1 /* SPDX-License-Identifier: GPL-2.0-or-later */
31 	/* nodes->parent points to next preallocated node */
37  * The bottom two bits of the slot determine how the remaining bits in the
38  * slot are interpreted:
40  * 00 - data pointer
41  * 10 - internal entry
42  * x1 - value entry
45  * sibling entry, or an indicator that the entry in this slot has been moved
47  * NULL fits the 'data pointer' pattern, it means that there is no entry in
48  * the tree for this index (no matter what level of the tree it is found at).
61 /*** radix-tree API starts here ***/
65 #define RADIX_TREE_MAP_MASK	(RADIX_TREE_MAP_SIZE-1)
88 	return root->xa_head == NULL;  in radix_tree_empty()
92  * struct radix_tree_iter - radix tree iterator state
94  * @index:	index of current slot
96  * @tags:	bit-mask for tag-iterating
97  * @node:	node that contains current slot
101  * described by a pointer to its first slot and a struct radix_tree_iter
103  * iteration radix_tree_iter also holds the slots' bit-mask for one chosen
114  * Radix-tree synchronization
116  * The radix-tree API requires that users provide all synchronisation (with
123  * - any function _modifying_ the tree or tags (inserting or deleting
126  * - any function _reading_ the tree or tags (looking up items or tags,
142  * regions. Other readers (lock-free or otherwise) and modifications may be
146  * of the items. So if RCU lock-free lookups are used, typically this would mean
147  * that the items have their own locks, or are amenable to lock-free access; and
165  * radix_tree_deref_slot - dereference a slot
166  * @slot: slot pointer, returned by radix_tree_lookup_slot
169  * locked across slot lookup and dereference. Not required if write lock is
175  * Return: entry stored in that slot.
177 static inline void *radix_tree_deref_slot(void __rcu **slot)  in radix_tree_deref_slot()  argument
179 	return rcu_dereference(*slot);  in radix_tree_deref_slot()
183  * radix_tree_deref_slot_protected - dereference a slot with tree lock held
184  * @slot: slot pointer, returned by radix_tree_lookup_slot
189  * Return: entry stored in that slot.
191 static inline void *radix_tree_deref_slot_protected(void __rcu **slot,  in radix_tree_deref_slot_protected()  argument
194 	return rcu_dereference_protected(*slot, lockdep_is_held(treelock));  in radix_tree_deref_slot_protected()
198  * radix_tree_deref_retry	- check radix_tree_deref_slot
210  * radix_tree_exception	- radix_tree_deref_slot returned either exception?
212  * Returns:	0 if well-aligned pointer, non-0 if either kind of exception.
227 			  void __rcu **slot, void *entry);
229 		const struct radix_tree_iter *, void __rcu **slot, void *entry);
231 			     void __rcu **slot, void *entry);
233 			struct radix_tree_iter *iter, void __rcu **slot);
274  * radix_tree_iter_init - initialize radix tree iterator
284 	 * Leave iter->tags uninitialized. radix_tree_next_chunk() will fill it  in radix_tree_iter_init()
286 	 * unsuccessful or non-tagged then nobody cares about ->tags.  in radix_tree_iter_init()
288 	 * Set index to zero to bypass next_index overflow protection.  in radix_tree_iter_init()
291 	iter->index = 0;  in radix_tree_iter_init()
292 	iter->next_index = start;  in radix_tree_iter_init()
297  * radix_tree_next_chunk - find next chunk of slots for iteration
302  * Returns:	pointer to chunk first slot, or NULL if there no more left
305  * @iter->next_index.  It returns a pointer to the chunk's first slot.
313  * radix_tree_iter_lookup - look up an index in the radix tree
318  * If @index is present in the radix tree, this function returns the slot
331  * radix_tree_iter_retry - retry this chunk of the iteration
335  * against deletion or creation may result in seeing a slot for which
342 	iter->next_index = iter->index;  in radix_tree_iter_retry()
343 	iter->tags = 0;  in radix_tree_iter_retry()
350 	return iter->index + slots;  in __radix_tree_iter_add()
354  * radix_tree_iter_resume - resume iterating when the chunk may be invalid
355  * @slot: pointer to current slot
357  * Returns: New slot pointer
363 void __rcu **__must_check radix_tree_iter_resume(void __rcu **slot,
367  * radix_tree_chunk_size - get current chunk size
375 	return iter->next_index - iter->index;  in radix_tree_chunk_size()
379  * radix_tree_next_slot - find next slot in chunk
381  * @slot:	pointer to current slot
384  * Returns:	pointer to next slot, or NULL if there no more left
386  * This function updates @iter->index in the case of a successful lookup.
387  * For tagged lookup it also eats @iter->tags.
389  * There are several cases where 'slot' can be passed in as NULL to this
392  * 'slot' because either:
393  * a) we are doing tagged iteration and iter->tags has been set to 0, or
394  * b) we are doing non-tagged iteration, and iter->index and iter->next_index
397 static __always_inline void __rcu **radix_tree_next_slot(void __rcu **slot,  in radix_tree_next_slot()  argument
401 		iter->tags >>= 1;  in radix_tree_next_slot()
402 		if (unlikely(!iter->tags))  in radix_tree_next_slot()
404 		if (likely(iter->tags & 1ul)) {  in radix_tree_next_slot()
405 			iter->index = __radix_tree_iter_add(iter, 1);  in radix_tree_next_slot()
406 			slot++;  in radix_tree_next_slot()
410 			unsigned offset = __ffs(iter->tags);  in radix_tree_next_slot()
412 			iter->tags >>= offset++;  in radix_tree_next_slot()
413 			iter->index = __radix_tree_iter_add(iter, offset);  in radix_tree_next_slot()
414 			slot += offset;  in radix_tree_next_slot()
420 		while (--count > 0) {  in radix_tree_next_slot()
421 			slot++;  in radix_tree_next_slot()
422 			iter->index = __radix_tree_iter_add(iter, 1);  in radix_tree_next_slot()
424 			if (likely(*slot))  in radix_tree_next_slot()
428 				iter->next_index = 0;  in radix_tree_next_slot()
436 	return slot;  in radix_tree_next_slot()
440  * radix_tree_for_each_slot - iterate over non-empty slots
442  * @slot:	the void** variable for pointer to slot
447  * @slot points to radix tree slot, @iter->index contains its index.
449 #define radix_tree_for_each_slot(slot, root, iter, start)		\  argument
450 	for (slot = radix_tree_iter_init(iter, start) ;			\
451 	     slot || (slot = radix_tree_next_chunk(root, iter, 0)) ;	\
452 	     slot = radix_tree_next_slot(slot, iter, 0))
455  * radix_tree_for_each_tagged - iterate over tagged slots
457  * @slot:	the void** variable for pointer to slot
463  * @slot points to radix tree slot, @iter->index contains its index.
465 #define radix_tree_for_each_tagged(slot, root, iter, start, tag)	\  argument
466 	for (slot = radix_tree_iter_init(iter, start) ;			\
467 	     slot || (slot = radix_tree_next_chunk(root, iter,		\
469 	     slot = radix_tree_next_slot(slot, iter,			\