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1da177e4 LT |
1 | /* |
2 | * Copyright (C) 2001 Momchil Velikov | |
3 | * Portions Copyright (C) 2001 Christoph Hellwig | |
7cf9c2c7 | 4 | * Copyright (C) 2006 Nick Piggin |
78c1d784 | 5 | * Copyright (C) 2012 Konstantin Khlebnikov |
1da177e4 LT |
6 | * |
7 | * This program is free software; you can redistribute it and/or | |
8 | * modify it under the terms of the GNU General Public License as | |
9 | * published by the Free Software Foundation; either version 2, or (at | |
10 | * your option) any later version. | |
11 | * | |
12 | * This program is distributed in the hope that it will be useful, but | |
13 | * WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
15 | * General Public License for more details. | |
16 | * | |
17 | * You should have received a copy of the GNU General Public License | |
18 | * along with this program; if not, write to the Free Software | |
19 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. | |
20 | */ | |
21 | #ifndef _LINUX_RADIX_TREE_H | |
22 | #define _LINUX_RADIX_TREE_H | |
23 | ||
f67c07f0 | 24 | #include <linux/bitops.h> |
1da177e4 LT |
25 | #include <linux/preempt.h> |
26 | #include <linux/types.h> | |
187f1882 | 27 | #include <linux/bug.h> |
7cf9c2c7 NP |
28 | #include <linux/kernel.h> |
29 | #include <linux/rcupdate.h> | |
30 | ||
31 | /* | |
3bcadd6f MW |
32 | * The bottom two bits of the slot determine how the remaining bits in the |
33 | * slot are interpreted: | |
7cf9c2c7 | 34 | * |
3bcadd6f MW |
35 | * 00 - data pointer |
36 | * 01 - internal entry | |
37 | * 10 - exceptional entry | |
a23216a2 | 38 | * 11 - this bit combination is currently unused/reserved |
3bcadd6f MW |
39 | * |
40 | * The internal entry may be a pointer to the next level in the tree, a | |
41 | * sibling entry, or an indicator that the entry in this slot has been moved | |
42 | * to another location in the tree and the lookup should be restarted. While | |
43 | * NULL fits the 'data pointer' pattern, it means that there is no entry in | |
44 | * the tree for this index (no matter what level of the tree it is found at). | |
45 | * This means that you cannot store NULL in the tree as a value for the index. | |
7cf9c2c7 | 46 | */ |
3bcadd6f MW |
47 | #define RADIX_TREE_ENTRY_MASK 3UL |
48 | #define RADIX_TREE_INTERNAL_NODE 1UL | |
30ff46cc | 49 | |
6328650b | 50 | /* |
3bcadd6f MW |
51 | * Most users of the radix tree store pointers but shmem/tmpfs stores swap |
52 | * entries in the same tree. They are marked as exceptional entries to | |
53 | * distinguish them from pointers to struct page. | |
6328650b HD |
54 | * EXCEPTIONAL_ENTRY tests the bit, EXCEPTIONAL_SHIFT shifts content past it. |
55 | */ | |
56 | #define RADIX_TREE_EXCEPTIONAL_ENTRY 2 | |
57 | #define RADIX_TREE_EXCEPTIONAL_SHIFT 2 | |
7cf9c2c7 | 58 | |
3bcadd6f | 59 | static inline bool radix_tree_is_internal_node(void *ptr) |
7cf9c2c7 | 60 | { |
3bcadd6f MW |
61 | return ((unsigned long)ptr & RADIX_TREE_ENTRY_MASK) == |
62 | RADIX_TREE_INTERNAL_NODE; | |
7cf9c2c7 NP |
63 | } |
64 | ||
65 | /*** radix-tree API starts here ***/ | |
1da177e4 | 66 | |
f446daae | 67 | #define RADIX_TREE_MAX_TAGS 3 |
612d6c19 | 68 | |
97d778b2 | 69 | #ifndef RADIX_TREE_MAP_SHIFT |
139e5616 | 70 | #define RADIX_TREE_MAP_SHIFT (CONFIG_BASE_SMALL ? 4 : 6) |
