| /* |
| * Copyright (C) 2001 Momchil Velikov |
| * Portions Copyright (C) 2001 Christoph Hellwig |
| * Copyright (C) 2005 SGI, Christoph Lameter |
| * Copyright (C) 2006 Nick Piggin |
| * Copyright (C) 2012 Konstantin Khlebnikov |
| * Copyright (C) 2016 Intel, Matthew Wilcox |
| * Copyright (C) 2016 Intel, Ross Zwisler |
| * |
| * 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/export.h> |
| #include <linux/radix-tree.h> |
| #include <linux/percpu.h> |
| #include <linux/slab.h> |
| #include <linux/kmemleak.h> |
| #include <linux/notifier.h> |
| #include <linux/cpu.h> |
| #include <linux/string.h> |
| #include <linux/bitops.h> |
| #include <linux/rcupdate.h> |
| #include <linux/preempt.h> /* in_interrupt() */ |
| |
| |
| /* Number of nodes in fully populated tree of given height */ |
| static unsigned long height_to_maxnodes[RADIX_TREE_MAX_PATH + 1] __read_mostly; |
| |
| /* |
| * Radix tree node cache. |
| */ |
| static struct kmem_cache *radix_tree_node_cachep; |
| |
| /* |
| * The radix tree is variable-height, so an insert operation not only has |
| * to build the branch to its corresponding item, it also has to build the |
| * branch to existing items if the size has to be increased (by |
| * radix_tree_extend). |
| * |
| * The worst case is a zero height tree with just a single item at index 0, |
| * and then inserting an item at index ULONG_MAX. This requires 2 new branches |
| * of RADIX_TREE_MAX_PATH size to be created, with only the root node shared. |
| * Hence: |
| */ |
| #define RADIX_TREE_PRELOAD_SIZE (RADIX_TREE_MAX_PATH * 2 - 1) |
| |
| /* |
| * Per-cpu pool of preloaded nodes |
| */ |
| struct radix_tree_preload { |
| unsigned nr; |
| /* nodes->private_data points to next preallocated node */ |
| struct radix_tree_node *nodes; |
| }; |
| static DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { 0, }; |
| |
| static inline void *node_to_entry(void *ptr) |
| { |
| return (void *)((unsigned long)ptr | RADIX_TREE_INTERNAL_NODE); |
| } |
| |
| #define RADIX_TREE_RETRY node_to_entry(NULL) |
| |
| #ifdef CONFIG_RADIX_TREE_MULTIORDER |
| /* Sibling slots point directly to another slot in the same node */ |
| static inline bool is_sibling_entry(struct radix_tree_node *parent, void *node) |
| { |
| void **ptr = node; |
| return (parent->slots <= ptr) && |
| (ptr < parent->slots + RADIX_TREE_MAP_SIZE); |
| } |
| #else |
| static inline bool is_sibling_entry(struct radix_tree_node *parent, void *node) |
| { |
| return false; |
| } |
| #endif |
| |
| static inline unsigned long get_slot_offset(struct radix_tree_node *parent, |
| void **slot) |
| { |
| return slot - parent->slots; |
| } |
| |
| static unsigned int radix_tree_descend(struct radix_tree_node *parent, |
| struct radix_tree_node **nodep, unsigned long index) |
| { |
| unsigned int offset = (index >> parent->shift) & RADIX_TREE_MAP_MASK; |
| void **entry = rcu_dereference_raw(parent->slots[offset]); |
| |
| #ifdef CONFIG_RADIX_TREE_MULTIORDER |
| if (radix_tree_is_internal_node(entry)) { |
| if (is_sibling_entry(parent, entry)) { |
| void **sibentry = (void **) entry_to_node(entry); |
| offset = get_slot_offset(parent, sibentry); |
| entry = rcu_dereference_raw(*sibentry); |
| } |
| } |
| #endif |
| |
| *nodep = (void *)entry; |
| return offset; |
| } |
| |
| 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 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 int)root->gfp_mask & (1 << (tag + __GFP_BITS_SHIFT)); |
| } |
| |
| static inline unsigned root_tags_get(struct radix_tree_root *root) |
| { |
| return (__force unsigned)root->gfp_mask >> __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) |
| { |
| unsigned idx; |
| for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) { |
| if (node->tags[tag][idx]) |
| return 1; |
| } |
| return 0; |
| } |
| |
| /** |
| * radix_tree_find_next_bit - find the next set bit in a memory region |
| * |
| * @addr: The address to base the search on |
| * @size: The bitmap size in bits |
| * @offset: The bitnumber to start searching at |
| * |
| * Unrollable variant of find_next_bit() for constant size arrays. |
| * Tail bits starting from size to roundup(size, BITS_PER_LONG) must be zero. |
| * Returns next bit offset, or size if nothing found. |
| */ |
| static __always_inline unsigned long |
| radix_tree_find_next_bit(const unsigned long *addr, |
| unsigned long size, unsigned long offset) |
| { |
| if (!__builtin_constant_p(size)) |
| return find_next_bit(addr, size, offset); |
| |
| if (offset < size) { |
| unsigned long tmp; |
| |
| addr += offset / BITS_PER_LONG; |
| tmp = *addr >> (offset % BITS_PER_LONG); |
| if (tmp) |
| return __ffs(tmp) + offset; |
| offset = (offset + BITS_PER_LONG) & ~(BITS_PER_LONG - 1); |
| while (offset < size) { |
| tmp = *++addr; |
| if (tmp) |
| return __ffs(tmp) + offset; |
| offset += BITS_PER_LONG; |
| } |
| } |
| return size; |
| } |
| |
| #ifndef __KERNEL__ |
