| 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) 2005 SGI, Christoph Lameter |
| 6 | * Copyright (C) 2006 Nick Piggin |
| 7 | * Copyright (C) 2012 Konstantin Khlebnikov |
| 8 | * Copyright (C) 2016 Intel, Matthew Wilcox |
| 9 | * Copyright (C) 2016 Intel, Ross Zwisler |
| 10 | */ |
| 11 | |
| 12 | #include <linux/bitmap.h> |
| 13 | #include <linux/bitops.h> |
| 14 | #include <linux/bug.h> |
| 15 | #include <linux/cpu.h> |
| 16 | #include <linux/errno.h> |
| 17 | #include <linux/export.h> |
| 18 | #include <linux/idr.h> |
| 19 | #include <linux/init.h> |
| 20 | #include <linux/kernel.h> |
| 21 | #include <linux/kmemleak.h> |
| 22 | #include <linux/percpu.h> |
| 23 | #include <linux/preempt.h> /* in_interrupt() */ |
| 24 | #include <linux/radix-tree.h> |
| 25 | #include <linux/rcupdate.h> |
| 26 | #include <linux/slab.h> |
| 27 | #include <linux/string.h> |
| 28 | #include <linux/xarray.h> |
| 29 | |
| 30 | #include "radix-tree.h" |
| 31 | |
| 32 | /* |
| 33 | * Radix tree node cache. |
| 34 | */ |
| 35 | struct kmem_cache *radix_tree_node_cachep; |
| 36 | |
| 37 | /* |
| 38 | * The radix tree is variable-height, so an insert operation not only has |
| 39 | * to build the branch to its corresponding item, it also has to build the |
| 40 | * branch to existing items if the size has to be increased (by |
| 41 | * radix_tree_extend). |
| 42 | * |
| 43 | * The worst case is a zero height tree with just a single item at index 0, |
| 44 | * and then inserting an item at index ULONG_MAX. This requires 2 new branches |
| 45 | * of RADIX_TREE_MAX_PATH size to be created, with only the root node shared. |
| 46 | * Hence: |
| 47 | */ |
| 48 | #define RADIX_TREE_PRELOAD_SIZE (RADIX_TREE_MAX_PATH * 2 - 1) |
| 49 | |
| 50 | /* |
| 51 | * The IDR does not have to be as high as the radix tree since it uses |
| 52 | * signed integers, not unsigned longs. |
| 53 | */ |
| 54 | #define IDR_INDEX_BITS (8 /* CHAR_BIT */ * sizeof(int) - 1) |
| 55 | #define IDR_MAX_PATH (DIV_ROUND_UP(IDR_INDEX_BITS, \ |
| 56 | RADIX_TREE_MAP_SHIFT)) |
| 57 | #define IDR_PRELOAD_SIZE (IDR_MAX_PATH * 2 - 1) |
| 58 | |
| 59 | /* |
| 60 | * Per-cpu pool of preloaded nodes |
| 61 | */ |
| 62 | DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { |
| 63 | .lock = INIT_LOCAL_LOCK(lock), |
| 64 | }; |
| 65 | EXPORT_PER_CPU_SYMBOL_GPL(radix_tree_preloads); |
| 66 | |
| 67 | static inline struct radix_tree_node *entry_to_node(void *ptr) |
| 68 | { |
| 69 | return (void *)((unsigned long)ptr & ~RADIX_TREE_INTERNAL_NODE); |
| 70 | } |
| 71 | |
| 72 | static inline void *node_to_entry(void *ptr) |
| 73 | { |
| 74 | return (void *)((unsigned long)ptr | RADIX_TREE_INTERNAL_NODE); |
| 75 | } |
| 76 | |
| 77 | #define RADIX_TREE_RETRY XA_RETRY_ENTRY |
| 78 | |
| 79 | static inline unsigned long |
| 80 | get_slot_offset(const struct radix_tree_node *parent, void __rcu **slot) |
| 81 | { |
| 82 | return parent ? slot - parent->slots : 0; |
| 83 | } |
| 84 | |
| 85 | static unsigned int radix_tree_descend(const struct radix_tree_node *parent, |
| 86 | struct radix_tree_node **nodep, unsigned long index) |
| 87 | { |
| 88 | unsigned int offset = (index >> parent->shift) & RADIX_TREE_MAP_MASK; |
| 89 | void __rcu **entry = rcu_dereference_raw(parent->slots[offset]); |
| 90 | |
| 91 | *nodep = (void *)entry; |
| 92 | return offset; |
| 93 | } |
| 94 | |
| 95 | static inline gfp_t root_gfp_mask(const struct radix_tree_root *root) |
| 96 | { |
| 97 | return root->xa_flags & (__GFP_BITS_MASK & ~GFP_ZONEMASK); |
| 98 | } |
| 99 | |
| 100 | static inline void tag_set(struct radix_tree_node *node, unsigned int tag, |
| 101 | int offset) |
| 102 | { |
| 103 | __set_bit(offset, node->tags[tag]); |
| 104 | } |
| 105 | |
| 106 | static inline void tag_clear(struct radix_tree_node *node, unsigned int tag, |
| 107 | int offset) |
| 108 | { |
| 109 | __clear_bit(offset, node->tags[tag]); |
| 110 | } |
| 111 | |
| 112 | static inline int tag_get(const struct radix_tree_node *node, unsigned int tag, |
| 113 | int offset) |
| 114 | { |
| 115 | return test_bit(offset, node->tags[tag]); |
| 116 | } |
| 117 | |
| 118 | static inline void root_tag_set(struct radix_tree_root *root, unsigned tag) |
| 119 | { |
| 120 | root->xa_flags |= (__force gfp_t)(1 << (tag + ROOT_TAG_SHIFT)); |
| 121 | } |
| 122 | |
| 123 | static inline void root_tag_clear(struct radix_tree_root *root, unsigned tag) |
| 124 | { |
| 125 | root->xa_flags &= (__force gfp_t)~(1 << (tag + ROOT_TAG_SHIFT)); |
| 126 | } |
| 127 | |
| 128 | static inline void root_tag_clear_all(struct radix_tree_root *root) |
| 129 | { |
| 130 | root->xa_flags &= (__force gfp_t)((1 << ROOT_TAG_SHIFT) - 1); |
| 131 | } |
| 132 | |
| 133 | static inline int root_tag_get(const struct radix_tree_root *root, unsigned tag) |
| 134 | { |
| 135 | return (__force int)root->xa_flags & (1 << (tag + ROOT_TAG_SHIFT)); |
| 136 | } |
| 137 | |
| 138 | static inline unsigned root_tags_get(const struct radix_tree_root *root) |
| 139 | { |
| 140 | return (__force unsigned)root->xa_flags >> ROOT_TAG_SHIFT; |
| 141 | } |
| 142 | |
| 143 | static inline bool is_idr(const struct radix_tree_root *root) |
| 144 | { |
| 145 | return !!(root->xa_flags & ROOT_IS_IDR); |
| 146 | } |
| 147 | |
| 148 | /* |
| 149 | * Returns 1 if any slot in the node has this tag set. |
| 150 | * Otherwise returns 0. |
| 151 | */ |
| 152 | static inline int any_tag_set(const struct radix_tree_node *node, |
| 153 | unsigned int tag) |
| 154 | { |
| 155 | unsigned idx; |
| 156 | for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) { |
| 157 | if (node->tags[tag][idx]) |
| 158 | return 1; |
| 159 | } |
| 160 | return 0; |
| 161 | } |
| 162 | |
| 163 | static inline void all_tag_set(struct radix_tree_node *node, unsigned int tag) |
| 164 | { |
| 165 | bitmap_fill(node->tags[tag], RADIX_TREE_MAP_SIZE); |
| 166 | } |
| 167 | |
| 168 | /** |
| 169 | * radix_tree_find_next_bit - find the next set bit in a memory region |
| 170 | * |
| 171 | * @node: where to begin the search |
| 172 | * @tag: the tag index |
| 173 | * @offset: the bitnumber to start searching at |
| 174 | * |
| 175 | * Unrollable variant of find_next_bit() for constant size arrays. |
| 176 | * Tail bits starting from size to roundup(size, BITS_PER_LONG) must be zero. |
| 177 | * Returns next bit offset, or size if nothing found. |
| 178 | */ |
| 179 | static __always_inline unsigned long |
| 180 | radix_tree_find_next_bit(struct radix_tree_node *node, unsigned int tag, |
| 181 | unsigned long offset) |
| 182 | { |
| 183 | const unsigned long *addr = node->tags[tag]; |
| 184 | |
| 185 | if (offset < RADIX_TREE_MAP_SIZE) { |
| 186 | unsigned long tmp; |
| 187 | |
| 188 | addr += offset / BITS_PER_LONG; |
| 189 | tmp = *addr >> (offset % BITS_PER_LONG); |
| 190 | if (tmp) |
| 191 | return __ffs(tmp) + offset; |
| 192 | offset = (offset + BITS_PER_LONG) & ~(BITS_PER_LONG - 1); |
| 193 | while (offset < RADIX_TREE_MAP_SIZE) { |
| 194 | tmp = *++addr; |
| 195 | if (tmp) |
| 196 | return __ffs(tmp) + offset; |
| 197 | offset += BITS_PER_LONG; |
| 198 | } |
| 199 | } |
| 200 | return RADIX_TREE_MAP_SIZE; |
| 201 | } |
| 202 | |
| 203 | static unsigned int iter_offset(const struct radix_tree_iter *iter) |
| 204 | { |
| 205 | return iter->index & RADIX_TREE_MAP_MASK; |
