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lib/radix-tree.c
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/* * Copyright (C) 2001 Momchil Velikov * Portions Copyright (C) 2001 Christoph Hellwig |
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* Copyright (C) 2005 SGI, Christoph Lameter |
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* Copyright (C) 2006 Nick Piggin |
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* * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License as * published by the Free Software Foundation; either version 2, or (at * your option) any later version. * * This program is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ #include <linux/errno.h> #include <linux/init.h> #include <linux/kernel.h> #include <linux/module.h> #include <linux/radix-tree.h> #include <linux/percpu.h> #include <linux/slab.h> #include <linux/notifier.h> #include <linux/cpu.h> #include <linux/gfp.h> #include <linux/string.h> #include <linux/bitops.h> |
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#include <linux/rcupdate.h> |
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#ifdef __KERNEL__ |
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#define RADIX_TREE_MAP_SHIFT (CONFIG_BASE_SMALL ? 4 : 6) |
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#else #define RADIX_TREE_MAP_SHIFT 3 /* For more stressful testing */ #endif |
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#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 { |
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unsigned int height; /* Height from the bottom */ |
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unsigned int count; |
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struct rcu_head rcu_head; |
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void *slots[RADIX_TREE_MAP_SIZE]; |
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unsigned long tags[RADIX_TREE_MAX_TAGS][RADIX_TREE_TAG_LONGS]; |
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}; struct radix_tree_path { |
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struct radix_tree_node *node; |
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int offset; }; #define RADIX_TREE_INDEX_BITS (8 /* CHAR_BIT */ * sizeof(unsigned long)) |
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#define RADIX_TREE_MAX_PATH (DIV_ROUND_UP(RADIX_TREE_INDEX_BITS, \ RADIX_TREE_MAP_SHIFT)) |
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/* * The height_to_maxindex array needs to be one deeper than the maximum * path as height 0 holds only 1 entry. */ static unsigned long height_to_maxindex[RADIX_TREE_MAX_PATH + 1] __read_mostly; |
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/* * Radix tree node cache. */ |
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static struct kmem_cache *radix_tree_node_cachep; |
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/* * Per-cpu pool of preloaded nodes */ struct radix_tree_preload { int nr; struct radix_tree_node *nodes[RADIX_TREE_MAX_PATH]; }; |
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static DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { 0, }; |
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static inline gfp_t root_gfp_mask(struct radix_tree_root *root) { return root->gfp_mask & __GFP_BITS_MASK; } |
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static inline void tag_set(struct radix_tree_node *node, unsigned int tag, int offset) { __set_bit(offset, node->tags[tag]); } static inline void tag_clear(struct radix_tree_node *node, unsigned int tag, int offset) { __clear_bit(offset, node->tags[tag]); } static inline int tag_get(struct radix_tree_node *node, unsigned int tag, int offset) { return test_bit(offset, node->tags[tag]); } static inline void root_tag_set(struct radix_tree_root *root, unsigned int tag) { root->gfp_mask |= (__force gfp_t)(1 << (tag + __GFP_BITS_SHIFT)); } static inline void root_tag_clear(struct radix_tree_root *root, unsigned int tag) { root->gfp_mask &= (__force gfp_t)~(1 << (tag + __GFP_BITS_SHIFT)); } static inline void root_tag_clear_all(struct radix_tree_root *root) { root->gfp_mask &= __GFP_BITS_MASK; } static inline int root_tag_get(struct radix_tree_root *root, unsigned int tag) { return (__force unsigned)root->gfp_mask & (1 << (tag + __GFP_BITS_SHIFT)); } /* * Returns 1 if any slot in the node has this tag set. * Otherwise returns 0. */ static inline int any_tag_set(struct radix_tree_node *node, unsigned int tag) { int idx; for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) { if (node->tags[tag][idx]) return 1; } return 0; } |
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/* * This assumes that the caller has performed appropriate preallocation, and * that the caller has pinned this thread of control to the current CPU. */ static struct radix_tree_node * radix_tree_node_alloc(struct radix_tree_root *root) { |
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struct radix_tree_node *ret = NULL; |
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gfp_t gfp_mask = root_gfp_mask(root); |
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if (!(gfp_mask & __GFP_WAIT)) { |
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struct radix_tree_preload *rtp; |
