[Intel-gfx] [PATCH 2/5] drm/i915: Extract node allocation from bind

[Ben Widawsky]

The DRM node allocation code was already a bit of an ugly bit of code
within a complex function. Removing it serves the purpose of cleaning
the function up. More importantly, it provides a way to have a
preallocated (address space) VMA to easily skip this code. Something
we're very likely to need.

This is essentially a wrapper for DRM node allocation with an eviction +
retry. It is something which could be moved to core DRM eventually, if
other drivers had similar eviction semantics.

This removes a goto used for something other than error unwinding, a
generally reviled (I am neutral) practice, and replaces it with a
function call to itself that should have the same effect. Note that it's
not a recursive function as all the problem set reduction is done in the
eviction code.

Some might say this change is worse than before because we are using
stack for each subsequent call. Frankly, I'd rather overflow the stack
and blow it up than loop forever. In either case, this is addressed in
the next patch.

I believe, and intend, that other than the stack usage, there is no
functional change here.

Signed-off-by: Ben Widawsky <ben at bwidawsk.net>
---
 drivers/gpu/drm/i915/i915_gem.c | 45 +++++++++++++++++++++++++++++------------
 1 file changed, 32 insertions(+), 13 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index ce9ad17..d03702ac 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -3216,6 +3216,34 @@ static void i915_gem_verify_gtt(struct drm_device *dev)
 #endif
 }
 
+static int
+i915_gem_find_vm_space(struct i915_address_space *vm,
+		       struct drm_mm_node *node,
+		       unsigned long size,
+		       unsigned long align,
+		       unsigned long color,
+		       unsigned long start,
+		       unsigned long end,
+		       uint32_t flags)
+{
+	int ret;
+	ret = drm_mm_insert_node_in_range_generic(&vm->mm, node,
+						  size, align, color,
+						  start, end,
+						  DRM_MM_SEARCH_DEFAULT,
+						  DRM_MM_CREATE_DEFAULT);
+	if (ret) {
+		ret = i915_gem_evict_something(vm->dev, vm, size, align, color,
+					       flags);
+		if (ret == 0)
+			return i915_gem_find_vm_space(vm, node,
+						      size, align, color,
+						      start, end, flags);
+	}
+
+	return ret;
+}
+
 /**
  * Finds free space in the GTT aperture and binds the object there.
  */
@@ -3275,20 +3303,11 @@ i915_gem_object_bind_to_vm(struct drm_i915_gem_object *obj,
 	if (IS_ERR(vma))
 		goto err_unpin;
 
-search_free:
-	ret = drm_mm_insert_node_in_range_generic(&vm->mm, &vma->node,
-						  size, alignment,
-						  obj->cache_level, 0, gtt_max,
-						  DRM_MM_SEARCH_DEFAULT,
-						  DRM_MM_CREATE_DEFAULT);
-	if (ret) {
-		ret = i915_gem_evict_something(dev, vm, size, alignment,
-					       obj->cache_level, flags);
-		if (ret == 0)
-			goto search_free;
-
+	ret = i915_gem_find_vm_space(vm, &vma->node, size, alignment,
+				     obj->cache_level, 0, gtt_max, flags);
+	if (ret)
 		goto err_free_vma;
-	}
+
 	if (WARN_ON(!i915_gem_valid_gtt_space(dev, &vma->node,
 					      obj->cache_level))) {
 		ret = -EINVAL;
-- 
1.9.2