/* * Copyright (C) 2001 Momchil Velikov * Portions Copyright (C) 2001 Christoph Hellwig * Copyright (C) 2005 SGI, Christoph Lameter <clameter@sgi.com> * * 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> #ifdef __KERNEL__ #define RADIX_TREE_MAP_SHIFT 6 #else #define RADIX_TREE_MAP_SHIFT 3 /* For more stressful testing */ #endif #define RADIX_TREE_TAGS 2 #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 count; void *slots[RADIX_TREE_MAP_SIZE]; unsigned long tags[RADIX_TREE_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 (RADIX_TREE_INDEX_BITS/RADIX_TREE_MAP_SHIFT + 2) static unsigned long height_to_maxindex[RADIX_TREE_MAX_PATH] __read_mostly; /* * Radix tree node cache. */ static kmem_cache_t *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]; }; DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { 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; ret = kmem_cache_alloc(radix_tree_node_cachep, root->gfp_mask); if (ret == NULL && !(root->gfp_mask & __GFP_WAIT)) { struct radix_tree_preload *rtp; rtp = &__get_cpu_var(radix_tree_preloads); if (rtp->nr) { ret = rtp->nodes[rtp->nr - 1]; rtp->nodes[rtp->nr - 1] = NULL; rtp->nr--; } } return ret; } static inline void radix_tree_node_free(struct radix_tree_node *node) { kmem_cache_free(radix_tree_node_cachep, node); } /* * 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. */ 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; } static inline void tag_set(struct radix_tree_node *node, int tag, int offset) { if (!test_bit(offset, &node->tags[tag][0])) __set_bit(offset, &node->tags[tag][0]); } static inline void tag_clear(struct radix_tree_node *node, int tag, int offset) { __clear_bit(offset, &node->tags[tag][0]); } static inline int tag_get(struct radix_tree_node *node, int tag, int offset) { return test_bit(offset, &node->tags[tag][0]); } /* * 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; char tags[RADIX_TREE_TAGS]; 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; } /* * Prepare the tag status of the top-level node for propagation * into the newly-pushed top-level node(s) */ for (tag = 0; tag < RADIX_TREE_TAGS; tag++) { int idx; tags[tag] = 0; for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) { if (root->rnode->tags[tag][idx]) { tags[tag] = 1; break; } } } do { if (!(node = radix_tree_node_alloc(root))) return -ENOMEM; /* Increase the height. */ node->slots[0] = root->rnode; /* Propagate the aggregated tag info into the new root */ for (tag = 0; tag < RADIX_TREE_TAGS; tag++) { if (tags[tag]) tag_set(node, tag, 0); } node->count = 1; root->rnode = node; root->height++; } 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; /* Make sure the tree is high enough. */ if ((!index && !root->rnode) || index > radix_tree_maxindex(root->height)) { error = radix_tree_extend(root, index); if (error) return error; } slot = 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; if (node) { node->slots[offset] = slot; node->count++; } else root->rnode = 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++; node->slots[offset] = item; BUG_ON(tag_get(node, 0, offset)); BUG_ON(tag_get(node, 1, offset)); } else root->rnode = item; return 0; } EXPORT_SYMBOL(radix_tree_insert); static inline void **__lookup_slot(struct radix_tree_root *root, unsigned long index) { unsigned int height, shift; struct radix_tree_node **slot; height = root->height; if (index > radix_tree_maxindex(height)) return NULL; shift = (height-1) * RADIX_TREE_MAP_SHIFT; slot = &root->rnode; while (height > 0) { if (*slot == NULL) return NULL; slot = (struct radix_tree_node **) ((*slot)->slots + ((index >> shift) & RADIX_TREE_MAP_MASK)); shift -= RADIX_TREE_MAP_SHIFT; height--; } return (void **)slot; } /** * radix_tree_lookup_slot - lookup a slot in a radix tree * @root: radix tree root * @index: index key * * Lookup the slot corresponding to the position @index in the radix tree * @root. This is useful for update-if-exists operations. */ void **radix_tree_lookup_slot(struct radix_tree_root *root, unsigned long index) { return __lookup_slot(root, index); } 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. */ void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index) { void **slot; slot = __lookup_slot(root, index); return slot != NULL ? *slot : NULL; } 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 corresponging 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, int tag) { unsigned int height, shift; struct radix_tree_node *slot; height = root->height; if (index > radix_tree_maxindex(height)) return NULL; shift = (height - 1) * RADIX_TREE_MAP_SHIFT; slot = root->rnode; while (height > 0) { int offset; offset = (index >> shift) & RADIX_TREE_MAP_MASK; tag_set(slot, tag, offset); slot = slot->slots[offset]; BUG_ON(slot == NULL); shift -= RADIX_TREE_MAP_SHIFT; height--; } 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 corresponging 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, int tag) { struct radix_tree_path path[RADIX_TREE_MAX_PATH], *pathp = path; struct radix_tree_node *slot; unsigned int height, shift; void *ret = NULL; height = root->height; if (index > radix_tree_maxindex(height)) goto out; shift = (height - 1) * RADIX_TREE_MAP_SHIFT; pathp->node = NULL; slot = 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--; } ret = slot; if (ret == NULL) goto out; do { int idx; tag_clear(pathp->node, tag, pathp->offset); for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) { if (pathp->node->tags[tag][idx]) goto out; } pathp--; } while (pathp->node); out: return ret; } EXPORT_SYMBOL(radix_tree_tag_clear); #ifndef __KERNEL__ /* Only the test harness uses this at present */ /** * radix_tree_tag_get - get a tag on a radix tree node * @root: radix tree root * @index: index key * @tag: tag index * * Return values: * * 0: tag not present * 1: tag present, set * -1: tag present, unset */ int radix_tree_tag_get(struct radix_tree_root *root, unsigned long index, int tag) { unsigned int height, shift; struct radix_tree_node *slot; int saw_unset_tag = 0; height = root->height; if (index > radix_tree_maxindex(height)) return 0; shift = (height - 1) * RADIX_TREE_MAP_SHIFT; slot = root->rnode; for ( ; ; ) { int offset; if (slot == 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(slot, tag, offset)) saw_unset_tag = 1; if (height == 1) { int ret = tag_get(slot, tag, offset); BUG_ON(ret && saw_unset_tag); return ret ? 1 : -1; } slot = slot->slots[offset]; shift -= RADIX_TREE_MAP_SHIFT; height--; } } EXPORT_SYMBOL(radix_tree_tag_get); #endif static unsigned int __lookup(struct radix_tree_root *root, void **results, unsigned long index, unsigned int max_items, unsigned long *next_index) { unsigned int nr_found = 0; unsigned int shift, height; struct radix_tree_node *slot; unsigned long i; height = root->height; if (height == 0) goto out; shift = (height-1) * RADIX_TREE_MAP_SHIFT; slot = root->rnode; for ( ; height > 1; height--) { for (i = (index >> shift) & RADIX_TREE_MAP_MASK ; i < RADIX_TREE_MAP_SIZE; i++) { if (slot->slots[i] != NULL) break; index &= ~((1UL << shift) - 1); index += 1UL << shift; if (index == 0) goto out; /* 32-bit wraparound */ } if (i == RADIX_TREE_MAP_SIZE) goto out; shift -= RADIX_TREE_MAP_SHIFT; slot = slot->slots[i]; } /* 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. */ unsigned int radix_tree_gang_lookup(struct radix_tree_root *root, void **results, unsigned long first_index, unsigned int max_items) { const unsigned long max_index = radix_tree_maxindex(root->height); unsigned long cur_index = first_index; unsigned int ret = 0; while (ret < max_items) { unsigned int nr_found; unsigned long next_index; /* Index of next search */ if (cur_index > max_index) break; nr_found = __lookup(root, results + ret, cur_index, max_items - ret, &next_index); ret += nr_found; if (next_index == 0) break; cur_index = next_index; } return ret; } EXPORT_SYMBOL(radix_tree_gang_lookup); /* * 