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       1                 :            : /* SPDX-License-Identifier: GPL-2.0-or-later */
       2                 :            : /*
       3                 :            :  * Copyright (C) 2001 Momchil Velikov
       4                 :            :  * Portions Copyright (C) 2001 Christoph Hellwig
       5                 :            :  * Copyright (C) 2006 Nick Piggin
       6                 :            :  * Copyright (C) 2012 Konstantin Khlebnikov
       7                 :            :  */
       8                 :            : #ifndef _LINUX_RADIX_TREE_H
       9                 :            : #define _LINUX_RADIX_TREE_H
      10                 :            : 
      11                 :            : #include <linux/bitops.h>
      12                 :            : #include <linux/kernel.h>
      13                 :            : #include <linux/list.h>
      14                 :            : #include <linux/preempt.h>
      15                 :            : #include <linux/rcupdate.h>
      16                 :            : #include <linux/spinlock.h>
      17                 :            : #include <linux/types.h>
      18                 :            : #include <linux/xarray.h>
      19                 :            : 
      20                 :            : /* Keep unconverted code working */
      21                 :            : #define radix_tree_root         xarray
      22                 :            : #define radix_tree_node         xa_node
      23                 :            : 
      24                 :            : /*
      25                 :            :  * The bottom two bits of the slot determine how the remaining bits in the
      26                 :            :  * slot are interpreted:
      27                 :            :  *
      28                 :            :  * 00 - data pointer
      29                 :            :  * 10 - internal entry
      30                 :            :  * x1 - value entry
      31                 :            :  *
      32                 :            :  * The internal entry may be a pointer to the next level in the tree, a
      33                 :            :  * sibling entry, or an indicator that the entry in this slot has been moved
      34                 :            :  * to another location in the tree and the lookup should be restarted.  While
      35                 :            :  * NULL fits the 'data pointer' pattern, it means that there is no entry in
      36                 :            :  * the tree for this index (no matter what level of the tree it is found at).
      37                 :            :  * This means that storing a NULL entry in the tree is the same as deleting
      38                 :            :  * the entry from the tree.
      39                 :            :  */
      40                 :            : #define RADIX_TREE_ENTRY_MASK           3UL
      41                 :            : #define RADIX_TREE_INTERNAL_NODE        2UL
      42                 :            : 
      43                 :            : static inline bool radix_tree_is_internal_node(void *ptr)
      44                 :            : {
      45                 :          3 :         return ((unsigned long)ptr & RADIX_TREE_ENTRY_MASK) ==
      46                 :            :                                 RADIX_TREE_INTERNAL_NODE;
      47                 :            : }
      48                 :            : 
      49                 :            : /*** radix-tree API starts here ***/
      50                 :            : 
      51                 :            : #define RADIX_TREE_MAP_SHIFT    XA_CHUNK_SHIFT
      52                 :            : #define RADIX_TREE_MAP_SIZE     (1UL << RADIX_TREE_MAP_SHIFT)
      53                 :            : #define RADIX_TREE_MAP_MASK     (RADIX_TREE_MAP_SIZE-1)
      54                 :            : 
      55                 :            : #define RADIX_TREE_MAX_TAGS     XA_MAX_MARKS
      56                 :            : #define RADIX_TREE_TAG_LONGS    XA_MARK_LONGS
      57                 :            : 
      58                 :            : #define RADIX_TREE_INDEX_BITS  (8 /* CHAR_BIT */ * sizeof(unsigned long))
      59                 :            : #define RADIX_TREE_MAX_PATH (DIV_ROUND_UP(RADIX_TREE_INDEX_BITS, \
      60                 :            :                                           RADIX_TREE_MAP_SHIFT))
      61                 :            : 
      62                 :            : /* The IDR tag is stored in the low bits of xa_flags */
      63                 :            : #define ROOT_IS_IDR     ((__force gfp_t)4)
      64                 :            : /* The top bits of xa_flags are used to store the root tags */
      65                 :            : #define ROOT_TAG_SHIFT  (__GFP_BITS_SHIFT)
      66                 :            : 
      67                 :            : #define RADIX_TREE_INIT(name, mask)     XARRAY_INIT(name, mask)
      68                 :            : 
      69                 :            : #define RADIX_TREE(name, mask) \
      70                 :            :         struct radix_tree_root name = RADIX_TREE_INIT(name, mask)
      71                 :            : 
      72                 :            : #define INIT_RADIX_TREE(root, mask) xa_init_flags(root, mask)
      73                 :            : 
      74                 :            : static inline bool radix_tree_empty(const struct radix_tree_root *root)
      75                 :            : {
      76                 :          0 :         return root->xa_head == NULL;
      77                 :            : }
      78                 :            : 
      79                 :            : /**
      80                 :            :  * struct radix_tree_iter - radix tree iterator state
      81                 :            :  *
      82                 :            :  * @index:      index of current slot
      83                 :            :  * @next_index: one beyond the last index for this chunk
      84                 :            :  * @tags:       bit-mask for tag-iterating
      85                 :            :  * @node:       node that contains current slot
      86                 :            :  *
      87                 :            :  * This radix tree iterator works in terms of "chunks" of slots.  A chunk is a
      88                 :            :  * subinterval of slots contained within one radix tree leaf node.  It is
      89                 :            :  * described by a pointer to its first slot and a struct radix_tree_iter
      90                 :            :  * which holds the chunk's position in the tree and its size.  For tagged
      91                 :            :  * iteration radix_tree_iter also holds the slots' bit-mask for one chosen
      92                 :            :  * radix tree tag.