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/* * Provided the caller has preloaded here, we will always * succeed in getting a node here (and never reach * kmem_cache_alloc) */ |
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rtp = &__get_cpu_var(radix_tree_preloads); if (rtp->nr) { ret = rtp->nodes[rtp->nr - 1]; rtp->nodes[rtp->nr - 1] = NULL; rtp->nr--; } } |
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if (ret == NULL) |
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ret = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask); |
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BUG_ON(radix_tree_is_indirect_ptr(ret)); |
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return ret; } |
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static void radix_tree_node_rcu_free(struct rcu_head *head) { struct radix_tree_node *node = container_of(head, struct radix_tree_node, rcu_head); |
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/* * must only free zeroed nodes into the slab. radix_tree_shrink * can leave us with a non-NULL entry in the first slot, so clear * that here to make sure. */ tag_clear(node, 0, 0); tag_clear(node, 1, 0); node->slots[0] = NULL; node->count = 0; |
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kmem_cache_free(radix_tree_node_cachep, node); } |
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static inline void radix_tree_node_free(struct radix_tree_node *node) { |
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call_rcu(&node->rcu_head, radix_tree_node_rcu_free); |
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} /* * Load up this CPU's radix_tree_node buffer with sufficient objects to * ensure that the addition of a single element in the tree cannot fail. On * success, return zero, with preemption disabled. On error, return -ENOMEM * with preemption not disabled. */ |
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int radix_tree_preload(gfp_t gfp_mask) |
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{ struct radix_tree_preload *rtp; struct radix_tree_node *node; int ret = -ENOMEM; preempt_disable(); rtp = &__get_cpu_var(radix_tree_preloads); while (rtp->nr < ARRAY_SIZE(rtp->nodes)) { preempt_enable(); |
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node = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask); |
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if (node == NULL) goto out; preempt_disable(); rtp = &__get_cpu_var(radix_tree_preloads); if (rtp->nr < ARRAY_SIZE(rtp->nodes)) rtp->nodes[rtp->nr++] = node; else kmem_cache_free(radix_tree_node_cachep, node); } ret = 0; out: return ret; } |
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EXPORT_SYMBOL(radix_tree_preload); |
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/* |
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* Return the maximum key which can be store into a * radix tree with height HEIGHT. */ static inline unsigned long radix_tree_maxindex(unsigned int height) { return height_to_maxindex[height]; } /* * Extend a radix tree so it can store key @index. */ static int radix_tree_extend(struct radix_tree_root *root, unsigned long index) { struct radix_tree_node *node; unsigned int height; |
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int tag; /* Figure out what the height should be. */ height = root->height + 1; while (index > radix_tree_maxindex(height)) height++; if (root->rnode == NULL) { root->height = height; goto out; } |
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do { |
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unsigned int newheight; |
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if (!(node = radix_tree_node_alloc(root))) return -ENOMEM; /* Increase the height. */ |
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node->slots[0] = radix_tree_indirect_to_ptr(root->rnode); |
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/* Propagate the aggregated tag info into the new root */ |
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for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) { |
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if (root_tag_get(root, tag)) |
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tag_set(node, tag, 0); } |
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newheight = root->height+1; node->height = newheight; |
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node->count = 1; |
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node = radix_tree_ptr_to_indirect(node); |
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rcu_assign_pointer(root->rnode, node); root->height = newheight; |
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} while (height > root->height); out: 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) { |
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struct radix_tree_node *node = NULL, *slot; |
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unsigned int height, shift; int offset; int error; |
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BUG_ON(radix_tree_is_indirect_ptr(item)); |
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/* Make sure the tree is high enough. */ |
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if (index > radix_tree_maxindex(root->height)) { |