| static void dump_node(struct radix_tree_node *node, unsigned long index) |
| { |
| unsigned long i; |
| |
| pr_debug("radix node: %p offset %d tags %lx %lx %lx shift %d count %d parent %p\n", |
| node, node->offset, |
| node->tags[0][0], node->tags[1][0], node->tags[2][0], |
| node->shift, node->count, node->parent); |
| |
| for (i = 0; i < RADIX_TREE_MAP_SIZE; i++) { |
| unsigned long first = index | (i << node->shift); |
| unsigned long last = first | ((1UL << node->shift) - 1); |
| void *entry = node->slots[i]; |
| if (!entry) |
| continue; |
| if (is_sibling_entry(node, entry)) { |
| pr_debug("radix sblng %p offset %ld val %p indices %ld-%ld\n", |
| entry, i, |
| *(void **)entry_to_node(entry), |
| first, last); |
| } else if (!radix_tree_is_internal_node(entry)) { |
| pr_debug("radix entry %p offset %ld indices %ld-%ld\n", |
| entry, i, first, last); |
| } else { |
| dump_node(entry_to_node(entry), first); |
| } |
| } |
| } |
| |
| /* For debug */ |
| static void radix_tree_dump(struct radix_tree_root *root) |
| { |
| pr_debug("radix root: %p rnode %p tags %x\n", |
| root, root->rnode, |
| root->gfp_mask >> __GFP_BITS_SHIFT); |
| if (!radix_tree_is_internal_node(root->rnode)) |
| return; |
| dump_node(entry_to_node(root->rnode), 0); |
| } |
| #endif |
| |
| /* |
| * 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); |
| |
| /* |
| * Preload code isn't irq safe and it doesn't make sense to use |
| * preloading during an interrupt anyway as all the allocations have |
| * to be atomic. So just do normal allocation when in interrupt. |
| */ |
| if (!gfpflags_allow_blocking(gfp_mask) && !in_interrupt()) { |
| struct radix_tree_preload *rtp; |
| |
| /* |
| * Even if the caller has preloaded, try to allocate from the |
| * cache first for the new node to get accounted to the memory |
| * cgroup. |
| */ |
| ret = kmem_cache_alloc(radix_tree_node_cachep, |
| gfp_mask | __GFP_NOWARN); |
| if (ret) |
| goto out; |
| |
| /* |
| * Provided the caller has preloaded here, we will always |
| * succeed in getting a node here (and never reach |
| * kmem_cache_alloc) |
| */ |
| rtp = this_cpu_ptr(&radix_tree_preloads); |
| if (rtp->nr) { |
| ret = rtp->nodes; |
| rtp->nodes = ret->private_data; |
| ret->private_data = NULL; |
| rtp->nr--; |
| } |
| /* |
| * Update the allocation stack trace as this is more useful |
| * for debugging. |
| */ |
| kmemleak_update_trace(ret); |
| goto out; |
| } |
| ret = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask); |
| out: |
| BUG_ON(radix_tree_is_internal_node(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); |
| int i; |
| |
| /* |
| * 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. |
| */ |
| for (i = 0; i < RADIX_TREE_MAX_TAGS; i++) |
| tag_clear(node, i, 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_DIRECT_RECLAIM being passed to INIT_RADIX_TREE(). |
| */ |
| static int __radix_tree_preload(gfp_t gfp_mask, int nr) |
| { |
| struct radix_tree_preload *rtp; |
| struct radix_tree_node *node; |
| int ret = -ENOMEM; |
| |
| /* |
| * Nodes preloaded by one cgroup can be be used by another cgroup, so |
| * they should never be accounted to any particular memory cgroup. |
| */ |
| gfp_mask &= ~__GFP_ACCOUNT; |
| |
| preempt_disable(); |
| rtp = this_cpu_ptr(&radix_tree_preloads); |
| while (rtp->nr < nr) { |
| preempt_enable(); |
| node = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask); |
| if (node == NULL) |
| goto out; |
| preempt_disable(); |
| rtp = this_cpu_ptr(&radix_tree_preloads); |
| if (rtp->nr < nr) { |
| node->private_data = rtp->nodes; |
| rtp->nodes = node; |
| rtp->nr++; |
| } else { |
| kmem_cache_free(radix_tree_node_cachep, node); |
| } |
| } |
| ret = 0; |
| out: |
| return ret; |
| } |
| |
| /* |
| * 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_DIRECT_RECLAIM being passed to INIT_RADIX_TREE(). |
| */ |
| int radix_tree_preload(gfp_t gfp_mask) |
| { |
| /* Warn on non-sensical use... */ |
| WARN_ON_ONCE(!gfpflags_allow_blocking(gfp_mask)); |
| return __radix_tree_preload(gfp_mask, RADIX_TREE_PRELOAD_SIZE); |
| } |
| EXPORT_SYMBOL(radix_tree_preload); |
| |
| /* |
| * The same as above function, except we don't guarantee preloading happens. |
| * We do it, if we decide it helps. On success, return zero with preemption |
| * disabled. On error, return -ENOMEM with preemption not disabled. |
| */ |
| int radix_tree_maybe_preload(gfp_t gfp_mask) |
| { |
| if (gfpflags_allow_blocking(gfp_mask)) |
| return __radix_tree_preload(gfp_mask, RADIX_TREE_PRELOAD_SIZE); |
| /* Preloading doesn't help anything with this gfp mask, skip it */ |
| preempt_disable(); |
| return 0; |
| } |
| EXPORT_SYMBOL(radix_tree_maybe_preload); |
| |
| /* |
| * The same as function above, but preload number of nodes required to insert |
| * (1 << order) continuous naturally-aligned elements. |
| */ |
| int radix_tree_maybe_preload_order(gfp_t gfp_mask, int order) |
| { |
| unsigned long nr_subtrees; |