      93                 :            :  */
      94                 :            : struct radix_tree_iter {
      95                 :            :         unsigned long   index;
      96                 :            :         unsigned long   next_index;
      97                 :            :         unsigned long   tags;
      98                 :            :         struct radix_tree_node *node;
      99                 :            : };
     100                 :            : 
     101                 :            : /**
     102                 :            :  * Radix-tree synchronization
     103                 :            :  *
     104                 :            :  * The radix-tree API requires that users provide all synchronisation (with
     105                 :            :  * specific exceptions, noted below).
     106                 :            :  *
     107                 :            :  * Synchronization of access to the data items being stored in the tree, and
     108                 :            :  * management of their lifetimes must be completely managed by API users.
     109                 :            :  *
     110                 :            :  * For API usage, in general,
     111                 :            :  * - any function _modifying_ the tree or tags (inserting or deleting
     112                 :            :  *   items, setting or clearing tags) must exclude other modifications, and
     113                 :            :  *   exclude any functions reading the tree.
     114                 :            :  * - any function _reading_ the tree or tags (looking up items or tags,
     115                 :            :  *   gang lookups) must exclude modifications to the tree, but may occur
     116                 :            :  *   concurrently with other readers.
     117                 :            :  *
     118                 :            :  * The notable exceptions to this rule are the following functions:
     119                 :            :  * __radix_tree_lookup
     120                 :            :  * radix_tree_lookup
     121                 :            :  * radix_tree_lookup_slot
     122                 :            :  * radix_tree_tag_get
     123                 :            :  * radix_tree_gang_lookup
     124                 :            :  * radix_tree_gang_lookup_tag
     125                 :            :  * radix_tree_gang_lookup_tag_slot
     126                 :            :  * radix_tree_tagged
     127                 :            :  *
     128                 :            :  * The first 7 functions are able to be called locklessly, using RCU. The
     129                 :            :  * caller must ensure calls to these functions are made within rcu_read_lock()
     130                 :            :  * regions. Other readers (lock-free or otherwise) and modifications may be
     131                 :            :  * running concurrently.
     132                 :            :  *
     133                 :            :  * It is still required that the caller manage the synchronization and lifetimes
     134                 :            :  * of the items. So if RCU lock-free lookups are used, typically this would mean
     135                 :            :  * that the items have their own locks, or are amenable to lock-free access; and
     136                 :            :  * that the items are freed by RCU (or only freed after having been deleted from
     137                 :            :  * the radix tree *and* a synchronize_rcu() grace period).
     138                 :            :  *
     139                 :            :  * (Note, rcu_assign_pointer and rcu_dereference are not needed to control
     140                 :            :  * access to data items when inserting into or looking up from the radix tree)
     141                 :            :  *
     142                 :            :  * Note that the value returned by radix_tree_tag_get() may not be relied upon
     143                 :            :  * if only the RCU read lock is held.  Functions to set/clear tags and to
     144                 :            :  * delete nodes running concurrently with it may affect its result such that
     145                 :            :  * two consecutive reads in the same locked section may return different
     146                 :            :  * values.  If reliability is required, modification functions must also be
     147                 :            :  * excluded from concurrency.
     148                 :            :  *
     149                 :            :  * radix_tree_tagged is able to be called without locking or RCU.