139e5616 JW |
71 | #endif |
72 | ||
73 | #define RADIX_TREE_MAP_SIZE (1UL << RADIX_TREE_MAP_SHIFT) | |
74 | #define RADIX_TREE_MAP_MASK (RADIX_TREE_MAP_SIZE-1) | |
75 | ||
76 | #define RADIX_TREE_TAG_LONGS \ | |
77 | ((RADIX_TREE_MAP_SIZE + BITS_PER_LONG - 1) / BITS_PER_LONG) | |
78 | ||
449dd698 JW |
79 | #define RADIX_TREE_INDEX_BITS (8 /* CHAR_BIT */ * sizeof(unsigned long)) |
80 | #define RADIX_TREE_MAX_PATH (DIV_ROUND_UP(RADIX_TREE_INDEX_BITS, \ | |
81 | RADIX_TREE_MAP_SHIFT)) | |
82 | ||
e157b555 MW |
83 | /* |
84 | * @count is the count of every non-NULL element in the ->slots array | |
85 | * whether that is an exceptional entry, a retry entry, a user pointer, | |
86 | * a sibling entry or a pointer to the next level of the tree. | |
87 | * @exceptional is the count of every element in ->slots which is | |
88 | * either radix_tree_exceptional_entry() or is a sibling entry for an | |
89 | * exceptional entry. | |
90 | */ | |
139e5616 | 91 | struct radix_tree_node { |
f7942430 JW |
92 | unsigned char shift; /* Bits remaining in each slot */ |
93 | unsigned char offset; /* Slot offset in parent */ | |
14b46879 | 94 | unsigned char count; /* Total entry count */ |
f7942430 | 95 | unsigned char exceptional; /* Exceptional entry count */ |
91d9c05a MW |
96 | struct radix_tree_node *parent; /* Used when ascending tree */ |
97 | void *private_data; /* For tree user */ | |
139e5616 | 98 | union { |
91d9c05a MW |
99 | struct list_head private_list; /* For tree user */ |
100 | struct rcu_head rcu_head; /* Used when freeing node */ | |
139e5616 JW |
101 | }; |
102 | void __rcu *slots[RADIX_TREE_MAP_SIZE]; | |
103 | unsigned long tags[RADIX_TREE_MAX_TAGS][RADIX_TREE_TAG_LONGS]; | |
104 | }; | |
105 | ||
612d6c19 | 106 | /* root tags are stored in gfp_mask, shifted by __GFP_BITS_SHIFT */ |
1da177e4 | 107 | struct radix_tree_root { |
fd4f2df2 | 108 | gfp_t gfp_mask; |
a1115570 | 109 | struct radix_tree_node __rcu *rnode; |
1da177e4 LT |
110 | }; |
111 | ||
112 | #define RADIX_TREE_INIT(mask) { \ | |
1da177e4 LT |
113 | .gfp_mask = (mask), \ |
114 | .rnode = NULL, \ | |
115 | } | |
116 | ||
117 | #define RADIX_TREE(name, mask) \ | |
118 | struct radix_tree_root name = RADIX_TREE_INIT(mask) | |
119 | ||
120 | #define INIT_RADIX_TREE(root, mask) \ | |
121 | do { \ | |
1da177e4 LT |
122 | (root)->gfp_mask = (mask); \ |
123 | (root)->rnode = NULL; \ | |
124 | } while (0) | |
125 | ||
e9256efc MW |
126 | static inline bool radix_tree_empty(struct radix_tree_root *root) |
127 | { | |
128 | return root->rnode == NULL; | |
129 | } | |
130 | ||
268f42de MW |
131 | /** |
132 | * struct radix_tree_iter - radix tree iterator state | |
133 | * | |
134 | * @index: index of current slot | |
135 | * @next_index: one beyond the last index for this chunk | |
136 | * @tags: bit-mask for tag-iterating | |
137 | * @node: node that contains current slot | |
138 | * @shift: shift for the node that holds our slots | |
139 | * | |
140 | * This radix tree iterator works in terms of "chunks" of slots. A chunk is a | |
141 | * subinterval of slots contained within one radix tree leaf node. It is | |
142 | * described by a pointer to its first slot and a struct radix_tree_iter | |
143 | * which holds the chunk's position in the tree and its size. For tagged | |
144 | * iteration radix_tree_iter also holds the slots' bit-mask for one chosen | |