| int nr_nodes, subtree_height; |
| |
| /* Preloading doesn't help anything with this gfp mask, skip it */ |
| if (!gfpflags_allow_blocking(gfp_mask)) { |
| preempt_disable(); |
| return 0; |
| } |
| |
| /* |
| * Calculate number and height of fully populated subtrees it takes to |
| * store (1 << order) elements. |
| */ |
| nr_subtrees = 1 << order; |
| for (subtree_height = 0; nr_subtrees > RADIX_TREE_MAP_SIZE; |
| subtree_height++) |
| nr_subtrees >>= RADIX_TREE_MAP_SHIFT; |
| |
| /* |
| * The worst case is zero height tree with a single item at index 0 and |
| * then inserting items starting at ULONG_MAX - (1 << order). |
| * |
| * This requires RADIX_TREE_MAX_PATH nodes to build branch from root to |
| * 0-index item. |
| */ |
| nr_nodes = RADIX_TREE_MAX_PATH; |
| |
| /* Plus branch to fully populated subtrees. */ |
| nr_nodes += RADIX_TREE_MAX_PATH - subtree_height; |
| |
| /* Root node is shared. */ |
| nr_nodes--; |
| |
| /* Plus nodes required to build subtrees. */ |
| nr_nodes += nr_subtrees * height_to_maxnodes[subtree_height]; |
| |
| return __radix_tree_preload(gfp_mask, nr_nodes); |
| } |
| |
| /* |
| * The maximum index which can be stored in a radix tree |
| */ |
| static inline unsigned long shift_maxindex(unsigned int shift) |
| { |
| return (RADIX_TREE_MAP_SIZE << shift) - 1; |
| } |
| |
| static inline unsigned long node_maxindex(struct radix_tree_node *node) |
| { |
| return shift_maxindex(node->shift); |
| } |
| |
| static unsigned radix_tree_load_root(struct radix_tree_root *root, |
| struct radix_tree_node **nodep, unsigned long *maxindex) |
| { |
| struct radix_tree_node *node = rcu_dereference_raw(root->rnode); |
| |
| *nodep = node; |
| |
| if (likely(radix_tree_is_internal_node(node))) { |
| node = entry_to_node(node); |
| *maxindex = node_maxindex(node); |
| return node->shift + RADIX_TREE_MAP_SHIFT; |
| } |
| |
| *maxindex = 0; |
| return 0; |
| } |
| |
| /* |
| * Extend a radix tree so it can store key @index. |
| */ |
| static int radix_tree_extend(struct radix_tree_root *root, |
| unsigned long index, unsigned int shift) |
| { |
| struct radix_tree_node *slot; |
| unsigned int maxshift; |
| int tag; |
| |
| /* Figure out what the shift should be. */ |
| maxshift = shift; |
| while (index > shift_maxindex(maxshift)) |
| maxshift += RADIX_TREE_MAP_SHIFT; |
| |
| slot = root->rnode; |
| if (!slot) |
| goto out; |
| |
| do { |
| struct radix_tree_node *node = radix_tree_node_alloc(root); |
| |
| if (!node) |
| return -ENOMEM; |
| |
| /* 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); |
| } |
| |
| BUG_ON(shift > BITS_PER_LONG); |
| node->shift = shift; |
| node->offset = 0; |
| node->count = 1; |
| node->parent = NULL; |
| if (radix_tree_is_internal_node(slot)) |
| entry_to_node(slot)->parent = node; |
| node->slots[0] = slot; |
| slot = node_to_entry(node); |
| rcu_assign_pointer(root->rnode, slot); |
| shift += RADIX_TREE_MAP_SHIFT; |
| } while (shift <= maxshift); |
| out: |
| return maxshift + RADIX_TREE_MAP_SHIFT; |
| } |
| |
| /** |
| * __radix_tree_create - create a slot in a radix tree |
| * @root: radix tree root |
| * @index: index key |
| * @order: index occupies 2^order aligned slots |
| * @nodep: returns node |
| * @slotp: returns slot |
| * |
| * Create, if necessary, and return the node and slot for an item |
| * at position @index in the radix tree @root. |
| * |
| * Until there is more than one item in the tree, no nodes are |
| * allocated and @root->rnode is used as a direct slot instead of |
| * pointing to a node, in which case *@nodep will be NULL. |
| * |
| * Returns -ENOMEM, or 0 for success. |
| */ |
| int __radix_tree_create(struct radix_tree_root *root, unsigned long index, |
| unsigned order, struct radix_tree_node **nodep, |
| void ***slotp) |
| { |
| struct radix_tree_node *node = NULL, *child; |
| void **slot = (void **)&root->rnode; |
| unsigned long maxindex; |
| unsigned int shift, offset = 0; |
| unsigned long max = index | ((1UL << order) - 1); |
| |
| shift = radix_tree_load_root(root, &child, &maxindex); |
| |
| /* Make sure the tree is high enough. */ |
| if (max > maxindex) { |
| int error = radix_tree_extend(root, max, shift); |
| if (error < 0) |
| return error; |
| shift = error; |
| child = root->rnode; |
| if (order == shift) |
| shift += RADIX_TREE_MAP_SHIFT; |
| } |
| |
| while (shift > order) { |
| shift -= RADIX_TREE_MAP_SHIFT; |
| if (child == NULL) { |
| /* Have to add a child node. */ |
| child = radix_tree_node_alloc(root); |
| if (!child) |
| return -ENOMEM; |
| child->shift = shift; |
| child->offset = offset; |
| child->parent = node; |
| rcu_assign_pointer(*slot, node_to_entry(child)); |
| if (node) |
| node->count++; |
| } else if (!radix_tree_is_internal_node(child)) |
| break; |
| |
| /* Go a level down */ |
| node = entry_to_node(child); |
| offset = radix_tree_descend(node, &child, index); |
| slot = &node->slots[offset]; |
| } |
| |
