drm/i915: Some cleanups for the ppgtt lifetime handling

So when reviewing Michel's patch I've noticed a few things and cleaned
them up:
- The early checks in ppgtt_release are now redundant: The inactive
  list should always be empty now, so we can ditch these checks. Even
  for the aliasing ppgtt (though that's a different confusion) since
  we tear that down after all the objects are gone.
- The ppgtt handling functions are splattered all over. Consolidate
  them in i915_gem_gtt.c, give them OCD prefixes and add wrappers for
  get/put.
- There was a bit a confusion in ppgtt_release about whether it cares
  about the active or inactive list. It should care about them both,
  so augment the WARNINGs to check for both.

There's still create_vm_for_ctx left to do, put that is blocked on the
removal of ppgtt->ctx. Once that's done we can rename it to
i915_ppgtt_create and move it to its siblings for handling ppgtts.

v2: Move the ppgtt checks into the inline get/put functions as
suggested by Chris.

v3: Inline the now redundant ppgtt local variable.

Cc: Michel Thierry <michel.thierry@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Michel Thierry <michel.thierry@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.h

@@ -2549,7 +2549,6 @@ void i915_gem_object_ggtt_unpin(struct drm_i915_gem_object *obj);
 #define ctx_to_ppgtt(ctx) container_of((ctx)->vm, struct i915_hw_ppgtt, base)
 #define vm_to_ppgtt(vm) container_of(vm, struct i915_hw_ppgtt, base)
 int __must_check i915_gem_context_init(struct drm_device *dev);
-void ppgtt_release(struct kref *kref);
 void i915_gem_context_fini(struct drm_device *dev);
 void i915_gem_context_reset(struct drm_device *dev);
 int i915_gem_context_open(struct drm_device *dev, struct drm_file *file);

drivers/gpu/drm/i915/i915_gem.c

@@ -4477,7 +4477,6 @@ struct i915_vma *i915_gem_obj_to_vma(struct drm_i915_gem_object *obj,
 void i915_gem_vma_destroy(struct i915_vma *vma)
 {
 	struct i915_address_space *vm = NULL;
-	struct i915_hw_ppgtt *ppgtt = NULL;
 	WARN_ON(vma->node.allocated);
 
 	/* Keep the vma as a placeholder in the execbuffer reservation lists */
@@ -4485,10 +4484,8 @@ void i915_gem_vma_destroy(struct i915_vma *vma)
 		return;
 
 	vm = vma->vm;
-	ppgtt = vm_to_ppgtt(vm);
 
-	if (ppgtt)
+	i915_ppgtt_put(vm_to_ppgtt(vm));
-		kref_put(&ppgtt->ref, ppgtt_release);
 
 	list_del(&vma->vma_link);
 

drivers/gpu/drm/i915/i915_gem_context.c

@@ -96,33 +96,6 @@
 #define GEN6_CONTEXT_ALIGN (64<<10)
 #define GEN7_CONTEXT_ALIGN 4096
 
-static void do_ppgtt_cleanup(struct i915_hw_ppgtt *ppgtt)
-{
-	struct drm_device *dev = ppgtt->base.dev;
-	struct drm_i915_private *dev_priv = dev->dev_private;
-	struct i915_address_space *vm = &ppgtt->base;
-
-	if (ppgtt == dev_priv->mm.aliasing_ppgtt ||
-	    (list_empty(&vm->active_list) && list_empty(&vm->inactive_list))) {
-		ppgtt->base.cleanup(&ppgtt->base);
-		return;
-	}
-
-	/* vmas should already be unbound */
-	WARN_ON(!list_empty(&vm->active_list));
-
-	ppgtt->base.cleanup(&ppgtt->base);
-}
-
-void ppgtt_release(struct kref *kref)
-{
-	struct i915_hw_ppgtt *ppgtt =
-		container_of(kref, struct i915_hw_ppgtt, ref);
-
-	do_ppgtt_cleanup(ppgtt);
-	kfree(ppgtt);
-}
-
 static size_t get_context_alignment(struct drm_device *dev)
 {
 	if (IS_GEN6(dev))
@@ -174,8 +147,7 @@ void i915_gem_context_free(struct kref *ctx_ref)
 			ppgtt = ctx_to_ppgtt(ctx);
 	}
 