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error = radix_tree_extend(root, index); if (error) return error; } |
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slot = radix_tree_indirect_to_ptr(root->rnode); |
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height = root->height; shift = (height-1) * RADIX_TREE_MAP_SHIFT; offset = 0; /* uninitialised var warning */ |
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while (height > 0) { |
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if (slot == NULL) { |
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/* Have to add a child node. */ |
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if (!(slot = radix_tree_node_alloc(root))) |
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return -ENOMEM; |
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slot->height = height; |
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if (node) { |
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rcu_assign_pointer(node->slots[offset], slot); |
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node->count++; |
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} else |
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rcu_assign_pointer(root->rnode, radix_tree_ptr_to_indirect(slot)); |
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} /* Go a level down */ offset = (index >> shift) & RADIX_TREE_MAP_MASK; |
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node = slot; slot = node->slots[offset]; |
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shift -= RADIX_TREE_MAP_SHIFT; height--; |
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} |
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if (slot != NULL) |
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return -EEXIST; |
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if (node) { node->count++; |
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rcu_assign_pointer(node->slots[offset], item); |
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BUG_ON(tag_get(node, 0, offset)); BUG_ON(tag_get(node, 1, offset)); } else { |
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rcu_assign_pointer(root->rnode, item); |
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BUG_ON(root_tag_get(root, 0)); BUG_ON(root_tag_get(root, 1)); } |
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return 0; } EXPORT_SYMBOL(radix_tree_insert); |
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/** * radix_tree_lookup_slot - lookup a slot in a radix tree * @root: radix tree root * @index: index key * * Returns: the slot corresponding to the position @index in the * radix tree @root. This is useful for update-if-exists operations. * |
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* This function can be called under rcu_read_lock iff the slot is not * modified by radix_tree_replace_slot, otherwise it must be called * exclusive from other writers. Any dereference of the slot must be done * using radix_tree_deref_slot. |
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*/ void **radix_tree_lookup_slot(struct radix_tree_root *root, unsigned long index) |
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{ unsigned int height, shift; |
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struct radix_tree_node *node, **slot; |
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node = rcu_dereference(root->rnode); |
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if (node == NULL) |
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return NULL; |
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if (!radix_tree_is_indirect_ptr(node)) { |
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if (index > 0) return NULL; |
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return (void **)&root->rnode; |
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} |
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node = radix_tree_indirect_to_ptr(node); |
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height = node->height; if (index > radix_tree_maxindex(height)) return NULL; |
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shift = (height-1) * RADIX_TREE_MAP_SHIFT; |
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do { slot = (struct radix_tree_node **) (node->slots + ((index>>shift) & RADIX_TREE_MAP_MASK)); |
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node = rcu_dereference(*slot); |
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if (node == NULL) |
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return NULL; |
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shift -= RADIX_TREE_MAP_SHIFT; height--; |
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} while (height > 0); |
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return (void **)slot; } |
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EXPORT_SYMBOL(radix_tree_lookup_slot); /** * radix_tree_lookup - perform lookup operation on a radix tree * @root: radix tree root * @index: index key * * Lookup the item at the position @index in the radix tree @root. |
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* * This function can be called under rcu_read_lock, however the caller * must manage lifetimes of leaf nodes (eg. RCU may also be used to free * them safely). No RCU barriers are required to access or modify the * returned item, however. |