| #ifdef CONFIG_RADIX_TREE_MULTIORDER |
| /* Insert pointers to the canonical entry */ |
| if (order > shift) { |
| unsigned i, n = 1 << (order - shift); |
| offset = offset & ~(n - 1); |
| slot = &node->slots[offset]; |
| child = node_to_entry(slot); |
| for (i = 0; i < n; i++) { |
| if (slot[i]) |
| return -EEXIST; |
| } |
| |
| for (i = 1; i < n; i++) { |
| rcu_assign_pointer(slot[i], child); |
| node->count++; |
| } |
| } |
| #endif |
| |
| if (nodep) |
| *nodep = node; |
| if (slotp) |
| *slotp = slot; |
| return 0; |
| } |
| |
| /** |
| * __radix_tree_insert - insert into a radix tree |
| * @root: radix tree root |
| * @index: index key |
| * @order: key covers the 2^order indices around index |
| * @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, |
| unsigned order, void *item) |
| { |
| struct radix_tree_node *node; |
| void **slot; |
| int error; |
| |
| BUG_ON(radix_tree_is_internal_node(item)); |
| |
| error = __radix_tree_create(root, index, order, &node, &slot); |
| if (error) |
| return error; |
| if (*slot != NULL) |
| return -EEXIST; |
| rcu_assign_pointer(*slot, item); |
| |
| if (node) { |
| unsigned offset = get_slot_offset(node, slot); |
| node->count++; |
| BUG_ON(tag_get(node, 0, offset)); |
| BUG_ON(tag_get(node, 1, offset)); |
| BUG_ON(tag_get(node, 2, offset)); |
| } else { |
| BUG_ON(root_tags_get(root)); |
| } |
| |
| return 0; |
| } |
| EXPORT_SYMBOL(__radix_tree_insert); |
| |
| /** |
| * __radix_tree_lookup - lookup an item in a radix tree |
| * @root: radix tree root |
| * @index: index key |
| * @nodep: returns node |
| * @slotp: returns slot |
| * |
| * Lookup and return the item at position @index in the radix |
| * tree @root. |
| * |
| * Until there is more than one item in the tree, no nodes are |
| * allocated and @root->rnode is used as a direct slot instead of |
| * pointing to a node, in which case *@nodep will be NULL. |
| */ |
| void *__radix_tree_lookup(struct radix_tree_root *root, unsigned long index, |
| struct radix_tree_node **nodep, void ***slotp) |
| { |
| struct radix_tree_node *node, *parent; |
| unsigned long maxindex; |
| void **slot; |
| |
| restart: |
| parent = NULL; |
| slot = (void **)&root->rnode; |
| radix_tree_load_root(root, &node, &maxindex); |
| if (index > maxindex) |
| return NULL; |
| |
| while (radix_tree_is_internal_node(node)) { |
| unsigned offset; |
| |
| if (node == RADIX_TREE_RETRY) |
| goto restart; |
| parent = entry_to_node(node); |
| offset = radix_tree_descend(parent, &node, index); |
| slot = parent->slots + offset; |
| } |
| |
| if (nodep) |
| *nodep = parent; |
| if (slotp) |
| *slotp = slot; |
| return 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) |
| { |
| void **slot; |
| |
| if (!__radix_tree_lookup(root, index, NULL, &slot)) |
| return NULL; |
| return slot; |
| } |
| 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(root, index, NULL, 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 (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) |
| { |
| struct radix_tree_node *node, *parent; |
| unsigned long maxindex; |
| |
| radix_tree_load_root(root, &node, &maxindex); |
| BUG_ON(index > maxindex); |
| |
| while (radix_tree_is_internal_node(node)) { |
| unsigned offset; |
| |
| parent = entry_to_node(node); |
| offset = radix_tree_descend(parent, &node, index); |
| BUG_ON(!node); |
| |
| if (!tag_get(parent, tag, offset)) |
| tag_set(parent, tag, offset); |
| } |
| |
| /* set the root's tag bit */ |
| if (!root_tag_get(root, tag)) |
| root_tag_set(root, tag); |
| |
| return node; |
| } |
| EXPORT_SYMBOL(radix_tree_tag_set); |
| |
| static void node_tag_clear(struct radix_tree_root *root, |
| struct radix_tree_node *node, |
| unsigned int tag, unsigned int offset) |
| { |
| while (node) { |
| if (!tag_get(node, tag, offset)) |
| return; |
| tag_clear(node, tag, offset); |
| if (any_tag_set(node, tag)) |
| return; |
| |
| offset = node->offset; |
| node = node->parent; |
| } |
| |
| /* clear the root's tag bit */ |
| if (root_tag_get(root, tag)) |
| root_tag_clear(root, tag); |
| } |
| |
| /** |
| * 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) |
| { |
| struct radix_tree_node *node, *parent; |
| unsigned long maxindex; |
| int uninitialized_var(offset); |
| |
| radix_tree_load_root(root, &node, &maxindex); |
| if (index > maxindex) |
| return NULL; |
| |
| parent = NULL; |
| |
| while (radix_tree_is_internal_node(node)) { |
| parent = entry_to_node(node); |
| offset = radix_tree_descend(parent, &node, index); |
| } |
| |
| if (node) |
| node_tag_clear(root, parent, tag, offset); |
| |
| return node; |
| } |
| 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 |
| * |
| * Note that the return value of this function may not be relied on, even if |
| * the RCU lock is held, unless tag modification and node deletion are excluded |
| * from concurrency. |
| */ |
| int radix_tree_tag_get(struct radix_tree_root *root, |