     150                 :            :  */
     151                 :            : 
     152                 :            : /**
     153                 :            :  * radix_tree_deref_slot - dereference a slot
     154                 :            :  * @slot: slot pointer, returned by radix_tree_lookup_slot
     155                 :            :  *
     156                 :            :  * For use with radix_tree_lookup_slot().  Caller must hold tree at least read
     157                 :            :  * locked across slot lookup and dereference. Not required if write lock is
     158                 :            :  * held (ie. items cannot be concurrently inserted).
     159                 :            :  *
     160                 :            :  * radix_tree_deref_retry must be used to confirm validity of the pointer if
     161                 :            :  * only the read lock is held.
     162                 :            :  *
     163                 :            :  * Return: entry stored in that slot.
     164                 :            :  */
     165                 :            : static inline void *radix_tree_deref_slot(void __rcu **slot)
     166                 :            : {
     167                 :            :         return rcu_dereference(*slot);
     168                 :            : }
     169                 :            : 
     170                 :            : /**
     171                 :            :  * radix_tree_deref_slot_protected - dereference a slot with tree lock held
     172                 :            :  * @slot: slot pointer, returned by radix_tree_lookup_slot
     173                 :            :  *
     174                 :            :  * Similar to radix_tree_deref_slot.  The caller does not hold the RCU read
     175                 :            :  * lock but it must hold the tree lock to prevent parallel updates.
     176                 :            :  *
     177                 :            :  * Return: entry stored in that slot.
     178                 :            :  */
     179                 :            : static inline void *radix_tree_deref_slot_protected(void __rcu **slot,
     180                 :            :                                                         spinlock_t *treelock)
     181                 :            : {
     182                 :            :         return rcu_dereference_protected(*slot, lockdep_is_held(treelock));
     183                 :            : }
     184                 :            : 
     185                 :            : /**
     186                 :            :  * radix_tree_deref_retry       - check radix_tree_deref_slot
     187                 :            :  * @arg:        pointer returned by radix_tree_deref_slot
     188                 :            :  * Returns:     0 if retry is not required, otherwise retry is required
     189                 :            :  *
     190                 :            :  * radix_tree_deref_retry must be used with radix_tree_deref_slot.
     191                 :            :  */
     192                 :            : static inline int radix_tree_deref_retry(void *arg)
     193                 :            : {
     194                 :            :         return unlikely(radix_tree_is_internal_node(arg));
     195                 :            : }
     196                 :            : 
     197                 :            : /**
     198                 :            :  * radix_tree_exception - radix_tree_deref_slot returned either exception?
     199                 :            :  * @arg:        value returned by radix_tree_deref_slot
     200                 :            :  * Returns:     0 if well-aligned pointer, non-0 if either kind of exception.
     201                 :            :  */
     202                 :            : static inline int radix_tree_exception(void *arg)
     203                 :            : {
     204                 :            :         return unlikely((unsigned long)arg & RADIX_TREE_ENTRY_MASK);
     205                 :            : }
     206                 :            : 
     207                 :            : int radix_tree_insert(struct radix_tree_root *, unsigned long index,
     208                 :            :                         void *);
     209                 :            : void *__radix_tree_lookup(const struct radix_tree_root *, unsigned long index,
     210                 :            :                           struct radix_tree_node **nodep, void __rcu ***slotp);
     211                 :            : void *radix_tree_lookup(const struct radix_tree_root *, unsigned long);
     212                 :            : void __rcu **radix_tree_lookup_slot(const struct radix_tree_root *,
     213                 :            :                                         unsigned long index);
     214                 :            : void __radix_tree_replace(struct radix_tree_root *, struct radix_tree_node *,
     215                 :            :                           void __rcu **slot, void *entry);
     216                 :            : void radix_tree_iter_replace(struct radix_tree_root *,
     217                 :            :                 const struct radix_tree_iter *, void __rcu **slot, void *entry);
     218                 :            : void radix_tree_replace_slot(struct radix_tree_root *,
     219                 :            :                              void __rcu **slot, void *entry);
     220                 :            : void radix_tree_iter_delete(struct radix_tree_root *,
     221                 :            :                         struct radix_tree_iter *iter, void __rcu **slot);
     222                 :            : void *radix_tree_delete_item(struct radix_tree_root *, unsigned long, void *);
     223                 :            : void *radix_tree_delete(struct radix_tree_root *, unsigned long);
