1 // SPDX-License-Identifier: GPL-2.0+ 2 /* 3 * XArray implementation 4 * Copyright (c) 2017-2018 Microsoft Corporation 5 * Copyright (c) 2018-2020 Oracle 6 * Author: Matthew Wilcox <willy@infradead.org> 7 */ 8 9 #include <linux/bitmap.h> 10 #include <linux/export.h> 11 #include <linux/list.h> 12 #include <linux/slab.h> 13 #include <linux/xarray.h> 14 15 /* 16 * Coding conventions in this file: 17 * 18 * @xa is used to refer to the entire xarray. 19 * @xas is the 'xarray operation state'. It may be either a pointer to 20 * an xa_state, or an xa_state stored on the stack. This is an unfortunate 21 * ambiguity. 22 * @index is the index of the entry being operated on 23 * @mark is an xa_mark_t; a small number indicating one of the mark bits. 24 * @node refers to an xa_node; usually the primary one being operated on by 25 * this function. 26 * @offset is the index into the slots array inside an xa_node. 27 * @parent refers to the @xa_node closer to the head than @node. 28 * @entry refers to something stored in a slot in the xarray 29 */ 30 31 static inline unsigned int xa_lock_type(const struct xarray *xa) 32 { 33 return (__force unsigned int)xa->xa_flags & 3; 34 } 35 36 static inline void xas_lock_type(struct xa_state *xas, unsigned int lock_type) 37 { 38 if (lock_type == XA_LOCK_IRQ) 39 xas_lock_irq(xas); 40 else if (lock_type == XA_LOCK_BH) 41 xas_lock_bh(xas); 42 else 43 xas_lock(xas); 44 } 45 46 static inline void xas_unlock_type(struct xa_state *xas, unsigned int lock_type) 47 { 48 if (lock_type == XA_LOCK_IRQ) 49 xas_unlock_irq(xas); 50 else if (lock_type == XA_LOCK_BH) 51 xas_unlock_bh(xas); 52 else 53 xas_unlock(xas); 54 } 55 56 static inline bool xa_track_free(const struct xarray *xa) 57 { 58 return xa->xa_flags & XA_FLAGS_TRACK_FREE; 59 } 60 61 static inline bool xa_zero_busy(const struct xarray *xa) 62 { 63 return xa->xa_flags & XA_FLAGS_ZERO_BUSY; 64 } 65 66 static inline void xa_mark_set(struct xarray *xa, xa_mark_t mark) 67 { 68 if (!(xa->xa_flags & XA_FLAGS_MARK(mark))) 69 xa->xa_flags |= XA_FLAGS_MARK(mark); 70 } 71 72 static inline void xa_mark_clear(struct xarray *xa, xa_mark_t mark) 73 { 74 if (xa->xa_flags & XA_FLAGS_MARK(mark)) 75 xa->xa_flags &= ~(XA_FLAGS_MARK(mark)); 76 } 77 78 static inline unsigned long *node_marks(struct xa_node *node, xa_mark_t mark) 79 { 80 return node->marks[(__force unsigned)mark]; 81 } 82 83 static inline bool node_get_mark(struct xa_node *node, 84 unsigned int offset, xa_mark_t mark) 85 { 86 return test_bit(offset, node_marks(node, mark)); 87 } 88 89 /* returns true if the bit was set */ 90 static inline bool node_set_mark(struct xa_node *node, unsigned int offset, 91 xa_mark_t mark) 92 { 93 return __test_and_set_bit(offset, node_marks(node, mark)); 94 } 95 96 /* returns true if the bit was set */ 97 static inline bool node_clear_mark(struct xa_node *node, unsigned int offset, 98 xa_mark_t mark) 99 { 100 return __test_and_clear_bit(offset, node_marks(node, mark)); 101 } 102 103 static inline bool node_any_mark(struct xa_node *node, xa_mark_t mark) 104 { 105 return !bitmap_empty(node_marks(node, mark), XA_CHUNK_SIZE); 106 } 107 108 static inline void node_mark_all(struct xa_node *node, xa_mark_t mark) 109 { 110 bitmap_fill(node_marks(node, mark), XA_CHUNK_SIZE); 111 } 112 113 #define mark_inc(mark) do { \ 114 mark = (__force xa_mark_t)((__force unsigned)(mark) + 1); \ 115 } while (0) 116 117 /* 118 * xas_squash_marks() - Merge all marks to the first entry 119 * @xas: Array operation state. 120 * 121 * Set a mark on the first entry if any entry has it set. Clear marks on 122 * all sibling entries. 