| 206 | } |
| 207 | |
| 208 | /* |
| 209 | * The maximum index which can be stored in a radix tree |
| 210 | */ |
| 211 | static inline unsigned long shift_maxindex(unsigned int shift) |
| 212 | { |
| 213 | return (RADIX_TREE_MAP_SIZE << shift) - 1; |
| 214 | } |
| 215 | |
| 216 | static inline unsigned long node_maxindex(const struct radix_tree_node *node) |
| 217 | { |
| 218 | return shift_maxindex(node->shift); |
| 219 | } |
| 220 | |
| 221 | static unsigned long next_index(unsigned long index, |
| 222 | const struct radix_tree_node *node, |
| 223 | unsigned long offset) |
| 224 | { |
| 225 | return (index & ~node_maxindex(node)) + (offset << node->shift); |
| 226 | } |
| 227 | |
| 228 | /* |
| 229 | * This assumes that the caller has performed appropriate preallocation, and |
| 230 | * that the caller has pinned this thread of control to the current CPU. |
| 231 | */ |
| 232 | static struct radix_tree_node * |
| 233 | radix_tree_node_alloc(gfp_t gfp_mask, struct radix_tree_node *parent, |
| 234 | struct radix_tree_root *root, |
| 235 | unsigned int shift, unsigned int offset, |
| 236 | unsigned int count, unsigned int nr_values) |
| 237 | { |
| 238 | struct radix_tree_node *ret = NULL; |
| 239 | |
| 240 | /* |
| 241 | * Preload code isn't irq safe and it doesn't make sense to use |
| 242 | * preloading during an interrupt anyway as all the allocations have |
| 243 | * to be atomic. So just do normal allocation when in interrupt. |
| 244 | */ |
| 245 | if (!gfpflags_allow_blocking(gfp_mask) && !in_interrupt()) { |
| 246 | struct radix_tree_preload *rtp; |
| 247 | |
| 248 | /* |
| 249 | * Even if the caller has preloaded, try to allocate from the |
| 250 | * cache first for the new node to get accounted to the memory |
| 251 | * cgroup. |
| 252 | */ |
| 253 | ret = kmem_cache_alloc(radix_tree_node_cachep, |
| 254 | gfp_mask | __GFP_NOWARN); |
| 255 | if (ret) |
| 256 | goto out; |
| 257 | |
| 258 | /* |
| 259 | * Provided the caller has preloaded here, we will always |
| 260 | * succeed in getting a node here (and never reach |
| 261 | * kmem_cache_alloc) |
| 262 | */ |
| 263 | rtp = this_cpu_ptr(&radix_tree_preloads); |
| 264 | if (rtp->nr) { |
| 265 | ret = rtp->nodes; |
| 266 | rtp->nodes = ret->parent; |
| 267 | rtp->nr--; |
| 268 | } |
| 269 | /* |
| 270 | * Update the allocation stack trace as this is more useful |
| 271 | * for debugging. |
| 272 | */ |
| 273 | kmemleak_update_trace(ret); |
| 274 | goto out; |
| 275 | } |
| 276 | ret = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask); |
| 277 | out: |
| 278 | BUG_ON(radix_tree_is_internal_node(ret)); |
| 279 | if (ret) { |
| 280 | ret->shift = shift; |
| 281 | ret->offset = offset; |
| 282 | ret->count = count; |
| 283 | ret->nr_values = nr_values; |
| 284 | ret->parent = parent; |
| 285 | ret->array = root; |
| 286 | } |
| 287 | return ret; |
| 288 | } |
| 289 | |
| 290 | void radix_tree_node_rcu_free(struct rcu_head *head) |
| 291 | { |
| 292 | struct radix_tree_node *node = |
| 293 | container_of(head, struct radix_tree_node, rcu_head); |
| 294 | |
| 295 | /* |
| 296 | * Must only free zeroed nodes into the slab. We can be left with |
| 297 | * non-NULL entries by radix_tree_free_nodes, so clear the entries |
| 298 | * and tags here. |
| 299 | */ |
| 300 | memset(node->slots, 0, sizeof(node->slots)); |
| 301 | memset(node->tags, 0, sizeof(node->tags)); |
| 302 | INIT_LIST_HEAD(&node->private_list); |
| 303 | |
| 304 | kmem_cache_free(radix_tree_node_cachep, node); |
| 305 | } |
| 306 | |
| 307 | static inline void |
| 308 | radix_tree_node_free(struct radix_tree_node *node) |
| 309 | { |
| 310 | call_rcu(&node->rcu_head, radix_tree_node_rcu_free); |
| 311 | } |
| 312 | |
| 313 | /* |
| 314 | * Load up this CPU's radix_tree_node buffer with sufficient objects to |
| 315 | * ensure that the addition of a single element in the tree cannot fail. On |
| 316 | * success, return zero, with preemption disabled. On error, return -ENOMEM |
| 317 | * with preemption not disabled. |
| 318 | * |
| 319 | * To make use of this facility, the radix tree must be initialised without |
| 320 | * __GFP_DIRECT_RECLAIM being passed to INIT_RADIX_TREE(). |
| 321 | */ |
| 322 | static __must_check int __radix_tree_preload(gfp_t gfp_mask, unsigned nr) |
| 323 | { |
| 324 | struct radix_tree_preload *rtp; |
| 325 | struct radix_tree_node *node; |
| 326 | int ret = -ENOMEM; |
| 327 | |
| 328 | /* |
| 329 | * Nodes preloaded by one cgroup can be used by another cgroup, so |
| 330 | * they should never be accounted to any particular memory cgroup. |
| 331 | */ |
| 332 | gfp_mask &= ~__GFP_ACCOUNT; |
| 333 | |
| 334 | local_lock(&radix_tree_preloads.lock); |
| 335 | rtp = this_cpu_ptr(&radix_tree_preloads); |
| 336 | while (rtp->nr < nr) { |
| 337 | local_unlock(&radix_tree_preloads.lock); |
| 338 | node = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask); |
| 339 | if (node == NULL) |
| 340 | goto out; |
| 341 | local_lock(&radix_tree_preloads.lock); |
| 342 | rtp = this_cpu_ptr(&radix_tree_preloads); |
| 343 | if (rtp->nr < nr) { |
| 344 | node->parent = rtp->nodes; |
| 345 | rtp->nodes = node; |
| 346 | rtp->nr++; |
| 347 | } else { |
| 348 | kmem_cache_free(radix_tree_node_cachep, node); |
| 349 | } |
| 350 | } |
| 351 | ret = 0; |
| 352 | out: |
| 353 | return ret; |
| 354 | } |
| 355 | |
| 356 | /* |
| 357 | * Load up this CPU's radix_tree_node buffer with sufficient objects to |
| 358 | * ensure that the addition of a single element in the tree cannot fail. On |
| 359 | * success, return zero, with preemption disabled. On error, return -ENOMEM |
| 360 | * with preemption not disabled. |
| 361 | * |
| 362 | * To make use of this facility, the radix tree must be initialised without |
| 363 | * __GFP_DIRECT_RECLAIM being passed to INIT_RADIX_TREE(). |
| 364 | */ |
| 365 | int radix_tree_preload(gfp_t gfp_mask) |
| 366 | { |
| 367 | /* Warn on non-sensical use... */ |
| 368 | WARN_ON_ONCE(!gfpflags_allow_blocking(gfp_mask)); |
| 369 | return __radix_tree_preload(gfp_mask, RADIX_TREE_PRELOAD_SIZE); |
| 370 | } |
| 371 | EXPORT_SYMBOL(radix_tree_preload); |
| 372 | |
| 373 | /* |
| 374 | * The same as above function, except we don't guarantee preloading happens. |
| 375 | * We do it, if we decide it helps. On success, return zero with preemption |
| 376 | * disabled. On error, return -ENOMEM with preemption not disabled. |
| 377 | */ |
| 378 | int radix_tree_maybe_preload(gfp_t gfp_mask) |
| 379 | { |
| 380 | if (gfpflags_allow_blocking(gfp_mask)) |
| 381 | return __radix_tree_preload(gfp_mask, RADIX_TREE_PRELOAD_SIZE); |
| 382 | /* Preloading doesn't help anything with this gfp mask, skip it */ |
| 383 | local_lock(&radix_tree_preloads.lock); |
| 384 | return 0; |
| 385 | } |
| 386 | EXPORT_SYMBOL(radix_tree_maybe_preload); |
| 387 | |
| 388 | static unsigned radix_tree_load_root(const struct radix_tree_root *root, |
| 389 | struct radix_tree_node **nodep, unsigned long *maxindex) |
| 390 | { |
| 391 | struct radix_tree_node *node = rcu_dereference_raw(root->xa_head); |
| 392 | |
| 393 | *nodep = node; |
| 394 | |
| 395 | if (likely(radix_tree_is_internal_node(node))) { |
| 396 | node = entry_to_node(node); |
| 397 | *maxindex = node_maxindex(node); |
| 398 | return node->shift + RADIX_TREE_MAP_SHIFT; |
