drm_atomic_state has a complicated single owner model that tracks the
single reference from allocation through to destruction on another
thread - or perhaps on a local error path. We can simplify this tracking
by using reference counting (at a cost of a few more atomics). This is
even more beneficial when the lifetime of the state becomes more
convoluted than being passed to a single worker thread for the commit.

v2: Double check !intel atomic_commit functions for missing gets
v3: Update kerneldocs

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
Cc: dri-devel at lists.freedesktop.org
Reviewed-by: Eric Engestrom <eric.engestrom at imgtec.com>
---
 drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c |  3 +-
 drivers/gpu/drm/drm_atomic.c                 | 25 +++----
 drivers/gpu/drm/drm_atomic_helper.c          | 98 +++++++---------------------
 drivers/gpu/drm/drm_fb_helper.c              |  9 +--
 drivers/gpu/drm/exynos/exynos_drm_drv.c      |  3 +-
 drivers/gpu/drm/i915/i915_debugfs.c          |  3 +-
 drivers/gpu/drm/i915/intel_display.c         | 32 ++++-----
 drivers/gpu/drm/i915/intel_sprite.c          |  4 +-
 drivers/gpu/drm/mediatek/mtk_drm_drv.c       |  3 +-
 drivers/gpu/drm/msm/msm_atomic.c             |  3 +-
 drivers/gpu/drm/omapdrm/omap_drv.c           |  3 +-
 drivers/gpu/drm/rcar-du/rcar_du_kms.c        |  3 +-
 drivers/gpu/drm/sti/sti_drv.c                |  3 +-
 drivers/gpu/drm/tegra/drm.c                  |  3 +-
 drivers/gpu/drm/tilcdc/tilcdc_drv.c          |  2 -
 drivers/gpu/drm/vc4/vc4_kms.c                |  3 +-
 include/drm/drm_atomic.h                     | 28 +++++++-
 include/drm/drm_crtc.h                       |  3 +
 18 files changed, 102 insertions(+), 129 deletions(-)

diff --git a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c 
b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c
index 8e7483d90c47..c9e645fa1233 100644
--- a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c
+++ b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c
@@ -464,7 +464,7 @@ atmel_hlcdc_dc_atomic_complete(struct atmel_hlcdc_dc_commit 
*commit)

        drm_atomic_helper_cleanup_planes(dev, old_state);

-       drm_atomic_state_free(old_state);
+       drm_atomic_state_put(old_state);

        /* Complete the commit, wake up any waiter. */
        spin_lock(&dc->commit.wait.lock);
@@ -521,6 +521,7 @@ static int atmel_hlcdc_dc_atomic_commit(struct drm_device 
*dev,
        /* Swap the state, this is the point of no return. */
        drm_atomic_helper_swap_state(state, true);

+       drm_atomic_state_get(state);
        if (async)
                queue_work(dc->wq, &commit->work);
        else
diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
index 0b8f33da1488..d3065ffe6611 100644
--- a/drivers/gpu/drm/drm_atomic.c
+++ b/drivers/gpu/drm/drm_atomic.c
@@ -74,6 +74,8 @@ EXPORT_SYMBOL(drm_atomic_state_default_release);
 int
 drm_atomic_state_init(struct drm_device *dev, struct drm_atomic_state *state)
 {
+       kref_init(&state->ref);
+
        /* TODO legacy paths should maybe do a better job about
         * setting this appropriately?
         */
@@ -215,22 +217,16 @@ void drm_atomic_state_clear(struct drm_atomic_state 
*state)
 EXPORT_SYMBOL(drm_atomic_state_clear);

 /**
- * drm_atomic_state_free - free all memory for an atomic state
- * @state: atomic state to deallocate
+ * __drm_atomic_state_free - free all memory for an atomic state
+ * @ref: This atomic state to deallocate
  *
  * This frees all memory associated with an atomic state, including all the
  * per-object state for planes, crtcs and connectors.
  */
-void drm_atomic_state_free(struct drm_atomic_state *state)
+void __drm_atomic_state_free(struct kref *ref)
 {
-       struct drm_device *dev;
-       struct drm_mode_config *config;
-
-       if (!state)
-               return;
-
-       dev = state->dev;
-       config = &dev->mode_config;
+       struct drm_atomic_state *state = container_of(ref, typeof(*state), ref);
+       struct drm_mode_config *config = &state->dev->mode_config;

        drm_atomic_state_clear(state);