145 | * radix tree tag. | |
146 | */ | |
147 | struct radix_tree_iter { | |
148 | unsigned long index; | |
149 | unsigned long next_index; | |
150 | unsigned long tags; | |
151 | struct radix_tree_node *node; | |
152 | #ifdef CONFIG_RADIX_TREE_MULTIORDER | |
153 | unsigned int shift; | |
154 | #endif | |
155 | }; | |
156 | ||
157 | static inline unsigned int iter_shift(const struct radix_tree_iter *iter) | |
158 | { | |
159 | #ifdef CONFIG_RADIX_TREE_MULTIORDER | |
160 | return iter->shift; | |
161 | #else | |
162 | return 0; | |
163 | #endif | |
164 | } | |
165 | ||
7cf9c2c7 NP |
166 | /** |
167 | * Radix-tree synchronization | |
168 | * | |
169 | * The radix-tree API requires that users provide all synchronisation (with | |
170 | * specific exceptions, noted below). | |
171 | * | |
172 | * Synchronization of access to the data items being stored in the tree, and | |
173 | * management of their lifetimes must be completely managed by API users. | |
174 | * | |
175 | * For API usage, in general, | |
59c51591 | 176 | * - any function _modifying_ the tree or tags (inserting or deleting |
eb8dc5e7 | 177 | * items, setting or clearing tags) must exclude other modifications, and |
7cf9c2c7 | 178 | * exclude any functions reading the tree. |
59c51591 | 179 | * - any function _reading_ the tree or tags (looking up items or tags, |
7cf9c2c7 NP |
180 | * gang lookups) must exclude modifications to the tree, but may occur |
181 | * concurrently with other readers. | |
182 | * | |
183 | * The notable exceptions to this rule are the following functions: | |
139e5616 | 184 | * __radix_tree_lookup |
7cf9c2c7 | 185 | * radix_tree_lookup |
47feff2c | 186 | * radix_tree_lookup_slot |
7cf9c2c7 NP |
187 | * radix_tree_tag_get |
188 | * radix_tree_gang_lookup | |
47feff2c | 189 | * radix_tree_gang_lookup_slot |
7cf9c2c7 | 190 | * radix_tree_gang_lookup_tag |
47feff2c | 191 | * radix_tree_gang_lookup_tag_slot |
7cf9c2c7 NP |
192 | * radix_tree_tagged |
193 | * | |
243c2137 | 194 | * The first 8 functions are able to be called locklessly, using RCU. The |
7cf9c2c7 NP |
195 | * caller must ensure calls to these functions are made within rcu_read_lock() |
196 | * regions. Other readers (lock-free or otherwise) and modifications may be | |
197 | * running concurrently. | |
198 | * | |
199 | * It is still required that the caller manage the synchronization and lifetimes | |
200 | * of the items. So if RCU lock-free lookups are used, typically this would mean | |
201 | * that the items have their own locks, or are amenable to lock-free access; and | |
202 | * that the items are freed by RCU (or only freed after having been deleted from | |
203 | * the radix tree *and* a synchronize_rcu() grace period). | |
204 | * | |
205 | * (Note, rcu_assign_pointer and rcu_dereference are not needed to control | |
206 | * access to data items when inserting into or looking up from the radix tree) | |
207 | * | |
ce82653d DH |
208 | * Note that the value returned by radix_tree_tag_get() may not be relied upon |
209 | * if only the RCU read lock is held. Functions to set/clear tags and to | |
210 | * delete nodes running concurrently with it may affect its result such that | |
211 | * two consecutive reads in the same locked section may return different | |