| 399 | } |
| 400 | |
| 401 | *maxindex = 0; |
| 402 | return 0; |
| 403 | } |
| 404 | |
| 405 | /* |
| 406 | * Extend a radix tree so it can store key @index. |
| 407 | */ |
| 408 | static int radix_tree_extend(struct radix_tree_root *root, gfp_t gfp, |
| 409 | unsigned long index, unsigned int shift) |
| 410 | { |
| 411 | void *entry; |
| 412 | unsigned int maxshift; |
| 413 | int tag; |
| 414 | |
| 415 | /* Figure out what the shift should be. */ |
| 416 | maxshift = shift; |
| 417 | while (index > shift_maxindex(maxshift)) |
| 418 | maxshift += RADIX_TREE_MAP_SHIFT; |
| 419 | |
| 420 | entry = rcu_dereference_raw(root->xa_head); |
| 421 | if (!entry && (!is_idr(root) || root_tag_get(root, IDR_FREE))) |
| 422 | goto out; |
| 423 | |
| 424 | do { |
| 425 | struct radix_tree_node *node = radix_tree_node_alloc(gfp, NULL, |
| 426 | root, shift, 0, 1, 0); |
| 427 | if (!node) |
| 428 | return -ENOMEM; |
| 429 | |
| 430 | if (is_idr(root)) { |
| 431 | all_tag_set(node, IDR_FREE); |
| 432 | if (!root_tag_get(root, IDR_FREE)) { |
| 433 | tag_clear(node, IDR_FREE, 0); |
| 434 | root_tag_set(root, IDR_FREE); |
| 435 | } |
| 436 | } else { |
| 437 | /* Propagate the aggregated tag info to the new child */ |
| 438 | for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) { |
| 439 | if (root_tag_get(root, tag)) |
| 440 | tag_set(node, tag, 0); |
| 441 | } |
| 442 | } |
| 443 | |
| 444 | BUG_ON(shift > BITS_PER_LONG); |
| 445 | if (radix_tree_is_internal_node(entry)) { |
| 446 | entry_to_node(entry)->parent = node; |
| 447 | } else if (xa_is_value(entry)) { |
| 448 | /* Moving a value entry root->xa_head to a node */ |
| 449 | node->nr_values = 1; |
| 450 | } |
| 451 | /* |
| 452 | * entry was already in the radix tree, so we do not need |
| 453 | * rcu_assign_pointer here |
| 454 | */ |
| 455 | node->slots[0] = (void __rcu *)entry; |
| 456 | entry = node_to_entry(node); |
| 457 | rcu_assign_pointer(root->xa_head, entry); |
| 458 | shift += RADIX_TREE_MAP_SHIFT; |
| 459 | } while (shift <= maxshift); |
| 460 | out: |
| 461 | return maxshift + RADIX_TREE_MAP_SHIFT; |
| 462 | } |
| 463 | |
| 464 | /** |
| 465 | * radix_tree_shrink - shrink radix tree to minimum height |
| 466 | * @root: radix tree root |
| 467 | */ |
| 468 | static inline bool radix_tree_shrink(struct radix_tree_root *root) |
| 469 | { |
| 470 | bool shrunk = false; |
| 471 | |
| 472 | for (;;) { |
| 473 | struct radix_tree_node *node = rcu_dereference_raw(root->xa_head); |
| 474 | struct radix_tree_node *child; |
| 475 | |
| 476 | if (!radix_tree_is_internal_node(node)) |
| 477 | break; |
| 478 | node = entry_to_node(node); |
| 479 | |
| 480 | /* |
| 481 | * The candidate node has more than one child, or its child |
| 482 | * is not at the leftmost slot, we cannot shrink. |
| 483 | */ |
| 484 | if (node->count != 1) |
| 485 | break; |
| 486 | child = rcu_dereference_raw(node->slots[0]); |
| 487 | if (!child) |
| 488 | break; |
| 489 | |
| 490 | /* |
| 491 | * For an IDR, we must not shrink entry 0 into the root in |
| 492 | * case somebody calls idr_replace() with a pointer that |
| 493 | * appears to be an internal entry |
| 494 | */ |
| 495 | if (!node->shift && is_idr(root)) |
| 496 | break; |
| 497 | |
| 498 | if (radix_tree_is_internal_node(child)) |
| 499 | entry_to_node(child)->parent = NULL; |
| 500 | |
| 501 | /* |
| 502 | * We don't need rcu_assign_pointer(), since we are simply |
| 503 | * moving the node from one part of the tree to another: if it |
| 504 | * was safe to dereference the old pointer to it |
| 505 | * (node->slots[0]), it will be safe to dereference the new |
| 506 | * one (root->xa_head) as far as dependent read barriers go. |
| 507 | */ |
| 508 | root->xa_head = (void __rcu *)child; |
| 509 | if (is_idr(root) && !tag_get(node, IDR_FREE, 0)) |
| 510 | root_tag_clear(root, IDR_FREE); |
| 511 | |
| 512 | /* |
| 513 | * We have a dilemma here. The node's slot[0] must not be |
| 514 | * NULLed in case there are concurrent lookups expecting to |
| 515 | * find the item. However if this was a bottom-level node, |
| 516 | * then it may be subject to the slot pointer being visible |
| 517 | * to callers dereferencing it. If item corresponding to |
| 518 | * slot[0] is subsequently deleted, these callers would expect |
| 519 | * their slot to become empty sooner or later. |
| 520 | * |
| 521 | * For example, lockless pagecache will look up a slot, deref |
| 522 | * the page pointer, and if the page has 0 refcount it means it |
| 523 | * was concurrently deleted from pagecache so try the deref |
| 524 | * again. Fortunately there is already a requirement for logic |
| 525 | * to retry the entire slot lookup -- the indirect pointer |
| 526 | * problem (replacing direct root node with an indirect pointer |
| 527 | * also results in a stale slot). So tag the slot as indirect |
| 528 | * to force callers to retry. |
| 529 | */ |
| 530 | node->count = 0; |
| 531 | if (!radix_tree_is_internal_node(child)) { |
| 532 | node->slots[0] = (void __rcu *)RADIX_TREE_RETRY; |
| 533 | } |
| 534 | |
| 535 | WARN_ON_ONCE(!list_empty(&node->private_list)); |
| 536 | radix_tree_node_free(node); |
| 537 | shrunk = true; |
| 538 | } |
| 539 | |
| 540 | return shrunk; |
| 541 | } |
| 542 | |
| 543 | static bool delete_node(struct radix_tree_root *root, |
| 544 | struct radix_tree_node *node) |
| 545 | { |
| 546 | bool deleted = false; |
| 547 | |
| 548 | do { |
| 549 | struct radix_tree_node *parent; |
| 550 | |
| 551 | if (node->count) { |
| 552 | if (node_to_entry(node) == |
| 553 | rcu_dereference_raw(root->xa_head)) |
| 554 | deleted |= radix_tree_shrink(root); |
| 555 | return deleted; |
| 556 | } |
| 557 | |
| 558 | parent = node->parent; |
| 559 | if (parent) { |
| 560 | parent->slots[node->offset] = NULL; |
| 561 | parent->count--; |
| 562 | } else { |
| 563 | /* |
| 564 | * Shouldn't the tags already have all been cleared |
| 565 | * by the caller? |
| 566 | */ |
| 567 | if (!is_idr(root)) |
| 568 | root_tag_clear_all(root); |
| 569 | root->xa_head = NULL; |
| 570 | } |
| 571 | |
| 572 | WARN_ON_ONCE(!list_empty(&node->private_list)); |
| 573 | radix_tree_node_free(node); |
| 574 | deleted = true; |
| 575 | |
| 576 | node = parent; |
| 577 | } while (node); |
| 578 | |
| 579 | return deleted; |
| 580 | } |
| 581 | |
| 582 | /** |
| 583 | * __radix_tree_create - create a slot in a radix tree |
| 584 | * @root: radix tree root |
| 585 | * @index: index key |
| 586 | * @nodep: returns node |
| 587 | * @slotp: returns slot |
| 588 | * |
| 589 | * Create, if necessary, and return the node and slot for an item |
| 590 | * at position @index in the radix tree @root. |
| 591 | * |
| 592 | * Until there is more than one item in the tree, no nodes are |
| 593 | * allocated and @root->xa_head is used as a direct slot instead of |
| 594 | * pointing to a node, in which case *@nodep will be NULL. |
| 595 | * |
| 596 | * Returns -ENOMEM, or 0 for success. |
| 597 | */ |
| 598 | static int __radix_tree_create(struct radix_tree_root *root, |
| 599 | unsigned long index, struct radix_tree_node **nodep, |
| 600 | void __rcu ***slotp) |
| 601 | { |
| 602 | struct radix_tree_node *node = NULL, *child; |
| 603 | void __rcu **slot = (void __rcu **)&root->xa_head; |
| 604 | unsigned long maxindex; |
