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);
 
 /*