drm/i915: Pull scheduling under standalone lock

Currently, the backend scheduling code abuses struct_mutex into order to
have a global lock to manipulate a temporary list (without widespread
allocation) and to protect against list modifications. This is an
extraneous coupling to struct_mutex and further can not extend beyond
the local device.

Pull all the code that needs to be under the one true lock into
i915_scheduler.c, and make it so.
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/20181001144755.7978-2-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/Makefile

@@ -75,6 +75,7 @@ i915-y += i915_cmd_parser.o \
 	  i915_gemfs.o \
 	  i915_query.o \
 	  i915_request.o \
+	  i915_scheduler.o \
 	  i915_timeline.o \
 	  i915_trace_points.o \
 	  i915_vma.o \

drivers/gpu/drm/i915/i915_request.c

@@ -111,91 +111,6 @@ i915_request_remove_from_client(struct i915_request *request)
 	spin_unlock(&file_priv->mm.lock);
 }
 
-static struct i915_dependency *
-i915_dependency_alloc(struct drm_i915_private *i915)
-{
-	return kmem_cache_alloc(i915->dependencies, GFP_KERNEL);
-}
-
-static void
-i915_dependency_free(struct drm_i915_private *i915,
-		     struct i915_dependency *dep)
-{
-	kmem_cache_free(i915->dependencies, dep);
-}
-
-static void
-__i915_sched_node_add_dependency(struct i915_sched_node *node,
-				 struct i915_sched_node *signal,
-				 struct i915_dependency *dep,
-				 unsigned long flags)
-{
-	INIT_LIST_HEAD(&dep->dfs_link);
-	list_add(&dep->wait_link, &signal->waiters_list);
-	list_add(&dep->signal_link, &node->signalers_list);
-	dep->signaler = signal;
-	dep->flags = flags;
-}
-
-static int
-i915_sched_node_add_dependency(struct drm_i915_private *i915,
-			       struct i915_sched_node *node,
-			       struct i915_sched_node *signal)
-{
-	struct i915_dependency *dep;
-
-	dep = i915_dependency_alloc(i915);
-	if (!dep)
-		return -ENOMEM;
-
-	__i915_sched_node_add_dependency(node, signal, dep,
-					 I915_DEPENDENCY_ALLOC);
-	return 0;
-}
-
-static void
-i915_sched_node_fini(struct drm_i915_private *i915,
-		     struct i915_sched_node *node)
-{
-	struct i915_dependency *dep, *tmp;
-
-	GEM_BUG_ON(!list_empty(&node->link));
-
-	/*
-	 * Everyone we depended upon (the fences we wait to be signaled)
-	 * should retire before us and remove themselves from our list.
-	 * However, retirement is run independently on each timeline and
-	 * so we may be called out-of-order.
-	 */
-	list_for_each_entry_safe(dep, tmp, &node->signalers_list, signal_link) {
-		GEM_BUG_ON(!i915_sched_node_signaled(dep->signaler));
-		GEM_BUG_ON(!list_empty(&dep->dfs_link));
-
-		list_del(&dep->wait_link);
-		if (dep->flags & I915_DEPENDENCY_ALLOC)
-			i915_dependency_free(i915, dep);
-	}
-
-	/* Remove ourselves from everyone who depends upon us */
-	list_for_each_entry_safe(dep, tmp, &node->waiters_list, wait_link) {
-		GEM_BUG_ON(dep->signaler != node);
-		GEM_BUG_ON(!list_empty(&dep->dfs_link));
-
-		list_del(&dep->signal_link);
-		if (dep->flags & I915_DEPENDENCY_ALLOC)
-			i915_dependency_free(i915, dep);
-	}
-}
-
-static void
-i915_sched_node_init(struct i915_sched_node *node)
-{
-	INIT_LIST_HEAD(&node->signalers_list);
-	INIT_LIST_HEAD(&node->waiters_list);
-	INIT_LIST_HEAD(&node->link);
-	node->attr.priority = I915_PRIORITY_INVALID;
-}
-
 static int reset_all_global_seqno(struct drm_i915_private *i915, u32 seqno)
 {
 	struct intel_engine_cs *engine;

drivers/gpu/drm/i915/i915_request.h

@@ -332,14 +332,6 @@ static inline bool i915_request_completed(const struct i915_request *rq)
 	return __i915_request_completed(rq, seqno);
 }
 
-static inline bool i915_sched_node_signaled(const struct i915_sched_node *node)
-{
-	const struct i915_request *rq =
-		container_of(node, const struct i915_request, sched);
-
-	return i915_request_completed(rq);
-}
-
 void i915_retire_requests(struct drm_i915_private *i915);
 
 /*

drivers/gpu/drm/i915/i915_scheduler.h

@@ -8,9 +8,14 @@
 #define _I915_SCHEDULER_H_
 
 #include <linux/bitops.h>
+#include <linux/kernel.h>
 
 #include <uapi/drm/i915_drm.h>
 
+struct drm_i915_private;
+struct i915_request;
+struct intel_engine_cs;
+
 enum {
 	I915_PRIORITY_MIN = I915_CONTEXT_MIN_USER_PRIORITY - 1,
 	I915_PRIORITY_NORMAL = I915_CONTEXT_DEFAULT_PRIORITY,
@@ -77,4 +82,24 @@ struct i915_dependency {
 #define I915_DEPENDENCY_ALLOC BIT(0)
 };
 
+void i915_sched_node_init(struct i915_sched_node *node);
+
+bool __i915_sched_node_add_dependency(struct i915_sched_node *node,
+				      struct i915_sched_node *signal,
+				      struct i915_dependency *dep,
+				      unsigned long flags);
+
+int i915_sched_node_add_dependency(struct drm_i915_private *i915,
+				   struct i915_sched_node *node,
+				   struct i915_sched_node *signal);
+
+void i915_sched_node_fini(struct drm_i915_private *i915,
+			  struct i915_sched_node *node);
+
+void i915_schedule(struct i915_request *request,
+		   const struct i915_sched_attr *attr);
+
+struct list_head *
+i915_sched_lookup_priolist(struct intel_engine_cs *engine, int prio);
+
 #endif /* _I915_SCHEDULER_H_ */

drivers/gpu/drm/i915/intel_display.c

@@ -13188,13 +13188,12 @@ intel_prepare_plane_fb(struct drm_plane *plane,
 
 	ret = intel_plane_pin_fb(to_intel_plane_state(new_state));
 
-	fb_obj_bump_render_priority(obj);
-
 	mutex_unlock(&dev_priv->drm.struct_mutex);
 	i915_gem_object_unpin_pages(obj);
 	if (ret)
 		return ret;
 
+	fb_obj_bump_render_priority(obj);
 	intel_fb_obj_flush(obj, ORIGIN_DIRTYFB);
 
 	if (!new_state->fence) { /* implicit fencing */

drivers/gpu/drm/i915/intel_ringbuffer.h

@@ -498,11 +498,10 @@ struct intel_engine_cs {
 	 */
 	void		(*submit_request)(struct i915_request *rq);
 
-	/* Call when the priority on a request has changed and it and its
+	/*
+	 * Call when the priority on a request has changed and it and its
 	 * dependencies may need rescheduling. Note the request itself may
 	 * not be ready to run!
-	 *
-	 * Called under the struct_mutex.
 	 */
 	void		(*schedule)(struct i915_request *request,
 				    const struct i915_sched_attr *attr);