-	if (ppgtt)
+	i915_ppgtt_put(ppgtt);
-		kref_put(&ppgtt->ref, ppgtt_release);
 	if (ctx->legacy_hw_ctx.rcs_state)
 		drm_gem_object_unreference(&ctx->legacy_hw_ctx.rcs_state->base);
 	list_del(&ctx->link);
@@ -222,7 +194,7 @@ create_vm_for_ctx(struct drm_device *dev, struct intel_context *ctx)
 	if (!ppgtt)
 		return ERR_PTR(-ENOMEM);
 
-	ret = i915_gem_init_ppgtt(dev, ppgtt);
+	ret = i915_ppgtt_init(dev, ppgtt);
 	if (ret) {
 		kfree(ppgtt);
 		return ERR_PTR(ret);
@@ -342,7 +314,7 @@ i915_gem_create_context(struct drm_device *dev,
 		/* For platforms which only have aliasing PPGTT, we fake the
 		 * address space and refcounting. */
 		ctx->vm = &dev_priv->mm.aliasing_ppgtt->base;
-		kref_get(&dev_priv->mm.aliasing_ppgtt->ref);
+		i915_ppgtt_get(dev_priv->mm.aliasing_ppgtt);
 	} else
 		ctx->vm = &dev_priv->gtt.base;
 

drivers/gpu/drm/i915/i915_gem_gtt.c

@@ -1180,7 +1180,7 @@ static int gen6_ppgtt_init(struct i915_hw_ppgtt *ppgtt)
 	return 0;
 }
 
-int i915_gem_init_ppgtt(struct drm_device *dev, struct i915_hw_ppgtt *ppgtt)
+int i915_ppgtt_init(struct drm_device *dev, struct i915_hw_ppgtt *ppgtt)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	int ret = 0;
@@ -1211,6 +1211,19 @@ int i915_gem_init_ppgtt(struct drm_device *dev, struct i915_hw_ppgtt *ppgtt)
 	return ret;
 }
 
+void  i915_ppgtt_release(struct kref *kref)
+{
+	struct i915_hw_ppgtt *ppgtt =
+		container_of(kref, struct i915_hw_ppgtt, ref);
+
+	/* vmas should already be unbound */
+	WARN_ON(!list_empty(&ppgtt->base.active_list));
+	WARN_ON(!list_empty(&ppgtt->base.inactive_list));
+
+	ppgtt->base.cleanup(&ppgtt->base);
+	kfree(ppgtt);
+}
+
 static void
 ppgtt_bind_vma(struct i915_vma *vma,
 	       enum i915_cache_level cache_level,
@@ -2148,15 +2161,12 @@ i915_gem_obj_lookup_or_create_vma(struct drm_i915_gem_object *obj,
 				  struct i915_address_space *vm)
 {
 	struct i915_vma *vma;
-	struct i915_hw_ppgtt *ppgtt = NULL;
 
 	vma = i915_gem_obj_to_vma(obj, vm);
 	if (!vma)
 		vma = __i915_gem_vma_create(obj, vm);
 
-	ppgtt = vm_to_ppgtt(vm);
+	i915_ppgtt_get(vm_to_ppgtt(vm));
-	if (ppgtt)
-		kref_get(&ppgtt->ref);
 
 	return vma;
 }

drivers/gpu/drm/i915/i915_gem_gtt.h

@@ -272,7 +272,19 @@ void i915_gem_init_global_gtt(struct drm_device *dev);
 void i915_gem_setup_global_gtt(struct drm_device *dev, unsigned long start,
 			       unsigned long mappable_end, unsigned long end);
 
-int i915_gem_init_ppgtt(struct drm_device *dev, struct i915_hw_ppgtt *ppgtt);
+
+int i915_ppgtt_init(struct drm_device *dev, struct i915_hw_ppgtt *ppgtt);
+void i915_ppgtt_release(struct kref *kref);
+static inline void i915_ppgtt_get(struct i915_hw_ppgtt *ppgtt)
+{
+	if (ppgtt)
+		kref_get(&ppgtt->ref);
+}
+static inline void i915_ppgtt_put(struct i915_hw_ppgtt *ppgtt)
+{
+	if (ppgtt)
+		kref_put(&ppgtt->ref, i915_ppgtt_release);
+}
 
 void i915_check_and_clear_faults(struct drm_device *dev);
 void i915_gem_suspend_gtt_mappings(struct drm_device *dev);