drm/i915: Only track bound elements of the GTT

The premise here is to simply avoiding having to acquire the vm->mutex
inside vma create/destroy to update the vm->unbound_lists, to avoid some
nasty lock recursions later.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191004134015.13204-2-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/gem/i915_gem_stolen.c

@@ -692,7 +692,7 @@ i915_gem_object_create_stolen_for_preallocated(struct drm_i915_private *dev_priv
 	__i915_vma_set_map_and_fenceable(vma);
 
 	mutex_lock(&ggtt->vm.mutex);
-	list_move_tail(&vma->vm_link, &ggtt->vm.bound_list);
+	list_add_tail(&vma->vm_link, &ggtt->vm.bound_list);
 	mutex_unlock(&ggtt->vm.mutex);
 
 	GEM_BUG_ON(i915_gem_object_is_shrinkable(obj));

drivers/gpu/drm/i915/i915_gem_gtt.c

@@ -505,19 +505,12 @@ static void i915_address_space_fini(struct i915_address_space *vm)
 
 static void ppgtt_destroy_vma(struct i915_address_space *vm)
 {
-	struct list_head *phases[] = {
-		&vm->bound_list,
-		&vm->unbound_list,
-		NULL,
-	}, **phase;
-
-	mutex_lock(&vm->i915->drm.struct_mutex);
-	for (phase = phases; *phase; phase++) {
 	struct i915_vma *vma, *vn;
 
-		list_for_each_entry_safe(vma, vn, *phase, vm_link)
+	mutex_lock(&vm->i915->drm.struct_mutex);
+	list_for_each_entry_safe(vma, vn, &vm->bound_list, vm_link)
 		i915_vma_destroy(vma);
-	}
+	GEM_BUG_ON(!list_empty(&vm->bound_list));
 	mutex_unlock(&vm->i915->drm.struct_mutex);
 }
 
@@ -528,9 +521,6 @@ static void __i915_vm_release(struct work_struct *work)
 
 	ppgtt_destroy_vma(vm);
 
-	GEM_BUG_ON(!list_empty(&vm->bound_list));
-	GEM_BUG_ON(!list_empty(&vm->unbound_list));
-
 	vm->cleanup(vm);
 	i915_address_space_fini(vm);
 
@@ -569,7 +559,6 @@ static void i915_address_space_init(struct i915_address_space *vm, int subclass)
 
 	stash_init(&vm->free_pages);
 
-	INIT_LIST_HEAD(&vm->unbound_list);
 	INIT_LIST_HEAD(&vm->bound_list);
 }
 
@@ -1887,10 +1876,6 @@ static struct i915_vma *pd_vma_create(struct gen6_ppgtt *ppgtt, int size)
 	INIT_LIST_HEAD(&vma->obj_link);
 	INIT_LIST_HEAD(&vma->closed_link);
 
-	mutex_lock(&vma->vm->mutex);
-	list_add(&vma->vm_link, &vma->vm->unbound_list);
-	mutex_unlock(&vma->vm->mutex);
-
 	return vma;
 }
 

drivers/gpu/drm/i915/i915_gem_gtt.h

@@ -320,11 +320,6 @@ struct i915_address_space {
 	 */
 	struct list_head bound_list;
 
-	/**
-	 * List of vma that are not unbound.
-	 */
-	struct list_head unbound_list;
-
 	struct pagestash free_pages;
 
 	/* Global GTT */

drivers/gpu/drm/i915/i915_vma.c

@@ -218,10 +218,6 @@ vma_create(struct drm_i915_gem_object *obj,
 
 	spin_unlock(&obj->vma.lock);
 
-	mutex_lock(&vm->mutex);
-	list_add(&vma->vm_link, &vm->unbound_list);
-	mutex_unlock(&vm->mutex);
-
 	return vma;
 
 err_vma:
@@ -657,7 +653,7 @@ i915_vma_insert(struct i915_vma *vma, u64 size, u64 alignment, u64 flags)
 	GEM_BUG_ON(!i915_gem_valid_gtt_space(vma, color));
 
 	mutex_lock(&vma->vm->mutex);
-	list_move_tail(&vma->vm_link, &vma->vm->bound_list);
+	list_add_tail(&vma->vm_link, &vma->vm->bound_list);
 	mutex_unlock(&vma->vm->mutex);
 
 	if (vma->obj) {
@@ -685,7 +681,7 @@ i915_vma_remove(struct i915_vma *vma)
 
 	mutex_lock(&vma->vm->mutex);
 	drm_mm_remove_node(&vma->node);
-	list_move_tail(&vma->vm_link, &vma->vm->unbound_list);
+	list_del(&vma->vm_link);
 	mutex_unlock(&vma->vm->mutex);
 
 	/*
@@ -798,10 +794,6 @@ static void __i915_vma_destroy(struct i915_vma *vma)
 	GEM_BUG_ON(drm_mm_node_allocated(&vma->node));
 	GEM_BUG_ON(vma->fence);
 
-	mutex_lock(&vma->vm->mutex);
-	list_del(&vma->vm_link);
-	mutex_unlock(&vma->vm->mutex);
-
 	if (vma->obj) {
 		struct drm_i915_gem_object *obj = vma->obj;
 

drivers/gpu/drm/i915/selftests/i915_gem_gtt.c

@@ -1242,7 +1242,7 @@ static void track_vma_bind(struct i915_vma *vma)
 	vma->pages = obj->mm.pages;
 
 	mutex_lock(&vma->vm->mutex);
-	list_move_tail(&vma->vm_link, &vma->vm->bound_list);
+	list_add_tail(&vma->vm_link, &vma->vm->bound_list);
 	mutex_unlock(&vma->vm->mutex);
 }