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SubjectRe: [PATCH v5 4/4] drm/fence: add out-fences support
Hi Gustavo,

I notice your branch has the sync_file refcount change in, but this
doesn't seem to take account for that. Will you be dropping that
change to match the semantics of fence_array?

Couple more comments below.

On Thu, Oct 20, 2016 at 12:50:05PM -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.
>
>In case of error userspace should receive a fd number of -1.
>
>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.
>
>Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
>---
> drivers/gpu/drm/drm_atomic.c | 116 ++++++++++++++++++++++++++++++++++---------
> drivers/gpu/drm/drm_crtc.c | 8 +++
> include/drm/drm_crtc.h | 19 +++++++
> 3 files changed, 119 insertions(+), 24 deletions(-)
>
>diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
>index b3284b2..07775fc 100644
>--- a/drivers/gpu/drm/drm_atomic.c
>+++ b/drivers/gpu/drm/drm_atomic.c
>@@ -490,6 +490,8 @@ 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) {
>+ state->out_fence_ptr = u64_to_user_ptr(val);
> } else if (crtc->funcs->atomic_set_property)
> return crtc->funcs->atomic_set_property(crtc, state, property, val);
> else
>@@ -532,6 +534,8 @@ 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
>@@ -1474,11 +1478,9 @@ 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 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)
>@@ -1488,17 +1490,6 @@ 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;
> }
>
>@@ -1603,6 +1594,40 @@ void drm_atomic_clean_old_fb(struct drm_device *dev,
> }
> EXPORT_SYMBOL(drm_atomic_clean_old_fb);
>
>+static int crtc_setup_out_fence(struct drm_crtc *crtc,
>+ struct drm_crtc_state *crtc_state,
>+ struct drm_out_fence_state *fence_state)
>+{
>+ struct fence *fence;
>+
>+ fence_state->fd = get_unused_fd_flags(O_CLOEXEC);
>+ if (fence_state->fd < 0) {
>+ return fence_state->fd;
>+ }
>+
>+ fence_state->out_fence_ptr = crtc_state->out_fence_ptr;
>+ crtc_state->out_fence_ptr = NULL;
>+
>+ if (put_user(fence_state->fd, fence_state->out_fence_ptr))
>+ return -EFAULT;
>+
>+ fence = kzalloc(sizeof(*fence), GFP_KERNEL);
>+ if (!fence)
>+ return -ENOMEM;
>+
>+ fence_init(fence, &drm_crtc_fence_ops, &crtc->fence_lock,
>+ crtc->fence_context, ++crtc->fence_seqno);
>+
>+ fence_state->sync_file = sync_file_create(fence);
>+ if(!fence_state->sync_file) {
>+ fence_put(fence);
>+ return -ENOMEM;
>+ }
>+
>+ crtc_state->event->base.fence = fence_get(fence);
>+ return 0;
>+}
>+
> int drm_mode_atomic_ioctl(struct drm_device *dev,
> void *data, struct drm_file *file_priv)
> {
>@@ -1617,9 +1642,10 @@ 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;
> 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))
>@@ -1734,12 +1760,19 @@ retry:
> drm_mode_object_unreference(obj);
> }
>
>- if (arg->flags & DRM_MODE_PAGE_FLIP_EVENT) {
>- for_each_crtc_in_state(state, crtc, crtc_state, i) {
>+ fence_state = kcalloc(dev->mode_config.num_crtc, sizeof(*fence_state),
>+ GFP_KERNEL);
>+ if (!fence_state) {
>+ ret = -ENOMEM;
>+ goto out;
>+ }
>+
>+ for_each_crtc_in_state(state, crtc, crtc_state, i) {
>+ if (arg->flags & DRM_MODE_PAGE_FLIP_EVENT ||
>+ crtc_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;
>@@ -1747,6 +1780,28 @@ retry:
>
> 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 (crtc_state->out_fence_ptr) {
>+ ret = crtc_setup_out_fence(crtc, crtc_state,
>+ &fence_state[fence_idx++]);
>+ if (ret)
>+ goto out;
>+ }
> }
>
> if (arg->flags & DRM_MODE_ATOMIC_TEST_ONLY) {
>@@ -1761,24 +1816,37 @@ retry:
> ret = drm_atomic_commit(state);
> }
>
>+ 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) {
>+ for_each_crtc_in_state(state, crtc, crtc_state, i) {

I think a check on ret is still needed before you iterate the CRTCs.
If the commit is successful then state has already been freed by this
point, and I get a splat.

> /*
> * 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 && crtc_state->event)
>+ drm_event_cancel_free(dev, &crtc_state->event->base);
>+ }
>
>- for_each_crtc_in_state(state, crtc, crtc_state, i) {
>- if (!crtc_state->event)
>- continue;
>+ if (ret && fence_state) {
>+ for (i = 0; i < fence_idx; i++) {
>+ if (fence_state[i].fd >= 0)
>+ put_unused_fd(fence_state[i].fd);
>+ if (fence_state[i].sync_file)
>+ fput(fence_state[i].sync_file->file);
>
>- drm_event_cancel_free(dev, &crtc_state->event->base);
>+ /* If this fails, there's not much we can do about it */
>+ if (put_user(-1, fence_state->out_fence_ptr))
>+ DRM_ERROR("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 b99090f..40bce97 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_crtc.h b/include/drm/drm_crtc.h
>index 657a33a..b898604 100644
>--- a/include/drm/drm_crtc.h
>+++ b/include/drm/drm_crtc.h
>@@ -165,6 +165,8 @@ struct drm_crtc_state {
> struct drm_property_blob *ctm;
> struct drm_property_blob *gamma_lut;
>
>+ u64 __user *out_fence_ptr;
>+

I'm somewhat not convinced about stashing a __user pointer in the
CRTC atomic state. I know it gets cleared before the driver sees it,
but if anything I think that hints that this isn't the right place to
store it.

I've been trying to think of other ways to get from a property to
something drm_mode_atomic_ioctl can use - maybe we can store some
stuff in drm_atomic_state which only lives for the length of the ioctl
call and put this pointer in there.

Thanks,
Brian

> /**
> * @event:
> *
>@@ -748,6 +750,18 @@ static inline struct drm_crtc *fence_to_crtc(struct 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
>@@ -1230,6 +1244,11 @@ 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
>
>_______________________________________________
>dri-devel mailing list
>dri-devel@lists.freedesktop.org
>https://lists.freedesktop.org/mailman/listinfo/dri-devel

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