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*/ void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index) { |
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unsigned int height, shift; struct radix_tree_node *node, **slot; node = rcu_dereference(root->rnode); if (node == NULL) return NULL; |
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if (!radix_tree_is_indirect_ptr(node)) { |
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if (index > 0) return NULL; |
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return node; |
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} |
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node = radix_tree_indirect_to_ptr(node); |
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height = node->height; if (index > radix_tree_maxindex(height)) return NULL; shift = (height-1) * RADIX_TREE_MAP_SHIFT; |
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do { slot = (struct radix_tree_node **) (node->slots + ((index>>shift) & RADIX_TREE_MAP_MASK)); node = rcu_dereference(*slot); if (node == NULL) return NULL; shift -= RADIX_TREE_MAP_SHIFT; height--; } while (height > 0); return node; |
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} EXPORT_SYMBOL(radix_tree_lookup); /** * radix_tree_tag_set - set a tag on a radix tree node * @root: radix tree root * @index: index key * @tag: tag index * |
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* Set the search tag (which must be < RADIX_TREE_MAX_TAGS) * corresponding to @index in the radix tree. From |
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* the root all the way down to the leaf node. * * Returns the address of the tagged item. Setting a tag on a not-present * item is a bug. */ void *radix_tree_tag_set(struct radix_tree_root *root, |
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unsigned long index, unsigned int tag) |
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{ unsigned int height, shift; |
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struct radix_tree_node *slot; |
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height = root->height; |
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BUG_ON(index > radix_tree_maxindex(height)); |
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slot = radix_tree_indirect_to_ptr(root->rnode); |
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shift = (height - 1) * RADIX_TREE_MAP_SHIFT; |
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while (height > 0) { int offset; offset = (index >> shift) & RADIX_TREE_MAP_MASK; |
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if (!tag_get(slot, tag, offset)) tag_set(slot, tag, offset); |
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slot = slot->slots[offset]; BUG_ON(slot == NULL); |
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shift -= RADIX_TREE_MAP_SHIFT; height--; } |
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/* set the root's tag bit */ if (slot && !root_tag_get(root, tag)) root_tag_set(root, tag); |
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return slot; |
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} EXPORT_SYMBOL(radix_tree_tag_set); /** * radix_tree_tag_clear - clear a tag on a radix tree node * @root: radix tree root * @index: index key * @tag: tag index * |
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* Clear the search tag (which must be < RADIX_TREE_MAX_TAGS) * corresponding to @index in the radix tree. If |
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* this causes the leaf node to have no tags set then clear the tag in the * next-to-leaf node, etc. * * Returns the address of the tagged item on success, else NULL. ie: * has the same return value and semantics as radix_tree_lookup(). */ void *radix_tree_tag_clear(struct radix_tree_root *root, |
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unsigned long index, unsigned int tag) |
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{ |
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/* * 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; |
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struct radix_tree_node *slot = NULL; |
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unsigned int height, shift; |
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height = root->height; if (index > radix_tree_maxindex(height)) goto out; shift = (height - 1) * RADIX_TREE_MAP_SHIFT; pathp->node = NULL; |
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slot = radix_tree_indirect_to_ptr(root->rnode); |
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while (height > 0) { int offset; |
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if (slot == NULL) |
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goto out; offset = (index >> shift) & RADIX_TREE_MAP_MASK; pathp[1].offset = offset; |
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pathp[1].node = slot; slot = slot->slots[offset]; |
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pathp++; shift -= RADIX_TREE_MAP_SHIFT; height--; } |
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if (slot == NULL) |
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goto out; |
