/* * Copyright (C) 2001 Momchil Velikov * Portions Copyright (C) 2001 Christoph Hellwig * Copyright (C) 2005 SGI, Christoph Lameter * Copyright (C) 2006 Nick Piggin * * 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> #include <linux/rcupdate.h> #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; struct rcu_head rcu_head; void *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)) /* * 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; /* * Radix tree node cache. */ static struct kmem_cache *radix_tree_node_cachep; /* * Per-cpu pool of preloaded nodes */ struct radix_tree_preload { int nr; struct radix_tree_node *nodes[RADIX_TREE_MAX_PATH]; }; static DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { 0, }; static inline gfp_t root_gfp_mask(struct radix_tree_root *root) { return root->gfp_mask & __GFP_BITS_MASK; } 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; } /* * 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) { struct radix_tree_node *ret = NULL; gfp_t gfp_mask = root_gfp_mask(root); if (!(gfp_mask & __GFP_WAIT)) { struct radix_tree_preload *rtp; /* * Provided the caller has preloaded here, we will always * succeed in getting a node here (and never reach * kmem_cache_alloc) */ rtp = &__get_cpu_var(radix_tree_preloads); if (rtp->nr) { ret = rtp->nodes[rtp->nr - 1]; rtp->nodes[rtp->nr - 1] = NULL; rtp->nr--; } } if (ret == NULL) ret = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask); BUG_ON(radix_tree_is_indirect_ptr(ret)); return ret; } 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); /* * 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; kmem_cache_free(radix_tree_node_cachep, node); } static inline void radix_tree_node_free(struct radix_tree_node *node) { call_rcu(&node->rcu_head, radix_tree_node_rcu_free); } /* * 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. * * To make use of this facility, the radix tree must be initialised without * __GFP_WAIT being passed to INIT_RADIX_TREE(). */ int radix_tree_preload(gfp_t gfp_mask) { 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(); node = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask); 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; } EXPORT_SYMBOL(radix_tree_preload); /* * 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; 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; } do { unsigned int newheight; if (!(node = radix_tree_node_alloc(root))) return -ENOMEM; /* Increase the height. */ node->slots[0] = radix_tree_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); } newheight = root->height+1; node->height = newheight; node->count = 1; node = radix_tree_ptr_to_indirect(node); rcu_assign_pointer(root->rnode, node); root->height = newheight; } 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) { struct radix_tree_node *node = NULL, *slot; unsigned int height, shift; int 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); if (error) return error; } slot = radix_tree_indirect_to_ptr(root->rnode); height = root->height; shift = (height-1) * RADIX_TREE_MAP_SHIFT; offset = 0; /* uninitialised var warning */ while (height > 0) { if (slot == NULL) { /* Have to add a child node. */ if (!(slot = radix_tree_node_alloc(root))) return -ENOMEM; slot->height = height; if (node) { rcu_assign_pointer(node->slots[offset], slot); node->count++; } else rcu_assign_pointer(root->rnode, radix_tree_ptr_to_indirect(slot)); } /* Go a level down */ offset = (index >> shift) & RADIX_TREE_MAP_MASK; node = slot; slot = node->slots[offset]; shift -= RADIX_TREE_MAP_SHIFT; height--; } if (slot != NULL) return -EEXIST; 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)); } else { rcu_assign_pointer(root->rnode, item); BUG_ON(root_tag_get(root, 0)); BUG_ON(root_tag_get(root, 1)); } return 0; } EXPORT_SYMBOL(radix_tree_insert); /* * is_slot == 1 : search for the slot. * is_slot == 0 : search for the node. */ static void *radix_tree_lookup_element(struct radix_tree_root *root, unsigned long index, int is_slot) { unsigned int height, shift; struct radix_tree_node *node, **slot; node = rcu_dereference(root->rnode); if (node == NULL) return NULL; if (!radix_tree_is_indirect_ptr(node)) { if (index > 0) return NULL; return is_slot ? (void *)&root->rnode : node; } node = radix_tree_indirect_to_ptr(node); height = node->height; 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)); node = rcu_dereference(*slot); if (node == NULL) return NULL; shift -= RADIX_TREE_MAP_SHIFT; height--; } while (height > 0); return is_slot ? (void *)slot:node; } /** * 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. * * 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. */ void **radix_tree_lookup_slot(struct radix_tree_root *root, unsigned long index) { return (void **)radix_tree_lookup_element(root, index, 1); } 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. * * 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. */ void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index) { return radix_tree_lookup_element(root, index, 0); } 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 * * Set the search tag (which must be < RADIX_TREE_MAX_TAGS) * corresponding to @index in the radix tree. From * 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, unsigned long index, unsigned int tag) { unsigned int height, shift; struct radix_tree_node *slot; height = root->height; BUG_ON(index > radix_tree_maxindex(height)); slot = radix_tree_indirect_to_ptr(root->rnode); shift = (height - 1) * RADIX_TREE_MAP_SHIFT; while (height > 0) { int offset; offset = (index >> shift) & RADIX_TREE_MAP_MASK; if (!tag_get(slot, tag, offset)) tag_set(slot, tag, offset); slot = slot->slots[offset]; BUG_ON(slot == NULL); shift -= RADIX_TREE_MAP_SHIFT; height--; } /* set the root's tag bit */ if (slot && !root_tag_get(root, tag)) root_tag_set(root, tag); return slot; } 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 * * Clear the search tag (which must be < RADIX_TREE_MAX_TAGS) * corresponding to @index in the radix tree. If * 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, 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 *slot = NULL; unsigned int height, shift; height = root->height; if (index > radix_tree_maxindex(height)) goto out; shift = (height - 1) * RADIX_TREE_MAP_SHIFT; pathp->node = NULL; slot = radix_tree_indirect_to_ptr(root->rnode); while (height > 0) { int offset; if (slot == NULL) goto out; offset = (index >> shift) & RADIX_TREE_MAP_MASK; pathp[1].offset = offset; pathp[1].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)) goto out; tag_clear(pathp->node, tag, pathp->offset); if (any_tag_set(pathp->node, tag)) goto out; pathp--; } /* clear the root's tag bit */ if (root_tag_get(root, tag)) root_tag_clear(root, tag); out: return slot; } EXPORT_SYMBOL(radix_tree_tag_clear); /** * radix_tree_tag_get - get a tag on a radix tree node * @root: radix tree root * @index: index key * @tag: tag index (< RADIX_TREE_MAX_TAGS) * * Return values: * * 0: tag not present or not set * 1: tag set */ int radix_tree_tag_get(struct radix_tree_root *root, unsigned long index, unsigned int tag) { unsigned int height, shift; struct radix_tree_node *node; int saw_unset_tag = 0; /* check the root's tag bit */ if (!root_tag_get(root, tag)) return 0; node = rcu_dereference(root->rnode); if (node == NULL) return 0; if (!radix_tree_is_indirect_ptr(node)) return (index == 0); node = radix_tree_indirect_to_ptr(node); height = node->height; if (index > radix_tree_maxindex(height)) return 0; shift = (height - 1) * RADIX_TREE_MAP_SHIFT; for ( ; ; ) { int offset; if (node == NULL) 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. */ if (!tag_get(node, tag, offset)) saw_unset_tag = 1; if (height == 1) { int ret = tag_get(node, tag, offset); BUG_ON(ret && saw_unset_tag); return !!ret; } node = rcu_dereference(node->slots[offset]); shift -= RADIX_TREE_MAP_SHIFT; height--; } } EXPORT_SYMBOL(radix_tree_tag_get); /** * 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, LONG_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 == LONG_MAX) break; } return index; } EXPORT_SYMBOL(radix_tree_prev_hole); static unsigned int __lookup(struct radix_tree_node *slot, void ***results, unsigned long index, unsigned int max_items, unsigned long *next_index) { unsigned int nr_found = 0; unsigned int shift, height; unsigned long i; height = slot->height; if (height == 0) goto out; shift = (height-1) * RADIX_TREE_MAP_SHIFT; for ( ; height > 1; height--) { i = (index >> shift) & RADIX_TREE_MAP_MASK; for (;;) { if (slot->slots[i] != NULL) break; index &= ~((1UL << shift) - 1); index += 1UL << shift; if (index == 0) goto out; /* 32-bit wraparound */ i++; if (i == RADIX_TREE_MAP_SIZE) goto out; } shift -= RADIX_TREE_MAP_SHIFT; slot = rcu_dereference(slot->slots[i]); if (slot == NULL) goto out; } /* Bottom level: grab some items */ for (i = index & RADIX_TREE_MAP_MASK; i < RADIX_TREE_MAP_SIZE; i++) { index++; if (slot->slots[i]) { results[nr_found++] = &(slot->slots[i]); if (nr_found == max_items) goto out; } } 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. * * 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'. */ unsigned int radix_tree_gang_lookup(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] = node; return 1; } node = radix_tree_indirect_to_ptr(node); max_index = radix_tree_maxindex(node->height); ret = 0; while (ret < max_items) { unsigned int nr_found, slots_found, i; unsigned long next_index; /* Index of next search */ if (cur_index > max_index) break; slots_found = __lookup(node, (void ***)results + ret, cur_index, max_items - ret, &next_index); 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++; } ret += nr_found; if (next_index == 0) break; cur_index = next_index; } return ret; } EXPORT_SYMBOL(radix_tree_gang_lookup); /** * 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); /* * FIXME: the two tag_get()s here should use find_next_bit() instead of * open-coding the search. */ static unsigned int __lookup_tag(struct radix_tree_node *slot, void ***results, unsigned long index, unsigned int max_items, unsigned long *next_index, unsigned int tag) { unsigned int nr_found = 0; unsigned int shift, height; height = slot->height; if (height == 0) goto out; shift = (height-1) * RADIX_TREE_MAP_SHIFT; while (height > 0) { unsigned long i = (index >> shift) & RADIX_TREE_MAP_MASK ; for (;;) { if (tag_get(slot, tag, i)) break; index &= ~((1UL << shift) - 1); index += 1UL << shift; if (index == 0) goto out; /* 32-bit wraparound */ i++; if (i == RADIX_TREE_MAP_SIZE) goto out; } 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++; if (!tag_get(slot, tag, j)) continue; /* * 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). */ if (slot->slots[j]) { results[nr_found++] = &(slot->slots[j]); if (nr_found == max_items) goto out; } } } shift -= RADIX_TREE_MAP_SHIFT; slot = rcu_dereference(slot->slots[i]); if (slot == NULL) break; } 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 * @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 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, 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] = node; return 1; } node = radix_tree_indirect_to_ptr(node); max_index = radix_tree_maxindex(node->height); ret = 0; while (ret < max_items) { unsigned int nr_found, slots_found, i; unsigned long next_index; /* Index of next search */ if (cur_index > max_index) break; 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++; } ret += nr_found; if (next_index == 0) break; cur_index = next_index; } return ret; } EXPORT_SYMBOL(radix_tree_gang_lookup_tag); /** * 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); /** * 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 */ while (root->height > 0) { struct radix_tree_node *to_free = root->rnode; void *newptr; 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; /* * 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]; if (root->height > 1) newptr = radix_tree_ptr_to_indirect(newptr); root->rnode = newptr; root->height--; radix_tree_node_free(to_free); } } /** * 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) { /* * 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 *slot = NULL; struct radix_tree_node *to_free; unsigned int height, shift; int tag; int offset; height = root->height; if (index > radix_tree_maxindex(height)) goto out; slot = root->rnode; if (height == 0) { root_tag_clear_all(root); root->rnode = NULL; goto out; } slot = radix_tree_indirect_to_ptr(slot); shift = (height - 1) * RADIX_TREE_MAP_SHIFT; pathp->node = NULL; do { if (slot == NULL) goto out; pathp++; offset = (index >> shift) & RADIX_TREE_MAP_MASK; pathp->offset = offset; pathp->node = slot; slot = slot->slots[offset]; shift -= RADIX_TREE_MAP_SHIFT; height--; } while (height > 0); if (slot == NULL) goto out; /* * Clear all tags associated with the just-deleted item */ for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) { if (tag_get(pathp->node, tag, pathp->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--; /* * 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 (pathp->node->count) { if (pathp->node == radix_tree_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--; } root_tag_clear_all(root); root->height = 0; root->rnode = NULL; if (to_free) radix_tree_node_free(to_free); out: return slot; } 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 */ int radix_tree_tagged(struct radix_tree_root *root, unsigned int tag) { return root_tag_get(root, tag); } EXPORT_SYMBOL(radix_tree_tagged); static void radix_tree_node_ctor(void *node) { memset(node, 0, sizeof(struct radix_tree_node)); } static __init unsigned long __maxindex(unsigned int height) { 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; } 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); } 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 */ if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) { 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; } void __init radix_tree_init(void) { radix_tree_node_cachep = kmem_cache_create("radix_tree_node", sizeof(struct radix_tree_node), 0, SLAB_PANIC | SLAB_RECLAIM_ACCOUNT, radix_tree_node_ctor); radix_tree_init_maxindex(); hotcpu_notifier(radix_tree_callback, 0); }