212 | * values. If reliability is required, modification functions must also be | |
213 | * excluded from concurrency. | |
214 | * | |
7cf9c2c7 NP |
215 | * radix_tree_tagged is able to be called without locking or RCU. |
216 | */ | |
217 | ||
218 | /** | |
219 | * radix_tree_deref_slot - dereference a slot | |
220 | * @pslot: pointer to slot, returned by radix_tree_lookup_slot | |
221 | * Returns: item that was stored in that slot with any direct pointer flag | |
222 | * removed. | |
223 | * | |
224 | * For use with radix_tree_lookup_slot(). Caller must hold tree at least read | |
27d20fdd NP |
225 | * locked across slot lookup and dereference. Not required if write lock is |
226 | * held (ie. items cannot be concurrently inserted). | |
227 | * | |
228 | * radix_tree_deref_retry must be used to confirm validity of the pointer if | |
229 | * only the read lock is held. | |
7cf9c2c7 NP |
230 | */ |
231 | static inline void *radix_tree_deref_slot(void **pslot) | |
232 | { | |
27d20fdd | 233 | return rcu_dereference(*pslot); |
7cf9c2c7 | 234 | } |
27d20fdd | 235 | |
29c1f677 MG |
236 | /** |
237 | * radix_tree_deref_slot_protected - dereference a slot without RCU lock but with tree lock held | |
238 | * @pslot: pointer to slot, returned by radix_tree_lookup_slot | |
239 | * Returns: item that was stored in that slot with any direct pointer flag | |
240 | * removed. | |
241 | * | |
242 | * Similar to radix_tree_deref_slot but only used during migration when a pages | |
243 | * mapping is being moved. The caller does not hold the RCU read lock but it | |
244 | * must hold the tree lock to prevent parallel updates. | |
245 | */ | |
246 | static inline void *radix_tree_deref_slot_protected(void **pslot, | |
247 | spinlock_t *treelock) | |
248 | { | |
249 | return rcu_dereference_protected(*pslot, lockdep_is_held(treelock)); | |
250 | } | |
251 | ||
27d20fdd NP |
252 | /** |
253 | * radix_tree_deref_retry - check radix_tree_deref_slot | |
254 | * @arg: pointer returned by radix_tree_deref_slot | |
255 | * Returns: 0 if retry is not required, otherwise retry is required | |
256 | * | |
257 | * radix_tree_deref_retry must be used with radix_tree_deref_slot. | |
258 | */ | |
259 | static inline int radix_tree_deref_retry(void *arg) | |
260 | { | |
b194d16c | 261 | return unlikely(radix_tree_is_internal_node(arg)); |
27d20fdd NP |
262 | } |
263 | ||
6328650b HD |
264 | /** |
265 | * radix_tree_exceptional_entry - radix_tree_deref_slot gave exceptional entry? | |
266 | * @arg: value returned by radix_tree_deref_slot | |
267 | * Returns: 0 if well-aligned pointer, non-0 if exceptional entry. | |
268 | */ | |
269 | static inline int radix_tree_exceptional_entry(void *arg) | |
270 | { | |
271 | /* Not unlikely because radix_tree_exception often tested first */ | |
272 | return (unsigned long)arg & RADIX_TREE_EXCEPTIONAL_ENTRY; | |
273 | } | |
274 | ||
275 | /** | |
276 | * radix_tree_exception - radix_tree_deref_slot returned either exception? | |
277 | * @arg: value returned by radix_tree_deref_slot | |
278 | * Returns: 0 if well-aligned pointer, non-0 if either kind of exception. | |
279 | */ | |
280 | static inline int radix_tree_exception(void *arg) | |
281 | { | |
3bcadd6f | 282 | return unlikely((unsigned long)arg & RADIX_TREE_ENTRY_MASK); |
6328650b HD |
283 | } |
284 | ||
