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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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SPDX-License-Identifier: GPL-2.0-or-later/* * 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 */
#include <linux/bitmap.h>#include <linux/bitops.h>#include <linux/bug.h>#include <linux/cpu.h>#include <linux/errno.h>#include <linux/export.h>#include <linux/idr.h>#include <linux/init.h>#include <linux/kernel.h>#include <linux/kmemleak.h>#include <linux/percpu.h>#include <linux/preempt.h> /* in_interrupt() */#include <linux/radix-tree.h>#include <linux/rcupdate.h>#include <linux/slab.h>#include <linux/string.h>#include <linux/xarray.h>
#include "radix-tree.h"
/* * Radix tree node cache. */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)
/* * The IDR does not have to be as high as the radix tree since it uses * signed integers, not unsigned longs. */#define IDR_INDEX_BITS (8 /* CHAR_BIT */ * sizeof(int) - 1)#define IDR_MAX_PATH (DIV_ROUND_UP(IDR_INDEX_BITS, \ RADIX_TREE_MAP_SHIFT))#define IDR_PRELOAD_SIZE (IDR_MAX_PATH * 2 - 1)
/* * Per-cpu pool of preloaded nodes */DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { .lock = INIT_LOCAL_LOCK(lock),};EXPORT_PER_CPU_SYMBOL_GPL(radix_tree_preloads);
static inline struct radix_tree_node *entry_to_node(void *ptr){ return (void *)((unsigned long)ptr & ~RADIX_TREE_INTERNAL_NODE);}
static inline void *node_to_entry(void *ptr){ return (void *)((unsigned long)ptr | RADIX_TREE_INTERNAL_NODE);}
#define RADIX_TREE_RETRY XA_RETRY_ENTRY
static inline unsigned longget_slot_offset(const struct radix_tree_node *parent, void __rcu **slot){ return parent ? slot - parent->slots : 0;}
static unsigned int radix_tree_descend(const struct radix_tree_node *parent, struct radix_tree_node **nodep, unsigned long index){ unsigned int offset = (index >> parent->shift) & RADIX_TREE_MAP_MASK; void __rcu **entry = rcu_dereference_raw(parent->slots[offset]);
*nodep = (void *)entry; return offset;}
static inline gfp_t root_gfp_mask(const struct radix_tree_root *root){ return root->xa_flags & (__GFP_BITS_MASK & ~GFP_ZONEMASK);}
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(const 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 tag){ root->xa_flags |= (__force gfp_t)(1 << (tag + ROOT_TAG_SHIFT));}
static inline void root_tag_clear(struct radix_tree_root *root, unsigned tag){ root->xa_flags &= (__force gfp_t)~(1 << (tag + ROOT_TAG_SHIFT));}
static inline void root_tag_clear_all(struct radix_tree_root *root){ root->xa_flags &= (__force gfp_t)((1 << ROOT_TAG_SHIFT) - 1);}
static inline int root_tag_get(const struct radix_tree_root *root, unsigned tag){ return (__force int)root->xa_flags & (1 << (tag + ROOT_TAG_SHIFT));}
static inline unsigned root_tags_get(const struct radix_tree_root *root){ return (__force unsigned)root->xa_flags >> ROOT_TAG_SHIFT;}
static inline bool is_idr(const struct radix_tree_root *root){ return !!(root->xa_flags & ROOT_IS_IDR);}
/* * Returns 1 if any slot in the node has this tag set. * Otherwise returns 0. */static inline int any_tag_set(const 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;}
static inline void all_tag_set(struct radix_tree_node *node, unsigned int tag){ bitmap_fill(node->tags[tag], RADIX_TREE_MAP_SIZE);}
/** * radix_tree_find_next_bit - find the next set bit in a memory region * * @node: where to begin the search * @tag: the tag index * @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 longradix_tree_find_next_bit(struct radix_tree_node *node, unsigned int tag, unsigned long offset){ const unsigned long *addr = node->tags[tag];
if (offset < RADIX_TREE_MAP_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 < RADIX_TREE_MAP_SIZE) { tmp = *++addr; if (tmp) return __ffs(tmp) + offset; offset += BITS_PER_LONG; } } return RADIX_TREE_MAP_SIZE;}
static unsigned int iter_offset(const struct radix_tree_iter *iter){ return iter->index & RADIX_TREE_MAP_MASK;}
/* * 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(const struct radix_tree_node *node){ return shift_maxindex(node->shift);}
static unsigned long next_index(unsigned long index, const struct radix_tree_node *node, unsigned long offset){ return (index & ~node_maxindex(node)) + (offset << node->shift);}