123 */ 124 static void xas_squash_marks(const struct xa_state *xas) 125 { 126 unsigned int mark = 0; 127 unsigned int limit = xas->xa_offset + xas->xa_sibs + 1; 128 129 if (!xas->xa_sibs) 130 return; 131 132 do { 133 unsigned long *marks = xas->xa_node->marks[mark]; 134 if (find_next_bit(marks, limit, xas->xa_offset + 1) == limit) 135 continue; 136 __set_bit(xas->xa_offset, marks); 137 bitmap_clear(marks, xas->xa_offset + 1, xas->xa_sibs); 138 } while (mark++ != (__force unsigned)XA_MARK_MAX); 139 } 140 141 /* extracts the offset within this node from the index */ 142 static unsigned int get_offset(unsigned long index, struct xa_node *node) 143 { 144 return (index >> node->shift) & XA_CHUNK_MASK; 145 } 146 147 static void xas_set_offset(struct xa_state *xas) 148 { 149 xas->xa_offset = get_offset(xas->xa_index, xas->xa_node); 150 } 151 152 /* move the index either forwards (find) or backwards (sibling slot) */ 153 static void xas_move_index(struct xa_state *xas, unsigned long offset) 154 { 155 unsigned int shift = xas->xa_node->shift; 156 xas->xa_index &= ~XA_CHUNK_MASK << shift; 157 xas->xa_index += offset << shift; 158 } 159 160 static void xas_advance(struct xa_state *xas) 161 { 162 xas->xa_offset++; 163 xas_move_index(xas, xas->xa_offset); 164 } 165 166 static void *set_bounds(struct xa_state *xas) 167 { 168 xas->xa_node = XAS_BOUNDS; 169 return NULL; 170 } 171 172 /* 173 * Starts a walk. If the @xas is already valid, we assume that it's on 174 * the right path and just return where we've got to. If we're in an 175 * error state, return NULL. If the index is outside the current scope 176 * of the xarray, return NULL without changing @xas->xa_node. Otherwise 177 * set @xas->xa_node to NULL and return the current head of the array. 178 */ 179 static void *xas_start(struct xa_state *xas) 180 { 181 void *entry; 182 183 if (xas_valid(xas)) 184 return xas_reload(xas); 185 if (xas_error(xas)) 186 return NULL; 187 188 entry = xa_head(xas->xa); 189 if (!xa_is_node(entry)) { 190 if (xas->xa_index) 191 return set_bounds(xas); 192 } else { 193 if ((xas->xa_index >> xa_to_node(entry)->shift) > XA_CHUNK_MASK) 194 return set_bounds(xas); 195 } 196 197 xas->xa_node = NULL; 198 return entry; 199 } 200 201 static void *xas_descend(struct xa_state *xas, struct xa_node *node) 202 { 203 unsigned int offset = get_offset(xas->xa_index, node); 204 void *entry = xa_entry(xas->xa, node, offset); 205 206 xas->xa_node = node; 207 if (xa_is_sibling(entry)) { 208 offset = xa_to_sibling(entry); 209 entry = xa_entry(xas->xa, node, offset); 210 } 211 212 xas->xa_offset = offset; 213 return entry; 214 } 215 216 /** 217 * xas_load() - Load an entry from the XArray (advanced). 218 * @xas: XArray operation state. 219 * 220 * Usually walks the @xas to the appropriate state to load the entry 221 * stored at xa_index. However, it will do nothing and return %NULL if 222 * @xas is in an error state. xas_load() will never expand the tree. 223 * 224 * If the xa_state is set up to operate on a multi-index entry, xas_load() 225 * may return %NULL or an internal entry, even if there are entries 226 * present within the range specified by @xas. 227 * 228 * Context: Any context. The caller should hold the xa_lock or the RCU lock. 229 * Return: Usually an entry in the XArray, but see description for exceptions. 230 */ 231 void *xas_load(struct xa_state *xas) 232 { 233 void *entry = xas_start(xas); 234 235 while (xa_is_node(entry)) { 236 struct xa_node *node = xa_to_node(entry); 237 238 if (xas->xa_shift > node->shift) 239 break; 240 entry = xas_descend(xas, node); 241 if (node->shift == 0) 242 break; 243 } 244 return entry; 245 } 246 EXPORT_SYMBOL_GPL(xas_load); 247 248 /* Move the radix tree node cache here */ 249 extern struct kmem_cache *radix_tree_node_cachep; 250 extern void radix_tree_node_rcu_free(struct rcu_head *head); 251 252 #define XA_RCU_FREE ((struct xarray *)1) 253 254 static void xa_node_free(struct xa_node *node) 255 { 256 XA_NODE_BUG_ON(node, !list_empty(&node->private_list)); 257 node->array = XA_RCU_FREE; 258 call_rcu(&node->rcu_head, radix_tree_node_rcu_free); 259 } 260 261 /* 262 * xas_destroy() - Free any resources allocated during the XArray operation. 