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while (pathp->node) { |
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if (!tag_get(pathp->node, tag, pathp->offset)) goto out; |
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tag_clear(pathp->node, tag, pathp->offset); |
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if (any_tag_set(pathp->node, tag)) goto out; |
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pathp--; |
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} /* clear the root's tag bit */ if (root_tag_get(root, tag)) root_tag_clear(root, tag); |
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out: |
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return slot; |
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} EXPORT_SYMBOL(radix_tree_tag_clear); #ifndef __KERNEL__ /* Only the test harness uses this at present */ /** |
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* radix_tree_tag_get - get a tag on a radix tree node * @root: radix tree root * @index: index key |
daff89f32
|
552 |
* @tag: tag index (< RADIX_TREE_MAX_TAGS) |
1da177e4c
|
553 |
* |
32605a181
|
554 |
* Return values: |
1da177e4c
|
555 |
* |
612d6c19d
|
556 557 |
* 0: tag not present or not set * 1: tag set |
1da177e4c
|
558 559 |
*/ int radix_tree_tag_get(struct radix_tree_root *root, |
daff89f32
|
560 |
unsigned long index, unsigned int tag) |
1da177e4c
|
561 562 |
{ unsigned int height, shift; |
7cf9c2c76
|
563 |
struct radix_tree_node *node; |
1da177e4c
|
564 |
int saw_unset_tag = 0; |
612d6c19d
|
565 566 567 |
/* check the root's tag bit */ if (!root_tag_get(root, tag)) return 0; |
7cf9c2c76
|
568 569 570 |
node = rcu_dereference(root->rnode); if (node == NULL) return 0; |
c0bc9875b
|
571 |
if (!radix_tree_is_indirect_ptr(node)) |
7cf9c2c76
|
572 |
return (index == 0); |
c0bc9875b
|
573 |
node = radix_tree_indirect_to_ptr(node); |
7cf9c2c76
|
574 575 576 577 |
height = node->height; if (index > radix_tree_maxindex(height)) return 0; |
612d6c19d
|
578 |
|
1da177e4c
|
579 |
shift = (height - 1) * RADIX_TREE_MAP_SHIFT; |
1da177e4c
|
580 581 582 |
for ( ; ; ) { int offset; |
7cf9c2c76
|
583 |
if (node == NULL) |
1da177e4c
|
584 585 586 587 588 589 590 591 |
return 0; offset = (index >> shift) & RADIX_TREE_MAP_MASK; /* * This is just a debug check. Later, we can bale as soon as * we see an unset tag. */ |
7cf9c2c76
|
592 |
if (!tag_get(node, tag, offset)) |
1da177e4c
|
593 594 |
saw_unset_tag = 1; if (height == 1) { |
7cf9c2c76
|
595 |
int ret = tag_get(node, tag, offset); |
1da177e4c
|
596 597 |
BUG_ON(ret && saw_unset_tag); |
e5dcd90b5
|
598 |
return !!ret; |
1da177e4c
|
599 |
} |
7cf9c2c76
|
600 |
node = rcu_dereference(node->slots[offset]); |
1da177e4c
|
601 602 603 604 605 606 |
shift -= RADIX_TREE_MAP_SHIFT; height--; } } EXPORT_SYMBOL(radix_tree_tag_get); #endif |
6df8ba4f8
|
607 608 609 610 611 612 613 614 615 616 617 |
/** * 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' |
8e6bdb7f8
|
618 |
* will be true). In rare cases of index wrap-around, 0 will be returned. |
6df8ba4f8
|
619 620 |
* * radix_tree_next_hole may be called under rcu_read_lock. However, like |
8e6bdb7f8
|
621 622 623 624 625 |
* 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. |
6df8ba4f8
|
626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 |
*/ 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); |
1da177e4c
|
643 |
static unsigned int |
47feff2c8
|
644 |
__lookup(struct radix_tree_node *slot, void ***results, unsigned long index, |
1da177e4c
|
645 646 647 |
unsigned int max_items, unsigned long *next_index) { unsigned int nr_found = 0; |
201b6264f
|
648 |
unsigned int shift, height; |
201b6264f
|
649 |
unsigned long i; |
7cf9c2c76
|
650 651 |
height = slot->height; if (height == 0) |
201b6264f
|
652 |
goto out; |
1da177e4c
|
653 |
shift = (height-1) * RADIX_TREE_MAP_SHIFT; |
1da177e4c
|
654 |
|
201b6264f
|
655 |
for ( ; height > 1; height--) { |
7cf9c2c76
|
656 657 |
i = (index >> shift) & RADIX_TREE_MAP_MASK; for (;;) { |
1da177e4c
|
658 659 660 661 662 663 |
if (slot->slots[i] != NULL) break; index &= ~((1UL << shift) - 1); index += 1UL << shift; if (index == 0) goto out; /* 32-bit wraparound */ |
7cf9c2c76
|
664 665 666 |
i++; if (i == RADIX_TREE_MAP_SIZE) goto out; |
1da177e4c
|
667 |
} |
1da177e4c
|
668 |
|
1da177e4c
|
669 |
shift -= RADIX_TREE_MAP_SHIFT; |
7cf9c2c76
|
670 671 672 |
slot = rcu_dereference(slot->slots[i]); if (slot == NULL) goto out; |
1da177e4c
|
673 |
} |
201b6264f
|
674 675 676 677 |
/* Bottom level: grab some items */ for (i = index & RADIX_TREE_MAP_MASK; i < RADIX_TREE_MAP_SIZE; i++) { index++; |
47feff2c8
|
678 679 |
if (slot->slots[i]) { results[nr_found++] = &(slot->slots[i]); |
201b6264f
|
680 681 682 683 |
if (nr_found == max_items) goto out; } } |
1da177e4c
|
684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 |
out: *next_index = index; return nr_found; } /** * radix_tree_gang_lookup - perform multiple lookup on a radix tree * @root: radix tree root * @results: where the results of the lookup are placed * @first_index: start the lookup from this key * @max_items: place up to this many items at *results * * Performs an index-ascending scan of the tree for present items. Places * them at *@results and returns the number of items which were placed at * *@results. * * The implementation is naive. |
