[26/41] drm: Add reference counting to drm_atomic_state

Submitted by Chris Wilson on Oct. 14, 2016, 12:18 p.m.

Details

Message ID 20161014121833.439-27-chris@chris-wilson.co.uk
State New
Headers show
Series "Series without cover letter" ( rev: 1 ) in Intel GFX

Browsing this patch as part of:
"Series without cover letter" rev 1 in Intel GFX
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Commit Message

Chris Wilson Oct. 14, 2016, 12:18 p.m.
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@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: dri-devel@lists.freedesktop.org
Reviewed-by: Eric Engestrom <eric.engestrom@imgtec.com>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
---
 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          |  5 +-
 drivers/gpu/drm/i915/intel_display.c         | 31 +++++----
 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                     | 31 ++++++++-
 include/drm/drm_plane.h                      |  1 -
 18 files changed, 102 insertions(+), 131 deletions(-)

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diff --git a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c
index 5f484310bee9..9f6222895212 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 23739609427d..5dd70540219c 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 c3f83476f996..df6e9b7c377c 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -1207,7 +1207,7 @@  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)
@@ -1289,6 +1289,7 @@  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
@@ -1590,7 +1591,7 @@  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.
@@ -2113,18 +2114,13 @@  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);
@@ -2186,18 +2182,13 @@  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);
@@ -2326,18 +2317,13 @@  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);
@@ -2479,11 +2465,8 @@  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);
@@ -2534,7 +2517,7 @@  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;
 	}
@@ -2623,18 +2606,13 @@  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);
@@ -2683,18 +2661,13 @@  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);
@@ -2743,18 +2716,13 @@  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);
@@ -2827,18 +2795,13 @@  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);
@@ -2914,19 +2877,14 @@  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);
@@ -3333,7 +3291,7 @@  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);
 	}
 
@@ -3448,22 +3406,14 @@  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 03414bde1f15..22d4f0e22101 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -367,9 +367,7 @@  fail:
 	if (ret == -EDEADLK)
 		goto backoff;
 
-	if (ret != 0)
-		drm_atomic_state_free(state);
-
+	drm_atomic_state_put(state);
 	return ret;
 
 backoff:
@@ -1361,16 +1359,13 @@  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 def78c8c1780..4a21a745c373 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_drv.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_drv.c
@@ -69,7 +69,7 @@  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;
@@ -254,6 +254,7 @@  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 3fcdfff273e4..0926ebb23410 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -4031,10 +4031,9 @@  static void hsw_trans_edp_pipe_A_crc_wa(struct drm_i915_private *dev_priv,
 
 	ret = drm_atomic_commit(state);
 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_modeset_unlock_all(dev);
+	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 1f1f792c5191..21820072dea2 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -3583,7 +3583,7 @@  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)
@@ -3643,6 +3643,8 @@  void intel_finish_reset(struct drm_i915_private *dev_priv)
 		intel_hpd_init(dev_priv);
 	}
 
+	if (state)
+		drm_atomic_state_put(state);
 	drm_modeset_drop_locks(ctx);
 	drm_modeset_acquire_fini(ctx);
 	mutex_unlock(&dev->mode_config.mutex);
@@ -6883,7 +6885,7 @@  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);
@@ -11273,8 +11275,8 @@  found:
 	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) {
@@ -11303,10 +11305,9 @@  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,
@@ -12355,8 +12356,7 @@  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);
@@ -14403,7 +14403,7 @@  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
@@ -14486,6 +14486,7 @@  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
@@ -14527,9 +14528,8 @@  retry:
 		goto retry;
 	}
 
-	if (ret)
 out:
-		drm_atomic_state_free(state);
+	drm_atomic_state_put(state);
 }
 
 /*
@@ -16264,8 +16264,8 @@  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);
 }
@@ -16902,10 +16902,9 @@  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 c7d9a20e370d..1ea19b6d7297 100644
--- a/drivers/gpu/drm/i915/intel_sprite.c
+++ b/drivers/gpu/drm/i915/intel_sprite.c
@@ -988,9 +988,7 @@  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 cf83f6507ec8..db61aa5f32ef 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 73bae382eac3..db193f835298 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 2784919a7366..7087499969bc 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 8ab47b502d83..a9630c2d6cb3 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 a694977c32f4..147fb28287ae 100644
--- a/drivers/gpu/drm/tilcdc/tilcdc_drv.c
+++ b/drivers/gpu/drm/tilcdc/tilcdc_drv.c
@@ -143,8 +143,6 @@  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 9701f2dfb784..01e1116f0084 100644
--- a/include/drm/drm_atomic.h
+++ b/include/drm/drm_atomic.h
@@ -153,6 +153,7 @@  struct __drm_connnectors_state {
 
 /**
  * struct drm_atomic_state - the global state object for atomic updates
+ * @ref: count of all references to this state (will not be freed until zero)
  * @dev: parent DRM device
  * @allow_modeset: allow full modeset
  * @legacy_cursor_update: hint to enforce legacy cursor IOCTL semantics
@@ -164,6 +165,8 @@  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;
@@ -193,7 +196,33 @@  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_plane.h b/include/drm/drm_plane.h
index 43cf193e54d6..02353904cdba 100644
--- a/include/drm/drm_plane.h
+++ b/include/drm/drm_plane.h
@@ -88,7 +88,6 @@  struct drm_plane_state {
 	struct drm_atomic_state *state;
 };
 
-
 /**
  * struct drm_plane_funcs - driver plane control functions
  */

Comments

On Fri, Oct 14, 2016 at 01:18:18PM +0100, Chris Wilson wrote:
> 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@chris-wilson.co.uk>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> Cc: dri-devel@lists.freedesktop.org
> Reviewed-by: Eric Engestrom <eric.engestrom@imgtec.com>
> Reviewed-by: Sean Paul <seanpaul@chromium.org>