/* * 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(gfp_t gfp_mask, struct radix_tree_node *parent, struct radix_tree_root *root, unsigned int shift, unsigned int offset, unsigned int count, unsigned int nr_values){ struct radix_tree_node *ret = NULL;
/* * 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->parent; 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)); if (ret) { ret->shift = shift; ret->offset = offset; ret->count = count; ret->nr_values = nr_values; ret->parent = parent; ret->array = root; } return ret;}
void radix_tree_node_rcu_free(struct rcu_head *head){ struct radix_tree_node *node = container_of(head, struct radix_tree_node, rcu_head);
/* * Must only free zeroed nodes into the slab. We can be left with * non-NULL entries by radix_tree_free_nodes, so clear the entries * and tags here. */ memset(node->slots, 0, sizeof(node->slots)); memset(node->tags, 0, sizeof(node->tags)); INIT_LIST_HEAD(&node->private_list);
kmem_cache_free(radix_tree_node_cachep, node);}
static inline voidradix_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 __must_check int __radix_tree_preload(gfp_t gfp_mask, unsigned nr){ struct radix_tree_preload *rtp; struct radix_tree_node *node; int ret = -ENOMEM;
/* * Nodes preloaded by one cgroup can be used by another cgroup, so * they should never be accounted to any particular memory cgroup. */ gfp_mask &= ~__GFP_ACCOUNT;
local_lock(&radix_tree_preloads.lock); rtp = this_cpu_ptr(&radix_tree_preloads); while (rtp->nr < nr) { local_unlock(&radix_tree_preloads.lock); node = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask); if (node == NULL) goto out; local_lock(&radix_tree_preloads.lock); rtp = this_cpu_ptr(&radix_tree_preloads); if (rtp->nr < nr) { node->parent = 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 */ local_lock(&radix_tree_preloads.lock); return 0;}EXPORT_SYMBOL(radix_tree_maybe_preload);
static unsigned radix_tree_load_root(const struct radix_tree_root *root, struct radix_tree_node **nodep, unsigned long *maxindex){ struct radix_tree_node *node = rcu_dereference_raw(root->xa_head);
*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, gfp_t gfp, unsigned long index, unsigned int shift){ void *entry; unsigned int maxshift; int tag;
/* Figure out what the shift should be. */ maxshift = shift; while (index > shift_maxindex(maxshift)) maxshift += RADIX_TREE_MAP_SHIFT;
entry = rcu_dereference_raw(root->xa_head); if (!entry && (!is_idr(root) || root_tag_get(root, IDR_FREE))) goto out;
do { struct radix_tree_node *node = radix_tree_node_alloc(gfp, NULL, root, shift, 0, 1, 0); if (!node) return -ENOMEM;
if (is_idr(root)) { all_tag_set(node, IDR_FREE); if (!root_tag_get(root, IDR_FREE)) { tag_clear(node, IDR_FREE, 0); root_tag_set(root, IDR_FREE); } } else { /* Propagate the aggregated tag info to the new child */ 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); if (radix_tree_is_internal_node(entry)) { entry_to_node(entry)->parent = node; } else if (xa_is_value(entry)) { /* Moving a value entry root->xa_head to a node */ node->nr_values = 1; } /* * entry was already in the radix tree, so we do not need * rcu_assign_pointer here */ node->slots[0] = (void __rcu *)entry; entry = node_to_entry(node); rcu_assign_pointer(root->xa_head, entry); shift += RADIX_TREE_MAP_SHIFT; } while (shift <= maxshift);out: return maxshift + RADIX_TREE_MAP_SHIFT;}
/** * 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 = rcu_dereference_raw(root->xa_head); 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, we cannot shrink. */ if (node->count != 1) break; child = rcu_dereference_raw(node->slots[0]); if (!child) break;
/* * For an IDR, we must not shrink entry 0 into the root in * case somebody calls idr_replace() with a pointer that * appears to be an internal entry */ if (!node->shift && is_idr(root)) 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->xa_head) as far as dependent read barriers go. */ root->xa_head = (void __rcu *)child; if (is_idr(root) && !tag_get(node, IDR_FREE, 0)) root_tag_clear(root, IDR_FREE);
/* * 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. */ node->count = 0; if (!radix_tree_is_internal_node(child)) { node->slots[0] = (void __rcu *)RADIX_TREE_RETRY; }