| unsigned long index, unsigned int tag) |
| { |
| struct radix_tree_node *node, *parent; |
| unsigned long maxindex; |
| |
| if (!root_tag_get(root, tag)) |
| return 0; |
| |
| radix_tree_load_root(root, &node, &maxindex); |
| if (index > maxindex) |
| return 0; |
| if (node == NULL) |
| return 0; |
| |
| while (radix_tree_is_internal_node(node)) { |
| unsigned offset; |
| |
| parent = entry_to_node(node); |
| offset = radix_tree_descend(parent, &node, index); |
| |
| if (!node) |
| return 0; |
| if (!tag_get(parent, tag, offset)) |
| return 0; |
| if (node == RADIX_TREE_RETRY) |
| break; |
| } |
| |
| return 1; |
| } |
| EXPORT_SYMBOL(radix_tree_tag_get); |
| |
| static inline void __set_iter_shift(struct radix_tree_iter *iter, |
| unsigned int shift) |
| { |
| #ifdef CONFIG_RADIX_TREE_MULTIORDER |
| iter->shift = shift; |
| #endif |
| } |
| |
| /** |
| * radix_tree_next_chunk - find next chunk of slots for iteration |
| * |
| * @root: radix tree root |
| * @iter: iterator state |
| * @flags: RADIX_TREE_ITER_* flags and tag index |
| * Returns: pointer to chunk first slot, or NULL if iteration is over |
| */ |
| void **radix_tree_next_chunk(struct radix_tree_root *root, |
| struct radix_tree_iter *iter, unsigned flags) |
| { |
| unsigned tag = flags & RADIX_TREE_ITER_TAG_MASK; |
| struct radix_tree_node *node, *child; |
| unsigned long index, offset, maxindex; |
| |
| if ((flags & RADIX_TREE_ITER_TAGGED) && !root_tag_get(root, tag)) |
| return NULL; |
| |
| /* |
| * Catch next_index overflow after ~0UL. iter->index never overflows |
| * during iterating; it can be zero only at the beginning. |
| * And we cannot overflow iter->next_index in a single step, |
| * because RADIX_TREE_MAP_SHIFT < BITS_PER_LONG. |
| * |
| * This condition also used by radix_tree_next_slot() to stop |
| * contiguous iterating, and forbid swithing to the next chunk. |
| */ |
| index = iter->next_index; |
| if (!index && iter->index) |
| return NULL; |
| |
| restart: |
| radix_tree_load_root(root, &child, &maxindex); |
| if (index > maxindex) |
| return NULL; |
| if (!child) |
| return NULL; |
| |
| if (!radix_tree_is_internal_node(child)) { |
| /* Single-slot tree */ |
| iter->index = index; |
| iter->next_index = maxindex + 1; |
| iter->tags = 1; |
| __set_iter_shift(iter, 0); |
| return (void **)&root->rnode; |
| } |
| |
| do { |
| node = entry_to_node(child); |
| offset = radix_tree_descend(node, &child, index); |
| |
| if ((flags & RADIX_TREE_ITER_TAGGED) ? |
| !tag_get(node, tag, offset) : !child) { |
| /* Hole detected */ |
| if (flags & RADIX_TREE_ITER_CONTIG) |
| return NULL; |
| |
| if (flags & RADIX_TREE_ITER_TAGGED) |
| offset = radix_tree_find_next_bit( |
| node->tags[tag], |
| RADIX_TREE_MAP_SIZE, |
| offset + 1); |
| else |
| while (++offset < RADIX_TREE_MAP_SIZE) { |
| void *slot = node->slots[offset]; |
| if (is_sibling_entry(node, slot)) |
| continue; |
| if (slot) |
| break; |
| } |
| index &= ~node_maxindex(node); |
| index += offset << node->shift; |
| /* Overflow after ~0UL */ |
| if (!index) |
| return NULL; |
| if (offset == RADIX_TREE_MAP_SIZE) |
| goto restart; |
| child = rcu_dereference_raw(node->slots[offset]); |
| } |
| |
| if ((child == NULL) || (child == RADIX_TREE_RETRY)) |
| goto restart; |
| } while (radix_tree_is_internal_node(child)); |
| |
| /* Update the iterator state */ |
| iter->index = (index &~ node_maxindex(node)) | (offset << node->shift); |
| iter->next_index = (index | node_maxindex(node)) + 1; |
| __set_iter_shift(iter, node->shift); |
| |
| /* Construct iter->tags bit-mask from node->tags[tag] array */ |
| if (flags & RADIX_TREE_ITER_TAGGED) { |
| unsigned tag_long, tag_bit; |
| |
| tag_long = offset / BITS_PER_LONG; |
| tag_bit = offset % BITS_PER_LONG; |
| iter->tags = node->tags[tag][tag_long] >> tag_bit; |
| /* This never happens if RADIX_TREE_TAG_LONGS == 1 */ |
| if (tag_long < RADIX_TREE_TAG_LONGS - 1) { |
| /* Pick tags from next element */ |
| if (tag_bit) |
| iter->tags |= node->tags[tag][tag_long + 1] << |
| (BITS_PER_LONG - tag_bit); |
| /* Clip chunk size, here only BITS_PER_LONG tags */ |
| iter->next_index = index + BITS_PER_LONG; |
| } |
| } |
| |
| return node->slots + offset; |
| } |
| EXPORT_SYMBOL(radix_tree_next_chunk); |
| |
| /** |
| * radix_tree_range_tag_if_tagged - for each item in given range set given |
| * tag if item has another tag set |
| * @root: radix tree root |
| * @first_indexp: pointer to a starting index of a range to scan |
| * @last_index: last index of a range to scan |
| * @nr_to_tag: maximum number items to tag |
| * @iftag: tag index to test |
| * @settag: tag index to set if tested tag is set |
| * |
| * This function scans range of radix tree from first_index to last_index |
| * (inclusive). For each item in the range if iftag is set, the function sets |
| * also settag. The function stops either after tagging nr_to_tag items or |
| * after reaching last_index. |
| * |