263 * @xas: XArray operation state. 264 * 265 * This function is now internal-only. 266 */ 267 static void xas_destroy(struct xa_state *xas) 268 { 269 struct xa_node *next, *node = xas->xa_alloc; 270 271 while (node) { 272 XA_NODE_BUG_ON(node, !list_empty(&node->private_list)); 273 next = rcu_dereference_raw(node->parent); 274 radix_tree_node_rcu_free(&node->rcu_head); 275 xas->xa_alloc = node = next; 276 } 277 } 278 279 /** 280 * xas_nomem() - Allocate memory if needed. 281 * @xas: XArray operation state. 282 * @gfp: Memory allocation flags. 283 * 284 * If we need to add new nodes to the XArray, we try to allocate memory 285 * with GFP_NOWAIT while holding the lock, which will usually succeed. 286 * If it fails, @xas is flagged as needing memory to continue. The caller 287 * should drop the lock and call xas_nomem(). If xas_nomem() succeeds, 288 * the caller should retry the operation. 289 * 290 * Forward progress is guaranteed as one node is allocated here and 291 * stored in the xa_state where it will be found by xas_alloc(). More 292 * nodes will likely be found in the slab allocator, but we do not tie 293 * them up here. 294 * 295 * Return: true if memory was needed, and was successfully allocated. 296 */ 297 bool xas_nomem(struct xa_state *xas, gfp_t gfp) 298 { 299 if (xas->xa_node != XA_ERROR(-ENOMEM)) { 300 xas_destroy(xas); 301 return false; 302 } 303 if (xas->xa->xa_flags & XA_FLAGS_ACCOUNT) 304 gfp |= __GFP_ACCOUNT; 305 xas->xa_alloc = kmem_cache_alloc(radix_tree_node_cachep, gfp); 306 if (!xas->xa_alloc) 307 return false; 308 xas->xa_alloc->parent = NULL; 309 XA_NODE_BUG_ON(xas->xa_alloc, !list_empty(&xas->xa_alloc->private_list)); 310 xas->xa_node = XAS_RESTART; 311 return true; 312 } 313 EXPORT_SYMBOL_GPL(xas_nomem); 314 315 /* 316 * __xas_nomem() - Drop locks and allocate memory if needed. 317 * @xas: XArray operation state. 318 * @gfp: Memory allocation flags. 319 * 320 * Internal variant of xas_nomem(). 321 * 322 * Return: true if memory was needed, and was successfully allocated. 323 */ 324 static bool __xas_nomem(struct xa_state *xas, gfp_t gfp) 325 __must_hold(xas->xa->xa_lock) 326 { 327 unsigned int lock_type = xa_lock_type(xas->xa); 328 329 if (xas->xa_node != XA_ERROR(-ENOMEM)) { 330 xas_destroy(xas); 331 return false; 332 } 333 if (xas->xa->xa_flags & XA_FLAGS_ACCOUNT) 334 gfp |= __GFP_ACCOUNT; 335 if (gfpflags_allow_blocking(gfp)) { 336 xas_unlock_type(xas, lock_type); 337 xas->xa_alloc = kmem_cache_alloc(radix_tree_node_cachep, gfp); 338 xas_lock_type(xas, lock_type); 339 } else { 340 xas->xa_alloc = kmem_cache_alloc(radix_tree_node_cachep, gfp); 341 } 342 if (!xas->xa_alloc) 343 return false; 344 xas->xa_alloc->parent = NULL; 345 XA_NODE_BUG_ON(xas->xa_alloc, !list_empty(&xas->xa_alloc->private_list)); 346 xas->xa_node = XAS_RESTART; 347 return true; 348 } 349 350 static void xas_update(struct xa_state *xas, struct xa_node *node) 351 { 352 if (xas->xa_update) 353 xas->xa_update(node); 354 else 355 XA_NODE_BUG_ON(node, !list_empty(&node->private_list)); 356 } 357 358 static void *xas_alloc(struct xa_state *xas, unsigned int shift) 359 { 360 struct xa_node *parent = xas->xa_node; 361 struct xa_node *node = xas->xa_alloc; 362 363 if (xas_invalid(xas)) 364 return NULL; 365 366 if (node) { 367 xas->xa_alloc = NULL; 368 } else { 369 gfp_t gfp = GFP_NOWAIT | __GFP_NOWARN; 370 371 if (xas->xa->xa_flags & XA_FLAGS_ACCOUNT) 372 gfp |= __GFP_ACCOUNT; 373 374 node = kmem_cache_alloc(radix_tree_node_cachep, gfp); 375 if (!node) { 376 xas_set_err(xas, -ENOMEM); 377 return NULL; 378 } 379 } 380 381 if (parent) { 382 node->offset = xas->xa_offset; 383 parent->count++; 384 