     224                 :            : unsigned int radix_tree_gang_lookup(const struct radix_tree_root *,
     225                 :            :                         void **results, unsigned long first_index,
     226                 :            :                         unsigned int max_items);
     227                 :            : int radix_tree_preload(gfp_t gfp_mask);
     228                 :            : int radix_tree_maybe_preload(gfp_t gfp_mask);
     229                 :            : void radix_tree_init(void);
     230                 :            : void *radix_tree_tag_set(struct radix_tree_root *,
     231                 :            :                         unsigned long index, unsigned int tag);
     232                 :            : void *radix_tree_tag_clear(struct radix_tree_root *,
     233                 :            :                         unsigned long index, unsigned int tag);
     234                 :            : int radix_tree_tag_get(const struct radix_tree_root *,
     235                 :            :                         unsigned long index, unsigned int tag);
     236                 :            : void radix_tree_iter_tag_clear(struct radix_tree_root *,
     237                 :            :                 const struct radix_tree_iter *iter, unsigned int tag);
     238                 :            : unsigned int radix_tree_gang_lookup_tag(const struct radix_tree_root *,
     239                 :            :                 void **results, unsigned long first_index,
     240                 :            :                 unsigned int max_items, unsigned int tag);
     241                 :            : unsigned int radix_tree_gang_lookup_tag_slot(const struct radix_tree_root *,
     242                 :            :                 void __rcu ***results, unsigned long first_index,
     243                 :            :                 unsigned int max_items, unsigned int tag);
     244                 :            : int radix_tree_tagged(const struct radix_tree_root *, unsigned int tag);
     245                 :            : 
     246                 :            : static inline void radix_tree_preload_end(void)
     247                 :            : {
     248                 :          3 :         preempt_enable();
     249                 :            : }
     250                 :            : 
     251                 :            : void __rcu **idr_get_free(struct radix_tree_root *root,
     252                 :            :                               struct radix_tree_iter *iter, gfp_t gfp,
     253                 :            :                               unsigned long max);
     254                 :            : 
     255                 :            : enum {
     256                 :            :         RADIX_TREE_ITER_TAG_MASK = 0x0f,        /* tag index in lower nybble */
     257                 :            :         RADIX_TREE_ITER_TAGGED   = 0x10,        /* lookup tagged slots */
     258                 :            :         RADIX_TREE_ITER_CONTIG   = 0x20,        /* stop at first hole */
     259                 :            : };
     260                 :            : 
     261                 :            : /**
     262                 :            :  * radix_tree_iter_init - initialize radix tree iterator
     263                 :            :  *
     264                 :            :  * @iter:       pointer to iterator state
     265                 :            :  * @start:      iteration starting index
     266                 :            :  * Returns:     NULL
     267                 :            :  */
     268                 :            : static __always_inline void __rcu **
     269                 :            : radix_tree_iter_init(struct radix_tree_iter *iter, unsigned long start)
     270                 :            : {
     271                 :            :         /*
     272                 :            :          * Leave iter->tags uninitialized. radix_tree_next_chunk() will fill it
     273                 :            :          * in the case of a successful tagged chunk lookup.  If the lookup was
     274                 :            :          * unsuccessful or non-tagged then nobody cares about ->tags.
     275                 :            :          *
     276                 :            :          * Set index to zero to bypass next_index overflow protection.
     277                 :            :          * See the comment in radix_tree_next_chunk() for details.
     278                 :            :          */
     279                 :          3 :         iter->index = 0;
     280                 :          3 :         iter->next_index = start;
     281                 :            :         return NULL;
     282                 :            : }
     283                 :            : 
     284                 :            : /**
     285                 :            :  * radix_tree_next_chunk - find next chunk of slots for iteration
     286                 :            :  *
     287                 :            :  * @root:       radix tree root
     288                 :            :  * @iter:       iterator state
     289                 :            :  * @flags:      RADIX_TREE_ITER_* flags and tag index
     290                 :            :  * Returns:     pointer to chunk first slot, or NULL if there no more left
     291                 :            :  *
     292                 :            :  * This function looks up the next chunk in the radix tree starting from
     293                 :            :  * @iter->next_index.  It returns a pointer to the chunk's first slot.
     294                 :            :  * Also it fills @iter with data about chunk: position in the tree (index),
     295                 :            :  * its end (next_index), and constructs a bit mask for tagged iterating (tags).