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_root *root, void **results, unsigned long index, unsigned int max_items, unsigned long *next_index, int tag) { unsigned int nr_found = 0; unsigned int shift; unsigned int height = root->height; struct radix_tree_node *slot; shift = (height - 1) * RADIX_TREE_MAP_SHIFT; slot = root->rnode; while (height > 0) { unsigned long i = (index >> shift) & RADIX_TREE_MAP_MASK; for ( ; i < RADIX_TREE_MAP_SIZE; i++) { if (tag_get(slot, tag, i)) { BUG_ON(slot->slots[i] == NULL); break; } index &= ~((1UL << shift) - 1); index += 1UL << shift; if (index == 0) goto out; /* 32-bit wraparound */ } 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)) { BUG_ON(slot->slots[j] == NULL); results[nr_found++] = slot->slots[j]; if (nr_found == max_items) goto out; } } } shift -= RADIX_TREE_MAP_SHIFT; slot = slot->slots[i]; } 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 * * 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, int tag) { const unsigned long max_index = radix_tree_maxindex(root->height); unsigned long cur_index = first_index; unsigned int ret = 0; while (ret < max_items) { unsigned int nr_found; unsigned long next_index; /* Index of next search */ if (cur_index > max_index) break; nr_found = __lookup_tag(root, results + ret, cur_index, max_items - ret, &next_index, tag); ret += nr_found; if (next_index == 0) break; cur_index = next_index; } return ret; } EXPORT_SYMBOL(radix_tree_gang_lookup_tag); /** * 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) { struct radix_tree_path path[RADIX_TREE_MAX_PATH], *pathp = path; struct radix_tree_path *orig_pathp; struct radix_tree_node *slot; unsigned int height, shift; void *ret = NULL; char tags[RADIX_TREE_TAGS]; int nr_cleared_tags; height = root->height; if (index > radix_tree_maxindex(height)) goto out; shift = (height - 1) * RADIX_TREE_MAP_SHIFT; pathp->node = NULL; slot = root->rnode; for ( ; height > 0; height--) { 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; } ret = slot; if (ret == NULL) goto out; orig_pathp = pathp; /* * Clear all tags associated with the just-deleted item */ memset(tags, 0, sizeof(tags)); do { int tag; nr_cleared_tags = RADIX_TREE_TAGS; for (tag = 0; tag < RADIX_TREE_TAGS; tag++) { int idx; if (tags[tag]) continue; tag_clear(pathp->node, tag, pathp->offset); for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) { if (pathp->node->tags[tag][idx]) { tags[tag] = 1; nr_cleared_tags--; break; } } } pathp--; } while (pathp->node && nr_cleared_tags); /* Now free the nodes we do not need anymore */ for (pathp = orig_pathp; pathp->node; pathp--) { pathp->node->slots[pathp->offset] = NULL; if (--pathp->node->count) goto out; /* Node with zero slots in use so free it */ radix_tree_node_free(pathp->node); } root->rnode = NULL; root->height = 0; out: return ret; } 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, int tag) { int idx; if (!root->rnode) return 0; for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) { if (root->rnode->tags[tag][idx]) return 1; } return 0; } EXPORT_SYMBOL(radix_tree_tagged); static void radix_tree_node_ctor(void *node, kmem_cache_t *cachep, unsigned long flags) { memset(node, 0, sizeof(struct radix_tree_node)); } static __init unsigned long __maxindex(unsigned int height) { unsigned int tmp = height * RADIX_TREE_MAP_SHIFT; unsigned long index = (~0UL >> (RADIX_TREE_INDEX_BITS - tmp - 1)) >> 1; if (tmp >= RADIX_TREE_INDEX_BITS) index = ~0UL; return index; } 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); } #ifdef CONFIG_HOTPLUG_CPU 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) { 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; } #endif /* CONFIG_HOTPLUG_CPU */ void __init radix_tree_init(void) { radix_tree_node_cachep = kmem_cache_create("radix_tree_node", sizeof(struct radix_tree_node), 0, SLAB_PANIC, radix_tree_node_ctor, NULL); radix_tree_init_maxindex(); hotcpu_notifier(radix_tree_callback, 0); }