X-Git-Url: http://git.cascardo.info/?a=blobdiff_plain;f=lib%2Fradix-tree.c;h=9599aa72d7a024795b300750e55147a60f58ed19;hb=449dd6984d0e;hp=bd4a8dfdf0b8052cdaedd0b3478eea4138ac100a;hpb=e090d5b6ad20056ec0ef58727e3ae95fd82be090;p=cascardo%2Flinux.git diff --git a/lib/radix-tree.c b/lib/radix-tree.c index bd4a8dfdf0b8..9599aa72d7a0 100644 --- a/lib/radix-tree.c +++ b/lib/radix-tree.c @@ -35,33 +35,6 @@ #include /* in_interrupt() */ -#ifdef __KERNEL__ -#define RADIX_TREE_MAP_SHIFT (CONFIG_BASE_SMALL ? 4 : 6) -#else -#define RADIX_TREE_MAP_SHIFT 3 /* For more stressful testing */ -#endif - -#define RADIX_TREE_MAP_SIZE (1UL << RADIX_TREE_MAP_SHIFT) -#define RADIX_TREE_MAP_MASK (RADIX_TREE_MAP_SIZE-1) - -#define RADIX_TREE_TAG_LONGS \ - ((RADIX_TREE_MAP_SIZE + BITS_PER_LONG - 1) / BITS_PER_LONG) - -struct radix_tree_node { - unsigned int height; /* Height from the bottom */ - unsigned int count; - 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]; -}; - -#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)) - /* * The height_to_maxindex array needs to be one deeper than the maximum * path as height 0 holds only 1 entry. @@ -369,7 +342,8 @@ static int radix_tree_extend(struct radix_tree_root *root, unsigned long index) /* Increase the height. */ newheight = root->height+1; - node->height = newheight; + BUG_ON(newheight & ~RADIX_TREE_HEIGHT_MASK); + node->path = newheight; node->count = 1; node->parent = NULL; slot = root->rnode; @@ -387,23 +361,28 @@ out: } /** - * radix_tree_insert - insert into a radix tree + * __radix_tree_create - create a slot in a radix tree * @root: radix tree root * @index: index key - * @item: item to insert + * @nodep: returns node + * @slotp: returns slot * - * Insert an item into the radix tree at position @index. + * Create, if necessary, and return the node and slot for an item + * at position @index in the radix tree @root. + * + * Until there is more than one item in the tree, no nodes are + * allocated and @root->rnode is used as a direct slot instead of + * pointing to a node, in which case *@nodep will be NULL. + * + * Returns -ENOMEM, or 0 for success. */ -int radix_tree_insert(struct radix_tree_root *root, - unsigned long index, void *item) +int __radix_tree_create(struct radix_tree_root *root, unsigned long index, + struct radix_tree_node **nodep, void ***slotp) { struct radix_tree_node *node = NULL, *slot; - unsigned int height, shift; - int offset; + unsigned int height, shift, offset; int error; - BUG_ON(radix_tree_is_indirect_ptr(item)); - /* Make sure the tree is high enough. */ if (index > radix_tree_maxindex(root->height)) { error = radix_tree_extend(root, index); @@ -422,11 +401,12 @@ int radix_tree_insert(struct radix_tree_root *root, /* Have to add a child node. */ if (!(slot = radix_tree_node_alloc(root))) return -ENOMEM; - slot->height = height; + slot->path = height; slot->parent = node; if (node) { rcu_assign_pointer(node->slots[offset], slot); node->count++; + slot->path |= offset << RADIX_TREE_HEIGHT_SHIFT; } else rcu_assign_pointer(root->rnode, ptr_to_indirect(slot)); } @@ -439,16 +419,42 @@ int radix_tree_insert(struct radix_tree_root *root, height--; } - if (slot != NULL) + if (nodep) + *nodep = node; + if (slotp) + *slotp = node ? node->slots + offset : (void **)&root->rnode; + return 0; +} + +/** + * radix_tree_insert - insert into a radix tree + * @root: radix tree root + * @index: index key + * @item: item to insert + * + * Insert an item into the radix tree at position @index. + */ +int radix_tree_insert(struct radix_tree_root *root, + unsigned long index, void *item) +{ + struct radix_tree_node *node; + void **slot; + int error; + + BUG_ON(radix_tree_is_indirect_ptr(item)); + + error = __radix_tree_create(root, index, &node, &slot); + if (error) + return error; + if (*slot != NULL) return -EEXIST; + rcu_assign_pointer(*slot, item); if (node) { node->count++; - rcu_assign_pointer(node->slots[offset], item); - BUG_ON(tag_get(node, 0, offset)); - BUG_ON(tag_get(node, 1, offset)); + BUG_ON(tag_get(node, 0, index & RADIX_TREE_MAP_MASK)); + BUG_ON(tag_get(node, 1, index & RADIX_TREE_MAP_MASK)); } else { - rcu_assign_pointer(root->rnode, item); BUG_ON(root_tag_get(root, 0)); BUG_ON(root_tag_get(root, 1)); } @@ -457,15 +463,26 @@ int radix_tree_insert(struct radix_tree_root *root, } EXPORT_SYMBOL(radix_tree_insert); -/* - * is_slot == 1 : search for the slot. - * is_slot == 0 : search for the node. +/** + * __radix_tree_lookup - lookup an item in a radix tree + * @root: radix tree root + * @index: index key + * @nodep: returns node + * @slotp: returns slot + * + * Lookup and return the item at position @index in the radix + * tree @root. + * + * Until there is more than one item in the tree, no nodes are + * allocated and @root->rnode is used as a direct slot instead of + * pointing to a node, in which case *@nodep will be NULL. */ -static void *radix_tree_lookup_element(struct radix_tree_root *root, - unsigned long index, int is_slot) +void *__radix_tree_lookup(struct radix_tree_root *root, unsigned long index, + struct radix_tree_node **nodep, void ***slotp) { + struct radix_tree_node *node, *parent; unsigned int height, shift; - struct radix_tree_node *node, **slot; + void **slot; node = rcu_dereference_raw(root->rnode); if (node == NULL) @@ -474,19 +491,24 @@ static void *radix_tree_lookup_element(struct radix_tree_root *root, if (!radix_tree_is_indirect_ptr(node)) { if (index > 0) return NULL; - return is_slot ? (void *)&root->rnode : node; + + if (nodep) + *nodep = NULL; + if (slotp) + *slotp = (void **)&root->rnode; + return node; } node = indirect_to_ptr(node); - height = node->height; + height = node->path & RADIX_TREE_HEIGHT_MASK; if (index > radix_tree_maxindex(height)) return NULL; shift = (height-1) * RADIX_TREE_MAP_SHIFT; do { - slot = (struct radix_tree_node **) - (node->slots + ((index>>shift) & RADIX_TREE_MAP_MASK)); + parent = node; + slot = node->slots + ((index >> shift) & RADIX_TREE_MAP_MASK); node = rcu_dereference_raw(*slot); if (node == NULL) return NULL; @@ -495,7 +517,11 @@ static void *radix_tree_lookup_element(struct radix_tree_root *root, height--; } while (height > 0); - return is_slot ? (void *)slot : indirect_to_ptr(node); + if (nodep) + *nodep = parent; + if (slotp) + *slotp = slot; + return node; } /** @@ -513,7 +539,11 @@ static void *radix_tree_lookup_element(struct radix_tree_root *root, */ void **radix_tree_lookup_slot(struct radix_tree_root *root, unsigned long index) { - return (void **)radix_tree_lookup_element(root, index, 1); + void **slot; + + if (!__radix_tree_lookup(root, index, NULL, &slot)) + return NULL; + return slot; } EXPORT_SYMBOL(radix_tree_lookup_slot); @@ -531,7 +561,7 @@ EXPORT_SYMBOL(radix_tree_lookup_slot); */ void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index) { - return radix_tree_lookup_element(root, index, 0); + return __radix_tree_lookup(root, index, NULL, NULL); } EXPORT_SYMBOL(radix_tree_lookup); @@ -676,7 +706,7 @@ int radix_tree_tag_get(struct radix_tree_root *root, return (index == 0); node = indirect_to_ptr(node); - height = node->height; + height = node->path & RADIX_TREE_HEIGHT_MASK; if (index > radix_tree_maxindex(height)) return 0; @@ -713,7 +743,7 @@ void **radix_tree_next_chunk(struct radix_tree_root *root, { unsigned shift, tag = flags & RADIX_TREE_ITER_TAG_MASK; struct radix_tree_node *rnode, *node; - unsigned long index, offset; + unsigned long index, offset, height; if ((flags & RADIX_TREE_ITER_TAGGED) && !root_tag_get(root, tag)) return NULL; @@ -744,7 +774,8 @@ void **radix_tree_next_chunk(struct radix_tree_root *root, return NULL; restart: - shift = (rnode->height - 1) * RADIX_TREE_MAP_SHIFT; + height = rnode->path & RADIX_TREE_HEIGHT_MASK; + shift = (height - 1) * RADIX_TREE_MAP_SHIFT; offset = index >> shift; /* Index outside