| 605 | unsigned int shift, offset = 0; |
| 606 | unsigned long max = index; |
| 607 | gfp_t gfp = root_gfp_mask(root); |
| 608 | |
| 609 | shift = radix_tree_load_root(root, &child, &maxindex); |
| 610 | |
| 611 | /* Make sure the tree is high enough. */ |
| 612 | if (max > maxindex) { |
| 613 | int error = radix_tree_extend(root, gfp, max, shift); |
| 614 | if (error < 0) |
| 615 | return error; |
| 616 | shift = error; |
| 617 | child = rcu_dereference_raw(root->xa_head); |
| 618 | } |
| 619 | |
| 620 | while (shift > 0) { |
| 621 | shift -= RADIX_TREE_MAP_SHIFT; |
| 622 | if (child == NULL) { |
| 623 | /* Have to add a child node. */ |
| 624 | child = radix_tree_node_alloc(gfp, node, root, shift, |
| 625 | offset, 0, 0); |
| 626 | if (!child) |
| 627 | return -ENOMEM; |
| 628 | rcu_assign_pointer(*slot, node_to_entry(child)); |
| 629 | if (node) |
| 630 | node->count++; |
| 631 | } else if (!radix_tree_is_internal_node(child)) |
| 632 | break; |
| 633 | |
| 634 | /* Go a level down */ |
| 635 | node = entry_to_node(child); |
| 636 | offset = radix_tree_descend(node, &child, index); |
| 637 | slot = &node->slots[offset]; |
| 638 | } |
| 639 | |
| 640 | if (nodep) |
| 641 | *nodep = node; |
| 642 | if (slotp) |
| 643 | *slotp = slot; |
| 644 | return 0; |
| 645 | } |
| 646 | |
| 647 | /* |
| 648 | * Free any nodes below this node. The tree is presumed to not need |
| 649 | * shrinking, and any user data in the tree is presumed to not need a |
| 650 | * destructor called on it. If we need to add a destructor, we can |
| 651 | * add that functionality later. Note that we may not clear tags or |
| 652 | * slots from the tree as an RCU walker may still have a pointer into |
| 653 | * this subtree. We could replace the entries with RADIX_TREE_RETRY, |
| 654 | * but we'll still have to clear those in rcu_free. |
| 655 | */ |
| 656 | static void radix_tree_free_nodes(struct radix_tree_node *node) |
| 657 | { |
| 658 | unsigned offset = 0; |
| 659 | struct radix_tree_node *child = entry_to_node(node); |
| 660 | |
| 661 | for (;;) { |
| 662 | void *entry = rcu_dereference_raw(child->slots[offset]); |
| 663 | if (xa_is_node(entry) && child->shift) { |
| 664 | child = entry_to_node(entry); |
| 665 | offset = 0; |
| 666 | continue; |
| 667 | } |
| 668 | offset++; |
| 669 | while (offset == RADIX_TREE_MAP_SIZE) { |
| 670 | struct radix_tree_node *old = child; |
| 671 | offset = child->offset + 1; |
| 672 | child = child->parent; |
| 673 | WARN_ON_ONCE(!list_empty(&old->private_list)); |
| 674 | radix_tree_node_free(old); |
| 675 | if (old == entry_to_node(node)) |
| 676 | return; |
| 677 | } |
| 678 | } |
| 679 | } |
| 680 | |
| 681 | static inline int insert_entries(struct radix_tree_node *node, |
| 682 | void __rcu **slot, void *item) |
| 683 | { |
| 684 | if (*slot) |
| 685 | return -EEXIST; |
| 686 | rcu_assign_pointer(*slot, item); |
| 687 | if (node) { |
| 688 | node->count++; |
| 689 | if (xa_is_value(item)) |
| 690 | node->nr_values++; |
| 691 | } |
| 692 | return 1; |
| 693 | } |
| 694 | |
| 695 | /** |
| 696 | * radix_tree_insert - insert into a radix tree |
| 697 | * @root: radix tree root |
| 698 | * @index: index key |
| 699 | * @item: item to insert |
| 700 | * |
| 701 | * Insert an item into the radix tree at position @index. |
| 702 | */ |
| 703 | int radix_tree_insert(struct radix_tree_root *root, unsigned long index, |
| 704 | void *item) |
| 705 | { |
| 706 | struct radix_tree_node *node; |
| 707 | void __rcu **slot; |
| 708 | int error; |
| 709 | |
| 710 | BUG_ON(radix_tree_is_internal_node(item)); |
| 711 | |
| 712 | error = __radix_tree_create(root, index, &node, &slot); |
| 713 | if (error) |
| 714 | return error; |
| 715 | |
| 716 | error = insert_entries(node, slot, item); |
| 717 | if (error < 0) |
| 718 | return error; |
| 719 | |
| 720 | if (node) { |
| 721 | unsigned offset = get_slot_offset(node, slot); |
| 722 | BUG_ON(tag_get(node, 0, offset)); |
| 723 | BUG_ON(tag_get(node, 1, offset)); |
| 724 | BUG_ON(tag_get(node, 2, offset)); |
| 725 | } else { |
| 726 | BUG_ON(root_tags_get(root)); |
| 727 | } |
| 728 | |
| 729 | return 0; |
| 730 | } |
| 731 | EXPORT_SYMBOL(radix_tree_insert); |
| 732 | |
| 733 | /** |
| 734 | * __radix_tree_lookup - lookup an item in a radix tree |
| 735 | * @root: radix tree root |
| 736 | * @index: index key |
| 737 | * @nodep: returns node |
| 738 | * @slotp: returns slot |
| 739 | * |
| 740 | * Lookup and return the item at position @index in the radix |
| 741 | * tree @root. |
| 742 | * |
| 743 | * Until there is more than one item in the tree, no nodes are |
| 744 | * allocated and @root->xa_head is used as a direct slot instead of |
| 745 | * pointing to a node, in which case *@nodep will be NULL. |
| 746 | */ |
| 747 | void *__radix_tree_lookup(const struct radix_tree_root *root, |
| 748 | unsigned long index, struct radix_tree_node **nodep, |
| 749 | void __rcu ***slotp) |
| 750 | { |
| 751 | struct radix_tree_node *node, *parent; |
| 752 | unsigned long maxindex; |
| 753 | void __rcu **slot; |
| 754 | |
| 755 | restart: |
| 756 | parent = NULL; |
| 757 | slot = (void __rcu **)&root->xa_head; |
| 758 | radix_tree_load_root(root, &node, &maxindex); |
| 759 | if (index > maxindex) |
| 760 | return NULL; |
| 761 | |
| 762 | while (radix_tree_is_internal_node(node)) { |
| 763 | unsigned offset; |
| 764 | |
| 765 | parent = entry_to_node(node); |
| 766 | offset = radix_tree_descend(parent, &node, index); |
| 767 | slot = parent->slots + offset; |
| 768 | if (node == RADIX_TREE_RETRY) |
| 769 | goto restart; |
| 770 | if (parent->shift == 0) |
| 771 | break; |
| 772 | } |
| 773 | |
| 774 | if (nodep) |
| 775 | *nodep = parent; |
| 776 | if (slotp) |
| 777 | *slotp = slot; |
| 778 | return node; |
| 779 | } |
| 780 | |
| 781 | /** |
| 782 | * radix_tree_lookup_slot - lookup a slot in a radix tree |
| 783 | * @root: radix tree root |
| 784 | * @index: index key |
| 785 | * |
| 786 | * Returns: the slot corresponding to the position @index in the |
| 787 | * radix tree @root. This is useful for update-if-exists operations. |
| 788 | * |
| 789 | * This function can be called under rcu_read_lock iff the slot is not |
| 790 | * modified by radix_tree_replace_slot, otherwise it must be called |
| 791 | * exclusive from other writers. Any dereference of the slot must be done |
| 792 | * using radix_tree_deref_slot. |
| 793 | */ |
| 794 | void __rcu **radix_tree_lookup_slot(const struct radix_tree_root *root, |
| 795 | unsigned long index) |
| 796 | { |
| 797 | void __rcu **slot; |
| 798 | |
| 799 | if (!__radix_tree_lookup(root, index, NULL, &slot)) |
| 800 | return NULL; |
| 801 | return slot; |
| 802 | } |
| 803 | EXPORT_SYMBOL(radix_tree_lookup_slot); |
| 804 | |
| 805 | /** |
| 806 | * radix_tree_lookup - perform lookup operation on a radix tree |
| 807 | * @root: radix tree root |
| 808 | * @index: index key |
| 809 | * |
| 810 | * Lookup the item at the position @index in the radix tree @root. |
| 811 | * |
| 812 | * This function can be called under rcu_read_lock, however the caller |
| 813 | * must manage lifetimes of leaf nodes (eg. RCU may also be used to free |
| 814 | * them safely). No RCU barriers are required to access or modify the |
| 815 | * returned item, however. |
| 816 | */ |
