| /* SPDX-License-Identifier: GPL-2.0-or-later */ |
| /* |
| * Copyright (C) 2001 Momchil Velikov |
| * Portions Copyright (C) 2001 Christoph Hellwig |
| * Copyright (C) 2006 Nick Piggin |
| * Copyright (C) 2012 Konstantin Khlebnikov |
| */ |
| #ifndef _LINUX_RADIX_TREE_H |
| #define _LINUX_RADIX_TREE_H |
| |
| #include <linux/bitops.h> |
| #include <linux/gfp.h> |
| #include <linux/list.h> |
| #include <linux/lockdep.h> |
| #include <linux/math.h> |
| #include <linux/percpu.h> |
| #include <linux/preempt.h> |
| #include <linux/rcupdate.h> |
| #include <linux/spinlock.h> |
| #include <linux/types.h> |
| #include <linux/xarray.h> |
| #include <linux/local_lock.h> |
| |
| /* Keep unconverted code working */ |
| #define radix_tree_root xarray |
| #define radix_tree_node xa_node |
| |
| struct radix_tree_preload { |
| local_lock_t lock; |
| unsigned nr; |
| /* nodes->parent points to next preallocated node */ |
| struct radix_tree_node *nodes; |
| }; |
| DECLARE_PER_CPU(struct radix_tree_preload, radix_tree_preloads); |
| |
| /* |
| * The bottom two bits of the slot determine how the remaining bits in the |
| * slot are interpreted: |
| * |
| * 00 - data pointer |
| * 10 - internal entry |
| * x1 - value entry |
| * |
| * The internal entry may be a pointer to the next level in the tree, a |
| * sibling entry, or an indicator that the entry in this slot has been moved |
| * to another location in the tree and the lookup should be restarted. While |
| * NULL fits the 'data pointer' pattern, it means that there is no entry in |
| * the tree for this index (no matter what level of the tree it is found at). |
| * This means that storing a NULL entry in the tree is the same as deleting |
| * the entry from the tree. |
| */ |
| #define RADIX_TREE_ENTRY_MASK 3UL |
| #define RADIX_TREE_INTERNAL_NODE 2UL |
| |
| static inline bool radix_tree_is_internal_node(void *ptr) |
| { |
| return ((unsigned long)ptr & RADIX_TREE_ENTRY_MASK) == |
| RADIX_TREE_INTERNAL_NODE; |
| } |
| |
| /*** radix-tree API starts here ***/ |
| |
| #define RADIX_TREE_MAP_SHIFT XA_CHUNK_SHIFT |
| #define RADIX_TREE_MAP_SIZE (1UL << RADIX_TREE_MAP_SHIFT) |
| #define RADIX_TREE_MAP_MASK (RADIX_TREE_MAP_SIZE-1) |
| |
| #define RADIX_TREE_MAX_TAGS XA_MAX_MARKS |
| #define RADIX_TREE_TAG_LONGS XA_MARK_LONGS |
| |
| #define RADIX_TREE_INDEX_BITS (8 /* CHAR_BIT */ * sizeof(unsigned long)) |
| #define RADIX_TREE_MAX_PATH (DIV_ROUND_UP(RADIX_TREE_INDEX_BITS, \ |
| RADIX_TREE_MAP_SHIFT)) |
| |
| /* The IDR tag is stored in the low bits of xa_flags */ |
| #define ROOT_IS_IDR ((__force gfp_t)4) |
| /* The top bits of xa_flags are used to store the root tags */ |
| #define ROOT_TAG_SHIFT (__GFP_BITS_SHIFT) |
| |
| #define RADIX_TREE_INIT(name, mask) XARRAY_INIT(name, mask) |
| |
| #define RADIX_TREE(name, mask) \ |
| struct radix_tree_root name = RADIX_TREE_INIT(name, mask) |
| |
| #define INIT_RADIX_TREE(root, mask) xa_init_flags(root, mask) |
| |
| static inline bool radix_tree_empty(const struct radix_tree_root *root) |
| { |
| return root->xa_head == NULL; |
| } |
| |
| /** |
| * struct radix_tree_iter - radix tree iterator state |
| * |
| * @index: index of current slot |
| * @next_index: one beyond the last index for this chunk |
| * @tags: bit-mask for tag-iterating |
| * @node: node that contains current slot |
| * |
| * This radix tree iterator works in terms of "chunks" of slots. A chunk is a |
| * subinterval of slots contained within one radix tree leaf node. It is |