WARN_ON_ONCE(!list_empty(&node->private_list)); radix_tree_node_free(node); shrunk = true; }
return shrunk;}
static bool 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_to_entry(node) == rcu_dereference_raw(root->xa_head)) deleted |= radix_tree_shrink(root); return deleted; }
parent = node->parent; if (parent) { parent->slots[node->offset] = NULL; parent->count--; } else { /* * Shouldn't the tags already have all been cleared * by the caller? */ if (!is_idr(root)) root_tag_clear_all(root); root->xa_head = NULL; }
WARN_ON_ONCE(!list_empty(&node->private_list)); radix_tree_node_free(node); deleted = true;
node = parent; } while (node);
return deleted;}
/** * __radix_tree_create - create a slot in a radix tree * @root: radix tree root * @index: index key * @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->xa_head 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. */static int __radix_tree_create(struct radix_tree_root *root, unsigned long index, struct radix_tree_node **nodep, void __rcu ***slotp){ struct radix_tree_node *node = NULL, *child; void __rcu **slot = (void __rcu **)&root->xa_head; unsigned long maxindex; unsigned int shift, offset = 0; unsigned long max = index; gfp_t gfp = root_gfp_mask(root);
shift = radix_tree_load_root(root, &child, &maxindex);
/* Make sure the tree is high enough. */ if (max > maxindex) { int error = radix_tree_extend(root, gfp, max, shift); if (error < 0) return error; shift = error; child = rcu_dereference_raw(root->xa_head); }
while (shift > 0) { shift -= RADIX_TREE_MAP_SHIFT; if (child == NULL) { /* Have to add a child node. */ child = radix_tree_node_alloc(gfp, node, root, shift, offset, 0, 0); if (!child) return -ENOMEM; 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]; }
if (nodep) *nodep = node; if (slotp) *slotp = slot; return 0;}
/* * Free any nodes below this node. The tree is presumed to not need * shrinking, and any user data in the tree is presumed to not need a * destructor called on it. If we need to add a destructor, we can * add that functionality later. Note that we may not clear tags or * slots from the tree as an RCU walker may still have a pointer into * this subtree. We could replace the entries with RADIX_TREE_RETRY, * but we'll still have to clear those in rcu_free. */static void radix_tree_free_nodes(struct radix_tree_node *node){ unsigned offset = 0; struct radix_tree_node *child = entry_to_node(node);
for (;;) { void *entry = rcu_dereference_raw(child->slots[offset]); if (xa_is_node(entry) && child->shift) { child = entry_to_node(entry); offset = 0; continue; } offset++; while (offset == RADIX_TREE_MAP_SIZE) { struct radix_tree_node *old = child; offset = child->offset + 1; child = child->parent; WARN_ON_ONCE(!list_empty(&old->private_list)); radix_tree_node_free(old); if (old == entry_to_node(node)) return; } }}
static inline int insert_entries(struct radix_tree_node *node, void __rcu **slot, void *item){ if (*slot) return -EEXIST; rcu_assign_pointer(*slot, item); if (node) { node->count++; if (xa_is_value(item)) node->nr_values++; } return 1;}
/** * 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; void __rcu **slot; int error;
BUG_ON(radix_tree_is_internal_node(item));
error = __radix_tree_create(root, index, &node, &slot); if (error) return error;
error = insert_entries(node, slot, item); if (error < 0) return error;
if (node) { unsigned offset = get_slot_offset(node, slot); 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->xa_head is used as a direct slot instead of * pointing to a node, in which case *@nodep will be NULL. */void *__radix_tree_lookup(const struct radix_tree_root *root, unsigned long index, struct radix_tree_node **nodep, void __rcu ***slotp){ struct radix_tree_node *node, *parent; unsigned long maxindex; void __rcu **slot;
restart: parent = NULL; slot = (void __rcu **)&root->xa_head; radix_tree_load_root(root, &node, &maxindex); if (index > maxindex) return NULL;
while (radix_tree_is_internal_node(node)) { unsigned offset;
parent = entry_to_node(node); offset = radix_tree_descend(parent, &node, index); slot = parent->slots + offset; if (node == RADIX_TREE_RETRY) goto restart; if (parent->shift == 0) break; }