@@ -243,7 +239,7 @@ void drm_atomic_state_free(struct drm_atomic_state *state)
                kfree(state);
        }
 }
-EXPORT_SYMBOL(drm_atomic_state_free);
+EXPORT_SYMBOL(__drm_atomic_state_free);

 /**
  * drm_atomic_get_crtc_state - get crtc state
@@ -1742,7 +1738,7 @@ retry:
        if (arg->flags & DRM_MODE_ATOMIC_TEST_ONLY) {
                /*
                 * Unlike commit, check_only does not clean up state.
-                * Below we call drm_atomic_state_free for it.
+                * Below we call drm_atomic_state_put for it.
                 */
                ret = drm_atomic_check_only(state);
        } else if (arg->flags & DRM_MODE_ATOMIC_NONBLOCK) {
@@ -1775,8 +1771,7 @@ out:
                goto retry;
        }

-       if (ret || arg->flags & DRM_MODE_ATOMIC_TEST_ONLY)
-               drm_atomic_state_free(state);
+       drm_atomic_state_put(state);

        drm_modeset_drop_locks(&ctx);
        drm_modeset_acquire_fini(&ctx);
diff --git a/drivers/gpu/drm/drm_atomic_helper.c 
b/drivers/gpu/drm/drm_atomic_helper.c
index 6fdd7ba47896..a5e8701f1ca3 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -1190,7 +1190,7 @@ static void commit_tail(struct drm_atomic_state *state)

        drm_atomic_helper_commit_cleanup_done(state);

-       drm_atomic_state_free(state);
+       drm_atomic_state_put(state);
 }

 static void commit_work(struct work_struct *work)
@@ -1266,6 +1266,7 @@ int drm_atomic_helper_commit(struct drm_device *dev,
         * make sure work items don't artifically stall on each another.
         */

+       drm_atomic_state_get(state);
        if (nonblock)
                queue_work(system_unbound_wq, &state->commit_work);
        else
@@ -1567,7 +1568,7 @@ EXPORT_SYMBOL(drm_atomic_helper_commit_hw_done);
  *
  * This signals completion of the atomic update @state, including any cleanup
  * work. If used, it must be called right before calling
- * drm_atomic_state_free().
+ * drm_atomic_state_put().
  *
  * This is part of the atomic helper support for nonblocking commits, see
  * drm_atomic_helper_setup_commit() for an overview.
@@ -2090,18 +2091,13 @@ retry:
                state->legacy_cursor_update = true;

        ret = drm_atomic_commit(state);
-       if (ret != 0)
-               goto fail;
-
-       /* Driver takes ownership of state on successful commit. */
-       return 0;
 fail:
        if (ret == -EDEADLK)
                goto backoff;

-       drm_atomic_state_free(state);
-
+       drm_atomic_state_put(state);
        return ret;
+
 backoff:
        drm_atomic_state_clear(state);
        drm_atomic_legacy_backoff(state);
@@ -2163,18 +2159,13 @@ retry:
                goto fail;

        ret = drm_atomic_commit(state);
-       if (ret != 0)
-               goto fail;
-
-       /* Driver takes ownership of state on successful commit. */
-       return 0;
 fail:
        if (ret == -EDEADLK)
                goto backoff;

-       drm_atomic_state_free(state);
-
+       drm_atomic_state_put(state);
        return ret;
+
 backoff:
        drm_atomic_state_clear(state);
        drm_atomic_legacy_backoff(state);
@@ -2303,18 +2294,13 @@ retry:
                goto fail;

        ret = drm_atomic_commit(state);
-       if (ret != 0)
-               goto fail;
-
-       /* Driver takes ownership of state on successful commit. */
-       return 0;
 fail:
        if (ret == -EDEADLK)
                goto backoff;