of the tree */ @@ -946,81 +977,6 @@ next: } EXPORT_SYMBOL(radix_tree_range_tag_if_tagged); - -/** - * radix_tree_next_hole - find the next hole (not-present entry) - * @root: tree root - * @index: index key - * @max_scan: maximum range to search - * - * Search the set [index, min(index+max_scan-1, MAX_INDEX)] for the lowest - * indexed hole. - * - * Returns: the index of the hole if found, otherwise returns an index - * outside of the set specified (in which case 'return - index >= max_scan' - * will be true). In rare cases of index wrap-around, 0 will be returned. - * - * radix_tree_next_hole may be called under rcu_read_lock. However, like - * radix_tree_gang_lookup, this will not atomically search a snapshot of - * the tree at a single point in time. For example, if a hole is created - * at index 5, then subsequently a hole is created at index 10, - * radix_tree_next_hole covering both indexes may return 10 if called - * under rcu_read_lock. - */ -unsigned long radix_tree_next_hole(struct radix_tree_root *root, - unsigned long index, unsigned long max_scan) -{ - unsigned long i; - - for (i = 0; i < max_scan; i++) { - if (!radix_tree_lookup(root, index)) - break; - index++; - if (index == 0) - break; - } - - return index; -} -EXPORT_SYMBOL(radix_tree_next_hole); - -/** - * radix_tree_prev_hole - find the prev hole (not-present entry) - * @root: tree root - * @index: index key - * @max_scan: maximum range to search - * - * Search backwards in the range [max(index-max_scan+1, 0), index] - * for the first hole. - * - * Returns: the index of the hole if found, otherwise returns an index - * outside of the set specified (in which case 'index - return >= max_scan' - * will be true). In rare cases of wrap-around, ULONG_MAX will be returned. - * - * radix_tree_next_hole may be called under rcu_read_lock. However, like - * radix_tree_gang_lookup, this will not atomically search a snapshot of - * the tree at a single point in time. For example, if a hole is created - * at index 10, then subsequently a hole is created at index 5, - * radix_tree_prev_hole covering both indexes may return 5 if called under - * rcu_read_lock. - */ -unsigned long radix_tree_prev_hole(struct radix_tree_root *root, - unsigned long index, unsigned long max_scan) -{ - unsigned long i; - - for (i = 0; i < max_scan; i++) { - if (!radix_tree_lookup(root, index)) - break; - index--; - if (index == ULONG_MAX) - break; - } - - return index; -} -EXPORT_SYMBOL(radix_tree_prev_hole); - /** * radix_tree_gang_lookup - perform multiple lookup on a radix tree * @root: radix tree root @@ -1189,7 +1145,7 @@ static unsigned long __locate(struct radix_tree_node *slot, void *item, unsigned int shift, height; unsigned long i; - height = slot->height; + height = slot->path & RADIX_TREE_HEIGHT_MASK; shift = (height-1) * RADIX_TREE_MAP_SHIFT; for ( ; height > 1; height--) { @@ -1252,7 +1208,8 @@ unsigned long radix_tree_locate_item(struct radix_tree_root *root, void *item) } node = indirect_to_ptr(node); - max_index = radix_tree_maxindex(node->height); + max_index = radix_tree_maxindex(node->path & + RADIX_TREE_HEIGHT_MASK); if (cur_index > max_index) { rcu_read_unlock(); break; @@ -1337,48 +1294,90 @@ static inline void radix_tree_shrink(struct radix_tree_root *root) } /** - * radix_tree_delete - delete an item from a radix tree + * __radix_tree_delete_node - try to free node after clearing a slot * @root: radix tree root * @index: index key + * @node: node containing @index * - * Remove the item at @index from the radix tree rooted at @root. + * After clearing the slot at @index in @node from radix tree + * rooted at @root, call this function to attempt freeing the + * node and shrinking the tree. * - * Returns the address of the deleted item, or NULL if it was not present. + * Returns %true if @node was freed, %false otherwise. */ -void *radix_tree_delete(struct radix_tree_root *root, unsigned