| 817 | void *radix_tree_lookup(const struct radix_tree_root *root, unsigned long index) |
| 818 | { |
| 819 | return __radix_tree_lookup(root, index, NULL, NULL); |
| 820 | } |
| 821 | EXPORT_SYMBOL(radix_tree_lookup); |
| 822 | |
| 823 | static void replace_slot(void __rcu **slot, void *item, |
| 824 | struct radix_tree_node *node, int count, int values) |
| 825 | { |
| 826 | if (node && (count || values)) { |
| 827 | node->count += count; |
| 828 | node->nr_values += values; |
| 829 | } |
| 830 | |
| 831 | rcu_assign_pointer(*slot, item); |
| 832 | } |
| 833 | |
| 834 | static bool node_tag_get(const struct radix_tree_root *root, |
| 835 | const struct radix_tree_node *node, |
| 836 | unsigned int tag, unsigned int offset) |
| 837 | { |
| 838 | if (node) |
| 839 | return tag_get(node, tag, offset); |
| 840 | return root_tag_get(root, tag); |
| 841 | } |
| 842 | |
| 843 | /* |
| 844 | * IDR users want to be able to store NULL in the tree, so if the slot isn't |
| 845 | * free, don't adjust the count, even if it's transitioning between NULL and |
| 846 | * non-NULL. For the IDA, we mark slots as being IDR_FREE while they still |
| 847 | * have empty bits, but it only stores NULL in slots when they're being |
| 848 | * deleted. |
| 849 | */ |
| 850 | static int calculate_count(struct radix_tree_root *root, |
| 851 | struct radix_tree_node *node, void __rcu **slot, |
| 852 | void *item, void *old) |
| 853 | { |
| 854 | if (is_idr(root)) { |
| 855 | unsigned offset = get_slot_offset(node, slot); |
| 856 | bool free = node_tag_get(root, node, IDR_FREE, offset); |
| 857 | if (!free) |
| 858 | return 0; |
| 859 | if (!old) |
| 860 | return 1; |
| 861 | } |
| 862 | return !!item - !!old; |
| 863 | } |
| 864 | |
| 865 | /** |
| 866 | * __radix_tree_replace - replace item in a slot |
| 867 | * @root: radix tree root |
| 868 | * @node: pointer to tree node |
| 869 | * @slot: pointer to slot in @node |
| 870 | * @item: new item to store in the slot. |
| 871 | * |
| 872 | * For use with __radix_tree_lookup(). Caller must hold tree write locked |
| 873 | * across slot lookup and replacement. |
| 874 | */ |
| 875 | void __radix_tree_replace(struct radix_tree_root *root, |
| 876 | struct radix_tree_node *node, |
| 877 | void __rcu **slot, void *item) |
| 878 | { |
| 879 | void *old = rcu_dereference_raw(*slot); |
| 880 | int values = !!xa_is_value(item) - !!xa_is_value(old); |
| 881 | int count = calculate_count(root, node, slot, item, old); |
| 882 | |
| 883 | /* |
| 884 | * This function supports replacing value entries and |
| 885 | * deleting entries, but that needs accounting against the |
| 886 | * node unless the slot is root->xa_head. |
| 887 | */ |
| 888 | WARN_ON_ONCE(!node && (slot != (void __rcu **)&root->xa_head) && |
| 889 | (count || values)); |
| 890 | replace_slot(slot, item, node, count, values); |
| 891 | |
| 892 | if (!node) |
| 893 | return; |
| 894 | |
| 895 | delete_node(root, node); |
| 896 | } |
| 897 | |
| 898 | /** |
| 899 | * radix_tree_replace_slot - replace item in a slot |
| 900 | * @root: radix tree root |
| 901 | * @slot: pointer to slot |
| 902 | * @item: new item to store in the slot. |
| 903 | * |
| 904 | * For use with radix_tree_lookup_slot() and |
| 905 | * radix_tree_gang_lookup_tag_slot(). Caller must hold tree write locked |
| 906 | * across slot lookup and replacement. |
| 907 | * |
| 908 | * NOTE: This cannot be used to switch between non-entries (empty slots), |
| 909 | * regular entries, and value entries, as that requires accounting |
| 910 | * inside the radix tree node. When switching from one type of entry or |
| 911 | * deleting, use __radix_tree_lookup() and __radix_tree_replace() or |
| 912 | * radix_tree_iter_replace(). |
| 913 | */ |
| 914 | void radix_tree_replace_slot(struct radix_tree_root *root, |
| 915 | void __rcu **slot, void *item) |
| 916 | { |
| 917 | __radix_tree_replace(root, NULL, slot, item); |
| 918 | } |
| 919 | EXPORT_SYMBOL(radix_tree_replace_slot); |
| 920 | |
| 921 | /** |
| 922 | * radix_tree_iter_replace - replace item in a slot |
| 923 | * @root: radix tree root |
| 924 | * @iter: iterator state |
| 925 | * @slot: pointer to slot |
| 926 | * @item: new item to store in the slot. |
| 927 | * |
| 928 | * For use with radix_tree_for_each_slot(). |
| 929 | * Caller must hold tree write locked. |
| 930 | */ |
| 931 | void radix_tree_iter_replace(struct radix_tree_root *root, |
| 932 | const struct radix_tree_iter *iter, |
| 933 | void __rcu **slot, void *item) |
| 934 | { |
| 935 | __radix_tree_replace(root, iter->node, slot, item); |
| 936 | } |
| 937 | |
| 938 | static void node_tag_set(struct radix_tree_root *root, |
| 939 | struct radix_tree_node *node, |
| 940 | unsigned int tag, unsigned int offset) |
| 941 | { |
| 942 | while (node) { |
| 943 | if (tag_get(node, tag, offset)) |
| 944 | return; |
| 945 | tag_set(node, tag, offset); |
| 946 | offset = node->offset; |
| 947 | node = node->parent; |
| 948 | } |
| 949 | |
| 950 | if (!root_tag_get(root, tag)) |
| 951 | root_tag_set(root, tag); |
| 952 | } |
| 953 | |
| 954 | /** |
| 955 | * radix_tree_tag_set - set a tag on a radix tree node |
| 956 | * @root: radix tree root |
| 957 | * @index: index key |
| 958 | * @tag: tag index |
| 959 | * |
| 960 | * Set the search tag (which must be < RADIX_TREE_MAX_TAGS) |
| 961 | * corresponding to @index in the radix tree. From |
| 962 | * the root all the way down to the leaf node. |
| 963 | * |
| 964 | * Returns the address of the tagged item. Setting a tag on a not-present |
| 965 | * item is a bug. |
| 966 | */ |
| 967 | void *radix_tree_tag_set(struct radix_tree_root *root, |
| 968 | unsigned long index, unsigned int tag) |
| 969 | { |
| 970 | struct radix_tree_node *node, *parent; |
| 971 | unsigned long maxindex; |
| 972 | |
| 973 | radix_tree_load_root(root, &node, &maxindex); |
| 974 | BUG_ON(index > maxindex); |
| 975 | |
| 976 | while (radix_tree_is_internal_node(node)) { |
| 977 | unsigned offset; |
| 978 | |
| 979 | parent = entry_to_node(node); |
| 980 | offset = radix_tree_descend(parent, &node, index); |
| 981 | BUG_ON(!node); |
| 982 | |
| 983 | if (!tag_get(parent, tag, offset)) |
| 984 | tag_set(parent, tag, offset); |
| 985 | } |
| 986 | |
| 987 | /* set the root's tag bit */ |
| 988 | if (!root_tag_get(root, tag)) |
| 989 | root_tag_set(root, tag); |
| 990 | |
| 991 | return node; |
| 992 | } |
| 993 | EXPORT_SYMBOL(radix_tree_tag_set); |
| 994 | |
| 995 | static void node_tag_clear(struct radix_tree_root *root, |
| 996 | struct radix_tree_node *node, |
| 997 | unsigned int tag, unsigned int offset) |
| 998 | { |
| 999 | while (node) { |
| 1000 | if (!tag_get(node, tag, offset)) |
| 1001 | return; |
| 1002 | tag_clear(node, tag, offset); |
| 1003 | if (any_tag_set(node, tag)) |
| 1004 | return; |
| 1005 | |
| 1006 | offset = node->offset; |
| 1007 | node = node->parent; |
| 1008 | } |
| 1009 | |
| 1010 | /* clear the root's tag bit */ |
| 1011 | if (root_tag_get(root, tag)) |
| 1012 | root_tag_clear(root, tag); |
| 1013 | } |
| 1014 | |
| 1015 | /** |
| 1016 | * radix_tree_tag_clear - clear a tag on a radix tree node |
| 1017 | * @root: radix tree root |
| 1018 | * @index: index key |
| 1019 | * @tag: tag index |
| 1020 | * |
| 1021 | * Clear the search tag (which must be < RADIX_TREE_MAX_TAGS) |
