Re: [PATCH v8 3/3] drm/fence: add out-fences support

Sean Paul
2016-11-11T16:49:14Z

On Fri, Nov 11, 2016 at 9:15 AM, Gustavo Padovan <gustavo@padovan.org> 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
>
> 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
>
> Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>

A couple of nits below, other than that, looks good to me

> ---
> drivers/gpu/drm/drm_atomic.c | 243 +++++++++++++++++++++++++++++++++++--------
> drivers/gpu/drm/drm_crtc.c | 8 ++
> include/drm/drm_atomic.h | 1 +
> include/drm/drm_crtc.h | 6 ++
> 4 files changed, 213 insertions(+), 45 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
> index 8e26ad1..34cdc6e 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
> @@ -491,6 +508,16 @@ 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 (!access_ok(VERIFY_WRITE, fence_ptr, sizeof(*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
> @@ -533,6 +560,8 @@ 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
> @@ -1659,11 +1688,9 @@ 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)
> @@ -1673,17 +1700,6 @@ 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;
> }
>
> @@ -1788,6 +1804,167 @@ 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;
> +
> + 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_ATOMIC_TEST_ONLY && fence_ptr) {
> + if (put_user(-1, fence_ptr))
> + return -EFAULT;
> +
> + continue;
> + }
> +
> + if (arg->flags & DRM_MODE_PAGE_FLIP_EVENT || fence_ptr) {

pedantic suggestion: If you did the inverse, you could just continue
and save yourself some indentation (and instantiate e once). ie:

if (!(arg->flags & DRM_MODE_PAGE_FLIP_EVENT) && !fence_ptr)
continue;

...

> + 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;
> +
> + f[*num_fences].out_fence_ptr = fence_ptr;
> + *fence_state = f;
> +
> + fence = get_crtc_fence(crtc);
> + if (!fence) {
> + (*num_fences)++;
> + 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, int ret)
> +{
> + struct drm_crtc *crtc;
> + struct drm_crtc_state *crtc_state;
> + int i;
> +
> + if (!ret) {

I don't think there's any reason to smash the fd install and clean-up
into one function. I think splitting into 2 functions and calling the
right one from atomic_ioctl would be better.

> + for (i = 0; i < num_fences; i++)
> + fd_install(fence_state[i].fd,
> + fence_state[i].sync_file->file);
> + 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)
> {
> @@ -1800,11 +1977,10 @@ 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))
> @@ -1919,20 +2095,10 @@ 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) {
> /*
> @@ -1952,20 +2118,7 @@ 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 9b9881b..e8bc1ae 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 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 0870de1..44571bc 100644
> --- a/include/drm/drm_crtc.h
> +++ b/include/drm/drm_crtc.h
> @@ -1264,6 +1264,12 @@ 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
>