drm/i915: Move list of timelines under its own lock

Currently, the list of timelines is serialised by the struct_mutex, but
to alleviate difficulties with using that mutex in future, move the
list management under its own dedicated mutex.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190128102356.15037-5-chris@chris-wilson.co.uk

1 files changed, 33 insertions, 5 deletions

diff --git a/drivers/gpu/drm/i915/i915_timeline.c b/drivers/gpu/drm/i915/i915_timeline.c
index 4667cc08c416..84550f17d3df 100644
--- a/drivers/gpu/drm/i915/i915_timeline.c
+++ b/drivers/gpu/drm/i915/i915_timeline.c
@@ -13,7 +13,7 @@ void i915_timeline_init(struct drm_i915_private *i915,
 			struct i915_timeline *timeline,
 			const char *name)
 {
-	lockdep_assert_held(&i915->drm.struct_mutex);
+	struct i915_gt_timelines *gt = &i915->gt.timelines;
 
 	/*
 	 * Ideally we want a set of engines on a single leaf as we expect
@@ -23,9 +23,12 @@ void i915_timeline_init(struct drm_i915_private *i915,
 	 */
 	BUILD_BUG_ON(KSYNCMAP < I915_NUM_ENGINES);
 
+	timeline->i915 = i915;
 	timeline->name = name;
 
-	list_add(&timeline->link, &i915->gt.timelines);
+	mutex_lock(&gt->mutex);
+	list_add(&timeline->link, &gt->list);
+	mutex_unlock(&gt->mutex);
 
 	/* Called during early_init before we know how many engines there are */
 
@@ -39,6 +42,17 @@ void i915_timeline_init(struct drm_i915_private *i915,
 	i915_syncmap_init(&timeline->sync);
 }
 
+void i915_timelines_init(struct drm_i915_private *i915)
+{
+	struct i915_gt_timelines *gt = &i915->gt.timelines;
+
+	mutex_init(&gt->mutex);
+	INIT_LIST_HEAD(&gt->list);
+
+	/* via i915_gem_wait_for_idle() */
+	i915_gem_shrinker_taints_mutex(i915, &gt->mutex);
+}
+
 /**
  * i915_timelines_park - called when the driver idles
  * @i915: the drm_i915_private device
@@ -51,11 +65,11 @@ void i915_timeline_init(struct drm_i915_private *i915,
  */
 void i915_timelines_park(struct drm_i915_private *i915)
 {
+	struct i915_gt_timelines *gt = &i915->gt.timelines;
 	struct i915_timeline *timeline;
 
-	lockdep_assert_held(&i915->drm.struct_mutex);
-
-	list_for_each_entry(timeline, &i915->gt.timelines, link) {
+	mutex_lock(&gt->mutex);
+	list_for_each_entry(timeline, &gt->list, link) {
 		/*
 		 * All known fences are completed so we can scrap
 		 * the current sync point tracking and start afresh,
@@ -64,15 +78,20 @@ void i915_timelines_park(struct drm_i915_private *i915)
 		 */
 		i915_syncmap_free(&timeline->sync);
 	}
+	mutex_unlock(&gt->mutex);
 }
 
 void i915_timeline_fini(struct i915_timeline *timeline)
 {
+	struct i915_gt_timelines *gt = &timeline->i915->gt.timelines;
+
 	GEM_BUG_ON(!list_empty(&timeline->requests));
 
 	i915_syncmap_free(&timeline->sync);
 
+	mutex_lock(&gt->mutex);
 	list_del(&timeline->link);
+	mutex_unlock(&gt->mutex);
 }
 
 struct i915_timeline *
@@ -99,6 +118,15 @@ void __i915_timeline_free(struct kref *kref)
 	kfree(timeline);
 }
 
+void i915_timelines_fini(struct drm_i915_private *i915)
+{
+	struct i915_gt_timelines *gt = &i915->gt.timelines;
+
+	GEM_BUG_ON(!list_empty(&gt->list));
+
+	mutex_destroy(&gt->mutex);
+}
+
 #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
 #include "selftests/mock_timeline.c"
 #include "selftests/i915_timeline.c"