[PATCH] drm: Add reference counting to drm_atomic_state

Chris Wilson chris at chris-wilson.co.uk
Tue Aug 23 21:43:31 UTC 2016


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.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
---
 drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c |  2 +-
 drivers/gpu/drm/drm_atomic.c                 | 23 +++----
 drivers/gpu/drm/drm_atomic_helper.c          | 98 +++++++---------------------
 drivers/gpu/drm/drm_fb_helper.c              |  8 +--
 drivers/gpu/drm/exynos/exynos_drm_drv.c      |  2 +-
 drivers/gpu/drm/i915/i915_debugfs.c          |  3 +-
 drivers/gpu/drm/i915/intel_display.c         | 25 +++----
 drivers/gpu/drm/i915/intel_sprite.c          |  4 +-
 drivers/gpu/drm/mediatek/mtk_drm_drv.c       |  2 +-
 drivers/gpu/drm/msm/msm_atomic.c             |  2 +-
 drivers/gpu/drm/omapdrm/omap_drv.c           |  2 +-
 drivers/gpu/drm/rcar-du/rcar_du_kms.c        |  2 +-
 drivers/gpu/drm/sti/sti_drv.c                |  2 +-
 drivers/gpu/drm/tegra/drm.c                  |  2 +-
 drivers/gpu/drm/tilcdc/tilcdc_drv.c          |  2 +-
 drivers/gpu/drm/vc4/vc4_kms.c                |  2 +-
 include/drm/drm_atomic.h                     | 12 +++-
 include/drm/drm_crtc.h                       |  2 +
 18 files changed, 73 insertions(+), 122 deletions(-)

diff --git a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c
index d4a3d61b7b06..00f30fbd2336 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);
diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
index 5cb2e22d5d55..349c2f0de900 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
+ * __drm_atomic_state_free - free all memory for an atomic state
  * @state: 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 9abe0a242f96..14dbae947a12 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -1187,7 +1187,7 @@ 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)
@@ -1263,6 +1263,7 @@ 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
@@ -1564,7 +1565,7 @@ 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.
@@ -2067,18 +2068,13 @@ 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);
@@ -2140,18 +2136,13 @@ 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);
@@ -2280,18 +2271,13 @@ 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);
@@ -2433,11 +2419,8 @@ 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);
@@ -2488,7 +2471,7 @@ 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;
 	}
@@ -2577,18 +2560,13 @@ 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);
@@ -2637,18 +2615,13 @@ 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);
@@ -2697,18 +2670,13 @@ 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);
@@ -2781,18 +2749,13 @@ 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);
@@ -2868,19 +2831,14 @@ 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);
@@ -3287,7 +3245,7 @@ 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);
 	}
 
@@ -3402,22 +3360,14 @@ 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..3a98b51058d5 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:
@@ -1366,9 +1364,7 @@ fail:
 	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 877d2efa28e2..7ea75cb1fdad 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;
diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 7d7b4d9280e9..6e0bd07039d3 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 b10bea630a0d..7cdb3bba83a4 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)
@@ -6885,7 +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);
@@ -11268,11 +11268,13 @@ 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) {
@@ -11303,7 +11305,7 @@ void intel_release_load_detect_pipe(struct drm_connector *connector,
 	ret = drm_atomic_commit(state);
 	if (ret) {
 		DRM_DEBUG_KMS("Couldn't release load detect pipe: %i\n", ret);
-		drm_atomic_state_free(state);
+		drm_atomic_state_put(state);
 	}
 }
 
@@ -12375,8 +12377,7 @@ 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);
@@ -14381,7 +14382,7 @@ 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
@@ -14464,6 +14465,7 @@ 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
@@ -14505,9 +14507,8 @@ retry:
 		goto retry;
 	}
 
-	if (ret)
 out:
-		drm_atomic_state_free(state);
+	drm_atomic_state_put(state);
 }
 
 #undef for_each_intel_crtc_masked
@@ -16246,7 +16247,7 @@ retry:
 		dev_priv->display.optimize_watermarks(cs);
 	}
 
-	drm_atomic_state_free(state);
+	drm_atomic_state_put(state);
 fail:
 	drm_modeset_drop_locks(&ctx);
 	drm_modeset_acquire_fini(&ctx);
@@ -16881,7 +16882,7 @@ void intel_display_resume(struct drm_device *dev)
 
 	if (ret) {
 		DRM_ERROR("Restoring old state failed with %i\n", ret);
-		drm_atomic_state_free(state);
+		drm_atomic_state_put(state);
 	}
 }
 
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 0e769abd0c2c..64c60d2b9246 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_drv.c
+++ b/drivers/gpu/drm/mediatek/mtk_drm_drv.c
@@ -81,7 +81,7 @@ 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)
diff --git a/drivers/gpu/drm/msm/msm_atomic.c b/drivers/gpu/drm/msm/msm_atomic.c
index 4a8a6f1f1151..032211e90d66 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);
 }
diff --git a/drivers/gpu/drm/omapdrm/omap_drv.c b/drivers/gpu/drm/omapdrm/omap_drv.c
index 3dd78f2045f9..e29f7051bb2c 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);
diff --git a/drivers/gpu/drm/rcar-du/rcar_du_kms.c b/drivers/gpu/drm/rcar-du/rcar_du_kms.c
index f03eb55318c1..6ac768f54123 100644
--- a/drivers/gpu/drm/rcar-du/rcar_du_kms.c
+++ b/drivers/gpu/drm/rcar-du/rcar_du_kms.c
@@ -263,7 +263,7 @@ 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);
diff --git a/drivers/gpu/drm/sti/sti_drv.c b/drivers/gpu/drm/sti/sti_drv.c
index f8311b2bc84e..a17e4e9a8037 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)
diff --git a/drivers/gpu/drm/tegra/drm.c b/drivers/gpu/drm/tegra/drm.c
index 755264d9db22..5a39ed4e817b 100644
--- a/drivers/gpu/drm/tegra/drm.c
+++ b/drivers/gpu/drm/tegra/drm.c
@@ -62,7 +62,7 @@ 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)
diff --git a/drivers/gpu/drm/tilcdc/tilcdc_drv.c b/drivers/gpu/drm/tilcdc/tilcdc_drv.c
index 3404d245d28d..6142d7039c95 100644
--- a/drivers/gpu/drm/tilcdc/tilcdc_drv.c
+++ b/drivers/gpu/drm/tilcdc/tilcdc_drv.c
@@ -129,7 +129,7 @@ static int tilcdc_commit(struct drm_device *dev,
 
 	drm_atomic_helper_cleanup_planes(dev, state);
 
-	drm_atomic_state_free(state);
+	drm_atomic_state_put(state);
 
 	return 0;
 }
diff --git a/drivers/gpu/drm/vc4/vc4_kms.c b/drivers/gpu/drm/vc4/vc4_kms.c
index 4ac894d993cd..2329e7ddb378 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);
 
diff --git a/include/drm/drm_atomic.h b/include/drm/drm_atomic.h
index 856a9c85a838..68d2b5d17ed3 100644
--- a/include/drm/drm_atomic.h
+++ b/include/drm/drm_atomic.h
@@ -39,7 +39,17 @@ 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);
+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);
+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 3fa0275e509f..823df1bc9248 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -1395,6 +1395,8 @@ 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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