-       drm_atomic_state_free(state);
-
+       drm_atomic_state_put(state);
        return ret;
+
 backoff:
        drm_atomic_state_clear(state);
        drm_atomic_legacy_backoff(state);
@@ -2456,11 +2442,8 @@ int drm_atomic_helper_disable_all(struct drm_device *dev,
        }

        err = drm_atomic_commit(state);
-
 free:
-       if (err < 0)
-               drm_atomic_state_free(state);
-
+       drm_atomic_state_put(state);
        return err;
 }
 EXPORT_SYMBOL(drm_atomic_helper_disable_all);
@@ -2511,7 +2494,7 @@ retry:

        err = drm_atomic_helper_disable_all(dev, &ctx);
        if (err < 0) {
-               drm_atomic_state_free(state);
+               drm_atomic_state_put(state);
                state = ERR_PTR(err);
                goto unlock;
        }
@@ -2600,18 +2583,13 @@ retry:
                goto fail;

        ret = drm_atomic_commit(state);
-       if (ret != 0)
-               goto fail;
-
-       /* Driver takes ownership of state on successful commit. */
-       return 0;
 fail:
        if (ret == -EDEADLK)
                goto backoff;

-       drm_atomic_state_free(state);
-
+       drm_atomic_state_put(state);
        return ret;
+
 backoff:
        drm_atomic_state_clear(state);
        drm_atomic_legacy_backoff(state);
@@ -2660,18 +2638,13 @@ retry:
                goto fail;

        ret = drm_atomic_commit(state);
-       if (ret != 0)
-               goto fail;
-
-       /* Driver takes ownership of state on successful commit. */
-       return 0;
 fail:
        if (ret == -EDEADLK)
                goto backoff;

-       drm_atomic_state_free(state);
-
+       drm_atomic_state_put(state);
        return ret;
+
 backoff:
        drm_atomic_state_clear(state);
        drm_atomic_legacy_backoff(state);
@@ -2720,18 +2693,13 @@ retry:
                goto fail;

        ret = drm_atomic_commit(state);
-       if (ret != 0)
-               goto fail;
-
-       /* Driver takes ownership of state on successful commit. */
-       return 0;
 fail:
        if (ret == -EDEADLK)
                goto backoff;

-       drm_atomic_state_free(state);
-
+       drm_atomic_state_put(state);
        return ret;
+
 backoff:
        drm_atomic_state_clear(state);
        drm_atomic_legacy_backoff(state);
@@ -2804,18 +2772,13 @@ retry:
        }

        ret = drm_atomic_nonblocking_commit(state);
-       if (ret != 0)
-               goto fail;
-
-       /* Driver takes ownership of state on successful commit. */
-       return 0;
 fail:
        if (ret == -EDEADLK)
                goto backoff;

-       drm_atomic_state_free(state);
-
+       drm_atomic_state_put(state);
        return ret;
+
 backoff:
        drm_atomic_state_clear(state);
        drm_atomic_legacy_backoff(state);
@@ -2891,19 +2854,14 @@ retry:
        crtc_state->active = active;

        ret = drm_atomic_commit(state);
-       if (ret != 0)
-               goto fail;
-
-       /* Driver takes ownership of state on successful commit. */
-       return 0;
 fail:
        if (ret == -EDEADLK)
                goto backoff;

        connector->dpms = old_mode;
-       drm_atomic_state_free(state);
-
+       drm_atomic_state_put(state);
        return ret;
+
 backoff:
        drm_atomic_state_clear(state);
        drm_atomic_legacy_backoff(state);
@@ -3310,7 +3268,7 @@ drm_atomic_helper_duplicate_state(struct drm_device *dev,

 free:
        if (err < 0) {
-               drm_atomic_state_free(state);
+               drm_atomic_state_put(state);
                state = ERR_PTR(err);
        }

@@ -3425,22 +3383,14 @@ retry:
                goto fail;

        ret = drm_atomic_commit(state);
-       if (ret)
-               goto fail;
-
-       /* Driver takes ownership of state on successful commit. */
-
-       drm_property_unreference_blob(blob);
-
-       return 0;
 fail:
        if (ret == -EDEADLK)
                goto backoff;

-       drm_atomic_state_free(state);
+       drm_atomic_state_put(state);
        drm_property_unreference_blob(blob);
-
        return ret;
+
 backoff:
        drm_atomic_state_clear(state);
        drm_atomic_legacy_backoff(state);
diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index dd8e3b68fd53..05a711ecf97a 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -365,9 +365,7 @@ fail:
        if (ret == -EDEADLK)
                goto backoff;

