtc(struct dma_fence *fence) }

/**

• • struct drm_out_fence_state - store out_fence data for install and clean up
• • @out_fence_ptr: user pointer to store the fence fd in.
• • @sync_file: sync_file related to the out_fence
• • @fd: file descriptor to installed on the sync_file.
• */

+struct drm_out_fence_state {

• u64 __user *out_fence_ptr;
• struct sync_file *sync_file;
• int fd;

+};

+/*

• struct drm_mode_set - new values for a CRTC config change
• @fb: framebuffer to use for new config
• @crtc: CRTC whose configuration we're about to change

@@ -1245,6 +1257,11 @@ 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.
  

• */
  

Is it worth noting that userspace should provide a pointer to a u64 and not a plain int? Either here or in some more detailed kernel-doc for the OUT_FENCE_PTR property.

Cheers, Brian

• struct drm_property *prop_out_fence_ptr;
• /**
  • @prop_crtc_id: Default atomic plane property to specify the
  • &drm_crtc.
  */

-- 2.5.5