long index) +bool __radix_tree_delete_node(struct radix_tree_root *root, + struct radix_tree_node *node) { - struct radix_tree_node *node = NULL; - struct radix_tree_node *slot = NULL; - struct radix_tree_node *to_free; - unsigned int height, shift; + bool deleted = false; + + do { + struct radix_tree_node *parent; + + if (node->count) { + if (node == indirect_to_ptr(root->rnode)) { + radix_tree_shrink(root); + if (root->height == 0) + deleted = true; + } + return deleted; + } + + parent = node->parent; + if (parent) { + unsigned int offset; + + offset = node->path >> RADIX_TREE_HEIGHT_SHIFT; + parent->slots[offset] = NULL; + parent->count--; + } else { + root_tag_clear_all(root); + root->height = 0; + root->rnode = NULL; + } + + radix_tree_node_free(node); + deleted = true; + + node = parent; + } while (node); + + return deleted; +} + +/** + * radix_tree_delete_item - delete an item from a radix tree + * @root: radix tree root + * @index: index key + * @item: expected item + * + * Remove @item at @index from the radix tree rooted at @root. + * + * Returns the address of the deleted item, or NULL if it was not present + * or the entry at the given @index was not @item. + */ +void *radix_tree_delete_item(struct radix_tree_root *root, + unsigned long index, void *item) +{ + struct radix_tree_node *node; + unsigned int offset; + void **slot; + void *entry; int tag; - int uninitialized_var(offset); - height = root->height; - if (index > radix_tree_maxindex(height)) - goto out; + entry = __radix_tree_lookup(root, index, &node, &slot); + if (!entry) + return NULL; - slot = root->rnode; - if (height == 0) { + if (item && entry != item) + return NULL; + + if (!node) { root_tag_clear_all(root); root->rnode = NULL; - goto out; + return entry; } - slot = indirect_to_ptr(slot); - shift = height * RADIX_TREE_MAP_SHIFT; - do { - if (slot == NULL) - goto out; - - shift -= RADIX_TREE_MAP_SHIFT; - offset = (index >> shift) & RADIX_TREE_MAP_MASK; - node = slot; - slot = slot->slots[offset]; - } while (shift); - - if (slot == NULL) - goto out; + offset = index & RADIX_TREE_MAP_MASK; /* * Clear all tags associated with the item to be deleted. @@ -1389,40 +1388,27 @@ void *radix_tree_delete(struct radix_tree_root *root, unsigned long index) radix_tree_tag_clear(root, index, tag); } - to_free = NULL; - /* Now free the nodes we do not need anymore */ - while (node) { - node->slots[offset] = NULL; - node->count--; - /* - * Queue the node for deferred freeing after the - * last reference to it disappears (set NULL, above). - */ - if (to_free) - radix_tree_node_free(to_free); - - if (node->count) { - if (node == indirect_to_ptr(root->rnode)) - radix_tree_shrink(root); - goto out; - } + node->slots[offset] = NULL; + node->count--; - /* Node with zero slots in use so free it */ - to_free = node; + __radix_tree_delete_node(root, 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; - if (to_free) - radix_tree_node_free(to_free); + return entry; +} +EXPORT_SYMBOL(radix_tree_delete_item); -out: - return slot; +/** + * radix_tree_delete - delete an item from a radix tree + * @root: radix tree root + * @index: index key + * + * Remove the item at @index from the radix tree rooted at @root. + * + * Returns the address of the deleted item, or NULL if it was not present. + */ +void *radix_tree_delete(struct radix_tree_root *root, unsigned long index) +{ + return radix_tree_delete_item(root, index, NULL); } EXPORT_SYMBOL(radix_tree_delete); @@ -1438,9 +1424,12 @@ int radix_tree_tagged(struct radix_tree_root *root, unsigned int tag) EXPORT_SYMBOL(radix_tree_tagged); static void -radix_tree_node_ctor(void *node) +radix_tree_node_ctor(void *arg) { - memset(node, 0, sizeof(struct radix_tree_node)); + struct radix_tree_node *node = arg; + + memset(node, 0, sizeof(*node)); + INIT_LIST_HEAD(&node->private_list); } static __init unsigned long __maxindex(unsigned int height)