| * described by a pointer to its first slot and a struct radix_tree_iter |
| * which holds the chunk's position in the tree and its size. For tagged |
| * iteration radix_tree_iter also holds the slots' bit-mask for one chosen |
| * radix tree tag. |
| */ |
| struct radix_tree_iter { |
| unsigned long index; |
| unsigned long next_index; |
| unsigned long tags; |
| struct radix_tree_node *node; |
| }; |
| |
| /** |
| * Radix-tree synchronization |
| * |
| * The radix-tree API requires that users provide all synchronisation (with |
| * specific exceptions, noted below). |
| * |
| * Synchronization of access to the data items being stored in the tree, and |
| * management of their lifetimes must be completely managed by API users. |
| * |
| * For API usage, in general, |
| * - any function _modifying_ the tree or tags (inserting or deleting |
| * items, setting or clearing tags) must exclude other modifications, and |
| * exclude any functions reading the tree. |
| * - any function _reading_ the tree or tags (looking up items or tags, |
| * gang lookups) must exclude modifications to the tree, but may occur |
| * concurrently with other readers. |
| * |
| * The notable exceptions to this rule are the following functions: |
| * __radix_tree_lookup |
| * radix_tree_lookup |
| * radix_tree_lookup_slot |
| * radix_tree_tag_get |
| * radix_tree_gang_lookup |
| * radix_tree_gang_lookup_tag |
| * radix_tree_gang_lookup_tag_slot |
| * radix_tree_tagged |
| * |
| * The first 7 functions are able to be called locklessly, using RCU. The |
| * caller must ensure calls to these functions are made within rcu_read_lock() |
| * regions. Other readers (lock-free or otherwise) and modifications may be |
| * running concurrently. |
| * |
| * It is still required that the caller manage the synchronization and lifetimes |
| * of the items. So if RCU lock-free lookups are used, typically this would mean |
| * that the items have their own locks, or are amenable to lock-free access; and |
| * that the items are freed by RCU (or only freed after having been deleted from |
| * the radix tree *and* a synchronize_rcu() grace period). |
| * |
| * (Note, rcu_assign_pointer and rcu_dereference are not needed to control |
| * access to data items when inserting into or looking up from the radix tree) |
| * |
| * Note that the value returned by radix_tree_tag_get() may not be relied upon |
| * if only the RCU read lock is held. Functions to set/clear tags and to |
| * delete nodes running concurrently with it may affect its result such that |
| * two consecutive reads in the same locked section may return different |
| * values. If reliability is required, modification functions must also be |
| * excluded from concurrency. |
| * |
| * radix_tree_tagged is able to be called without locking or RCU. |
| */ |
| |
| /** |
| * radix_tree_deref_slot - dereference a slot |
| * @slot: slot pointer, returned by radix_tree_lookup_slot |
| * |
| * For use with radix_tree_lookup_slot(). Caller must hold tree at least read |
| * locked across slot lookup and dereference. Not required if write lock is |
| * held (ie. items cannot be concurrently inserted). |
| * |
| * radix_tree_deref_retry must be used to confirm validity of the pointer if |
| * only the read lock is held. |
| * |
| * Return: entry stored in that slot. |
| */ |
| static inline void *radix_tree_deref_slot(void __rcu **slot) |
| { |
| return rcu_dereference(*slot); |
| } |
| |
| /** |