| * The tags must be set from the leaf level only and propagated back up the |
| * path to the root. We must do this so that we resolve the full path before |
| * setting any tags on intermediate nodes. If we set tags as we descend, then |
| * we can get to the leaf node and find that the index that has the iftag |
| * set is outside the range we are scanning. This reults in dangling tags and |
| * can lead to problems with later tag operations (e.g. livelocks on lookups). |
| * |
| * The function returns the number of leaves where the tag was set and sets |
| * *first_indexp to the first unscanned index. |
| * WARNING! *first_indexp can wrap if last_index is ULONG_MAX. Caller must |
| * be prepared to handle that. |
| */ |
| unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root, |
| unsigned long *first_indexp, unsigned long last_index, |
| unsigned long nr_to_tag, |
| unsigned int iftag, unsigned int settag) |
| { |
| struct radix_tree_node *parent, *node, *child; |
| unsigned long maxindex; |
| unsigned long tagged = 0; |
| unsigned long index = *first_indexp; |
| |
| radix_tree_load_root(root, &child, &maxindex); |
| last_index = min(last_index, maxindex); |
| if (index > last_index) |
| return 0; |
| if (!nr_to_tag) |
| return 0; |
| if (!root_tag_get(root, iftag)) { |
| *first_indexp = last_index + 1; |
| return 0; |
| } |
| if (!radix_tree_is_internal_node(child)) { |
| *first_indexp = last_index + 1; |
| root_tag_set(root, settag); |
| return 1; |
| } |
| |
| node = entry_to_node(child); |
| |
| for (;;) { |
| unsigned offset = radix_tree_descend(node, &child, index); |
| if (!child) |
| goto next; |
| if (!tag_get(node, iftag, offset)) |
| goto next; |
| /* Sibling slots never have tags set on them */ |
| if (radix_tree_is_internal_node(child)) { |
| node = entry_to_node(child); |
| continue; |
| } |
| |
| /* tag the leaf */ |
| tagged++; |
| tag_set(node, settag, offset); |
| |
| /* walk back up the path tagging interior nodes */ |
| parent = node; |
| for (;;) { |
| offset = parent->offset; |
| parent = parent->parent; |
| if (!parent) |
| break; |
| /* stop if we find a node with the tag already set */ |
| if (tag_get(parent, settag, offset)) |
| break; |
| tag_set(parent, settag, offset); |
| } |
| next: |
| /* Go to next entry in node */ |
| index = ((index >> node->shift) + 1) << node->shift; |
| /* Overflow can happen when last_index is ~0UL... */ |
| if (index > last_index || !index) |
| break; |
| offset = (index >> node->shift) & RADIX_TREE_MAP_MASK; |
| while (offset == 0) { |
| /* |
| * We've fully scanned this node. Go up. Because |
| * last_index is guaranteed to be in the tree, what |
| * we do below cannot wander astray. |
| */ |
| node = node->parent; |
| offset = (index >> node->shift) & RADIX_TREE_MAP_MASK; |
| } |
| if (is_sibling_entry(node, node->slots[offset])) |
| goto next; |
| if (tagged >= nr_to_tag) |
| break; |
| } |
| /* |
| * We need not to tag the root tag if there is no tag which is set with |
| * settag within the range from *first_indexp to last_index. |
| */ |
| if (tagged > 0) |
| root_tag_set(root, settag); |
| *first_indexp = index; |
| |
| return tagged; |
| } |
| EXPORT_SYMBOL(radix_tree_range_tag_if_tagged); |
| |
| /** |
| * 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) |
| { |
| struct radix_tree_iter iter; |
| void **slot; |
| unsigned int ret = 0; |
| |
| if (unlikely(!max_items)) |
| return 0; |
| |
| radix_tree_for_each_slot(slot, root, &iter, first_index) { |
| results[ret] = rcu_dereference_raw(*slot); |
| if (!results[ret]) |
| continue; |
| if (radix_tree_is_internal_node(results[ret])) { |
| slot = radix_tree_iter_retry(&iter); |
| continue; |
| } |
| if (++ret == max_items) |
| break; |
| } |
| |
| 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 |
| * @indices: where their indices should be placed (but usually NULL) |
| * @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 *indices, |
| unsigned long first_index, unsigned int max_items) |
| { |
| struct radix_tree_iter iter; |
| void **slot; |
| unsigned int ret = 0; |
| |
| if (unlikely(!max_items)) |
| return 0; |
| |
| radix_tree_for_each_slot(slot, root, &iter, first_index) { |
| results[ret] = slot; |
| if (indices) |
| indices[ret] = iter.index; |
| if (++ret == max_items) |
| break; |
| } |
| |
| return ret; |
| } |
| EXPORT_SYMBOL(radix_tree_gang_lookup_slot); |
| |
| /** |
| * 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_iter iter; |
| void **slot; |
| unsigned int ret = 0; |
| |
| if (unlikely(!max_items)) |
| return 0; |
| |
| radix_tree_for_each_tagged(slot, root, &iter, first_index, tag) { |
| results[ret] = rcu_dereference_raw(*slot); |
| if (!results[ret]) |
| continue; |
| if (radix_tree_is_internal_node(results[ret])) { |
| slot = radix_tree_iter_retry(&iter); |
| continue; |
| } |
| if (++ret == max_items) |
| break; |
| } |
| |
| 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_iter iter; |
