X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=lib%2Fradix-tree.c;h=d69ddbe438655be6b65672d2c7366371baadfd85;hb=97bf2856c6014879bd04983a3e9dfcdac1e7fe85;hp=1e5b17dc7e3d5c6da19bdb2376e7a0a120cbc722;hpb=76828883507a47dae78837ab5dec5a5b4513c667;p=linux-2.6.git diff --git a/lib/radix-tree.c b/lib/radix-tree.c index 1e5b17dc7..d69ddbe43 100644 --- a/lib/radix-tree.c +++ b/lib/radix-tree.c @@ -2,6 +2,7 @@ * 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 @@ -30,14 +31,14 @@ #include #include #include +#include #ifdef __KERNEL__ -#define RADIX_TREE_MAP_SHIFT 6 +#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_TAGS 2 #define RADIX_TREE_MAP_SIZE (1UL << RADIX_TREE_MAP_SHIFT) #define RADIX_TREE_MAP_MASK (RADIX_TREE_MAP_SIZE-1) @@ -46,9 +47,11 @@ ((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_TAGS][RADIX_TREE_TAG_LONGS]; + unsigned long tags[RADIX_TREE_MAX_TAGS][RADIX_TREE_TAG_LONGS]; }; struct radix_tree_path { @@ -64,7 +67,7 @@ static unsigned long height_to_maxindex[RADIX_TREE_MAX_PATH] __read_mostly; /* * Radix tree node cache. */ -static kmem_cache_t *radix_tree_node_cachep; +static struct kmem_cache *radix_tree_node_cachep; /* * Per-cpu pool of preloaded nodes @@ -75,6 +78,11 @@ struct radix_tree_preload { }; 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; +} + /* * This assumes that the caller has performed appropriate preallocation, and * that the caller has pinned this thread of control to the current CPU. @@ -83,9 +91,10 @@ static struct radix_tree_node * radix_tree_node_alloc(struct radix_tree_root *root) { struct radix_tree_node *ret; + gfp_t gfp_mask = root_gfp_mask(root); - ret = kmem_cache_alloc(radix_tree_node_cachep, root->gfp_mask); - if (ret == NULL && !(root->gfp_mask & __GFP_WAIT)) { + ret = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask); + if (ret == NULL && !(gfp_mask & __GFP_WAIT)) { struct radix_tree_preload *rtp; rtp = &__get_cpu_var(radix_tree_preloads); @@ -95,13 +104,21 @@ radix_tree_node_alloc(struct radix_tree_root *root) rtp->nr--; } } + BUG_ON(radix_tree_is_direct_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); + kmem_cache_free(radix_tree_node_cachep, node); +} + static inline void radix_tree_node_free(struct radix_tree_node *node) { - kmem_cache_free(radix_tree_node_cachep, node); + call_rcu(&node->rcu_head, radix_tree_node_rcu_free); } /* @@ -135,26 +152,50 @@ out: return ret; } -static inline void tag_set(struct radix_tree_node *node, int tag, int offset) +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, int tag, int offset) +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, int tag, int offset) +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, int tag) +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++) { @@ -180,7 +221,6 @@ 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. */ @@ -193,32 +233,25 @@ static int radix_tree_extend(struct radix_tree_root *root, unsigned long index) 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++) { - tags[tag] = 0; - if (any_tag_set(root->rnode, tag)) - tags[tag] = 1; - } - do { + unsigned int newheight; if (!(node = radix_tree_node_alloc(root))) return -ENOMEM; /* Increase the height. */ - node->slots[0] = root->rnode; + node->slots[0] = radix_tree_direct_to_ptr(root->rnode); /* Propagate the aggregated tag info into the new root */ - for (tag = 0; tag < RADIX_TREE_TAGS; tag++) { - if (tags[tag]) + 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; - root->rnode = node; - root->height++; + rcu_assign_pointer(root->rnode, node); + root->height = newheight; } while (height > root->height); out: return 0; @@ -240,9 +273,10 @@ int radix_tree_insert(struct radix_tree_root *root, int offset; int error; + BUG_ON(radix_tree_is_direct_ptr(item)); + /* Make sure the tree is high enough. */ - if ((!index && !root->rnode) || - index > radix_tree_maxindex(root->height)) { + if (index > radix_tree_maxindex(root->height)) { error = radix_tree_extend(root, index); if (error) return error; @@ -253,16 +287,17 @@ int radix_tree_insert(struct radix_tree_root *root, shift = (height-1) * RADIX_TREE_MAP_SHIFT; offset = 0; /* uninitialised var warning */ - do { + 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) { - node->slots[offset] = slot; + rcu_assign_pointer(node->slots[offset], slot); node->count++; } else - root->rnode = slot; + rcu_assign_pointer(root->rnode, slot); } /* Go