7cf9c2c76
|
701 702 703 704 705 706 |
* * Like radix_tree_lookup, radix_tree_gang_lookup may be called under * rcu_read_lock. In this case, rather than the returned results being * an atomic snapshot of the tree at a single point in time, the semantics * of an RCU protected gang lookup are as though multiple radix_tree_lookups * have been issued in individual locks, and results stored in 'results'. |
1da177e4c
|
707 708 709 710 711 |
*/ unsigned int radix_tree_gang_lookup(struct radix_tree_root *root, void **results, unsigned long first_index, unsigned int max_items) { |
7cf9c2c76
|
712 713 |
unsigned long max_index; struct radix_tree_node *node; |
1da177e4c
|
714 |
unsigned long cur_index = first_index; |
7cf9c2c76
|
715 716 717 718 719 |
unsigned int ret; node = rcu_dereference(root->rnode); if (!node) return 0; |
1da177e4c
|
720 |
|
c0bc9875b
|
721 |
if (!radix_tree_is_indirect_ptr(node)) { |
7cf9c2c76
|
722 723 |
if (first_index > 0) return 0; |
c0bc9875b
|
724 |
results[0] = node; |
7cf9c2c76
|
725 726 |
return 1; } |
c0bc9875b
|
727 |
node = radix_tree_indirect_to_ptr(node); |
7cf9c2c76
|
728 729 730 731 |
max_index = radix_tree_maxindex(node->height); ret = 0; |
1da177e4c
|
732 |
while (ret < max_items) { |
47feff2c8
|
733 |
unsigned int nr_found, slots_found, i; |
1da177e4c
|
734 735 736 737 |
unsigned long next_index; /* Index of next search */ if (cur_index > max_index) break; |
47feff2c8
|
738 |
slots_found = __lookup(node, (void ***)results + ret, cur_index, |
1da177e4c
|
739 |
max_items - ret, &next_index); |
47feff2c8
|
740 741 742 743 744 745 746 747 748 |
nr_found = 0; for (i = 0; i < slots_found; i++) { struct radix_tree_node *slot; slot = *(((void ***)results)[ret + i]); if (!slot) continue; results[ret + nr_found] = rcu_dereference(slot); nr_found++; } |
1da177e4c
|
749 750 751 752 753 |
ret += nr_found; if (next_index == 0) break; cur_index = next_index; } |
7cf9c2c76
|
754 |
|
1da177e4c
|
755 756 757 |
return ret; } EXPORT_SYMBOL(radix_tree_gang_lookup); |
47feff2c8
|
758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 |
/** * radix_tree_gang_lookup_slot - perform multiple slot lookup on radix tree * @root: radix tree root * @results: where the results of the lookup are placed * @first_index: start the lookup from this key * @max_items: place up to this many items at *results * * Performs an index-ascending scan of the tree for present items. Places * their slots at *@results and returns the number of items which were * placed at *@results. * * The implementation is naive. * * Like radix_tree_gang_lookup as far as RCU and locking goes. Slots must * be dereferenced with radix_tree_deref_slot, and if using only RCU * protection, radix_tree_deref_slot may fail requiring a retry. */ unsigned int radix_tree_gang_lookup_slot(struct radix_tree_root *root, void ***results, unsigned long first_index, unsigned int max_items) { unsigned long max_index; struct radix_tree_node *node; unsigned long cur_index = first_index; unsigned int ret; node = rcu_dereference(root->rnode); if (!node) return 0; if (!radix_tree_is_indirect_ptr(node)) { if (first_index > 0) return 0; results[0] = (void **)&root->rnode; return 1; } node = radix_tree_indirect_to_ptr(node); max_index = radix_tree_maxindex(node->height); ret = 0; while (ret < max_items) { unsigned int slots_found; unsigned long next_index; /* Index of next search */ if (cur_index > max_index) break; slots_found = __lookup(node, results + ret, cur_index, max_items - ret, &next_index); ret += slots_found; if (next_index == 0) break; cur_index = next_index; } return ret; } EXPORT_SYMBOL(radix_tree_gang_lookup_slot); |
1da177e4c
|
816 817 818 819 820 |
/* * FIXME: the two tag_get()s here should use find_next_bit() instead of * open-coding the search. */ static unsigned int |
47feff2c8
|
821 |
__lookup_tag(struct radix_tree_node *slot, void ***results, unsigned long index, |
daff89f32
|
822 |
unsigned int max_items, unsigned long *next_index, unsigned int tag) |
1da177e4c
|
823 824 |
{ unsigned int nr_found = 0; |
7cf9c2c76
|
825 |
unsigned int shift, height; |
1da177e4c
|
826 |
|
7cf9c2c76
|
827 828 |
height = slot->height; if (height == 0) |
612d6c19d
|
829 |
goto out; |
7cf9c2c76
|
830 |
shift = (height-1) * RADIX_TREE_MAP_SHIFT; |
1da177e4c
|
831 |
|
7cf9c2c76
|
832 833 |
while (height > 0) { unsigned long i = (index >> shift) & RADIX_TREE_MAP_MASK ; |
1da177e4c
|
834 |
|
7cf9c2c76
|
835 836 |
for (;;) { if (tag_get(slot, tag, i)) |
1da177e4c
|
837 |
break; |
1da177e4c
|
838 839 840 841 |
index &= ~((1UL << shift) - 1); index += 1UL << shift; if (index == 0) goto out; /* 32-bit wraparound */ |
7cf9c2c76
|
842 843 844 |
i++; if (i == RADIX_TREE_MAP_SIZE) goto out; |
1da177e4c
|
845 |
} |
1da177e4c
|
846 847 848 849 850 851 |
height--; if (height == 0) { /* Bottom level: grab some items */ unsigned long j = index & RADIX_TREE_MAP_MASK; for ( ; j < RADIX_TREE_MAP_SIZE; j++) { index++; |
7cf9c2c76
|
852 853 |
if (!tag_get(slot, tag, j)) continue; |
7cf9c2c76
|
854 855 856 857 858 859 860 861 862 863 |
/* * Even though the tag was found set, we need to * recheck that we have a non-NULL node, because * if this lookup is lockless, it may have been * subsequently deleted. * * Similar care must be taken in any place that * lookup ->slots[x] without a lock (ie. can't * rely on its value remaining the same). */ |