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 __rcu **radix_tree_lookup_slot(const struct radix_tree_root *root, unsigned long index){ void __rcu **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(const struct radix_tree_root *root, unsigned long index){ return __radix_tree_lookup(root, index, NULL, NULL);}EXPORT_SYMBOL(radix_tree_lookup);
static void replace_slot(void __rcu **slot, void *item, struct radix_tree_node *node, int count, int values){ if (node && (count || values)) { node->count += count; node->nr_values += values; }
rcu_assign_pointer(*slot, item);}
static bool node_tag_get(const struct radix_tree_root *root, const struct radix_tree_node *node, unsigned int tag, unsigned int offset){ if (node) return tag_get(node, tag, offset); return root_tag_get(root, tag);}
/* * IDR users want to be able to store NULL in the tree, so if the slot isn't * free, don't adjust the count, even if it's transitioning between NULL and * non-NULL. For the IDA, we mark slots as being IDR_FREE while they still * have empty bits, but it only stores NULL in slots when they're being * deleted. */static int calculate_count(struct radix_tree_root *root, struct radix_tree_node *node, void __rcu **slot, void *item, void *old){ if (is_idr(root)) { unsigned offset = get_slot_offset(node, slot); bool free = node_tag_get(root, node, IDR_FREE, offset); if (!free) return 0; if (!old) return 1; } return !!item - !!old;}
/** * __radix_tree_replace - replace item in a slot * @root: radix tree root * @node: pointer to tree node * @slot: pointer to slot in @node * @item: new item to store in the slot. * * For use with __radix_tree_lookup(). Caller must hold tree write locked * across slot lookup and replacement. */void __radix_tree_replace(struct radix_tree_root *root, struct radix_tree_node *node, void __rcu **slot, void *item){ void *old = rcu_dereference_raw(*slot); int values = !!xa_is_value(item) - !!xa_is_value(old); int count = calculate_count(root, node, slot, item, old);
/* * This function supports replacing value entries and * deleting entries, but that needs accounting against the * node unless the slot is root->xa_head. */ WARN_ON_ONCE(!node && (slot != (void __rcu **)&root->xa_head) && (count || values)); replace_slot(slot, item, node, count, values);
if (!node) return;
delete_node(root, node);}
/** * radix_tree_replace_slot - replace item in a slot * @root: radix tree root * @slot: pointer to slot * @item: new item to store in the slot. * * For use with radix_tree_lookup_slot() and * radix_tree_gang_lookup_tag_slot(). Caller must hold tree write locked * across slot lookup and replacement. * * NOTE: This cannot be used to switch between non-entries (empty slots), * regular entries, and value entries, as that requires accounting * inside the radix tree node. When switching from one type of entry or * deleting, use __radix_tree_lookup() and __radix_tree_replace() or * radix_tree_iter_replace(). */void radix_tree_replace_slot(struct radix_tree_root *root, void __rcu **slot, void *item){ __radix_tree_replace(root, NULL, slot, item);}EXPORT_SYMBOL(radix_tree_replace_slot);
/** * radix_tree_iter_replace - replace item in a slot * @root: radix tree root * @iter: iterator state * @slot: pointer to slot * @item: new item to store in the slot. * * For use with radix_tree_for_each_slot(). * Caller must hold tree write locked. */void radix_tree_iter_replace(struct radix_tree_root *root, const struct radix_tree_iter *iter, void __rcu **slot, void *item){ __radix_tree_replace(root, iter->node, slot, item);}
static void node_tag_set(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_set(node, tag, offset); offset = node->offset; node = node->parent; }
if (!root_tag_get(root, tag)) root_tag_set(root, tag);}
/** * 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 offset = 0;
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_iter_tag_clear - clear a tag on the current iterator entry * @root: radix tree root * @iter: iterator state * @tag: tag to clear */void radix_tree_iter_tag_clear(struct radix_tree_root *root, const struct radix_tree_iter *iter, unsigned int tag){ node_tag_clear(root, iter->node, tag, iter_offset(iter));}
/** * 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(const 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;
while (radix_tree_is_internal_node(node)) { unsigned offset;
