drm: don't let crtc_ww_class leak out

kbuild spotted this error, with drm/msm patches that add a new
modeset-lock in the driver and driver built as a module:

  ERROR: "crtc_ww_class" [drivers/gpu/drm/msm/msm.ko] undefined!

Really the only reason for crtc_ww_class not being internal to
drm_modeset_lock.c is that drm_modeset_lock_init() was static-inline
(for no particularly good reason).

Fix that, and move crtc_ww_class into drm_modeset_lock.c.
Signed-off-by: NRob Clark <robdclark@gmail.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1479163257-18703-1-git-send-email-robdclark@gmail.com

drivers/gpu/drm/drm_crtc.c

@@ -102,8 +102,6 @@ int drm_crtc_force_disable_all(struct drm_device *dev)
 }
 EXPORT_SYMBOL(drm_crtc_force_disable_all);
 
-DEFINE_WW_CLASS(crtc_ww_class);
-
 static unsigned int drm_num_crtcs(struct drm_device *dev)
 {
 	unsigned int num = 0;

drivers/gpu/drm/drm_modeset_lock.c

@@ -60,6 +60,8 @@
  *  lists and lookup data structures.
  */
 
+static DEFINE_WW_CLASS(crtc_ww_class);
+
 /**
  * drm_modeset_lock_all - take all modeset locks
  * @dev: DRM device
@@ -397,6 +399,17 @@ int drm_modeset_backoff_interruptible(struct drm_modeset_acquire_ctx *ctx)
 }
 EXPORT_SYMBOL(drm_modeset_backoff_interruptible);
 
+/**
+ * drm_modeset_lock_init - initialize lock
+ * @lock: lock to init
+ */
+void drm_modeset_lock_init(struct drm_modeset_lock *lock)
+{
+	ww_mutex_init(&lock->mutex, &crtc_ww_class);
+	INIT_LIST_HEAD(&lock->head);
+}
+EXPORT_SYMBOL(drm_modeset_lock_init);
+
 /**
  * drm_modeset_lock - take modeset lock
  * @lock: lock to take

include/drm/drm_modeset_lock.h

@@ -82,8 +82,6 @@ struct drm_modeset_lock {
 	struct list_head head;
 };
 
-extern struct ww_class crtc_ww_class;
-
 void drm_modeset_acquire_init(struct drm_modeset_acquire_ctx *ctx,
 		uint32_t flags);
 void drm_modeset_acquire_fini(struct drm_modeset_acquire_ctx *ctx);
@@ -91,15 +89,7 @@ void drm_modeset_drop_locks(struct drm_modeset_acquire_ctx *ctx);
 void drm_modeset_backoff(struct drm_modeset_acquire_ctx *ctx);
 int drm_modeset_backoff_interruptible(struct drm_modeset_acquire_ctx *ctx);
 
-/**
- * drm_modeset_lock_init - initialize lock
- * @lock: lock to init
- */
-static inline void drm_modeset_lock_init(struct drm_modeset_lock *lock)
-{
-	ww_mutex_init(&lock->mutex, &crtc_ww_class);
-	INIT_LIST_HEAD(&lock->head);
-}
+void drm_modeset_lock_init(struct drm_modeset_lock *lock);
 
 /**
  * drm_modeset_lock_fini - cleanup lock