[PATCH v2 2/4] drm/atomic: Add accessor macros for the current state.

[Maarten Lankhorst]

With checks! This will allow safe access to the current state,
while ensuring that the correct locks are held.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
---
 include/drm/drm_atomic.h       | 66 ++++++++++++++++++++++++++++++++++++++++++
 include/drm/drm_modeset_lock.h | 21 ++++++++++++++
 2 files changed, 87 insertions(+)

diff --git a/include/drm/drm_atomic.h b/include/drm/drm_atomic.h
index e527684dd394..462408a2d1b8 100644
--- a/include/drm/drm_atomic.h
+++ b/include/drm/drm_atomic.h
@@ -334,6 +334,72 @@ __drm_atomic_get_current_plane_state(struct drm_atomic_state *state,
 	return plane->state;
 }
 
+
+/**
+ * drm_atomic_get_current_plane_state - get current plane state
+ * @plane: plane to grab
+ *
+ * This function returns the current plane state for the given plane,
+ * with extra locking checks to make sure that the plane state can be
+ * retrieved safely.
+ *
+ * Returns:
+ *
+ * Pointer to the current plane state.
+ */
+static inline struct drm_plane_state *
+drm_atomic_get_current_plane_state(struct drm_plane *plane)
+{
+	struct drm_plane_state *plane_state = plane->state;
+	struct drm_crtc *crtc = plane_state ? plane_state->crtc : NULL;
+
+	if (crtc)
+		drm_modeset_lock_assert_one_held(&plane->mutex, &crtc->mutex);
+	else
+		drm_modeset_lock_assert_held(&plane->mutex);
+
+	return plane_state;
+}
+
+/**
+ * drm_atomic_get_current_crtc_state - get current crtc state
+ * @crtc: crtc to grab
+ *
+ * This function returns the current crtc state for the given crtc,
+ * with extra locking checks to make sure that the crtc state can be
+ * retrieved safely.
+ *
+ * Returns:
+ *
+ * Pointer to the current crtc state.
+ */
+static inline struct drm_crtc_state *
+drm_atomic_get_current_crtc_state(struct drm_crtc *crtc)
+{
+	drm_modeset_lock_assert_held(&crtc->mutex);
+
+	return crtc->state;
+}
+
+/**
+ * drm_atomic_get_current_connector_state - get current connector state
+ * @connector: connector to grab
+ *
+ * This function returns the current connector state for the given connector,
+ * with extra locking checks to make sure that the connector state can be
+ * retrieved safely.
+ *
+ * Returns:
+ *
+ * Pointer to the current connector state.
+ */
+#define drm_atomic_get_current_connector_state(connector) \
+({ /* Implemented as macro to avoid including drmP for struct drm_device */ \
+	struct drm_connector *con__ = (connector); \
+	drm_modeset_lock_assert_held(&con__->dev->mode_config.connection_mutex); \
+	con__->state; \
+})
+
 int __must_check
 drm_atomic_set_mode_for_crtc(struct drm_crtc_state *state,
 			     struct drm_display_mode *mode);
diff --git a/include/drm/drm_modeset_lock.h b/include/drm/drm_modeset_lock.h
index d918ce45ec2c..7635ff18ab99 100644
--- a/include/drm/drm_modeset_lock.h
+++ b/include/drm/drm_modeset_lock.h
@@ -109,6 +109,27 @@ static inline bool drm_modeset_is_locked(struct drm_modeset_lock *lock)
 	return ww_mutex_is_locked(&lock->mutex);
 }
 
+static inline void drm_modeset_lock_assert_held(struct drm_modeset_lock *lock)
+{
+#ifdef CONFIG_LOCKDEP
+	lockdep_assert_held(&lock->mutex.base);
+#else
+	WARN_ON(!drm_modeset_is_locked(lock));
+#endif
+}
+
+static inline void drm_modeset_lock_assert_one_held(struct drm_modeset_lock *lock1,
+						    struct drm_modeset_lock *lock2)
+{
+#ifdef CONFIG_LOCKDEP
+	WARN_ON(debug_locks &&
+		!lockdep_is_held(&lock1->mutex.base) &&
+		!lockdep_is_held(&lock2->mutex.base));
+#else
+	WARN_ON(!drm_modeset_is_locked(lock1) && !drm_modeset_is_locked(lock2));
+#endif
+}
+
 int drm_modeset_lock(struct drm_modeset_lock *lock,
 		struct drm_modeset_acquire_ctx *ctx);
 int drm_modeset_lock_interruptible(struct drm_modeset_lock *lock,
-- 
2.7.4