parent = entry_to_node(node); offset = radix_tree_descend(parent, &node, index);
if (!tag_get(parent, tag, offset)) return 0; if (node == RADIX_TREE_RETRY) break; }
return 1;}EXPORT_SYMBOL(radix_tree_tag_get);
/* Construct iter->tags bit-mask from node->tags[tag] array */static void set_iter_tags(struct radix_tree_iter *iter, struct radix_tree_node *node, unsigned offset, unsigned tag){ unsigned tag_long = offset / BITS_PER_LONG; unsigned tag_bit = offset % BITS_PER_LONG;
if (!node) { iter->tags = 1; return; }
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 = __radix_tree_iter_add(iter, BITS_PER_LONG); }}
void __rcu **radix_tree_iter_resume(void __rcu **slot, struct radix_tree_iter *iter){ iter->index = __radix_tree_iter_add(iter, 1); iter->next_index = iter->index; iter->tags = 0; return NULL;}EXPORT_SYMBOL(radix_tree_iter_resume);
/** * 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 __rcu **radix_tree_next_chunk(const 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 switching 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; iter->node = NULL; return (void __rcu **)&root->xa_head; }
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, tag, offset + 1); else while (++offset < RADIX_TREE_MAP_SIZE) { void *slot = rcu_dereference_raw( node->slots[offset]); 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) goto restart; if (child == RADIX_TREE_RETRY) break; } while (node->shift && radix_tree_is_internal_node(child));
/* Update the iterator state */ iter->index = (index &~ node_maxindex(node)) | offset; iter->next_index = (index | node_maxindex(node)) + 1; iter->node = node;
if (flags & RADIX_TREE_ITER_TAGGED) set_iter_tags(iter, node, offset, tag);
return node->slots + offset;}EXPORT_SYMBOL(radix_tree_next_chunk);
/** * 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 intradix_tree_gang_lookup(const struct radix_tree_root *root, void **results, unsigned long first_index, unsigned int max_items){ struct radix_tree_iter iter; void __rcu **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_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 intradix_tree_gang_lookup_tag(const struct radix_tree_root *root, void **results, unsigned long first_index, unsigned int max_items, unsigned int tag){ struct radix_tree_iter iter; void __rcu **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 intradix_tree_gang_lookup_tag_slot(const struct radix_tree_root *root, void __rcu ***results, unsigned long first_index, unsigned int max_items, unsigned int tag){ struct radix_tree_iter iter; void __rcu **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);
static bool __radix_tree_delete(struct radix_tree_root *root, struct radix_tree_node *node, void __rcu **slot){ void *old = rcu_dereference_raw(*slot); int values = xa_is_value(old) ? -1 : 0; unsigned offset = get_slot_offset(node, slot); int tag;
if (is_idr(root)) node_tag_set(root, node, IDR_FREE, offset); else for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) node_tag_clear(root, node, tag, offset);
replace_slot(slot, NULL, node, -1, values); return node && delete_node(root, node);}
/** * radix_tree_iter_delete - delete the entry at this iterator position * @root: radix tree root * @iter: iterator state * @slot: pointer to slot * * Delete the entry at the position currently pointed to by the iterator. * This may result in the current node being freed; if it is, the iterator * is advanced so that it will not reference the freed memory. This * function may be called without any locking if there are no other threads * which can access this tree. */void radix_tree_iter_delete(struct radix_tree_root *root, struct radix_tree_iter *iter, void __rcu **slot){ if (__radix_tree_delete(root, iter->node, slot)) iter->index = iter->next_index;}EXPORT_SYMBOL(radix_tree_iter_delete);
/** * 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. * * Return: the deleted entry, 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 = NULL; void __rcu **slot = NULL; void *entry;
entry = __radix_tree_lookup(root, index, &node, &slot); if (!slot) return NULL; if (!entry && (!is_idr(root) || node_tag_get(root, node, IDR_FREE, get_slot_offset(node, slot)))) return NULL;
if (item && entry != item) return NULL;