47feff2c8
|
864 865 |
if (slot->slots[j]) { results[nr_found++] = &(slot->slots[j]); |
1da177e4c
|
866 867 868 869 870 871 |
if (nr_found == max_items) goto out; } } } shift -= RADIX_TREE_MAP_SHIFT; |
7cf9c2c76
|
872 873 874 875 |
slot = rcu_dereference(slot->slots[i]); if (slot == NULL) break; } |
1da177e4c
|
876 877 878 879 880 881 882 883 884 885 886 887 |
out: *next_index = index; return nr_found; } /** * radix_tree_gang_lookup_tag - perform multiple lookup on a radix tree * based on a tag * @root: radix tree root * @results: where the results of the lookup are placed * @first_index: start the lookup from this key * @max_items: place up to this many items at *results |
daff89f32
|
888 |
* @tag: the tag index (< RADIX_TREE_MAX_TAGS) |
1da177e4c
|
889 890 891 892 893 894 895 |
* * Performs an index-ascending scan of the tree for present items which * have the tag indexed by @tag set. Places the items at *@results and * returns the number of items which were placed at *@results. */ unsigned int radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results, |
daff89f32
|
896 897 |
unsigned long first_index, unsigned int max_items, unsigned int tag) |
1da177e4c
|
898 |
{ |
7cf9c2c76
|
899 900 |
struct radix_tree_node *node; unsigned long max_index; |
1da177e4c
|
901 |
unsigned long cur_index = first_index; |
7cf9c2c76
|
902 |
unsigned int ret; |
1da177e4c
|
903 |
|
612d6c19d
|
904 905 906 |
/* check the root's tag bit */ if (!root_tag_get(root, tag)) return 0; |
7cf9c2c76
|
907 908 909 |
node = rcu_dereference(root->rnode); if (!node) return 0; |
c0bc9875b
|
910 |
if (!radix_tree_is_indirect_ptr(node)) { |
7cf9c2c76
|
911 912 |
if (first_index > 0) return 0; |
c0bc9875b
|
913 |
results[0] = node; |
7cf9c2c76
|
914 915 |
return 1; } |
c0bc9875b
|
916 |
node = radix_tree_indirect_to_ptr(node); |
7cf9c2c76
|
917 918 919 920 |
max_index = radix_tree_maxindex(node->height); ret = 0; |
1da177e4c
|
921 |
while (ret < max_items) { |
47feff2c8
|
922 |
unsigned int nr_found, slots_found, i; |
1da177e4c
|
923 924 925 926 |
unsigned long next_index; /* Index of next search */ if (cur_index > max_index) break; |
47feff2c8
|
927 928 929 930 931 932 933 934 935 936 937 |
slots_found = __lookup_tag(node, (void ***)results + ret, cur_index, max_items - ret, &next_index, tag); nr_found = 0; for (i = 0; i < slots_found; i++) { struct radix_tree_node *slot; slot = *(((void ***)results)[ret + i]); if (!slot) continue; results[ret + nr_found] = rcu_dereference(slot); nr_found++; } |
1da177e4c
|
938 939 940 941 942 |
ret += nr_found; if (next_index == 0) break; cur_index = next_index; } |
7cf9c2c76
|
943 |
|
1da177e4c
|
944 945 946 947 948 |
return ret; } EXPORT_SYMBOL(radix_tree_gang_lookup_tag); /** |
47feff2c8
|
949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 |
* radix_tree_gang_lookup_tag_slot - perform multiple slot lookup on a * radix tree based on a tag * @root: radix tree root * @results: where the results of the lookup are placed * @first_index: start the lookup from this key * @max_items: place up to this many items at *results * @tag: the tag index (< RADIX_TREE_MAX_TAGS) * * Performs an index-ascending scan of the tree for present items which * have the tag indexed by @tag set. Places the slots at *@results and * returns the number of slots which were placed at *@results. */ unsigned int radix_tree_gang_lookup_tag_slot(struct radix_tree_root *root, void ***results, unsigned long first_index, unsigned int max_items, unsigned int tag) { struct radix_tree_node *node; unsigned long max_index; unsigned long cur_index = first_index; unsigned int ret; /* check the root's tag bit */ if (!root_tag_get(root, tag)) return 0; node = rcu_dereference(root->rnode); if (!node) return 0; if (!radix_tree_is_indirect_ptr(node)) { if (first_index > 0) return 0; results[0] = (void **)&root->rnode; return 1; } node = radix_tree_indirect_to_ptr(node); max_index = radix_tree_maxindex(node->height); ret = 0; while (ret < max_items) { unsigned int slots_found; unsigned long next_index; /* Index of next search */ if (cur_index > max_index) break; slots_found = __lookup_tag(node, results + ret, cur_index, max_items - ret, &next_index, tag); ret += slots_found; if (next_index == 0) break; cur_index = next_index; } return ret; } EXPORT_SYMBOL(radix_tree_gang_lookup_tag_slot); /** |
a5f51c966
|
1010 1011 1012 1013 1014 1015 |
* radix_tree_shrink - shrink height of a radix tree to minimal * @root radix tree root */ static inline void radix_tree_shrink(struct radix_tree_root *root) { /* try to shrink tree height */ |
c0bc9875b
|
1016 |
while (root->height > 0) { |
a5f51c966
|
1017 |
struct radix_tree_node *to_free = root->rnode; |
7cf9c2c76
|
1018 |
void *newptr; |
a5f51c966
|
1019 |
|
c0bc9875b
|
1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 |
BUG_ON(!radix_tree_is_indirect_ptr(to_free)); to_free = radix_tree_indirect_to_ptr(to_free); /* * The candidate node has more than one child, or its child * is not at the leftmost slot, we cannot shrink. */ if (to_free->count != 1) break; if (!to_free->slots[0]) break; |
7cf9c2c76
|
1031 1032 1033 1034 1035 1036 1037 1038 |