| 1022 | * corresponding to @index in the radix tree. If this causes |
| 1023 | * the leaf node to have no tags set then clear the tag in the |
| 1024 | * next-to-leaf node, etc. |
| 1025 | * |
| 1026 | * Returns the address of the tagged item on success, else NULL. ie: |
| 1027 | * has the same return value and semantics as radix_tree_lookup(). |
| 1028 | */ |
| 1029 | void *radix_tree_tag_clear(struct radix_tree_root *root, |
| 1030 | unsigned long index, unsigned int tag) |
| 1031 | { |
| 1032 | struct radix_tree_node *node, *parent; |
| 1033 | unsigned long maxindex; |
| 1034 | int offset = 0; |
| 1035 | |
| 1036 | radix_tree_load_root(root, &node, &maxindex); |
| 1037 | if (index > maxindex) |
| 1038 | return NULL; |
| 1039 | |
| 1040 | parent = NULL; |
| 1041 | |
| 1042 | while (radix_tree_is_internal_node(node)) { |
| 1043 | parent = entry_to_node(node); |
| 1044 | offset = radix_tree_descend(parent, &node, index); |
| 1045 | } |
| 1046 | |
| 1047 | if (node) |
| 1048 | node_tag_clear(root, parent, tag, offset); |
| 1049 | |
| 1050 | return node; |
| 1051 | } |
| 1052 | EXPORT_SYMBOL(radix_tree_tag_clear); |
| 1053 | |
| 1054 | /** |
| 1055 | * radix_tree_iter_tag_clear - clear a tag on the current iterator entry |
| 1056 | * @root: radix tree root |
| 1057 | * @iter: iterator state |
| 1058 | * @tag: tag to clear |
| 1059 | */ |
| 1060 | void radix_tree_iter_tag_clear(struct radix_tree_root *root, |
| 1061 | const struct radix_tree_iter *iter, unsigned int tag) |
| 1062 | { |
| 1063 | node_tag_clear(root, iter->node, tag, iter_offset(iter)); |
| 1064 | } |
| 1065 | |
| 1066 | /** |
| 1067 | * radix_tree_tag_get - get a tag on a radix tree node |
| 1068 | * @root: radix tree root |
| 1069 | * @index: index key |
| 1070 | * @tag: tag index (< RADIX_TREE_MAX_TAGS) |
| 1071 | * |
| 1072 | * Return values: |
| 1073 | * |
| 1074 | * 0: tag not present or not set |
| 1075 | * 1: tag set |
| 1076 | * |
| 1077 | * Note that the return value of this function may not be relied on, even if |
| 1078 | * the RCU lock is held, unless tag modification and node deletion are excluded |
| 1079 | * from concurrency. |
| 1080 | */ |
| 1081 | int radix_tree_tag_get(const struct radix_tree_root *root, |
| 1082 | unsigned long index, unsigned int tag) |
| 1083 | { |
| 1084 | struct radix_tree_node *node, *parent; |
| 1085 | unsigned long maxindex; |
| 1086 | |
| 1087 | if (!root_tag_get(root, tag)) |
| 1088 | return 0; |
| 1089 | |
| 1090 | radix_tree_load_root(root, &node, &maxindex); |
| 1091 | if (index > maxindex) |
| 1092 | return 0; |
| 1093 | |
| 1094 | while (radix_tree_is_internal_node(node)) { |
| 1095 | unsigned offset; |
| 1096 | |
| 1097 | parent = entry_to_node(node); |
| 1098 | offset = radix_tree_descend(parent, &node, index); |
| 1099 | |
| 1100 | if (!tag_get(parent, tag, offset)) |
| 1101 | return 0; |
| 1102 | if (node == RADIX_TREE_RETRY) |
| 1103 | break; |
| 1104 | } |
| 1105 | |
| 1106 | return 1; |
| 1107 | } |
| 1108 | EXPORT_SYMBOL(radix_tree_tag_get); |
| 1109 | |
| 1110 | /* Construct iter->tags bit-mask from node->tags[tag] array */ |
| 1111 | static void set_iter_tags(struct radix_tree_iter *iter, |
| 1112 | struct radix_tree_node *node, unsigned offset, |
| 1113 | unsigned tag) |
| 1114 | { |
| 1115 | unsigned tag_long = offset / BITS_PER_LONG; |
| 1116 | unsigned tag_bit = offset % BITS_PER_LONG; |
| 1117 | |
| 1118 | if (!node) { |
| 1119 | iter->tags = 1; |
| 1120 | return; |
| 1121 | } |
| 1122 | |
| 1123 | iter->tags = node->tags[tag][tag_long] >> tag_bit; |
| 1124 | |
| 1125 | /* This never happens if RADIX_TREE_TAG_LONGS == 1 */ |
| 1126 | if (tag_long < RADIX_TREE_TAG_LONGS - 1) { |
| 1127 | /* Pick tags from next element */ |
| 1128 | if (tag_bit) |
| 1129 | iter->tags |= node->tags[tag][tag_long + 1] << |
| 1130 | (BITS_PER_LONG - tag_bit); |
| 1131 | /* Clip chunk size, here only BITS_PER_LONG tags */ |
| 1132 | iter->next_index = __radix_tree_iter_add(iter, BITS_PER_LONG); |
| 1133 | } |
| 1134 | } |
| 1135 | |
| 1136 | void __rcu **radix_tree_iter_resume(void __rcu **slot, |
| 1137 | struct radix_tree_iter *iter) |
| 1138 | { |
| 1139 | iter->index = __radix_tree_iter_add(iter, 1); |
| 1140 | iter->next_index = iter->index; |
| 1141 | iter->tags = 0; |
| 1142 | return NULL; |
| 1143 | } |
| 1144 | EXPORT_SYMBOL(radix_tree_iter_resume); |
| 1145 | |
| 1146 | /** |
| 1147 | * radix_tree_next_chunk - find next chunk of slots for iteration |
| 1148 | * |
| 1149 | * @root: radix tree root |
| 1150 | * @iter: iterator state |
| 1151 | * @flags: RADIX_TREE_ITER_* flags and tag index |
| 1152 | * Returns: pointer to chunk first slot, or NULL if iteration is over |
| 1153 | */ |
| 1154 | void __rcu **radix_tree_next_chunk(const struct radix_tree_root *root, |
| 1155 | struct radix_tree_iter *iter, unsigned flags) |
| 1156 | { |
| 1157 | unsigned tag = flags & RADIX_TREE_ITER_TAG_MASK; |
| 1158 | struct radix_tree_node *node, *child; |
| 1159 | unsigned long index, offset, maxindex; |
| 1160 | |
| 1161 | if ((flags & RADIX_TREE_ITER_TAGGED) && !root_tag_get(root, tag)) |
| 1162 | return NULL; |
| 1163 | |
| 1164 | /* |
| 1165 | * Catch next_index overflow after ~0UL. iter->index never overflows |
| 1166 | * during iterating; it can be zero only at the beginning. |
| 1167 | * And we cannot overflow iter->next_index in a single step, |
| 1168 | * because RADIX_TREE_MAP_SHIFT < BITS_PER_LONG. |
| 1169 | * |
| 1170 | * This condition also used by radix_tree_next_slot() to stop |
| 1171 | * contiguous iterating, and forbid switching to the next chunk. |
| 1172 | */ |
| 1173 | index = iter->next_index; |
| 1174 | if (!index && iter->index) |
| 1175 | return NULL; |
| 1176 | |
| 1177 | restart: |
| 1178 | radix_tree_load_root(root, &child, &maxindex); |
| 1179 | if (index > maxindex) |
| 1180 | return NULL; |
| 1181 | if (!child) |
| 1182 | return NULL; |
| 1183 | |
| 1184 | if (!radix_tree_is_internal_node(child)) { |
| 1185 | /* Single-slot tree */ |
| 1186 | iter->index = index; |
| 1187 | iter->next_index = maxindex + 1; |
| 1188 | iter->tags = 1; |
| 1189 | iter->node = NULL; |
| 1190 | return (void __rcu **)&root->xa_head; |
| 1191 | } |
| 1192 | |
| 1193 | do { |
| 1194 | node = entry_to_node(child); |
| 1195 | offset = radix_tree_descend(node, &child, index); |
| 1196 | |
| 1197 | if ((flags & RADIX_TREE_ITER_TAGGED) ? |
| 1198 | !tag_get(node, tag, offset) : !child) { |
| 1199 | /* Hole detected */ |
| 1200 | if (flags & RADIX_TREE_ITER_CONTIG) |
| 1201 | return NULL; |
| 1202 | |
| 1203 | if (flags & RADIX_TREE_ITER_TAGGED) |
| 1204 | offset = radix_tree_find_next_bit(node, tag, |
| 1205 | offset + 1); |
| 1206 | else |
| 1207 | while (++offset < RADIX_TREE_MAP_SIZE) { |
| 1208 | void *slot = rcu_dereference_raw( |
| 1209 | node->slots[offset]); |
| 1210 | if (slot) |
| 1211 | break; |
| 1212 | } |
| 1213 | index &= ~node_maxindex(node); |
| 1214 | index += offset << node->shift; |
| 1215 | /* Overflow after ~0UL */ |
| 1216 | if (!index) |
| 1217 | return NULL; |
| 1218 | if (offset == RADIX_TREE_MAP_SIZE) |
| 1219 | goto restart; |
| 1220 | child = rcu_dereference_raw(node->slots[offset]); |
| 1221 | } |
| 1222 | |
| 1223 | if (!child) |
| 1224 | goto restart; |
| 1225 | if (child == RADIX_TREE_RETRY) |
