[PATCH v2 2/4] drm/ttm: replace drm_mm_pre_get() by direct alloc

[David Herrmann]

Instead of calling drm_mm_pre_get() in a row, we now preallocate the node
and then use the atomic insertion functions. This has the exact same
semantics and there is no reason to use the racy pre-allocations.

Note that ttm_bo_man_get_node() does not run in atomic context. Nouveau
already uses GFP_KERNEL alloc in nouveau/nouveau_ttm.c in
nouveau_gart_manager_new(). So we can do the same in
ttm_bo_man_get_node().

Signed-off-by: David Herrmann <dh.herrmann at gmail.com>
Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>
---
 drivers/gpu/drm/ttm/ttm_bo_manager.c | 42 +++++++++++++++++-------------------
 1 file changed, 20 insertions(+), 22 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_bo_manager.c 
b/drivers/gpu/drm/ttm/ttm_bo_manager.c
index e4be29e..c58eba33 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_manager.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_manager.c
@@ -61,29 +61,25 @@ static int ttm_bo_man_get_node(struct ttm_mem_type_manager 
*man,
        lpfn = placement->lpfn;
        if (!lpfn)
                lpfn = man->size;
-       do {
-               ret = drm_mm_pre_get(mm);
-               if (unlikely(ret))
-                       return ret;

-               spin_lock(&rman->lock);
-               node = drm_mm_search_free_in_range(mm,
-                                       mem->num_pages, mem->page_alignment,
-                                       placement->fpfn, lpfn,
-                                       DRM_MM_SEARCH_BEST);
-               if (unlikely(node == NULL)) {
-                       spin_unlock(&rman->lock);
-                       return 0;
-               }
-               node = drm_mm_get_block_atomic_range(node, mem->num_pages,
-                                                    mem->page_alignment,
-                                                    placement->fpfn,
-                                                    lpfn);
-               spin_unlock(&rman->lock);
-       } while (node == NULL);
+       node = kzalloc(sizeof(*node), GFP_KERNEL);
+       if (!node)
+               return -ENOMEM;
+
+       spin_lock(&rman->lock);
+       ret = drm_mm_insert_node_in_range(mm, node, mem->num_pages,
+                                         mem->page_alignment,
+                                         placement->fpfn, lpfn,
+                                         DRM_MM_SEARCH_BEST);
+       spin_unlock(&rman->lock);
+
+       if (unlikely(ret)) {
+               kfree(node);
+       } else {
+               mem->mm_node = node;
+               mem->start = node->start;
+       }

-       mem->mm_node = node;
-       mem->start = node->start;
        return 0;
 }

@@ -94,8 +90,10 @@ static void ttm_bo_man_put_node(struct ttm_mem_type_manager 
*man,

        if (mem->mm_node) {
                spin_lock(&rman->lock);
-               drm_mm_put_block(mem->mm_node);
+               drm_mm_remove_node(mem->mm_node);
                spin_unlock(&rman->lock);
+
+               kfree(mem->mm_node);
                mem->mm_node = NULL;
        }
 }
-- 
1.8.3.4