From: Gustavo Padovan <gustavo.pado...@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.pado...@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)
+{
+       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);
+
+               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);
+                       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.
+        */
+       struct drm_property *prop_out_fence_ptr;
+       /**
         * @prop_crtc_id: Default atomic plane property to specify the
         * &drm_crtc.
         */
-- 
2.5.5

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