| void **slot; |
| unsigned int ret = 0; |
| |
| if (unlikely(!max_items)) |
| return 0; |
| |
| radix_tree_for_each_tagged(slot, root, &iter, first_index, tag) { |
| results[ret] = slot; |
| if (++ret == max_items) |
| break; |
| } |
| |
| return ret; |
| } |
| EXPORT_SYMBOL(radix_tree_gang_lookup_tag_slot); |
| |
| #if defined(CONFIG_SHMEM) && defined(CONFIG_SWAP) |
| #include <linux/sched.h> /* for cond_resched() */ |
| |
| struct locate_info { |
| unsigned long found_index; |
| bool stop; |
| }; |
| |
| /* |
| * This linear search is at present only useful to shmem_unuse_inode(). |
| */ |
| static unsigned long __locate(struct radix_tree_node *slot, void *item, |
| unsigned long index, struct locate_info *info) |
| { |
| unsigned long i; |
| |
| do { |
| unsigned int shift = slot->shift; |
| |
| for (i = (index >> shift) & RADIX_TREE_MAP_MASK; |
| i < RADIX_TREE_MAP_SIZE; |
| i++, index += (1UL << shift)) { |
| struct radix_tree_node *node = |
| rcu_dereference_raw(slot->slots[i]); |
| if (node == RADIX_TREE_RETRY) |
| goto out; |
| if (!radix_tree_is_internal_node(node)) { |
| if (node == item) { |
| info->found_index = index; |
| info->stop = true; |
| goto out; |
| } |
| continue; |
| } |
| node = entry_to_node(node); |
| if (is_sibling_entry(slot, node)) |
| continue; |
| slot = node; |
| break; |
| } |
| } while (i < RADIX_TREE_MAP_SIZE); |
| |
| out: |
| if ((index == 0) && (i == RADIX_TREE_MAP_SIZE)) |
| info->stop = true; |
| return index; |
| } |
| |
| /** |
| * radix_tree_locate_item - search through radix tree for item |
| * @root: radix tree root |
| * @item: item to be found |
| * |
| * Returns index where item was found, or -1 if not found. |
| * Caller must hold no lock (since this time-consuming function needs |
| * to be preemptible), and must check afterwards if item is still there. |
| */ |
| unsigned long radix_tree_locate_item(struct radix_tree_root *root, void *item) |
| { |
| struct radix_tree_node *node; |
| unsigned long max_index; |
| unsigned long cur_index = 0; |
| struct locate_info info = { |
| .found_index = -1, |
| .stop = false, |
| }; |
| |
| do { |
| rcu_read_lock(); |
| node = rcu_dereference_raw(root->rnode); |
| if (!radix_tree_is_internal_node(node)) { |
| rcu_read_unlock(); |
| if (node == item) |
| info.found_index = 0; |
| break; |
| } |
| |
| node = entry_to_node(node); |
| |
| max_index = node_maxindex(node); |
| if (cur_index > max_index) { |
| rcu_read_unlock(); |
| break; |
| } |
| |
| cur_index = __locate(node, item, cur_index, &info); |
| rcu_read_unlock(); |
| cond_resched(); |
| } while (!info.stop && cur_index <= max_index); |
| |
| return info.found_index; |
| } |
| #else |
| unsigned long radix_tree_locate_item(struct radix_tree_root *root, void *item) |
| { |
| return -1; |
| } |
| #endif /* CONFIG_SHMEM && CONFIG_SWAP */ |
| |
| /** |
| * radix_tree_shrink - shrink radix tree to minimum height |
| * @root radix tree root |
| */ |
| static inline bool radix_tree_shrink(struct radix_tree_root *root) |
| { |
| bool shrunk = false; |
| |
| for (;;) { |
| struct radix_tree_node *node = root->rnode; |
| struct radix_tree_node *child; |
| |
| if (!radix_tree_is_internal_node(node)) |
| break; |
| node = entry_to_node(node); |
| |
| /* |
| * The candidate node has more than one child, or its child |
| * is not at the leftmost slot, or the child is a multiorder |
| * entry, we cannot shrink. |
| */ |
| if (node->count != 1) |
| break; |
| child = node->slots[0]; |
| if (!child) |
| break; |
| if (!radix_tree_is_internal_node(child) && node->shift) |
| break; |
| |
| if (radix_tree_is_internal_node(child)) |
| entry_to_node(child)->parent = NULL; |
| |
| /* |
| * 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 |
| * (node->slots[0]), it will be safe to dereference the new |
| * one (root->rnode) as far as dependent read barriers go. |
| */ |
| root->rnode = child; |
| |
| /* |
| * We have a dilemma here. The node's slot[0] must not be |
| * NULLed in case there are concurrent lookups expecting to |
| * find the item. However if this was a bottom-level node, |
| * then it may be subject to the slot pointer being visible |
| * to callers dereferencing it. If item corresponding to |
| * slot[0] is subsequently deleted, these callers would expect |
| * their slot to become empty sooner or later. |
| * |
| * For example, lockless pagecache will look up a slot, deref |
| * the page pointer, and if the page has 0 refcount it means it |
| * was concurrently deleted from pagecache so try the deref |
| * again. Fortunately there is already a requirement for logic |
| * to retry the entire slot lookup -- the indirect pointer |
| * problem (replacing direct root node with an indirect pointer |
| * also results in a stale slot). So tag the slot as indirect |
| * to force callers to retry. |
| */ |
| if (!radix_tree_is_internal_node(child)) |
| node->slots[0] = RADIX_TREE_RETRY; |
| |
| radix_tree_node_free(node); |
