diff options
| -rw-r--r-- | lib/radix-tree.c | 154 |
1 files changed, 76 insertions, 78 deletions
diff --git a/lib/radix-tree.c b/lib/radix-tree.c index d9df745..dc63d08 100644 --- a/lib/radix-tree.c +++ b/lib/radix-tree.c @@ -48,16 +48,14 @@ struct radix_tree_node { unsigned int height; /* Height from the bottom */ unsigned int count; - struct rcu_head rcu_head; + union { + struct radix_tree_node *parent; /* Used when ascending tree */ + struct rcu_head rcu_head; /* Used when freeing node */ + }; void __rcu *slots[RADIX_TREE_MAP_SIZE]; unsigned long tags[RADIX_TREE_MAX_TAGS][RADIX_TREE_TAG_LONGS]; }; -struct radix_tree_path { - struct radix_tree_node *node; - int offset; -}; - #define RADIX_TREE_INDEX_BITS (8 /* CHAR_BIT */ * sizeof(unsigned long)) #define RADIX_TREE_MAX_PATH (DIV_ROUND_UP(RADIX_TREE_INDEX_BITS, \ RADIX_TREE_MAP_SHIFT)) @@ -256,6 +254,7 @@ static inline unsigned long radix_tree_maxindex(unsigned int height) static int radix_tree_extend(struct radix_tree_root *root, unsigned long index) { struct radix_tree_node *node; + struct radix_tree_node *slot; unsigned int height; int tag; @@ -274,18 +273,23 @@ static int radix_tree_extend(struct radix_tree_root *root, unsigned long index) if (!(node = radix_tree_node_alloc(root))) return -ENOMEM; - /* Increase the height. */ - node->slots[0] = indirect_to_ptr(root->rnode); - /* Propagate the aggregated tag info into the new root */ for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) { if (root_tag_get(root, tag)) tag_set(node, tag, 0); } + /* Increase the height. */ newheight = root->height+1; node->height = newheight; node->count = 1; + node->parent = NULL; + slot = root->rnode; + if (newheight > 1) { + slot = indirect_to_ptr(slot); + slot->parent = node; + } + node->slots[0] = slot; node = ptr_to_indirect(node); rcu_assign_pointer(root->rnode, node); root->height = newheight; @@ -331,6 +335,7 @@ int radix_tree_insert(struct radix_tree_root *root, if (!(slot = radix_tree_node_alloc(root))) return -ENOMEM; slot->height = height; + slot->parent = node; if (node) { rcu_assign_pointer(node->slots[offset], slot); node->count++; @@ -504,47 +509,41 @@ EXPORT_SYMBOL(radix_tree_tag_set); void *radix_tree_tag_clear(struct radix_tree_root *root, unsigned long index, unsigned int tag) { - /* - * The radix tree path needs to be one longer than the maximum path - * since the "list" is null terminated. - */ - struct radix_tree_path path[RADIX_TREE_MAX_PATH + 1], *pathp = path; + struct radix_tree_node *node = NULL; struct radix_tree_node *slot = NULL; unsigned int height, shift; + int uninitialized_var(offset); height = root->height; if (index > radix_tree_maxindex(height)) goto out; - shift = (height - 1) * RADIX_TREE_MAP_SHIFT; - pathp->node = NULL; + shift = height * RADIX_TREE_MAP_SHIFT; slot = indirect_to_ptr(root->rnode); - while (height > 0) { - int offset; - + while (shift) { if (slot == NULL) goto out; + shift -= RADIX_TREE_MAP_SHIFT; offset = (index >> shift) & RADIX_TREE_MAP_MASK; - pathp[1].offset = offset; - pathp[1].node = slot; + node = slot; slot = slot->slots[offset]; - pathp++; - shift -= RADIX_TREE_MAP_SHIFT; - height--; } if (slot == NULL) goto out; - while (pathp->node) { - if (!tag_get(pathp->node, tag, pathp->offset)) + while (node) { + if (!tag_get(node, tag, offset)) goto out; - tag_clear(pathp->node, tag, pathp->offset); - if (any_tag_set(pathp->node, tag)) + tag_clear(node, tag, offset); + if (any_tag_set(node, tag)) goto out; - pathp--; + + index >>= RADIX_TREE_MAP_SHIFT; + offset = index & RADIX_TREE_MAP_MASK; + node = node->parent; } /* clear the root's tag bit */ @@ -646,8 +645,7 @@ unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root, unsigned int iftag, unsigned int settag) { unsigned int height = root->height; - struct radix_tree_path path[height]; - struct radix_tree_path *pathp = path; + struct radix_tree_node *node = NULL; struct radix_tree_node *slot; unsigned int shift; unsigned long tagged = 0; @@ -671,14 +669,8 @@ unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root, shift = (height - 1) * RADIX_TREE_MAP_SHIFT; slot = indirect_to_ptr(root->rnode); - /* - * we fill the path from (root->height - 2) to 0, leaving the index at - * (root->height - 1) as a terminator. Zero the node in the terminator - * so that we can use this to end walk loops back up the path. - */ - path[height - 1].node = NULL; - for (;;) { + unsigned long upindex; int offset; offset = (index >> shift) & RADIX_TREE_MAP_MASK; @@ -686,12 +678,10 @@ unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root, goto next; if (!tag_get(slot, iftag, offset)) goto next; - if (height > 1) { + if (shift) { /* Go down one level */ - height--; shift -= RADIX_TREE_MAP_SHIFT; - path[height - 1].node = slot; - path[height - 1].offset = offset; + node = slot; slot = slot->slots[offset]; continue; } @@ -701,15 +691,27 @@ unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root, tag_set(slot, settag, offset); /* walk back up the path tagging interior nodes */ - pathp = &path[0]; - while (pathp->node) { + upindex = index; + while (node) { + upindex >>= RADIX_TREE_MAP_SHIFT; + offset = upindex & RADIX_TREE_MAP_MASK; + /* stop if we find a node with the tag already set */ - if (tag_get(pathp->node, settag, pathp->offset)) + if (tag_get(node, settag, offset)) break; - tag_set(pathp->node, settag, pathp->offset); - pathp++; + tag_set(node, settag, offset); + node = node->parent; } + /* + * Small optimization: now clear that node pointer. + * Since all of this slot's ancestors now have the tag set + * from setting it above, we have no further need to walk + * back up the tree setting tags, until we update slot to + * point to another radix_tree_node. + */ + node = NULL; + next: /* Go to next item at level determined by 'shift' */ index = ((index >> shift) + 1) << shift; @@ -724,8 +726,7 @@ next: * last_index is guaranteed to be in the tree, what * we do below cannot wander astray. */ - slot = path[height - 1].node; - height++; + slot = slot->parent; shift += RADIX_TREE_MAP_SHIFT; } } @@ -1299,7 +1300,7 @@ static inline void radix_tree_shrink(struct radix_tree_root *root) /* try to shrink tree height */ while (root->height > 0) { struct radix_tree_node *to_free = root->rnode; - void *newptr; + struct radix_tree_node *slot; BUG_ON(!radix_tree_is_indirect_ptr(to_free)); to_free = indirect_to_ptr(to_free); @@ -1320,10 +1321,12 @@ static inline void radix_tree_shrink(struct radix_tree_root *root) * (to_free->slots[0]), it will be safe to dereference the new * one (root->rnode) as far as dependent read barriers go. */ - newptr = to_free->slots[0]; - if (root->height > 1) - newptr = ptr_to_indirect(newptr); - root->rnode = newptr; + slot = to_free->slots[0]; + if (root->height > 1) { + slot->parent = NULL; + slot = ptr_to_indirect(slot); + } + root->rnode = slot; root->height--; /* @@ -1363,16 +1366,12 @@ static inline void radix_tree_shrink(struct radix_tree_root *root) */ void *radix_tree_delete(struct radix_tree_root *root, unsigned long index) { - /* - * The radix tree path needs to be one longer than the maximum path - * since the "list" is null terminated. - */ - struct radix_tree_path path[RADIX_TREE_MAX_PATH + 1], *pathp = path; + struct radix_tree_node *node = NULL; struct radix_tree_node *slot = NULL; struct radix_tree_node *to_free; unsigned int height, shift; int tag; - int offset; + int uninitialized_var(offset); height = root->height; if (index > radix_tree_maxindex(height)) @@ -1385,39 +1384,35 @@ void *radix_tree_delete(struct radix_tree_root *root, unsigned long index) goto out; } slot = indirect_to_ptr(slot); - - shift = (height - 1) * RADIX_TREE_MAP_SHIFT; - pathp->node = NULL; + shift = height * RADIX_TREE_MAP_SHIFT; do { if (slot == NULL) goto out; - pathp++; + shift -= RADIX_TREE_MAP_SHIFT; offset = (index >> shift) & RADIX_TREE_MAP_MASK; - pathp->offset = offset; - pathp->node = slot; + node = slot; slot = slot->slots[offset]; - shift -= RADIX_TREE_MAP_SHIFT; - height--; - } while (height > 0); + } while (shift); if (slot == NULL) goto out; /* - * Clear all tags associated with the just-deleted item + * Clear all tags associated with the item to be deleted. + * This way of doing it would be inefficient, but seldom is any set. */ for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) { - if (tag_get(pathp->node, tag, pathp->offset)) + if (tag_get(node, tag, offset)) radix_tree_tag_clear(root, index, tag); } to_free = NULL; /* Now free the nodes we do not need anymore */ - while (pathp->node) { - pathp->node->slots[pathp->offset] = NULL; - pathp->node->count--; + while (node) { + node->slots[offset] = NULL; + node->count--; /* * Queue the node for deferred freeing after the * last reference to it disappears (set NULL, above). @@ -1425,17 +1420,20 @@ void *radix_tree_delete(struct radix_tree_root *root, unsigned long index) if (to_free) radix_tree_node_free(to_free); - if (pathp->node->count) { - if (pathp->node == indirect_to_ptr(root->rnode)) + if (node->count) { + if (node == indirect_to_ptr(root->rnode)) radix_tree_shrink(root); goto out; } /* Node with zero slots in use so free it */ - to_free = pathp->node; - pathp--; + to_free = node; + index >>= RADIX_TREE_MAP_SHIFT; + offset = index & RADIX_TREE_MAP_MASK; + node = node->parent; } + root_tag_clear_all(root); root->height = 0; root->rnode = NULL; |