     296                 :            :  */
     297                 :            : void __rcu **radix_tree_next_chunk(const struct radix_tree_root *,
     298                 :            :                              struct radix_tree_iter *iter, unsigned flags);
     299                 :            : 
     300                 :            : /**
     301                 :            :  * radix_tree_iter_lookup - look up an index in the radix tree
     302                 :            :  * @root: radix tree root
     303                 :            :  * @iter: iterator state
     304                 :            :  * @index: key to look up
     305                 :            :  *
     306                 :            :  * If @index is present in the radix tree, this function returns the slot
     307                 :            :  * containing it and updates @iter to describe the entry.  If @index is not
     308                 :            :  * present, it returns NULL.
     309                 :            :  */
     310                 :            : static inline void __rcu **
     311                 :            : radix_tree_iter_lookup(const struct radix_tree_root *root,
     312                 :            :                         struct radix_tree_iter *iter, unsigned long index)
     313                 :            : {
     314                 :            :         radix_tree_iter_init(iter, index);
     315                 :            :         return radix_tree_next_chunk(root, iter, RADIX_TREE_ITER_CONTIG);
     316                 :            : }
     317                 :            : 
     318                 :            : /**
     319                 :            :  * radix_tree_iter_retry - retry this chunk of the iteration
     320                 :            :  * @iter:       iterator state
     321                 :            :  *
     322                 :            :  * If we iterate over a tree protected only by the RCU lock, a race
     323                 :            :  * against deletion or creation may result in seeing a slot for which
     324                 :            :  * radix_tree_deref_retry() returns true.  If so, call this function
     325                 :            :  * and continue the iteration.
     326                 :            :  */
     327                 :            : static inline __must_check
     328                 :            : void __rcu **radix_tree_iter_retry(struct radix_tree_iter *iter)
     329                 :            : {
     330                 :          0 :         iter->next_index = iter->index;
     331                 :          0 :         iter->tags = 0;
     332                 :            :         return NULL;
     333                 :            : }
     334                 :            : 
     335                 :            : static inline unsigned long
     336                 :          0 : __radix_tree_iter_add(struct radix_tree_iter *iter, unsigned long slots)
     337                 :            : {
     338                 :          3 :         return iter->index + slots;
     339                 :            : }
     340                 :            : 
     341                 :            : /**
     342                 :            :  * radix_tree_iter_resume - resume iterating when the chunk may be invalid
     343                 :            :  * @slot: pointer to current slot
     344                 :            :  * @iter: iterator state
     345                 :            :  * Returns: New slot pointer
     346                 :            :  *
     347                 :            :  * If the iterator needs to release then reacquire a lock, the chunk may
     348                 :            :  * have been invalidated by an insertion or deletion.  Call this function
     349                 :            :  * before releasing the lock to continue the iteration from the next index.
     350                 :            :  */
     351                 :            : void __rcu **__must_check radix_tree_iter_resume(void __rcu **slot,
     352                 :            :                                         struct radix_tree_iter *iter);
     353                 :            : 
     354                 :            : /**
     355                 :            :  * radix_tree_chunk_size - get current chunk size
     356                 :            :  *
     357                 :            :  * @iter:       pointer to radix tree iterator
     358                 :            :  * Returns:     current chunk size
     359                 :            :  */
     360                 :            : static __always_inline long
     361                 :            : radix_tree_chunk_size(struct radix_tree_iter *iter)
     362                 :            : {
     363                 :          0 :         return iter->next_index - iter->index;
     364                 :            : }
     365                 :            : 
     366                 :            : /**
     367                 :            :  * radix_tree_next_slot - find next slot in chunk
     368                 :            :  *
     369                 :            :  * @slot:       pointer to current slot
     370                 :            :  * @iter:       pointer to interator state
     371                 :            :  * @flags:      RADIX_TREE_ITER_*, should be constant
     372                 :            :  * Returns:     pointer to next slot, or NULL if there no more left
     373                 :            :  *
     374                 :            :  * This function updates @iter->index in the case of a successful lookup.
     375                 :            :  * For tagged lookup it also eats @iter->tags.
     376                 :            :  *
     377                 :            :  * There are several cases where 'slot' can be passed in as NULL to this
     378                 :            :  * function.  These cases result from the use of radix_tree_iter_resume() or
     379                 :            :  * radix_tree_iter_retry().  In these cases we don't end up dereferencing
     380                 :            :  * 'slot' because either:
     381                 :            :  * a) we are doing tagged iteration and iter->tags has been set to 0, or
     382                 :            :  * b) we are doing non-tagged iteration, and iter->index and iter->next_index
     383                 :            :  *    have been set up so that radix_tree_chunk_size() returns 1 or 0.