139e5616 | 285 | int __radix_tree_create(struct radix_tree_root *root, unsigned long index, |
e6145236 MW |
286 | unsigned order, struct radix_tree_node **nodep, |
287 | void ***slotp); | |
288 | int __radix_tree_insert(struct radix_tree_root *, unsigned long index, | |
289 | unsigned order, void *); | |
290 | static inline int radix_tree_insert(struct radix_tree_root *root, | |
291 | unsigned long index, void *entry) | |
292 | { | |
293 | return __radix_tree_insert(root, index, 0, entry); | |
294 | } | |
139e5616 JW |
295 | void *__radix_tree_lookup(struct radix_tree_root *root, unsigned long index, |
296 | struct radix_tree_node **nodep, void ***slotp); | |
1da177e4 | 297 | void *radix_tree_lookup(struct radix_tree_root *, unsigned long); |
a4331366 | 298 | void **radix_tree_lookup_slot(struct radix_tree_root *, unsigned long); |
4d693d08 | 299 | typedef void (*radix_tree_update_node_t)(struct radix_tree_node *, void *); |
f7942430 JW |
300 | void __radix_tree_replace(struct radix_tree_root *root, |
301 | struct radix_tree_node *node, | |
4d693d08 JW |
302 | void **slot, void *item, |
303 | radix_tree_update_node_t update_node, void *private); | |
e157b555 MW |
304 | void radix_tree_iter_replace(struct radix_tree_root *, |
305 | const struct radix_tree_iter *, void **slot, void *item); | |
6d75f366 JW |
306 | void radix_tree_replace_slot(struct radix_tree_root *root, |
307 | void **slot, void *item); | |
14b46879 | 308 | void __radix_tree_delete_node(struct radix_tree_root *root, |
139e5616 | 309 | struct radix_tree_node *node); |
53c59f26 | 310 | void *radix_tree_delete_item(struct radix_tree_root *, unsigned long, void *); |
1da177e4 | 311 | void *radix_tree_delete(struct radix_tree_root *, unsigned long); |
d3798ae8 JW |
312 | void radix_tree_clear_tags(struct radix_tree_root *root, |
313 | struct radix_tree_node *node, | |
314 | void **slot); | |
d604c324 MW |
315 | unsigned int radix_tree_gang_lookup(struct radix_tree_root *root, |
316 | void **results, unsigned long first_index, | |
317 | unsigned int max_items); | |
6328650b HD |
318 | unsigned int radix_tree_gang_lookup_slot(struct radix_tree_root *root, |
319 | void ***results, unsigned long *indices, | |
47feff2c | 320 | unsigned long first_index, unsigned int max_items); |
dd0fc66f | 321 | int radix_tree_preload(gfp_t gfp_mask); |
5e4c0d97 | 322 | int radix_tree_maybe_preload(gfp_t gfp_mask); |
c78c66d1 | 323 | int radix_tree_maybe_preload_order(gfp_t gfp_mask, int order); |
1da177e4 LT |
324 | void radix_tree_init(void); |
325 | void *radix_tree_tag_set(struct radix_tree_root *root, | |
daff89f3 | 326 | unsigned long index, unsigned int tag); |
1da177e4 | 327 | void *radix_tree_tag_clear(struct radix_tree_root *root, |
daff89f3 | 328 | unsigned long index, unsigned int tag); |
1da177e4 | 329 | int radix_tree_tag_get(struct radix_tree_root *root, |
daff89f3 | 330 | unsigned long index, unsigned int tag); |
268f42de MW |
331 | void radix_tree_iter_tag_set(struct radix_tree_root *root, |
332 | const struct radix_tree_iter *iter, unsigned int tag); | |
1da177e4 LT |
333 | unsigned int |
334 | radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results, | |
daff89f3 JC |
335 | unsigned long first_index, unsigned int max_items, |
336 | unsigned int tag); | |
47feff2c NP |
337 | unsigned int |