| * radix_tree_deref_slot_protected - dereference a slot with tree lock held |
| * @slot: slot pointer, returned by radix_tree_lookup_slot |
| * |
| * Similar to radix_tree_deref_slot. The caller does not hold the RCU read |
| * lock but it must hold the tree lock to prevent parallel updates. |
| * |
| * Return: entry stored in that slot. |
| */ |
| static inline void *radix_tree_deref_slot_protected(void __rcu **slot, |
| spinlock_t *treelock) |
| { |
| return rcu_dereference_protected(*slot, lockdep_is_held(treelock)); |
| } |
| |
| /** |
| * radix_tree_deref_retry - check radix_tree_deref_slot |
| * @arg: pointer returned by radix_tree_deref_slot |
| * Returns: 0 if retry is not required, otherwise retry is required |
| * |
| * radix_tree_deref_retry must be used with radix_tree_deref_slot. |
| */ |
| static inline int radix_tree_deref_retry(void *arg) |
| { |
| return unlikely(radix_tree_is_internal_node(arg)); |
| } |
| |
| /** |
| * radix_tree_exception - radix_tree_deref_slot returned either exception? |
| * @arg: value returned by radix_tree_deref_slot |
| * Returns: 0 if well-aligned pointer, non-0 if either kind of exception. |
| */ |
| static inline int radix_tree_exception(void *arg) |
| { |
| return unlikely((unsigned long)arg & RADIX_TREE_ENTRY_MASK); |
| } |
| |
| int radix_tree_insert(struct radix_tree_root *, unsigned long index, |
| void *); |
| void *__radix_tree_lookup(const struct radix_tree_root *, unsigned long index, |
| struct radix_tree_node **nodep, void __rcu ***slotp); |
| void *radix_tree_lookup(const struct radix_tree_root *, unsigned long); |
| void __rcu **radix_tree_lookup_slot(const struct radix_tree_root *, |
| unsigned long index); |
| void __radix_tree_replace(struct radix_tree_root *, struct radix_tree_node *, |
| void __rcu **slot, void *entry); |
| void radix_tree_iter_replace(struct radix_tree_root *, |
| const struct radix_tree_iter *, void __rcu **slot, void *entry); |
| void radix_tree_replace_slot(struct radix_tree_root *, |
| void __rcu **slot, void *entry); |
| void radix_tree_iter_delete(struct radix_tree_root *, |
| struct radix_tree_iter *iter, void __rcu **slot); |
| void *radix_tree_delete_item(struct radix_tree_root *, unsigned long, void *); |
| void *radix_tree_delete(struct radix_tree_root *, unsigned long); |
| unsigned int radix_tree_gang_lookup(const struct radix_tree_root *, |
| void **results, unsigned long first_index, |
| unsigned int max_items); |
| int radix_tree_preload(gfp_t gfp_mask); |
| int radix_tree_maybe_preload(gfp_t gfp_mask); |
| void radix_tree_init(void); |
| void *radix_tree_tag_set(struct radix_tree_root *, |
| unsigned long index, unsigned int tag); |
| void *radix_tree_tag_clear(struct radix_tree_root *, |
| unsigned long index, unsigned int tag); |
| int radix_tree_tag_get(const struct radix_tree_root *, |
| unsigned long index, unsigned int tag); |
| void radix_tree_iter_tag_clear(struct radix_tree_root *, |
| const struct radix_tree_iter *iter, unsigned int tag); |
| unsigned int radix_tree_gang_lookup_tag(const struct radix_tree_root *, |
| void **results, unsigned long first_index, |
| unsigned int max_items, unsigned int tag); |
| unsigned int radix_tree_gang_lookup_tag_slot(const struct radix_tree_root *, |
| void __rcu ***results, unsigned long first_index, |
| unsigned int max_items, unsigned int tag); |
| int radix_tree_tagged(const struct radix_tree_root *, unsigned int tag); |
| |
| static inline void radix_tree_preload_end(void) |
| { |
| local_unlock(&radix_tree_preloads.lock); |