-       if (ret != 0)
-               drm_atomic_state_free(state);
-
+       drm_atomic_state_put(state);
        return ret;

 backoff:
@@ -1359,16 +1357,13 @@ retry:
        info->var.xoffset = var->xoffset;
        info->var.yoffset = var->yoffset;

-
 fail:
        drm_atomic_clean_old_fb(dev, plane_mask, ret);

        if (ret == -EDEADLK)
                goto backoff;

-       if (ret != 0)
-               drm_atomic_state_free(state);
-
+       drm_atomic_state_put(state);
        return ret;

 backoff:
diff --git a/drivers/gpu/drm/exynos/exynos_drm_drv.c 
b/drivers/gpu/drm/exynos/exynos_drm_drv.c
index 486943e70f70..f11ba20781ce 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_drv.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_drv.c
@@ -111,7 +111,7 @@ static void exynos_atomic_commit_complete(struct 
exynos_atomic_commit *commit)

        drm_atomic_helper_cleanup_planes(dev, state);

-       drm_atomic_state_free(state);
+       drm_atomic_state_put(state);

        spin_lock(&priv->lock);
        priv->pending &= ~commit->crtcs;
@@ -296,6 +296,7 @@ int exynos_atomic_commit(struct drm_device *dev, struct 
drm_atomic_state *state,

        drm_atomic_helper_swap_state(state, true);

+       drm_atomic_state_get(state);
        if (nonblock)
                schedule_work(&commit->work);
        else
diff --git a/drivers/gpu/drm/i915/i915_debugfs.c 
b/drivers/gpu/drm/i915/i915_debugfs.c
index d89359a50742..f51a750bc57a 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -3954,8 +3954,7 @@ static void hsw_trans_edp_pipe_A_crc_wa(struct 
drm_i915_private *dev_priv,
 out:
        drm_modeset_unlock_all(dev);
        WARN(ret, "Toggling workaround to %i returns %i\n", enable, ret);
-       if (ret)
-               drm_atomic_state_free(state);
+       drm_atomic_state_put(state);
 }

 static int ivb_pipe_crc_ctl_reg(struct drm_i915_private *dev_priv,
diff --git a/drivers/gpu/drm/i915/intel_display.c 
b/drivers/gpu/drm/i915/intel_display.c
index 19ffd024ddec..fc2453919035 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -3577,7 +3577,7 @@ void intel_prepare_reset(struct drm_i915_private 
*dev_priv)
        return;

 err:
-       drm_atomic_state_free(state);
+       drm_atomic_state_put(state);
 }

 void intel_finish_reset(struct drm_i915_private *dev_priv)
@@ -3638,6 +3638,7 @@ void intel_finish_reset(struct drm_i915_private *dev_priv)
                intel_hpd_init(dev_priv);
        }

+       drm_atomic_state_put(state);
        drm_modeset_drop_locks(ctx);
        drm_modeset_acquire_fini(ctx);
        mutex_unlock(&dev->mode_config.mutex);
@@ -6866,7 +6867,7 @@ static void intel_crtc_disable_noatomic(struct drm_crtc 
*crtc)

        dev_priv->display.crtc_disable(crtc_state, state);

-       drm_atomic_state_free(state);
+       drm_atomic_state_put(state);

        DRM_DEBUG_KMS("[CRTC:%d:%s] hw state adjusted, was enabled, now 
disabled\n",
                      crtc->base.id, crtc->name);
@@ -11249,11 +11250,13 @@ found:

        /* let the connector get through one full cycle before testing */
        intel_wait_for_vblank(dev, intel_crtc->pipe);
+       drm_atomic_state_put(state);
+       drm_atomic_state_put(restore_state);
        return true;

 fail:
-       drm_atomic_state_free(state);
-       drm_atomic_state_free(restore_state);
+       drm_atomic_state_put(state);
+       drm_atomic_state_put(restore_state);
        restore_state = state = NULL;

        if (ret == -EDEADLK) {
@@ -11282,10 +11285,9 @@ void intel_release_load_detect_pipe(struct 
drm_connector *connector,
                return;

        ret = drm_atomic_commit(state);
-       if (ret) {
+       if (ret)
                DRM_DEBUG_KMS("Couldn't release load detect pipe: %i\n", ret);
-               drm_atomic_state_free(state);
-       }
+       drm_atomic_state_put(state);
 }

 static int i9xx_pll_refclk(struct drm_device *dev,
@@ -12356,8 +12358,7 @@ retry:
                        goto retry;
                }