| 1226 | break; |
| 1227 | } while (node->shift && radix_tree_is_internal_node(child)); |
| 1228 | |
| 1229 | /* Update the iterator state */ |
| 1230 | iter->index = (index &~ node_maxindex(node)) | offset; |
| 1231 | iter->next_index = (index | node_maxindex(node)) + 1; |
| 1232 | iter->node = node; |
| 1233 | |
| 1234 | if (flags & RADIX_TREE_ITER_TAGGED) |
| 1235 | set_iter_tags(iter, node, offset, tag); |
| 1236 | |
| 1237 | return node->slots + offset; |
| 1238 | } |
| 1239 | EXPORT_SYMBOL(radix_tree_next_chunk); |
| 1240 | |
| 1241 | /** |
| 1242 | * radix_tree_gang_lookup - perform multiple lookup on a radix tree |
| 1243 | * @root: radix tree root |
| 1244 | * @results: where the results of the lookup are placed |
| 1245 | * @first_index: start the lookup from this key |
| 1246 | * @max_items: place up to this many items at *results |
| 1247 | * |
| 1248 | * Performs an index-ascending scan of the tree for present items. Places |
| 1249 | * them at *@results and returns the number of items which were placed at |
| 1250 | * *@results. |
| 1251 | * |
| 1252 | * The implementation is naive. |
| 1253 | * |
| 1254 | * Like radix_tree_lookup, radix_tree_gang_lookup may be called under |
| 1255 | * rcu_read_lock. In this case, rather than the returned results being |
| 1256 | * an atomic snapshot of the tree at a single point in time, the |
| 1257 | * semantics of an RCU protected gang lookup are as though multiple |
| 1258 | * radix_tree_lookups have been issued in individual locks, and results |
| 1259 | * stored in 'results'. |
| 1260 | */ |
| 1261 | unsigned int |
| 1262 | radix_tree_gang_lookup(const struct radix_tree_root *root, void **results, |
| 1263 | unsigned long first_index, unsigned int max_items) |
| 1264 | { |
| 1265 | struct radix_tree_iter iter; |
| 1266 | void __rcu **slot; |
| 1267 | unsigned int ret = 0; |
| 1268 | |
| 1269 | if (unlikely(!max_items)) |
| 1270 | return 0; |
| 1271 | |
| 1272 | radix_tree_for_each_slot(slot, root, &iter, first_index) { |
| 1273 | results[ret] = rcu_dereference_raw(*slot); |
| 1274 | if (!results[ret]) |
| 1275 | continue; |
| 1276 | if (radix_tree_is_internal_node(results[ret])) { |
| 1277 | slot = radix_tree_iter_retry(&iter); |
| 1278 | continue; |
| 1279 | } |
| 1280 | if (++ret == max_items) |
| 1281 | break; |
| 1282 | } |
| 1283 | |
| 1284 | return ret; |
| 1285 | } |
| 1286 | EXPORT_SYMBOL(radix_tree_gang_lookup); |
| 1287 | |
| 1288 | /** |
| 1289 | * radix_tree_gang_lookup_tag - perform multiple lookup on a radix tree |
| 1290 | * based on a tag |
| 1291 | * @root: radix tree root |
| 1292 | * @results: where the results of the lookup are placed |
| 1293 | * @first_index: start the lookup from this key |
| 1294 | * @max_items: place up to this many items at *results |
| 1295 | * @tag: the tag index (< RADIX_TREE_MAX_TAGS) |
| 1296 | * |
| 1297 | * Performs an index-ascending scan of the tree for present items which |
| 1298 | * have the tag indexed by @tag set. Places the items at *@results and |
| 1299 | * returns the number of items which were placed at *@results. |
| 1300 | */ |
| 1301 | unsigned int |
| 1302 | radix_tree_gang_lookup_tag(const struct radix_tree_root *root, void **results, |
| 1303 | unsigned long first_index, unsigned int max_items, |
| 1304 | unsigned int tag) |
| 1305 | { |
| 1306 | struct radix_tree_iter iter; |
| 1307 | void __rcu **slot; |
| 1308 | unsigned int ret = 0; |
| 1309 | |
| 1310 | if (unlikely(!max_items)) |
| 1311 | return 0; |
| 1312 | |
| 1313 | radix_tree_for_each_tagged(slot, root, &iter, first_index, tag) { |
| 1314 | results[ret] = rcu_dereference_raw(*slot); |
| 1315 | if (!results[ret]) |
| 1316 | continue; |
| 1317 | if (radix_tree_is_internal_node(results[ret])) { |
| 1318 | slot = radix_tree_iter_retry(&iter); |
| 1319 | continue; |
| 1320 | } |
| 1321 | if (++ret == max_items) |
| 1322 | break; |
| 1323 | } |
| 1324 | |
| 1325 | return ret; |
| 1326 | } |
| 1327 | EXPORT_SYMBOL(radix_tree_gang_lookup_tag); |
| 1328 | |
| 1329 | /** |
| 1330 | * radix_tree_gang_lookup_tag_slot - perform multiple slot lookup on a |
| 1331 | * radix tree based on a tag |
| 1332 | * @root: radix tree root |
| 1333 | * @results: where the results of the lookup are placed |
| 1334 | * @first_index: start the lookup from this key |
| 1335 | * @max_items: place up to this many items at *results |
| 1336 | * @tag: the tag index (< RADIX_TREE_MAX_TAGS) |
| 1337 | * |
| 1338 | * Performs an index-ascending scan of the tree for present items which |
| 1339 | * have the tag indexed by @tag set. Places the slots at *@results and |
| 1340 | * returns the number of slots which were placed at *@results. |
| 1341 | */ |
| 1342 | unsigned int |
| 1343 | radix_tree_gang_lookup_tag_slot(const struct radix_tree_root *root, |
| 1344 | void __rcu ***results, unsigned long first_index, |
| 1345 | unsigned int max_items, unsigned int tag) |
| 1346 | { |
| 1347 | struct radix_tree_iter iter; |
| 1348 | void __rcu **slot; |
| 1349 | unsigned int ret = 0; |
| 1350 | |
| 1351 | if (unlikely(!max_items)) |
| 1352 | return 0; |
| 1353 | |
| 1354 | radix_tree_for_each_tagged(slot, root, &iter, first_index, tag) { |
| 1355 | results[ret] = slot; |
| 1356 | if (++ret == max_items) |
| 1357 | break; |
| 1358 | } |
| 1359 | |
| 1360 | return ret; |
| 1361 | } |
| 1362 | EXPORT_SYMBOL(radix_tree_gang_lookup_tag_slot); |
| 1363 | |
| 1364 | static bool __radix_tree_delete(struct radix_tree_root *root, |
| 1365 | struct radix_tree_node *node, void __rcu **slot) |
| 1366 | { |
| 1367 | void *old = rcu_dereference_raw(*slot); |
| 1368 | int values = xa_is_value(old) ? -1 : 0; |
| 1369 | unsigned offset = get_slot_offset(node, slot); |
| 1370 | int tag; |
| 1371 | |
| 1372 | if (is_idr(root)) |
| 1373 | node_tag_set(root, node, IDR_FREE, offset); |
| 1374 | else |
| 1375 | for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) |
| 1376 | node_tag_clear(root, node, tag, offset); |
| 1377 | |
| 1378 | replace_slot(slot, NULL, node, -1, values); |
| 1379 | return node && delete_node(root, node); |
| 1380 | } |
| 1381 | |
| 1382 | /** |
| 1383 | * radix_tree_iter_delete - delete the entry at this iterator position |
| 1384 | * @root: radix tree root |
| 1385 | * @iter: iterator state |
| 1386 | * @slot: pointer to slot |
| 1387 | * |
| 1388 | * Delete the entry at the position currently pointed to by the iterator. |
| 1389 | * This may result in the current node being freed; if it is, the iterator |
| 1390 | * is advanced so that it will not reference the freed memory. This |
| 1391 | * function may be called without any locking if there are no other threads |
| 1392 | * which can access this tree. |
| 1393 | */ |
| 1394 | void radix_tree_iter_delete(struct radix_tree_root *root, |
| 1395 | struct radix_tree_iter *iter, void __rcu **slot) |
| 1396 | { |
| 1397 | if (__radix_tree_delete(root, iter->node, slot)) |
| 1398 | iter->index = iter->next_index; |
| 1399 | } |
| 1400 | EXPORT_SYMBOL(radix_tree_iter_delete); |
| 1401 | |
| 1402 | /** |
| 1403 | * radix_tree_delete_item - delete an item from a radix tree |
| 1404 | * @root: radix tree root |
| 1405 | * @index: index key |
| 1406 | * @item: expected item |
| 1407 | * |
| 1408 | * Remove @item at @index from the radix tree rooted at @root. |