     384                 :            :  */
     385                 :            : static __always_inline void __rcu **radix_tree_next_slot(void __rcu **slot,
     386                 :            :                                 struct radix_tree_iter *iter, unsigned flags)
     387                 :            : {
     388                 :            :         if (flags & RADIX_TREE_ITER_TAGGED) {
     389                 :          0 :                 iter->tags >>= 1;
     390                 :          0 :                 if (unlikely(!iter->tags))
     391                 :            :                         return NULL;
     392                 :          0 :                 if (likely(iter->tags & 1ul)) {
     393                 :          0 :                         iter->index = __radix_tree_iter_add(iter, 1);
     394                 :          0 :                         slot++;
     395                 :            :                         goto found;
     396                 :            :                 }
     397                 :          0 :                 if (!(flags & RADIX_TREE_ITER_CONTIG)) {
     398                 :            :                         unsigned offset = __ffs(iter->tags);
     399                 :            : 
     400                 :          0 :                         iter->tags >>= offset++;
     401                 :          0 :                         iter->index = __radix_tree_iter_add(iter, offset);
     402                 :          0 :                         slot += offset;
     403                 :            :                         goto found;
     404                 :            :                 }
     405                 :            :         } else {
     406                 :            :                 long count = radix_tree_chunk_size(iter);
     407                 :            : 
     408                 :          0 :                 while (--count > 0) {
     409                 :          0 :                         slot++;
     410                 :          0 :                         iter->index = __radix_tree_iter_add(iter, 1);
     411                 :            : 
     412                 :          0 :                         if (likely(*slot))
     413                 :            :                                 goto found;
     414                 :            :                         if (flags & RADIX_TREE_ITER_CONTIG) {
     415                 :            :                                 /* forbid switching to the next chunk */
     416                 :            :                                 iter->next_index = 0;
     417                 :            :                                 break;
     418                 :            :                         }
     419                 :            :                 }
     420                 :            :         }
     421                 :            :         return NULL;
     422                 :            : 
     423                 :            :  found:
     424                 :            :         return slot;
     425                 :            : }
     426                 :            : 
     427                 :            : /**
     428                 :            :  * radix_tree_for_each_slot - iterate over non-empty slots
     429                 :            :  *
     430                 :            :  * @slot:       the void** variable for pointer to slot
     431                 :            :  * @root:       the struct radix_tree_root pointer
     432                 :            :  * @iter:       the struct radix_tree_iter pointer
     433                 :            :  * @start:      iteration starting index
     434                 :            :  *
     435                 :            :  * @slot points to radix tree slot, @iter->index contains its index.
     436                 :            :  */
     437                 :            : #define radix_tree_for_each_slot(slot, root, iter, start)               \
     438                 :            :         for (slot = radix_tree_iter_init(iter, start) ;                 \
     439                 :            :              slot || (slot = radix_tree_next_chunk(root, iter, 0)) ;    \
     440                 :            :              slot = radix_tree_next_slot(slot, iter, 0))
     441                 :            : 
     442                 :            : /**
     443                 :            :  * radix_tree_for_each_tagged - iterate over tagged slots
     444                 :            :  *
     445                 :            :  * @slot:       the void** variable for pointer to slot
     446                 :            :  * @root:       the struct radix_tree_root pointer
     447                 :            :  * @iter:       the struct radix_tree_iter pointer
     448                 :            :  * @start:      iteration starting index
     449                 :            :  * @tag:        tag index
     450                 :            :  *
     451                 :            :  * @slot points to radix tree slot, @iter->index contains its index.
     452                 :            :  */
     453                 :            : #define radix_tree_for_each_tagged(slot, root, iter, start, tag)        \
     454                 :            :         for (slot = radix_tree_iter_init(iter, start) ;                 \
     455                 :            :              slot || (slot = radix_tree_next_chunk(root, iter,          \
     456                 :            :                               RADIX_TREE_ITER_TAGGED | tag)) ;          \
     457                 :            :              slot = radix_tree_next_slot(slot, iter,                    \
     458                 :            :                                 RADIX_TREE_ITER_TAGGED | tag))
     459                 :            : 
     460                 :            : #endif /* _LINUX_RADIX_TREE_H */