[PATCH 2/2] drm/atomic: WARN about invalid drm_foo_get_state() usage

[Ville Syrjala <ville.syrjala@linux.intel.com>]

From: Ville Syrjälä <ville.syrjala@linux.intel.com>

drm_{crtc,plane,connector,private_obj}_get_state() must not
be called after the atomic check phase. At that point the commit
has been carved in stone and no new objects must be introduced
into it. WARN if anyone attempts to violate this rule.

Cc: Maxime Ripard <mripard@kernel.org>
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
 drivers/gpu/drm/drm_atomic.c | 8 ++++++++
 include/drm/drm_atomic.h     | 8 ++++++++
 2 files changed, 16 insertions(+)

diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
index 5d31b20e67ab..e05820b18832 100644
--- a/drivers/gpu/drm/drm_atomic.c
+++ b/drivers/gpu/drm/drm_atomic.c
@@ -200,6 +200,8 @@ void drm_atomic_state_default_clear(struct drm_atomic_state *state)
 
 	drm_dbg_atomic(dev, "Clearing atomic state %p\n", state);
 
+	state->checked = false;
+
 	for (i = 0; i < state->num_connector; i++) {
 		struct drm_connector *connector = state->connectors[i].ptr;
 
@@ -348,6 +350,7 @@ drm_atomic_get_crtc_state(struct drm_atomic_state *state,
 	struct drm_crtc_state *crtc_state;
 
 	WARN_ON(!state->acquire_ctx);
+	drm_WARN_ON(state->dev, state->checked);
 
 	crtc_state = drm_atomic_get_new_crtc_state(state, crtc);
 	if (crtc_state)
@@ -528,6 +531,7 @@ drm_atomic_get_plane_state(struct drm_atomic_state *state,
 	struct drm_plane_state *plane_state;
 
 	WARN_ON(!state->acquire_ctx);
+	drm_WARN_ON(state->dev, state->checked);
 
 	/* the legacy pointers should never be set */
 	WARN_ON(plane->fb);
@@ -837,6 +841,7 @@ drm_atomic_get_private_obj_state(struct drm_atomic_state *state,
 	struct drm_private_state *obj_state;
 
 	WARN_ON(!state->acquire_ctx);
+	drm_WARN_ON(state->dev, state->checked);
 
 	obj_state = drm_atomic_get_new_private_obj_state(state, obj);
 	if (obj_state)
@@ -1131,6 +1136,7 @@ drm_atomic_get_connector_state(struct drm_atomic_state *state,
 	struct drm_connector_state *connector_state;
 
 	WARN_ON(!state->acquire_ctx);
+	drm_WARN_ON(state->dev, state->checked);
 
 	ret = drm_modeset_lock(&config->connection_mutex, state->acquire_ctx);
 	if (ret)
@@ -1543,6 +1549,8 @@ int drm_atomic_check_only(struct drm_atomic_state *state)
 		     requested_crtc, affected_crtc);
 	}
 
+	state->checked = true;
+
 	return 0;
 }
 EXPORT_SYMBOL(drm_atomic_check_only);
diff --git a/include/drm/drm_atomic.h b/include/drm/drm_atomic.h
index 155e82f87e4d..2e433d44658d 100644
--- a/include/drm/drm_atomic.h
+++ b/include/drm/drm_atomic.h
@@ -523,6 +523,14 @@ struct drm_atomic_state {
 	 */
 	bool duplicated : 1;
 
+	/**
+	 * @checked:
+	 *
+	 * Indicates the state has been checked and thus must no longer
+	 * be mutated. For internal use only, do not consult from drivers.
+	 */
+	bool checked : 1;
+
 	/**
 	 * @planes:
 	 *
-- 
2.49.1