| 1409 | * |
| 1410 | * Return: the deleted entry, or %NULL if it was not present |
| 1411 | * or the entry at the given @index was not @item. |
| 1412 | */ |
| 1413 | void *radix_tree_delete_item(struct radix_tree_root *root, |
| 1414 | unsigned long index, void *item) |
| 1415 | { |
| 1416 | struct radix_tree_node *node = NULL; |
| 1417 | void __rcu **slot = NULL; |
| 1418 | void *entry; |
| 1419 | |
| 1420 | entry = __radix_tree_lookup(root, index, &node, &slot); |
| 1421 | if (!slot) |
| 1422 | return NULL; |
| 1423 | if (!entry && (!is_idr(root) || node_tag_get(root, node, IDR_FREE, |
| 1424 | get_slot_offset(node, slot)))) |
| 1425 | return NULL; |
| 1426 | |
| 1427 | if (item && entry != item) |
| 1428 | return NULL; |
| 1429 | |
| 1430 | __radix_tree_delete(root, node, slot); |
| 1431 | |
| 1432 | return entry; |
| 1433 | } |
| 1434 | EXPORT_SYMBOL(radix_tree_delete_item); |
| 1435 | |
| 1436 | /** |
| 1437 | * radix_tree_delete - delete an entry from a radix tree |
| 1438 | * @root: radix tree root |
| 1439 | * @index: index key |
| 1440 | * |
| 1441 | * Remove the entry at @index from the radix tree rooted at @root. |
| 1442 | * |
| 1443 | * Return: The deleted entry, or %NULL if it was not present. |
| 1444 | */ |
| 1445 | void *radix_tree_delete(struct radix_tree_root *root, unsigned long index) |
| 1446 | { |
| 1447 | return radix_tree_delete_item(root, index, NULL); |
| 1448 | } |
| 1449 | EXPORT_SYMBOL(radix_tree_delete); |
| 1450 | |
| 1451 | /** |
| 1452 | * radix_tree_tagged - test whether any items in the tree are tagged |
| 1453 | * @root: radix tree root |
| 1454 | * @tag: tag to test |
| 1455 | */ |
| 1456 | int radix_tree_tagged(const struct radix_tree_root *root, unsigned int tag) |
| 1457 | { |
| 1458 | return root_tag_get(root, tag); |
| 1459 | } |
| 1460 | EXPORT_SYMBOL(radix_tree_tagged); |
| 1461 | |
| 1462 | /** |
| 1463 | * idr_preload - preload for idr_alloc() |
| 1464 | * @gfp_mask: allocation mask to use for preloading |
| 1465 | * |
| 1466 | * Preallocate memory to use for the next call to idr_alloc(). This function |
| 1467 | * returns with preemption disabled. It will be enabled by idr_preload_end(). |
| 1468 | */ |
| 1469 | void idr_preload(gfp_t gfp_mask) |
| 1470 | { |
| 1471 | if (__radix_tree_preload(gfp_mask, IDR_PRELOAD_SIZE)) |
| 1472 | local_lock(&radix_tree_preloads.lock); |
| 1473 | } |
| 1474 | EXPORT_SYMBOL(idr_preload); |
| 1475 | |
| 1476 | void __rcu **idr_get_free(struct radix_tree_root *root, |
| 1477 | struct radix_tree_iter *iter, gfp_t gfp, |
| 1478 | unsigned long max) |
| 1479 | { |
| 1480 | struct radix_tree_node *node = NULL, *child; |
| 1481 | void __rcu **slot = (void __rcu **)&root->xa_head; |
| 1482 | unsigned long maxindex, start = iter->next_index; |
| 1483 | unsigned int shift, offset = 0; |
| 1484 | |
| 1485 | grow: |
| 1486 | shift = radix_tree_load_root(root, &child, &maxindex); |
| 1487 | if (!radix_tree_tagged(root, IDR_FREE)) |
| 1488 | start = max(start, maxindex + 1); |
| 1489 | if (start > max) |
| 1490 | return ERR_PTR(-ENOSPC); |
| 1491 | |
| 1492 | if (start > maxindex) { |
| 1493 | int error = radix_tree_extend(root, gfp, start, shift); |
| 1494 | if (error < 0) |
| 1495 | return ERR_PTR(error); |
| 1496 | shift = error; |
| 1497 | child = rcu_dereference_raw(root->xa_head); |
| 1498 | } |
| 1499 | if (start == 0 && shift == 0) |
| 1500 | shift = RADIX_TREE_MAP_SHIFT; |
| 1501 | |
| 1502 | while (shift) { |
| 1503 | shift -= RADIX_TREE_MAP_SHIFT; |
| 1504 | if (child == NULL) { |
| 1505 | /* Have to add a child node. */ |
| 1506 | child = radix_tree_node_alloc(gfp, node, root, shift, |
| 1507 | offset, 0, 0); |
| 1508 | if (!child) |
| 1509 | return ERR_PTR(-ENOMEM); |
| 1510 | all_tag_set(child, IDR_FREE); |
| 1511 | rcu_assign_pointer(*slot, node_to_entry(child)); |
| 1512 | if (node) |
| 1513 | node->count++; |
| 1514 | } else if (!radix_tree_is_internal_node(child)) |
| 1515 | break; |
| 1516 | |
| 1517 | node = entry_to_node(child); |
| 1518 | offset = radix_tree_descend(node, &child, start); |
| 1519 | if (!tag_get(node, IDR_FREE, offset)) { |
| 1520 | offset = radix_tree_find_next_bit(node, IDR_FREE, |
| 1521 | offset + 1); |
| 1522 | start = next_index(start, node, offset); |
| 1523 | if (start > max || start == 0) |
| 1524 | return ERR_PTR(-ENOSPC); |
| 1525 | while (offset == RADIX_TREE_MAP_SIZE) { |
| 1526 | offset = node->offset + 1; |
| 1527 | node = node->parent; |
| 1528 | if (!node) |
| 1529 | goto grow; |
| 1530 | shift = node->shift; |
| 1531 | } |
| 1532 | child = rcu_dereference_raw(node->slots[offset]); |
| 1533 | } |
| 1534 | slot = &node->slots[offset]; |
| 1535 | } |
| 1536 | |
| 1537 | iter->index = start; |
| 1538 | if (node) |
| 1539 | iter->next_index = 1 + min(max, (start | node_maxindex(node))); |
| 1540 | else |
| 1541 | iter->next_index = 1; |
| 1542 | iter->node = node; |
| 1543 | set_iter_tags(iter, node, offset, IDR_FREE); |
| 1544 | |
| 1545 | return slot; |
| 1546 | } |
| 1547 | |
| 1548 | /** |
| 1549 | * idr_destroy - release all internal memory from an IDR |
| 1550 | * @idr: idr handle |
| 1551 | * |
| 1552 | * After this function is called, the IDR is empty, and may be reused or |
| 1553 | * the data structure containing it may be freed. |
| 1554 | * |
| 1555 | * A typical clean-up sequence for objects stored in an idr tree will use |
| 1556 | * idr_for_each() to free all objects, if necessary, then idr_destroy() to |
| 1557 | * free the memory used to keep track of those objects. |
| 1558 | */ |
| 1559 | void idr_destroy(struct idr *idr) |
| 1560 | { |
| 1561 | struct radix_tree_node *node = rcu_dereference_raw(idr->idr_rt.xa_head); |
| 1562 | if (radix_tree_is_internal_node(node)) |
| 1563 | radix_tree_free_nodes(node); |
| 1564 | idr->idr_rt.xa_head = NULL; |
| 1565 | root_tag_set(&idr->idr_rt, IDR_FREE); |
| 1566 | } |
| 1567 | EXPORT_SYMBOL(idr_destroy); |
| 1568 | |
| 1569 | static void |
| 1570 | radix_tree_node_ctor(void *arg) |
| 1571 | { |
| 1572 | struct radix_tree_node *node = arg; |
| 1573 | |
| 1574 | memset(node, 0, sizeof(*node)); |
| 1575 | INIT_LIST_HEAD(&node->private_list); |
| 1576 | } |
| 1577 | |
| 1578 | static int radix_tree_cpu_dead(unsigned int cpu) |
| 1579 | { |
| 1580 | struct radix_tree_preload *rtp; |
| 1581 | struct radix_tree_node *node; |
| 1582 | |
| 1583 | /* Free per-cpu pool of preloaded nodes */ |
| 1584 | rtp = &per_cpu(radix_tree_preloads, cpu); |
| 1585 | while (rtp->nr) { |
| 1586 | node = rtp->nodes; |
| 1587 | rtp->nodes = node->parent; |
| 1588 | kmem_cache_free(radix_tree_node_cachep, node); |
| 1589 | rtp->nr--; |
| 1590 | } |
| 1591 | return 0; |
| 1592 | } |
| 1593 | |
| 1594 | void __init radix_tree_init(void) |
| 1595 | { |
| 1596 | int ret; |
| 1597 | |
| 1598 | BUILD_BUG_ON(RADIX_TREE_MAX_TAGS + __GFP_BITS_SHIFT > 32); |
| 1599 | BUILD_BUG_ON(ROOT_IS_IDR & ~GFP_ZONEMASK); |
| 1600 | BUILD_BUG_ON(XA_CHUNK_SIZE > 255); |
| 1601 | radix_tree_node_cachep = kmem_cache_create("radix_tree_node", |
| 1602 | sizeof(struct radix_tree_node), 0, |
| 1603 | SLAB_PANIC | SLAB_RECLAIM_ACCOUNT, |
| 1604 | radix_tree_node_ctor); |
| 1605 | ret = cpuhp_setup_state_nocalls(CPUHP_RADIX_DEAD, "lib/radix:dead", |
| 1606 | NULL, radix_tree_cpu_dead); |
| 1607 | WARN_ON(ret < 0); |
| 1608 | } |