drm/msm: Add priv->mm_lock to protect active/inactive lists

Rather than relying on the big dev->struct_mutex hammer, introduce a
more specific lock for protecting the bo lists.

Change-Id: I4c876a1c3ae51ff62372703a99a8daff0c4a7950
Signed-off-by: Rob Clark <[email protected]>
Git-commit: d984457b31c4c53d2af374d5e78b3eb64debd483
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
[[email protected]: avoid changes related to debugfs and shrinker]
Signed-off-by: Samantha Tran <[email protected]>

msm/msm_drv.c

@@ -798,6 +798,7 @@ static int msm_drm_component_init(struct device *dev)
 	INIT_LIST_HEAD(&priv->client_event_list);
 	INIT_LIST_HEAD(&priv->inactive_list);
 	INIT_LIST_HEAD(&priv->vm_client_list);
+	mutex_init(&priv->mm_lock);
 
 	mutex_init(&priv->vm_client_lock);
 

msm/msm_drv.h

@@ -888,8 +888,19 @@ struct msm_drm_private {
 	struct msm_rd_state *hangrd;   /* debugfs to dump hanging submits */
 	struct msm_perf_state *perf;
 
-	/* list of GEM objects: */
+	/*
+	 * List of inactive GEM objects.  Every bo is either in the inactive_list
+	 * or gpu->active_list (for the gpu it is active on[1])
+	 *
+	 * These lists are protected by mm_lock.  If struct_mutex is involved, it
+	 * should be aquired prior to mm_lock.  One should *not* hold mm_lock in
+	 * get_pages()/vmap()/etc paths, as they can trigger the shrinker.
+	 *
+	 * [1] if someone ever added support for the old 2d cores, there could be
+	 *     more than one gpu object
+	 */
 	struct list_head inactive_list;
+	struct mutex mm_lock;
 
 	/* worker for delayed free of objects: */
 	struct work_struct free_work;

msm/msm_gem.c

@@ -1017,11 +1017,15 @@ void msm_gem_free_object(struct drm_gem_object *obj)
 static void free_object(struct msm_gem_object *msm_obj)
 {
 	struct drm_gem_object *obj = &msm_obj->base;
+	struct drm_device *dev = obj->dev;
+	struct msm_drm_private *priv = dev->dev_private;
 
 	/* object should not be on active list: */
 	WARN_ON(is_active(msm_obj));
 
+	mutex_lock(&priv->mm_lock);
 	list_del(&msm_obj->mm_list);
+	mutex_unlock(&priv->mm_lock);
 
 	mutex_lock(&msm_obj->lock);
 
@@ -1149,14 +1153,9 @@ static int msm_gem_new_impl(struct drm_device *dev,
 	msm_obj->in_active_list = false;
 	msm_obj->obj_dirty = false;
 
-	if (struct_mutex_locked) {
-		WARN_ON(!mutex_is_locked(&dev->struct_mutex));
-		list_add_tail(&msm_obj->mm_list, &priv->inactive_list);
-	} else {
-		mutex_lock(&dev->struct_mutex);
-		list_add_tail(&msm_obj->mm_list, &priv->inactive_list);
-		mutex_unlock(&dev->struct_mutex);
-	}
+	mutex_lock(&priv->mm_lock);
+	list_add_tail(&msm_obj->mm_list, &priv->inactive_list);
+	mutex_unlock(&priv->mm_lock);
 
 	*obj = &msm_obj->base;