-               if (ret)
-                       drm_atomic_state_free(state);
+               drm_atomic_state_put(state);

                if (ret == 0 && event) {
                        spin_lock_irq(&dev->event_lock);
@@ -14450,7 +14451,7 @@ static void intel_atomic_commit_tail(struct 
drm_atomic_state *state)

        drm_atomic_helper_commit_cleanup_done(state);

-       drm_atomic_state_free(state);
+       drm_atomic_state_put(state);

        /* As one of the primary mmio accessors, KMS has a high likelihood
         * of triggering bugs in unclaimed access. After we finish
@@ -14533,6 +14534,7 @@ static int intel_atomic_commit(struct drm_device *dev,
        intel_shared_dpll_commit(state);
        intel_atomic_track_fbs(state);

+       drm_atomic_state_get(state);
        if (nonblock)
                queue_work(system_unbound_wq, &state->commit_work);
        else
@@ -14574,9 +14576,8 @@ retry:
                goto retry;
        }

-       if (ret)
 out:
-               drm_atomic_state_free(state);
+       drm_atomic_state_put(state);
 }

 /*
@@ -16318,8 +16319,8 @@ retry:
                dev_priv->display.optimize_watermarks(cs);
        }

-       drm_atomic_state_free(state);
 fail:
+       drm_atomic_state_put(state);
        drm_modeset_drop_locks(&ctx);
        drm_modeset_acquire_fini(&ctx);
 }
@@ -16956,10 +16957,9 @@ void intel_display_resume(struct drm_device *dev)
        drm_modeset_acquire_fini(&ctx);
        mutex_unlock(&dev->mode_config.mutex);

-       if (ret) {
+       if (ret)
                DRM_ERROR("Restoring old state failed with %i\n", ret);
-               drm_atomic_state_free(state);
-       }
+       drm_atomic_state_put(state);
 }

 void intel_modeset_gem_init(struct drm_device *dev)
diff --git a/drivers/gpu/drm/i915/intel_sprite.c 
b/drivers/gpu/drm/i915/intel_sprite.c
index 0df783a66bfb..be819d86beae 100644
--- a/drivers/gpu/drm/i915/intel_sprite.c
+++ b/drivers/gpu/drm/i915/intel_sprite.c
@@ -982,9 +982,7 @@ int intel_sprite_set_colorkey(struct drm_device *dev, void 
*data,
                drm_modeset_backoff(&ctx);
        }

-       if (ret)
-               drm_atomic_state_free(state);
-
+       drm_atomic_state_put(state);
 out:
        drm_modeset_drop_locks(&ctx);
        drm_modeset_acquire_fini(&ctx);
diff --git a/drivers/gpu/drm/mediatek/mtk_drm_drv.c 
b/drivers/gpu/drm/mediatek/mtk_drm_drv.c
index 72c1ae4e02d4..5ab6017575ea 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_drv.c
+++ b/drivers/gpu/drm/mediatek/mtk_drm_drv.c
@@ -83,7 +83,7 @@ static void mtk_atomic_complete(struct mtk_drm_private 
*private,
        drm_atomic_helper_wait_for_vblanks(drm, state);

        drm_atomic_helper_cleanup_planes(drm, state);
-       drm_atomic_state_free(state);
+       drm_atomic_state_put(state);
 }

 static void mtk_atomic_work(struct work_struct *work)
@@ -110,6 +110,7 @@ static int mtk_atomic_commit(struct drm_device *drm,

        drm_atomic_helper_swap_state(state, true);

+       drm_atomic_state_get(state);
        if (async)
                mtk_atomic_schedule(private, state);
        else
diff --git a/drivers/gpu/drm/msm/msm_atomic.c b/drivers/gpu/drm/msm/msm_atomic.c
index 5df252cebf1c..9a268efeb740 100644
--- a/drivers/gpu/drm/msm/msm_atomic.c
+++ b/drivers/gpu/drm/msm/msm_atomic.c
@@ -141,7 +141,7 @@ static void complete_commit(struct msm_commit *c, bool 
async)

        kms->funcs->complete_commit(kms, state);