| } |
| |
| void __rcu **idr_get_free(struct radix_tree_root *root, |
| struct radix_tree_iter *iter, gfp_t gfp, |
| unsigned long max); |
| |
| enum { |
| RADIX_TREE_ITER_TAG_MASK = 0x0f, /* tag index in lower nybble */ |
| RADIX_TREE_ITER_TAGGED = 0x10, /* lookup tagged slots */ |
| RADIX_TREE_ITER_CONTIG = 0x20, /* stop at first hole */ |
| }; |
| |
| /** |
| * radix_tree_iter_init - initialize radix tree iterator |
| * |
| * @iter: pointer to iterator state |
| * @start: iteration starting index |
| * Returns: NULL |
| */ |
| static __always_inline void __rcu ** |
| radix_tree_iter_init(struct radix_tree_iter *iter, unsigned long start) |
| { |
| /* |
| * Leave iter->tags uninitialized. radix_tree_next_chunk() will fill it |
| * in the case of a successful tagged chunk lookup. If the lookup was |
| * unsuccessful or non-tagged then nobody cares about ->tags. |
| * |
| * Set index to zero to bypass next_index overflow protection. |
| * See the comment in radix_tree_next_chunk() for details. |
| */ |
| iter->index = 0; |
| iter->next_index = start; |
| return NULL; |
| } |
| |
| /** |
| * 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 there no more left |
| * |
| * This function looks up the next chunk in the radix tree starting from |
| * @iter->next_index. It returns a pointer to the chunk's first slot. |
| * Also it fills @iter with data about chunk: position in the tree (index), |
| * its end (next_index), and constructs a bit mask for tagged iterating (tags). |
| */ |
| void __rcu **radix_tree_next_chunk(const struct radix_tree_root *, |
| struct radix_tree_iter *iter, unsigned flags); |
| |
| /** |
| * radix_tree_iter_lookup - look up an index in the radix tree |
| * @root: radix tree root |
| * @iter: iterator state |
| * @index: key to look up |
| * |
| * If @index is present in the radix tree, this function returns the slot |
| * containing it and updates @iter to describe the entry. If @index is not |
| * present, it returns NULL. |
| */ |
| static inline void __rcu ** |
| radix_tree_iter_lookup(const struct radix_tree_root *root, |
| struct radix_tree_iter *iter, unsigned long index) |
| { |
| radix_tree_iter_init(iter, index); |
| return radix_tree_next_chunk(root, iter, RADIX_TREE_ITER_CONTIG); |
| } |
| |
| /** |
| * radix_tree_iter_retry - retry this chunk of the iteration |
| * @iter: iterator state |
| * |
| * If we iterate over a tree protected only by the RCU lock, a race |
| * against deletion or creation may result in seeing a slot for which |
| * radix_tree_deref_retry() returns true. If so, call this function |
| * and continue the iteration. |
| */ |
| static inline __must_check |
| void __rcu **radix_tree_iter_retry(struct radix_tree_iter *iter) |
| { |
| iter->next_index = iter->index; |
| iter->tags = 0; |
| return NULL; |
| } |
| |
| static inline unsigned long |
| __radix_tree_iter_add(struct radix_tree_iter *iter, unsigned long slots) |
| { |
| return iter->index + slots; |
| } |
| |
| /** |
| * radix_tree_iter_resume - resume iterating when the chunk may be invalid |
| * @slot: pointer to current slot |
| * @iter: iterator state |
| * Returns: New slot pointer |
| * |
| * If the iterator needs to release then reacquire a lock, the chunk may |
| * have been invalidated by an insertion or deletion. Call this function |
| * before releasing the lock to continue the iteration from the next index. |
| */ |
| void __rcu **__must_check radix_tree_iter_resume(void __rcu **slot, |