/* * We don't need rcu_assign_pointer(), since we are simply * moving the node from one part of the tree to another. If * it was safe to dereference the old pointer to it * (to_free->slots[0]), it will be safe to dereference the new * one (root->rnode). */ newptr = to_free->slots[0]; |
c0bc9875b
|
1039 1040 |
if (root->height > 1) newptr = radix_tree_ptr_to_indirect(newptr); |
7cf9c2c76
|
1041 |
root->rnode = newptr; |
a5f51c966
|
1042 |
root->height--; |
a5f51c966
|
1043 1044 1045 1046 1047 |
radix_tree_node_free(to_free); } } /** |
1da177e4c
|
1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 |
* 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) { |
26fb1589c
|
1058 1059 1060 1061 1062 |
/* * 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; |
612d6c19d
|
1063 |
struct radix_tree_node *slot = NULL; |
7cf9c2c76
|
1064 |
struct radix_tree_node *to_free; |
1da177e4c
|
1065 |
unsigned int height, shift; |
d5274261e
|
1066 1067 |
int tag; int offset; |
1da177e4c
|
1068 1069 1070 1071 |
height = root->height; if (index > radix_tree_maxindex(height)) goto out; |
612d6c19d
|
1072 |
slot = root->rnode; |
c0bc9875b
|
1073 |
if (height == 0) { |
612d6c19d
|
1074 1075 1076 1077 |
root_tag_clear_all(root); root->rnode = NULL; goto out; } |
c0bc9875b
|
1078 |
slot = radix_tree_indirect_to_ptr(slot); |
612d6c19d
|
1079 |
|
1da177e4c
|
1080 1081 |
shift = (height - 1) * RADIX_TREE_MAP_SHIFT; pathp->node = NULL; |
1da177e4c
|
1082 |
|
612d6c19d
|
1083 |
do { |
201b6264f
|
1084 |
if (slot == NULL) |
1da177e4c
|
1085 |
goto out; |
d5274261e
|
1086 |
pathp++; |
1da177e4c
|
1087 |
offset = (index >> shift) & RADIX_TREE_MAP_MASK; |
d5274261e
|
1088 1089 |
pathp->offset = offset; pathp->node = slot; |
201b6264f
|
1090 |
slot = slot->slots[offset]; |
1da177e4c
|
1091 |
shift -= RADIX_TREE_MAP_SHIFT; |
612d6c19d
|
1092 1093 |
height--; } while (height > 0); |
1da177e4c
|
1094 |
|
612d6c19d
|
1095 |
if (slot == NULL) |
1da177e4c
|
1096 |
goto out; |
1da177e4c
|
1097 1098 1099 |
/* * Clear all tags associated with the just-deleted item */ |
daff89f32
|
1100 |
for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) { |
612d6c19d
|
1101 1102 |
if (tag_get(pathp->node, tag, pathp->offset)) radix_tree_tag_clear(root, index, tag); |
d5274261e
|
1103 |
} |
1da177e4c
|
1104 |
|
7cf9c2c76
|
1105 |
to_free = NULL; |
201b6264f
|
1106 |
/* Now free the nodes we do not need anymore */ |
612d6c19d
|
1107 |
while (pathp->node) { |
201b6264f
|
1108 |
pathp->node->slots[pathp->offset] = NULL; |
a5f51c966
|
1109 |
pathp->node->count--; |
7cf9c2c76
|
1110 1111 1112 1113 1114 1115 |
/* * 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); |
a5f51c966
|
1116 1117 |
if (pathp->node->count) { |
c0bc9875b
|
1118 1119 |
if (pathp->node == radix_tree_indirect_to_ptr(root->rnode)) |
a5f51c966
|
1120 |
radix_tree_shrink(root); |
201b6264f
|
1121 |
goto out; |
a5f51c966
|
1122 |
} |
201b6264f
|
1123 1124 |
/* Node with zero slots in use so free it */ |
7cf9c2c76
|
1125 |
to_free = pathp->node; |
612d6c19d
|
1126 |
pathp--; |
7cf9c2c76
|
1127 |
|
1da177e4c
|
1128 |
} |
612d6c19d
|
1129 |
root_tag_clear_all(root); |
201b6264f
|
1130 |
root->height = 0; |
612d6c19d
|
1131 |
root->rnode = NULL; |
7cf9c2c76
|
1132 1133 |
if (to_free) radix_tree_node_free(to_free); |
612d6c19d
|
1134 |
|
1da177e4c
|
1135 |
out: |
612d6c19d
|
1136 |
return slot; |
1da177e4c
|
1137 1138 1139 1140 1141 1142 1143 1144 |
} EXPORT_SYMBOL(radix_tree_delete); /** * radix_tree_tagged - test whether any items in the tree are tagged * @root: radix tree root * @tag: tag to test */ |
daff89f32
|
1145 |
int radix_tree_tagged(struct radix_tree_root *root, unsigned int tag) |
1da177e4c
|
1146 |
{ |
612d6c19d
|
1147 |
return root_tag_get(root, tag); |
1da177e4c
|
1148 1149 1150 1151 |
} EXPORT_SYMBOL(radix_tree_tagged); static void |
51cc50685
|
1152 |
radix_tree_node_ctor(void *node) |
1da177e4c
|
1153 1154 1155 1156 1157 1158 |
{ memset(node, 0, sizeof(struct radix_tree_node)); } static __init unsigned long __maxindex(unsigned int height) { |
430d275a3
|
1159 1160 1161 1162 1163 1164 1165 1166 |
unsigned int width = height * RADIX_TREE_MAP_SHIFT; int shift = RADIX_TREE_INDEX_BITS - width; if (shift < 0) return ~0UL; if (shift >= BITS_PER_LONG) return 0UL; return ~0UL >> shift; |
1da177e4c
|
1167 1168 1169 1170 1171 1172 1173 1174 1175 |
} static __init void radix_tree_init_maxindex(void) { unsigned int i; for (i = 0; i < ARRAY_SIZE(height_to_maxindex); i++) height_to_maxindex[i] = __maxindex(i); } |
1da177e4c
|
1176 1177 1178 1179 1180 1181 1182 1183 |
static int radix_tree_callback(struct notifier_block *nfb, unsigned long action, void *hcpu) { int cpu = (long)hcpu; struct radix_tree_preload *rtp; /* Free per-cpu pool of perloaded nodes */ |
8bb784428
|
1184 |
if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) { |
1da177e4c
|
1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 |
rtp = &per_cpu(radix_tree_preloads, cpu); while (rtp->nr) { kmem_cache_free(radix_tree_node_cachep, rtp->nodes[rtp->nr-1]); rtp->nodes[rtp->nr-1] = NULL; rtp->nr--; } } return NOTIFY_OK; } |
1da177e4c
|
1195 1196 1197 1198 1199 |
void __init radix_tree_init(void) { radix_tree_node_cachep = kmem_cache_create("radix_tree_node", sizeof(struct radix_tree_node), 0, |
488514d17
|
1200 1201 |
SLAB_PANIC | SLAB_RECLAIM_ACCOUNT, radix_tree_node_ctor); |
1da177e4c
|
1202 1203 1204 |
radix_tree_init_maxindex(); hotcpu_notifier(radix_tree_callback, 0); } |