-       drm_atomic_state_free(state);
+       drm_atomic_state_put(state);

        commit_destroy(c);
 }
@@ -256,6 +256,7 @@ int msm_atomic_commit(struct drm_device *dev,
         * current layout.
         */

+       drm_atomic_state_get(state);
        if (nonblock) {
                queue_work(priv->atomic_wq, &c->work);
                return 0;
diff --git a/drivers/gpu/drm/omapdrm/omap_drv.c 
b/drivers/gpu/drm/omapdrm/omap_drv.c
index e1cfba51cff6..1735c7accf72 100644
--- a/drivers/gpu/drm/omapdrm/omap_drv.c
+++ b/drivers/gpu/drm/omapdrm/omap_drv.c
@@ -105,7 +105,7 @@ static void omap_atomic_complete(struct 
omap_atomic_state_commit *commit)

        dispc_runtime_put();

-       drm_atomic_state_free(old_state);
+       drm_atomic_state_put(old_state);

        /* Complete the commit, wake up any waiter. */
        spin_lock(&priv->commit.lock);
@@ -176,6 +176,7 @@ static int omap_atomic_commit(struct drm_device *dev,
        /* Swap the state, this is the point of no return. */
        drm_atomic_helper_swap_state(state, true);

+       drm_atomic_state_get(state);
        if (nonblock)
                schedule_work(&commit->work);
        else
diff --git a/drivers/gpu/drm/rcar-du/rcar_du_kms.c 
b/drivers/gpu/drm/rcar-du/rcar_du_kms.c
index bd9c3bb9252c..c76ed9ee6a01 100644
--- a/drivers/gpu/drm/rcar-du/rcar_du_kms.c
+++ b/drivers/gpu/drm/rcar-du/rcar_du_kms.c
@@ -264,7 +264,7 @@ static void rcar_du_atomic_complete(struct rcar_du_commit 
*commit)

        drm_atomic_helper_cleanup_planes(dev, old_state);

-       drm_atomic_state_free(old_state);
+       drm_atomic_state_put(old_state);

        /* Complete the commit, wake up any waiter. */
        spin_lock(&rcdu->commit.wait.lock);
@@ -330,6 +330,7 @@ static int rcar_du_atomic_commit(struct drm_device *dev,
        /* Swap the state, this is the point of no return. */
        drm_atomic_helper_swap_state(state, true);

+       drm_atomic_state_get(state);
        if (nonblock)
                schedule_work(&commit->work);
        else
diff --git a/drivers/gpu/drm/sti/sti_drv.c b/drivers/gpu/drm/sti/sti_drv.c
index 7cd3804c6dee..7ad8d42dba28 100644
--- a/drivers/gpu/drm/sti/sti_drv.c
+++ b/drivers/gpu/drm/sti/sti_drv.c
@@ -184,7 +184,7 @@ static void sti_atomic_complete(struct sti_private *private,
        drm_atomic_helper_wait_for_vblanks(drm, state);

        drm_atomic_helper_cleanup_planes(drm, state);
-       drm_atomic_state_free(state);
+       drm_atomic_state_put(state);
 }

 static void sti_atomic_work(struct work_struct *work)
@@ -217,6 +217,7 @@ static int sti_atomic_commit(struct drm_device *drm,

        drm_atomic_helper_swap_state(state, true);

+       drm_atomic_state_get(state);
        if (nonblock)
                sti_atomic_schedule(private, state);
        else
diff --git a/drivers/gpu/drm/tegra/drm.c b/drivers/gpu/drm/tegra/drm.c
index 4b9f1c79cd7b..4ca8f2f3c46b 100644
--- a/drivers/gpu/drm/tegra/drm.c
+++ b/drivers/gpu/drm/tegra/drm.c
@@ -63,7 +63,7 @@ static void tegra_atomic_complete(struct tegra_drm *tegra,
        drm_atomic_helper_wait_for_vblanks(drm, state);

        drm_atomic_helper_cleanup_planes(drm, state);
-       drm_atomic_state_free(state);
+       drm_atomic_state_put(state);
 }

 static void tegra_atomic_work(struct work_struct *work)
@@ -96,6 +96,7 @@ static int tegra_atomic_commit(struct drm_device *drm,

        drm_atomic_helper_swap_state(state, true);