338 | radix_tree_gang_lookup_tag_slot(struct radix_tree_root *root, void ***results, | |
339 | unsigned long first_index, unsigned int max_items, | |
340 | unsigned int tag); | |
daff89f3 | 341 | int radix_tree_tagged(struct radix_tree_root *root, unsigned int tag); |
1da177e4 LT |
342 | |
343 | static inline void radix_tree_preload_end(void) | |
344 | { | |
345 | preempt_enable(); | |
346 | } | |
347 | ||
e157b555 MW |
348 | int radix_tree_split(struct radix_tree_root *, unsigned long index, |
349 | unsigned new_order); | |
175542f5 MW |
350 | int radix_tree_join(struct radix_tree_root *, unsigned long index, |
351 | unsigned new_order, void *); | |
352 | ||
78c1d784 KK |
353 | #define RADIX_TREE_ITER_TAG_MASK 0x00FF /* tag index in lower byte */ |
354 | #define RADIX_TREE_ITER_TAGGED 0x0100 /* lookup tagged slots */ | |
355 | #define RADIX_TREE_ITER_CONTIG 0x0200 /* stop at first hole */ | |
356 | ||
357 | /** | |
358 | * radix_tree_iter_init - initialize radix tree iterator | |
359 | * | |
360 | * @iter: pointer to iterator state | |
361 | * @start: iteration starting index | |
362 | * Returns: NULL | |
363 | */ | |
364 | static __always_inline void ** | |
365 | radix_tree_iter_init(struct radix_tree_iter *iter, unsigned long start) | |
366 | { | |
367 | /* | |
368 | * Leave iter->tags uninitialized. radix_tree_next_chunk() will fill it | |
369 | * in the case of a successful tagged chunk lookup. If the lookup was | |
370 | * unsuccessful or non-tagged then nobody cares about ->tags. | |
371 | * | |
372 | * Set index to zero to bypass next_index overflow protection. | |
373 | * See the comment in radix_tree_next_chunk() for details. | |
374 | */ | |
375 | iter->index = 0; | |
376 | iter->next_index = start; | |
377 | return NULL; | |
378 | } | |
379 | ||
380 | /** | |
381 | * radix_tree_next_chunk - find next chunk of slots for iteration | |
382 | * | |
383 | * @root: radix tree root | |
384 | * @iter: iterator state | |
385 | * @flags: RADIX_TREE_ITER_* flags and tag index | |
386 | * Returns: pointer to chunk first slot, or NULL if there no more left | |
387 | * | |
388 | * This function looks up the next chunk in the radix tree starting from | |
389 | * @iter->next_index. It returns a pointer to the chunk's first slot. | |
390 | * Also it fills @iter with data about chunk: position in the tree (index), | |
391 | * its end (next_index), and constructs a bit mask for tagged iterating (tags). | |
392 | */ | |
393 | void **radix_tree_next_chunk(struct radix_tree_root *root, | |
394 | struct radix_tree_iter *iter, unsigned flags); | |
395 | ||
46437f9a MW |
396 | /** |
397 | * radix_tree_iter_retry - retry this chunk of the iteration | |
398 | * @iter: iterator state | |
399 | * | |
400 | * If we iterate over a tree protected only by the RCU lock, a race | |
401 | * against deletion or creation may result in seeing a slot for which | |
402 | * radix_tree_deref_retry() returns true. If so, call this function | |
403 | * and continue the iteration. | |
404 | */ | |
405 | static inline __must_check | |
406 | void **radix_tree_iter_retry(struct radix_tree_iter *iter) | |
407 | { | |
408 | iter->next_index = iter->index; | |
3cb9185c | 409 | iter->tags = 0; |
46437f9a MW |
410 | return NULL; |
411 | } | |
412 | ||
21ef5339 RZ |
413 | static inline unsigned long |
414 | __radix_tree_iter_add(struct radix_tree_iter *iter, unsigned long slots) | |