__radix_tree_delete(root, node, slot);
return entry;}EXPORT_SYMBOL(radix_tree_delete_item);
/** * radix_tree_delete - delete an entry from a radix tree * @root: radix tree root * @index: index key * * Remove the entry at @index from the radix tree rooted at @root. * * Return: The deleted entry, 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);
/** * radix_tree_tagged - test whether any items in the tree are tagged * @root: radix tree root * @tag: tag to test */int radix_tree_tagged(const struct radix_tree_root *root, unsigned int tag){ return root_tag_get(root, tag);}EXPORT_SYMBOL(radix_tree_tagged);
/** * idr_preload - preload for idr_alloc() * @gfp_mask: allocation mask to use for preloading * * Preallocate memory to use for the next call to idr_alloc(). This function * returns with preemption disabled. It will be enabled by idr_preload_end(). */void idr_preload(gfp_t gfp_mask){ if (__radix_tree_preload(gfp_mask, IDR_PRELOAD_SIZE)) local_lock(&radix_tree_preloads.lock);}EXPORT_SYMBOL(idr_preload);
void __rcu **idr_get_free(struct radix_tree_root *root, struct radix_tree_iter *iter, gfp_t gfp, unsigned long max){ struct radix_tree_node *node = NULL, *child; void __rcu **slot = (void __rcu **)&root->xa_head; unsigned long maxindex, start = iter->next_index; unsigned int shift, offset = 0;
grow: shift = radix_tree_load_root(root, &child, &maxindex); if (!radix_tree_tagged(root, IDR_FREE)) start = max(start, maxindex + 1); if (start > max) return ERR_PTR(-ENOSPC);
if (start > maxindex) { int error = radix_tree_extend(root, gfp, start, shift); if (error < 0) return ERR_PTR(error); shift = error; child = rcu_dereference_raw(root->xa_head); } if (start == 0 && shift == 0) shift = RADIX_TREE_MAP_SHIFT;
while (shift) { shift -= RADIX_TREE_MAP_SHIFT; if (child == NULL) { /* Have to add a child node. */ child = radix_tree_node_alloc(gfp, node, root, shift, offset, 0, 0); if (!child) return ERR_PTR(-ENOMEM); all_tag_set(child, IDR_FREE); rcu_assign_pointer(*slot, node_to_entry(child)); if (node) node->count++; } else if (!radix_tree_is_internal_node(child)) break;
node = entry_to_node(child); offset = radix_tree_descend(node, &child, start); if (!tag_get(node, IDR_FREE, offset)) { offset = radix_tree_find_next_bit(node, IDR_FREE, offset + 1); start = next_index(start, node, offset); if (start > max || start == 0) return ERR_PTR(-ENOSPC); while (offset == RADIX_TREE_MAP_SIZE) { offset = node->offset + 1; node = node->parent; if (!node) goto grow; shift = node->shift; } child = rcu_dereference_raw(node->slots[offset]); } slot = &node->slots[offset]; }
iter->index = start; if (node) iter->next_index = 1 + min(max, (start | node_maxindex(node))); else iter->next_index = 1; iter->node = node; set_iter_tags(iter, node, offset, IDR_FREE);
return slot;}
/** * idr_destroy - release all internal memory from an IDR * @idr: idr handle * * After this function is called, the IDR is empty, and may be reused or * the data structure containing it may be freed. * * A typical clean-up sequence for objects stored in an idr tree will use * idr_for_each() to free all objects, if necessary, then idr_destroy() to * free the memory used to keep track of those objects. */void idr_destroy(struct idr *idr){ struct radix_tree_node *node = rcu_dereference_raw(idr->idr_rt.xa_head); if (radix_tree_is_internal_node(node)) radix_tree_free_nodes(node); idr->idr_rt.xa_head = NULL; root_tag_set(&idr->idr_rt, IDR_FREE);}EXPORT_SYMBOL(idr_destroy);
static voidradix_tree_node_ctor(void *arg){ struct radix_tree_node *node = arg;
memset(node, 0, sizeof(*node)); INIT_LIST_HEAD(&node->private_list);}
static int radix_tree_cpu_dead(unsigned int cpu){ struct radix_tree_preload *rtp; struct radix_tree_node *node;
/* Free per-cpu pool of preloaded nodes */ rtp = &per_cpu(radix_tree_preloads, cpu); while (rtp->nr) { node = rtp->nodes; rtp->nodes = node->parent; kmem_cache_free(radix_tree_node_cachep, node); rtp->nr--; } return 0;}
void __init radix_tree_init(void){ int ret;
BUILD_BUG_ON(RADIX_TREE_MAX_TAGS + __GFP_BITS_SHIFT > 32); BUILD_BUG_ON(ROOT_IS_IDR & ~GFP_ZONEMASK); BUILD_BUG_ON(XA_CHUNK_SIZE > 255); 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); ret = cpuhp_setup_state_nocalls(CPUHP_RADIX_DEAD, "lib/radix:dead", NULL, radix_tree_cpu_dead); WARN_ON(ret < 0);}