+       drm_atomic_state_get(state);
        if (nonblock)
                tegra_atomic_schedule(tegra, state);
        else
diff --git a/drivers/gpu/drm/tilcdc/tilcdc_drv.c 
b/drivers/gpu/drm/tilcdc/tilcdc_drv.c
index 4405e4bc8056..432af1fea238 100644
--- a/drivers/gpu/drm/tilcdc/tilcdc_drv.c
+++ b/drivers/gpu/drm/tilcdc/tilcdc_drv.c
@@ -129,8 +129,6 @@ static int tilcdc_commit(struct drm_device *dev,

        drm_atomic_helper_cleanup_planes(dev, state);

-       drm_atomic_state_free(state);
-
        return 0;
 }

diff --git a/drivers/gpu/drm/vc4/vc4_kms.c b/drivers/gpu/drm/vc4/vc4_kms.c
index c1f65c6c8e60..f31f72af8551 100644
--- a/drivers/gpu/drm/vc4/vc4_kms.c
+++ b/drivers/gpu/drm/vc4/vc4_kms.c
@@ -61,7 +61,7 @@ vc4_atomic_complete_commit(struct vc4_commit *c)

        drm_atomic_helper_cleanup_planes(dev, state);

-       drm_atomic_state_free(state);
+       drm_atomic_state_put(state);

        up(&vc4->async_modeset);

@@ -173,6 +173,7 @@ static int vc4_atomic_commit(struct drm_device *dev,
         * current layout.
         */

+       drm_atomic_state_get(state);
        if (nonblock) {
                vc4_queue_seqno_cb(dev, &c->cb, wait_seqno,
                                   vc4_atomic_complete_commit_seqno_cb);
diff --git a/include/drm/drm_atomic.h b/include/drm/drm_atomic.h
index 856a9c85a838..1c6210e7a791 100644
--- a/include/drm/drm_atomic.h
+++ b/include/drm/drm_atomic.h
@@ -39,7 +39,33 @@ static inline void drm_crtc_commit_get(struct 
drm_crtc_commit *commit)
 struct drm_atomic_state * __must_check
 drm_atomic_state_alloc(struct drm_device *dev);
 void drm_atomic_state_clear(struct drm_atomic_state *state);
-void drm_atomic_state_free(struct drm_atomic_state *state);
+
+/**
+ * drm_atomic_state_get - acquire a reference to the atomic state
+ * @state: The atomic state
+ *
+ * Returns a new reference to the @state
+ */
+static inline struct drm_atomic_state *
+drm_atomic_state_get(struct drm_atomic_state *state)
+{
+       kref_get(&state->ref);
+       return state;
+}
+
+void __drm_atomic_state_free(struct kref *ref);
+
+/**
+ * drm_atomic_state_put - release a reference to the atomic state
+ * @state: The atomic state
+ *
+ * This releases a reference to @state which is freed after removing the
+ * final reference. No locking required and callable from any context.
+ */
+static inline void drm_atomic_state_put(struct drm_atomic_state *state)
+{
+       kref_put(&state->ref, __drm_atomic_state_free);
+}

 int  __must_check
 drm_atomic_state_init(struct drm_device *dev, struct drm_atomic_state *state);
diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index 3d33c90da9e5..caf03ccaf77c 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -1291,6 +1291,7 @@ struct __drm_connnectors_state {

 /**
  * struct drm_atomic_state - the global state object for atomic updates
+ * @ref: count of all references to this state
  * @dev: parent DRM device
  * @allow_modeset: allow full modeset
  * @legacy_cursor_update: hint to enforce legacy cursor IOCTL semantics
@@ -1302,6 +1303,8 @@ struct __drm_connnectors_state {
  * @acquire_ctx: acquire context for this atomic modeset state update
  */
 struct drm_atomic_state {
+       struct kref ref;
+
        struct drm_device *dev;
        bool allow_modeset : 1;
        bool legacy_cursor_update : 1;
-- 
2.9.3

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