a level down */ @@ -271,60 +306,74 @@ int radix_tree_insert(struct radix_tree_root *root, slot = node->slots[offset]; shift -= RADIX_TREE_MAP_SHIFT; height--; - } while (height > 0); + } if (slot != NULL) return -EEXIST; - BUG_ON(!node); - node->count++; - node->slots[offset] = item; - BUG_ON(tag_get(node, 0, offset)); - BUG_ON(tag_get(node, 1, offset)); + 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, radix_tree_ptr_to_direct(item)); + BUG_ON(root_tag_get(root, 0)); + BUG_ON(root_tag_get(root, 1)); + } return 0; } EXPORT_SYMBOL(radix_tree_insert); -static inline void **__lookup_slot(struct radix_tree_root *root, - unsigned long index) +/** + * 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 cannot be called under rcu_read_lock, it must be + * excluded from writers, as must the returned slot for subsequent + * use by radix_tree_deref_slot() and radix_tree_replace slot. + * Caller must hold tree write locked across slot lookup and + * replace. + */ +void **radix_tree_lookup_slot(struct radix_tree_root *root, unsigned long index) { unsigned int height, shift; - struct radix_tree_node **slot; + struct radix_tree_node *node, **slot; - height = root->height; + node = root->rnode; + if (node == NULL) + return NULL; + + if (radix_tree_is_direct_ptr(node)) { + if (index > 0) + return NULL; + return (void **)&root->rnode; + } + + height = node->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) + do { + slot = (struct radix_tree_node **) + (node->slots + ((index>>shift) & RADIX_TREE_MAP_MASK)); + node = *slot; + if (node == NULL) return NULL; - slot = (struct radix_tree_node **) - ((*slot)->slots + - ((index >> shift) & RADIX_TREE_MAP_MASK)); shift -= RADIX_TREE_MAP_SHIFT; height--; - } + } while (height > 0); 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); /** @@ -333,13 +382,45 @@ EXPORT_SYMBOL(radix_tree_lookup_slot); * @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) { - void **slot; + unsigned int height, shift; + struct radix_tree_node *node, **slot; + + node = rcu_dereference(root->rnode); + if (node == NULL) + return NULL; - slot = __lookup_slot(root, index); - return slot != NULL ? *slot : NULL; + if (radix_tree_is_direct_ptr(node)) { + if (index > 0) + return NULL; + return radix_tree_direct_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 node; } EXPORT_SYMBOL(radix_tree_lookup); @@ -349,24 +430,24 @@ EXPORT_SYMBOL(radix_tree_lookup); * @index: index key * @tag: tag index * - * Set the search tag corresponging to @index in the radix tree. From + * 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, int tag) + unsigned long index, unsigned int tag) { unsigned int height, shift; struct radix_tree_node *slot; height = root->height; - if (index > radix_tree_maxindex(height)) - return NULL; + BUG_ON(index > radix_tree_maxindex(height)); - shift = (height - 1) * RADIX_TREE_MAP_SHIFT; slot = root->rnode; + shift = (height - 1) * RADIX_TREE_MAP_SHIFT; while (height > 0) { int offset; @@ -380,6 +461,10 @@ void *radix_tree_tag_set(struct radix_tree_root *root, 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); @@ -390,7 +475,8 @@ EXPORT_SYMBOL(radix_tree_tag_set); * @index: index key * @tag: tag index * - * Clear the search tag corresponging to @index in the radix tree. If + * 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. * @@ -398,12 +484,11 @@ EXPORT_SYMBOL(radix_tree_tag_set); * 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) + unsigned long index, unsigned int tag) { struct radix_tree_path path[RADIX_TREE_MAX_PATH], *pathp = path; - struct radix_tree_node *slot; + struct radix_tree_node *slot = NULL; unsigned int height, shift; - void *ret = NULL; height = root->height; if (index > radix_tree_maxindex(height)) @@ -428,20 +513,24 @@ void *radix_tree_tag_clear(struct radix_tree_root *root, height--; } - ret = slot; - if (ret == NULL) + if (slot == NULL) goto out; - do { + 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--; - } while (pathp->node); + } + + /* clear the root's tag bit */ + if (root_tag_get(root, tag)) + root_tag_clear(root, tag); + out: - return ret; + return slot; } EXPORT_SYMBOL(radix_tree_tag_clear); @@ -450,32 +539,41 @@ 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 + * @tag: tag index (< RADIX_TREE_MAX_TAGS) * * Return values: * - * 0: tag not present - * 1: tag present, set - * -1: tag present, unset + * 0: tag not present or not set + * 1: tag set */ int radix_tree_tag_get(struct radix_tree_root *root, - unsigned long index, int tag) + unsigned long index, unsigned int tag) { unsigned int height, shift; - struct radix_tree_node *slot; + struct radix_tree_node *node; int saw_unset_tag = 0; - height = root->height; + /* 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_direct_ptr(node)) + return (index == 0); + + height = node->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) + if (node == NULL) return 0; offset = (index >> shift) & RADIX_TREE_MAP_MASK; @@ -484,15 +582,15 @@ int radix_tree_tag_get(struct radix_tree_root *root, * This is just a debug check. Later, we can bale as soon as * we see an unset tag. */ - if (!tag_get(slot, tag, offset)) + if (!tag_get(node, tag, offset)) saw_unset_tag = 1; if (height == 1) { - int ret = tag_get(slot, tag, offset); + int ret = tag_get(node, tag, offset); BUG_ON(ret && saw_unset_tag); - return ret ? 1 : -1; + return !!ret; } - slot = slot->slots[offset]; + node = rcu_dereference(node->slots[offset]); shift -= RADIX_TREE_MAP_SHIFT; height--; } @@ -501,44 +599,45 @@ EXPORT_SYMBOL(radix_tree_tag_get); #endif static unsigned int -__lookup(struct radix_tree_root *root, void **results, unsigned long index, +__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; - struct radix_tree_node *slot; unsigned long i; - height = root->height; + height = slot->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++) { + 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; } - if (i == RADIX_TREE_MAP_SIZE) - goto out; shift -= RADIX_TREE_MAP_SHIFT; - slot = slot->slots[i]; + 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++) { + struct radix_tree_node *node; index++; - if (slot->slots[i]) { - results[nr_found++] = slot->slots[i]; + node = slot->slots[i]; + if (node) { + results[nr_found++] = rcu_dereference(node); if (nr_found == max_items) goto out; } @@ -560,28 +659,51 @@ out: * *@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) { - const unsigned long max_index = radix_tree_maxindex(root->height); + unsigned long max_index; + struct radix_tree_node *node; unsigned long cur_index = first_index; - unsigned int ret = 0; + unsigned int ret; + + node = rcu_dereference(root->rnode); + if (!node) + return 0; + + if (radix_tree_is_direct_ptr(node)) { + if (first_index > 0) + return 0; + node = radix_tree_direct_to_ptr(node); + results[0] = rcu_dereference(node); + return 1; + } + max_index = radix_tree_maxindex(node->height); + + 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, + nr_found = __lookup(node, 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); @@ -591,48 +713,63 @@ EXPORT_SYMBOL(radix_tree_gang_lookup); * 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) +__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; - unsigned int height = root->height; - struct radix_tree_node *slot; + unsigned int shift, height; - shift = (height - 1) * RADIX_TREE_MAP_SHIFT; - slot = root->rnode; + 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; + 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); + 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; } - 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++) { + struct radix_tree_node *node; index++; - if (tag_get(slot, tag, j)) { - BUG_ON(slot->slots[j] == NULL); - results[nr_found++] = slot->slots[j]; + if (!tag_get(slot, tag, j)) + continue; + node = slot->slots[j]; + /* + * 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 (node) { + node = rcu_dereference(node); + results[nr_found++] = node; if (nr_found == max_items) goto out; } } } shift -= RADIX_TREE_MAP_SHIFT; - slot = slot->slots[i]; + slot = rcu_dereference(slot->slots[i]); + if (slot == NULL) + break; } out: *next_index = index; @@ -646,7 +783,7 @@ out: * @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 + * @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 @@ -654,25 +791,47 @@ out: */ unsigned int radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results, - unsigned long first_index, unsigned int max_items, int tag) + unsigned long first_index, unsigned int max_items, + unsigned int tag) { - const unsigned long max_index = radix_tree_maxindex(root->height); + struct radix_tree_node *node; + unsigned long max_index; unsigned long cur_index = first_index; - unsigned