| struct radix_tree_iter *iter); |
| |
| /** |
| * radix_tree_chunk_size - get current chunk size |
| * |
| * @iter: pointer to radix tree iterator |
| * Returns: current chunk size |
| */ |
| static __always_inline long |
| radix_tree_chunk_size(struct radix_tree_iter *iter) |
| { |
| return iter->next_index - iter->index; |
| } |
| |
| /** |
| * radix_tree_next_slot - find next slot in chunk |
| * |
| * @slot: pointer to current slot |
| * @iter: pointer to iterator state |
| * @flags: RADIX_TREE_ITER_*, should be constant |
| * Returns: pointer to next slot, or NULL if there no more left |
| * |
| * This function updates @iter->index in the case of a successful lookup. |
| * For tagged lookup it also eats @iter->tags. |
| * |
| * There are several cases where 'slot' can be passed in as NULL to this |
| * function. These cases result from the use of radix_tree_iter_resume() or |
| * radix_tree_iter_retry(). In these cases we don't end up dereferencing |
| * 'slot' because either: |
| * a) we are doing tagged iteration and iter->tags has been set to 0, or |
| * b) we are doing non-tagged iteration, and iter->index and iter->next_index |
| * have been set up so that radix_tree_chunk_size() returns 1 or 0. |
| */ |
| static __always_inline void __rcu **radix_tree_next_slot(void __rcu **slot, |
| struct radix_tree_iter *iter, unsigned flags) |
| { |
| if (flags & RADIX_TREE_ITER_TAGGED) { |
| iter->tags >>= 1; |
| if (unlikely(!iter->tags)) |
| return NULL; |
| if (likely(iter->tags & 1ul)) { |
| iter->index = __radix_tree_iter_add(iter, 1); |
| slot++; |
| goto found; |
| } |
| if (!(flags & RADIX_TREE_ITER_CONTIG)) { |
| unsigned offset = __ffs(iter->tags); |
| |
| iter->tags >>= offset++; |
| iter->index = __radix_tree_iter_add(iter, offset); |
| slot += offset; |
| goto found; |
| } |
| } else { |
| long count = radix_tree_chunk_size(iter); |
| |
| while (--count > 0) { |
| slot++; |
| iter->index = __radix_tree_iter_add(iter, 1); |
| |
| if (likely(*slot)) |
| goto found; |
| if (flags & RADIX_TREE_ITER_CONTIG) { |
| /* forbid switching to the next chunk */ |
| iter->next_index = 0; |
| break; |
| } |
| } |
| } |
| return NULL; |
| |
| found: |
| return slot; |
| } |
| |
| /** |
| * radix_tree_for_each_slot - iterate over non-empty slots |
| * |
| * @slot: the void** variable for pointer to slot |
| * @root: the struct radix_tree_root pointer |
| * @iter: the struct radix_tree_iter pointer |
| * @start: iteration starting index |
| * |
| * @slot points to radix tree slot, @iter->index contains its index. |
| */ |
| #define radix_tree_for_each_slot(slot, root, iter, start) \ |
| for (slot = radix_tree_iter_init(iter, start) ; \ |
| slot || (slot = radix_tree_next_chunk(root, iter, 0)) ; \ |
| slot = radix_tree_next_slot(slot, iter, 0)) |
| |
| /** |
| * radix_tree_for_each_tagged - iterate over tagged slots |
| * |
| * @slot: the void** variable for pointer to slot |
| * @root: the struct radix_tree_root pointer |
| * @iter: the struct radix_tree_iter pointer |
| * @start: iteration starting index |
| * @tag: tag index |
| * |
| * @slot points to radix tree slot, @iter->index contains its index. |
| */ |
| #define radix_tree_for_each_tagged(slot, root, iter, start, tag) \ |
| for (slot = radix_tree_iter_init(iter, start) ; \ |
| slot || (slot = radix_tree_next_chunk(root, iter, \ |
| RADIX_TREE_ITER_TAGGED | tag)) ; \ |
| slot = radix_tree_next_slot(slot, iter, \ |
| RADIX_TREE_ITER_TAGGED | tag)) |
| |
| #endif /* _LINUX_RADIX_TREE_H */ |