| shrunk = true; |
| } |
| |
| return shrunk; |
| } |
| |
| /** |
| * __radix_tree_delete_node - try to free node after clearing a slot |
| * @root: radix tree root |
| * @node: node containing @index |
| * |
| * After clearing the slot at @index in @node from radix tree |
| * rooted at @root, call this function to attempt freeing the |
| * node and shrinking the tree. |
| * |
| * Returns %true if @node was freed, %false otherwise. |
| */ |
| bool __radix_tree_delete_node(struct radix_tree_root *root, |
| struct radix_tree_node *node) |
| { |
| bool deleted = false; |
| |
| do { |
| struct radix_tree_node *parent; |
| |
| if (node->count) { |
| if (node == entry_to_node(root->rnode)) |
| deleted |= radix_tree_shrink(root); |
| return deleted; |
| } |
| |
| parent = node->parent; |
| if (parent) { |
| parent->slots[node->offset] = NULL; |
| parent->count--; |
| } else { |
| root_tag_clear_all(root); |
| root->rnode = NULL; |
| } |
| |
| radix_tree_node_free(node); |
| deleted = true; |
| |
| node = parent; |
| } while (node); |
| |
| return deleted; |
| } |
| |
| static inline void delete_sibling_entries(struct radix_tree_node *node, |
| void *ptr, unsigned offset) |
| { |
| #ifdef CONFIG_RADIX_TREE_MULTIORDER |
| int i; |
| for (i = 1; offset + i < RADIX_TREE_MAP_SIZE; i++) { |
| if (node->slots[offset + i] != ptr) |
| break; |
| node->slots[offset + i] = NULL; |
| node->count--; |
| } |
| #endif |
| } |
| |
| /** |
| * radix_tree_delete_item - delete an item from a radix tree |
| * @root: radix tree root |
| * @index: index key |
| * @item: expected item |
| * |
| * Remove @item at @index from the radix tree rooted at @root. |
| * |
| * Returns the address of the deleted item, or NULL if it was not present |
| * or the entry at the given @index was not @item. |
| */ |
| void *radix_tree_delete_item(struct radix_tree_root *root, |
| unsigned long index, void *item) |
| { |
| struct radix_tree_node *node; |
| unsigned int offset; |
| void **slot; |
| void *entry; |
| int tag; |
| |
| entry = __radix_tree_lookup(root, index, &node, &slot); |
| if (!entry) |
| return NULL; |
| |
| if (item && entry != item) |
| return NULL; |
| |
| if (!node) { |
| root_tag_clear_all(root); |
| root->rnode = NULL; |
| return entry; |
| } |
| |
| offset = get_slot_offset(node, slot); |
| |
| /* Clear all tags associated with the item to be deleted. */ |
| for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) |
| node_tag_clear(root, node, tag, offset); |
| |
| delete_sibling_entries(node, node_to_entry(slot), offset); |
| node->slots[offset] = NULL; |
| node->count--; |
| |
| __radix_tree_delete_node(root, node); |
| |
| return entry; |
| } |
| EXPORT_SYMBOL(radix_tree_delete_item); |
| |
| /** |
| * radix_tree_delete - delete an item from a radix tree |
| * @root: radix tree root |
| * @index: index key |
| * |
| * Remove the item at @index from the radix tree rooted at @root. |
| * |
| * Returns the address of the deleted item, or NULL if it was not present. |
| */ |
| void *radix_tree_delete(struct radix_tree_root *root, unsigned long index) |
| { |
| return radix_tree_delete_item(root, index, NULL); |
| } |
| EXPORT_SYMBOL(radix_tree_delete); |
| |
| void radix_tree_clear_tags(struct radix_tree_root *root, |
| struct radix_tree_node *node, |
| void **slot) |
| { |
| if (node) { |
| unsigned int tag, offset = get_slot_offset(node, slot); |
| for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) |
| node_tag_clear(root, node, tag, offset); |
| } else { |
| /* Clear root node tags */ |
| root->gfp_mask &= __GFP_BITS_MASK; |
| } |
| } |
| |
| /** |
| * 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 *arg) |
| { |
| struct radix_tree_node *node = arg; |
| |
| memset(node, 0, sizeof(*node)); |
| INIT_LIST_HEAD(&node->private_list); |
| } |
| |
| static __init unsigned long __maxindex(unsigned int height) |
| { |
| 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_maxnodes(void) |
| { |
| unsigned long height_to_maxindex[RADIX_TREE_MAX_PATH + 1]; |
| unsigned int i, j; |
| |
| for (i = 0; i < ARRAY_SIZE(height_to_maxindex); i++) |
| height_to_maxindex[i] = __maxindex(i); |
| for (i = 0; i < ARRAY_SIZE(height_to_maxnodes); i++) { |
| for (j = i; j > 0; j--) |
| height_to_maxnodes[i] += height_to_maxindex[j - 1] + 1; |
| } |
| } |
| |
| static int radix_tree_callback(struct notifier_block *nfb, |
| unsigned long action, void *hcpu) |
| { |
| int cpu = (long)hcpu; |
| struct radix_tree_preload *rtp; |
| struct radix_tree_node *node; |
| |
| /* Free per-cpu pool of preloaded nodes */ |
| if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) { |
| rtp = &per_cpu(radix_tree_preloads, cpu); |
| while (rtp->nr) { |
| node = rtp->nodes; |
| rtp->nodes = node->private_data; |
| kmem_cache_free(radix_tree_node_cachep, node); |
| 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_maxnodes(); |
| hotcpu_notifier(radix_tree_callback, 0); |
| } |