int ret = 0; + 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_direct_ptr(node)) { + if (first_index > 0) + return 0; + node = radix_tree_direct_to_ptr(node); + results[0] = rcu_dereference(node); + return 1; + } + max_index = radix_tree_maxindex(node->height); + + 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, + nr_found = __lookup_tag(node, 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); @@ -684,12 +843,23 @@ EXPORT_SYMBOL(radix_tree_gang_lookup_tag); static inline void radix_tree_shrink(struct radix_tree_root *root) { /* try to shrink tree height */ - while (root->height > 1 && + while (root->height > 0 && root->rnode->count == 1 && root->rnode->slots[0]) { struct radix_tree_node *to_free = root->rnode; + void *newptr; - root->rnode = to_free->slots[0]; + /* + * 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_direct(newptr); + root->rnode = newptr; root->height--; /* must only free zeroed nodes into the slab */ tag_clear(to_free, 0, 0); @@ -712,12 +882,9 @@ static inline void radix_tree_shrink(struct radix_tree_root *root) 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; + struct radix_tree_node *slot = NULL; + struct radix_tree_node *to_free; unsigned int height, shift; - void *ret = NULL; - char tags[RADIX_TREE_TAGS]; - int nr_cleared_tags; int tag; int offset; @@ -725,11 +892,18 @@ void *radix_tree_delete(struct radix_tree_root *root, unsigned long index) if (index > radix_tree_maxindex(height)) goto out; + slot = root->rnode; + if (height == 0 && root->rnode) { + slot = radix_tree_direct_to_ptr(slot); + root_tag_clear_all(root); + root->rnode = NULL; + goto out; + } + shift = (height - 1) * RADIX_TREE_MAP_SHIFT; pathp->node = NULL; - slot = root->rnode; - for ( ; height > 0; height--) { + do { if (slot == NULL) goto out; @@ -739,46 +913,31 @@ void *radix_tree_delete(struct radix_tree_root *root, unsigned long index) pathp->node = slot; slot = slot->slots[offset]; shift -= RADIX_TREE_MAP_SHIFT; - } + height--; + } while (height > 0); - ret = slot; - if (ret == NULL) + if (slot == NULL) goto out; - orig_pathp = pathp; - /* * Clear all tags associated with the just-deleted item */ - nr_cleared_tags = 0; - for (tag = 0; tag < RADIX_TREE_TAGS; tag++) { - tags[tag] = 1; - if (tag_get(pathp->node, tag, pathp->offset)) { - tag_clear(pathp->node, tag, pathp->offset); - if (!any_tag_set(pathp->node, tag)) { - tags[tag] = 0; - nr_cleared_tags++; - } - } - } - - for (pathp--; nr_cleared_tags && pathp->node; pathp--) { - for (tag = 0; tag < RADIX_TREE_TAGS; tag++) { - if (tags[tag]) - continue; - - tag_clear(pathp->node, tag, pathp->offset); - if (any_tag_set(pathp->node, tag)) { - tags[tag] = 1; - nr_cleared_tags--; - } - } + 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 */ - for (pathp = orig_pathp; pathp->node; pathp--) { + 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 == root->rnode) @@ -787,12 +946,18 @@ void *radix_tree_delete(struct radix_tree_root *root, unsigned long index) } /* Node with zero slots in use so free it */ - radix_tree_node_free(pathp->node); + to_free = pathp->node; + pathp--; + } - root->rnode = NULL; + root_tag_clear_all(root); root->height = 0; + root->rnode = NULL; + if (to_free) + radix_tree_node_free(to_free); + out: - return ret; + return slot; } EXPORT_SYMBOL(radix_tree_delete); @@ -801,18 +966,14 @@ EXPORT_SYMBOL(radix_tree_delete); * @root: radix tree root * @tag: tag to test */ -int radix_tree_tagged(struct radix_tree_root *root, int tag) +int radix_tree_tagged(struct radix_tree_root *root, unsigned int tag) { - struct radix_tree_node *rnode; - rnode = root->rnode; - if (!rnode) - return 0; - return any_tag_set(rnode, tag); + return root_tag_get(root, tag); } EXPORT_SYMBOL(radix_tree_tagged); static void -radix_tree_node_ctor(void *node, kmem_cache_t *cachep, unsigned long flags) +radix_tree_node_ctor(void *node, struct kmem_cache *cachep, unsigned long flags) { memset(node, 0, sizeof(struct radix_tree_node)); } @@ -835,7 +996,6 @@ static __init void radix_tree_init_maxindex(void) height_to_maxindex[i] = __maxindex(i); } -#ifdef CONFIG_HOTPLUG_CPU static int radix_tree_callback(struct notifier_block *nfb, unsigned long action, void *hcpu) @@ -855,7 +1015,6 @@ static int radix_tree_callback(struct notifier_block *nfb, } return NOTIFY_OK; } -#endif /* CONFIG_HOTPLUG_CPU */ void __init radix_tree_init(void) {