415 | { | |
416 | return iter->index + (slots << iter_shift(iter)); | |
417 | } | |
418 | ||
7165092f | 419 | /** |
148deab2 MW |
420 | * radix_tree_iter_resume - resume iterating when the chunk may be invalid |
421 | * @slot: pointer to current slot | |
422 | * @iter: iterator state | |
423 | * Returns: New slot pointer | |
7165092f MW |
424 | * |
425 | * If the iterator needs to release then reacquire a lock, the chunk may | |
426 | * have been invalidated by an insertion or deletion. Call this function | |
148deab2 | 427 | * before releasing the lock to continue the iteration from the next index. |
7165092f | 428 | */ |
148deab2 MW |
429 | void **__must_check radix_tree_iter_resume(void **slot, |
430 | struct radix_tree_iter *iter); | |
7165092f | 431 | |
78c1d784 KK |
432 | /** |
433 | * radix_tree_chunk_size - get current chunk size | |
434 | * | |
435 | * @iter: pointer to radix tree iterator | |
436 | * Returns: current chunk size | |
437 | */ | |
73204282 | 438 | static __always_inline long |
78c1d784 KK |
439 | radix_tree_chunk_size(struct radix_tree_iter *iter) |
440 | { | |
21ef5339 RZ |
441 | return (iter->next_index - iter->index) >> iter_shift(iter); |
442 | } | |
443 | ||
148deab2 MW |
444 | #ifdef CONFIG_RADIX_TREE_MULTIORDER |
445 | void ** __radix_tree_next_slot(void **slot, struct radix_tree_iter *iter, | |
446 | unsigned flags); | |
447 | #else | |
448 | /* Can't happen without sibling entries, but the compiler can't tell that */ | |
449 | static inline void ** __radix_tree_next_slot(void **slot, | |
450 | struct radix_tree_iter *iter, unsigned flags) | |
21ef5339 | 451 | { |
148deab2 | 452 | return slot; |
78c1d784 | 453 | } |
148deab2 | 454 | #endif |
78c1d784 KK |
455 | |
456 | /** | |
457 | * radix_tree_next_slot - find next slot in chunk | |
458 | * | |
459 | * @slot: pointer to current slot | |
460 | * @iter: pointer to interator state | |
461 | * @flags: RADIX_TREE_ITER_*, should be constant | |
462 | * Returns: pointer to next slot, or NULL if there no more left | |
463 | * | |
464 | * This function updates @iter->index in the case of a successful lookup. | |
465 | * For tagged lookup it also eats @iter->tags. | |
915045fe RZ |
466 | * |
467 | * There are several cases where 'slot' can be passed in as NULL to this | |
148deab2 | 468 | * function. These cases result from the use of radix_tree_iter_resume() or |
915045fe RZ |
469 | * radix_tree_iter_retry(). In these cases we don't end up dereferencing |
470 | * 'slot' because either: | |
471 | * a) we are doing tagged iteration and iter->tags has been set to 0, or | |
472 | * b) we are doing non-tagged iteration, and iter->index and iter->next_index | |
473 | * have been set up so that radix_tree_chunk_size() returns 1 or 0. | |
78c1d784 KK |
474 | */ |
475 | static __always_inline void ** | |
476 | radix_tree_next_slot(void **slot, struct radix_tree_iter *iter, unsigned flags) | |
477 | { | |
478 | if (flags & RADIX_TREE_ITER_TAGGED) { | |
479 | iter->tags >>= 1; | |
21ef5339 RZ |
480 | if (unlikely(!iter->tags)) |
481 | return NULL; | |
78c1d784 | 482 | if (likely(iter->tags & 1ul)) { |
21ef5339 | 483 | iter->index = __radix_tree_iter_add(iter, 1); |
148deab2 MW |
484 | slot++; |
485 | goto found; | |
78c1d784 | 486 | } |
21ef5339 | 487 | if (!(flags & RADIX_TREE_ITER_CONTIG)) { |