Applied to drm-misc, thanks.
-Daniel

> ---
>  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          |  5 +-
>  drivers/gpu/drm/i915/intel_display.c         | 31 +++++----
>  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                     | 31 ++++++++-
>  include/drm/drm_plane.h                      |  1 -
>  18 files changed, 102 insertions(+), 131 deletions(-)
> 
> diff --git a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c
> index 5f484310bee9..9f6222895212 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 23739609427d..5dd70540219c 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 c3f83476f996..df6e9b7c377c 100644
> --- a/drivers/gpu/drm/drm_atomic_helper.c
> +++ b/drivers/gpu/drm/drm_atomic_helper.c
> @@ -1207,7 +1207,7 @@ 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)
> @@ -1289,6 +1289,7 @@ 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
> @@ -1590,7 +1591,7 @@ 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.
> @@ -2113,18 +2114,13 @@ 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);
> @@ -2186,18 +2182,13 @@ 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);
> @@ -2326,18 +2317,13 @@ 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);
> @@ -2479,11 +2465,8 @@ 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);
> @@ -2534,7 +2517,7 @@ 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;
>  	}
> @@ -2623,18 +2606,13 @@ 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);
> @@ -2683,18 +2661,13 @@ 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);
> @@ -2743,18 +2716,13 @@ 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);
> @@ -2827,18 +2795,13 @@ 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);
> @@ -2914,19 +2877,14 @@ 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);
> @@ -3333,7 +3291,7 @@ 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);
>  	}
>  
> @@ -3448,22 +3406,14 @@ 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 03414bde1f15..22d4f0e22101 100644
> --- a/drivers/gpu/drm/drm_fb_helper.c
> +++ b/drivers/gpu/drm/drm_fb_helper.c
> @@ -367,9 +367,7 @@ fail:
>  	if (ret == -EDEADLK)
>  		goto backoff;
>  
> -	if (ret != 0)
> -		drm_atomic_state_free(state);
> -
> +	drm_atomic_state_put(state);
>  	return ret;
>  
>  backoff:
> @@ -1361,16 +1359,13 @@ 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 def78c8c1780..4a21a745c373 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_drv.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_drv.c
> @@ -69,7 +69,7 @@ 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;
> @@ -254,6 +254,7 @@ 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 3fcdfff273e4..0926ebb23410 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -4031,10 +4031,9 @@ static void hsw_trans_edp_pipe_A_crc_wa(struct drm_i915_private *dev_priv,
>  
>  	ret = drm_atomic_commit(state);
>  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_modeset_unlock_all(dev);
> +	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 1f1f792c5191..21820072dea2 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -3583,7 +3583,7 @@ 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)
> @@ -3643,6 +3643,8 @@ void intel_finish_reset(struct drm_i915_private *dev_priv)
>  		intel_hpd_init(dev_priv);
>  	}
>  
> +	if (state)
> +		drm_atomic_state_put(state);
>  	drm_modeset_drop_locks(ctx);
>  	drm_modeset_acquire_fini(ctx);
>  	mutex_unlock(&dev->mode_config.mutex);
> @@ -6883,7 +6885,7 @@ 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);
> @@ -11273,8 +11275,8 @@ found:
>  	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) {
> @@ -11303,10 +11305,9 @@ 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,
> @@ -12355,8 +12356,7 @@ 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);
> @@ -14403,7 +14403,7 @@ 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
> @@ -14486,6 +14486,7 @@ 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
> @@ -14527,9 +14528,8 @@ retry:
>  		goto retry;
>  	}
>  
> -	if (ret)
>  out:
> -		drm_atomic_state_free(state);
> +	drm_atomic_state_put(state);
>  }
>  
>  /*
> @@ -16264,8 +16264,8 @@ 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);
>  }
> @@ -16902,10 +16902,9 @@ 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 c7d9a20e370d..1ea19b6d7297 100644
> --- a/drivers/gpu/drm/i915/intel_sprite.c
> +++ b/drivers/gpu/drm/i915/intel_sprite.c
> @@ -988,9 +988,7 @@ 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 cf83f6507ec8..db61aa5f32ef 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 73bae382eac3..db193f835298 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 2784919a7366..7087499969bc 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 8ab47b502d83..a9630c2d6cb3 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 a694977c32f4..147fb28287ae 100644
> --- a/drivers/gpu/drm/tilcdc/tilcdc_drv.c
> +++ b/drivers/gpu/drm/tilcdc/tilcdc_drv.c
> @@ -143,8 +143,6 @@ 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 9701f2dfb784..01e1116f0084 100644
> --- a/include/drm/drm_atomic.h
> +++ b/include/drm/drm_atomic.h
> @@ -153,6 +153,7 @@ struct __drm_connnectors_state {
>  
>  /**
>   * struct drm_atomic_state - the global state object for atomic updates
> + * @ref: count of all references to this state (will not be freed until zero)
>   * @dev: parent DRM device
>   * @allow_modeset: allow full modeset
>   * @legacy_cursor_update: hint to enforce legacy cursor IOCTL semantics
> @@ -164,6 +165,8 @@ 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;
> @@ -193,7 +196,33 @@ 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_plane.h b/include/drm/drm_plane.h
> index 43cf193e54d6..02353904cdba 100644
> --- a/include/drm/drm_plane.h
> +++ b/include/drm/drm_plane.h
> @@ -88,7 +88,6 @@ struct drm_plane_state {
>  	struct drm_atomic_state *state;
>  };
>  
> -
>  /**
>   * struct drm_plane_funcs - driver plane control functions
>   */
> -- 
> 2.9.3
>