78c1d784 KK |
488 | unsigned offset = __ffs(iter->tags); |
489 | ||
148deab2 MW |
490 | iter->tags >>= offset++; |
491 | iter->index = __radix_tree_iter_add(iter, offset); | |
492 | slot += offset; | |
493 | goto found; | |
78c1d784 KK |
494 | } |
495 | } else { | |
21ef5339 | 496 | long count = radix_tree_chunk_size(iter); |
78c1d784 | 497 | |
21ef5339 | 498 | while (--count > 0) { |
78c1d784 | 499 | slot++; |
21ef5339 RZ |
500 | iter->index = __radix_tree_iter_add(iter, 1); |
501 | ||
78c1d784 | 502 | if (likely(*slot)) |
148deab2 | 503 | goto found; |
fffaee36 KK |
504 | if (flags & RADIX_TREE_ITER_CONTIG) { |
505 | /* forbid switching to the next chunk */ | |
506 | iter->next_index = 0; | |
78c1d784 | 507 | break; |
fffaee36 | 508 | } |
78c1d784 KK |
509 | } |
510 | } | |
511 | return NULL; | |
148deab2 MW |
512 | |
513 | found: | |
514 | if (unlikely(radix_tree_is_internal_node(*slot))) | |
515 | return __radix_tree_next_slot(slot, iter, flags); | |
516 | return slot; | |
78c1d784 KK |
517 | } |
518 | ||
78c1d784 KK |
519 | /** |
520 | * radix_tree_for_each_slot - iterate over non-empty slots | |
521 | * | |
522 | * @slot: the void** variable for pointer to slot | |
523 | * @root: the struct radix_tree_root pointer | |
524 | * @iter: the struct radix_tree_iter pointer | |
525 | * @start: iteration starting index | |
526 | * | |
527 | * @slot points to radix tree slot, @iter->index contains its index. | |
528 | */ | |
529 | #define radix_tree_for_each_slot(slot, root, iter, start) \ | |
530 | for (slot = radix_tree_iter_init(iter, start) ; \ | |
531 | slot || (slot = radix_tree_next_chunk(root, iter, 0)) ; \ | |
532 | slot = radix_tree_next_slot(slot, iter, 0)) | |
533 | ||
534 | /** | |
535 | * radix_tree_for_each_contig - iterate over contiguous slots | |
536 | * | |
537 | * @slot: the void** variable for pointer to slot | |
538 | * @root: the struct radix_tree_root pointer | |
539 | * @iter: the struct radix_tree_iter pointer | |
540 | * @start: iteration starting index | |
541 | * | |
542 | * @slot points to radix tree slot, @iter->index contains its index. | |
543 | */ | |
544 | #define radix_tree_for_each_contig(slot, root, iter, start) \ | |
545 | for (slot = radix_tree_iter_init(iter, start) ; \ | |
546 | slot || (slot = radix_tree_next_chunk(root, iter, \ | |
547 | RADIX_TREE_ITER_CONTIG)) ; \ | |
548 | slot = radix_tree_next_slot(slot, iter, \ | |
549 | RADIX_TREE_ITER_CONTIG)) | |
550 | ||
551 | /** | |
552 | * radix_tree_for_each_tagged - iterate over tagged slots | |
553 | * | |
554 | * @slot: the void** variable for pointer to slot | |
555 | * @root: the struct radix_tree_root pointer | |
556 | * @iter: the struct radix_tree_iter pointer | |
557 | * @start: iteration starting index | |
558 | * @tag: tag index | |
559 | * | |
560 | * @slot points to radix tree slot, @iter->index contains its index. | |
561 | */ | |
562 | #define radix_tree_for_each_tagged(slot, root, iter, start, tag) \ | |
563 | for (slot = radix_tree_iter_init(iter, start) ; \ | |
564 | slot || (slot = radix_tree_next_chunk(root, iter, \ | |
565 | RADIX_TREE_ITER_TAGGED | tag)) ; \ | |
566 | slot = radix_tree_next_slot(slot, iter, \ | |
148deab2 | 567 | RADIX_TREE_ITER_TAGGED | tag)) |
78c1d784 | 568 | |
1da177e4 | 569 | #endif /* _LINUX_RADIX_TREE_H */ |