XA_NODE_BUG_ON(node, parent->count > XA_CHUNK_SIZE); 385 xas_update(xas, parent); 386 } 387 XA_NODE_BUG_ON(node, shift > BITS_PER_LONG); 388 XA_NODE_BUG_ON(node, !list_empty(&node->private_list)); 389 node->shift = shift; 390 node->count = 0; 391 node->nr_values = 0; 392 RCU_INIT_POINTER(node->parent, xas->xa_node); 393 node->array = xas->xa; 394 395 return node; 396 } 397 398 #ifdef CONFIG_XARRAY_MULTI 399 /* Returns the number of indices covered by a given xa_state */ 400 static unsigned long xas_size(const struct xa_state *xas) 401 { 402 return (xas->xa_sibs + 1UL) << xas->xa_shift; 403 } 404 #endif 405 406 /* 407 * Use this to calculate the maximum index that will need to be created 408 * in order to add the entry described by @xas. Because we cannot store a 409 * multi-index entry at index 0, the calculation is a little more complex 410 * than you might expect. 411 */ 412 static unsigned long xas_max(struct xa_state *xas) 413 { 414 unsigned long max = xas->xa_index; 415 416 #ifdef CONFIG_XARRAY_MULTI 417 if (xas->xa_shift || xas->xa_sibs) { 418 unsigned long mask = xas_size(xas) - 1; 419 max |= mask; 420 if (mask == max) 421 max++; 422 } 423 #endif 424 425 return max; 426 } 427 428 /* The maximum index that can be contained in the array without expanding it */ 429 static unsigned long max_index(void *entry) 430 { 431 if (!xa_is_node(entry)) 432 return 0; 433 return (XA_CHUNK_SIZE << xa_to_node(entry)->shift) - 1; 434 } 435 436 static void xas_shrink(struct xa_state *xas) 437 { 438 struct xarray *xa = xas->xa; 439 struct xa_node *node = xas->xa_node; 440 441 for (;;) { 442 void *entry; 443 444 XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE); 445 if (node->count != 1) 446 break; 447 entry = xa_entry_locked(xa, node, 0); 448 if (!entry) 449 break; 450 if (!xa_is_node(entry) && node->shift) 451 break; 452 if (xa_is_zero(entry) && xa_zero_busy(xa)) 453 entry = NULL; 454 xas->xa_node = XAS_BOUNDS; 455 456 RCU_INIT_POINTER(xa->xa_head, entry); 457 if (xa_track_free(xa) && !node_get_mark(node, 0, XA_FREE_MARK)) 458 xa_mark_clear(xa, XA_FREE_MARK); 459 460 node->count = 0; 461 node->nr_values = 0; 462 if (!xa_is_node(entry)) 463 RCU_INIT_POINTER(node->slots[0], XA_RETRY_ENTRY); 464 xas_update(xas, node); 465 xa_node_free(node); 466 if (!xa_is_node(entry)) 467 break; 468 node = xa_to_node(entry); 469 node->parent = NULL; 470 } 471 } 472 473 /* 474 * xas_delete_node() - Attempt to delete an xa_node 475 * @xas: Array operation state. 476 * 477 * Attempts to delete the @xas->xa_node. This will fail if xa->node has 478 * a non-zero reference count. 479 */ 480 static void xas_delete_node(struct xa_state *xas) 481 { 482 struct xa_node *node = xas->xa_node; 483 484 for (;;) { 485 struct xa_node *parent; 486 487 XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE); 488 if (node->count) 489 break; 490 491 parent = xa_parent_locked(xas->xa, node); 492 xas->xa_node = parent; 493 xas->xa_offset = node->offset; 494 xa_node_free(node); 495 496 if (!parent) { 497 xas->xa->xa_head = NULL; 498 xas->xa_node = XAS_BOUNDS; 499 return; 500 } 501 502 parent->slots[xas->xa_offset] = NULL; 503 parent->count--; 504 XA_NODE_BUG_ON(parent, parent->count > XA_CHUNK_SIZE); 505 node = parent; 506 xas_update(xas, node); 507 } 508 509 if (!node->parent) 510 xas_shrink(xas); 511 } 512 513 /** 514 * xas_free_nodes() - Free this node and all nodes that it references 515 * @xas: Array operation state. 516 * @top: Node to free 517 * 518 * This node has been removed from the tree. We must now free it and all 519 * of its subnodes. There may be RCU walkers with references into the tree, 520 * so we must replace all entries with retry markers. 521 */ 522 static void xas_free_nodes(struct xa_state *xas, struct xa_node *top) 523 { 524 unsigned int offset = 0; 525 struct xa_node *node = top; 526 527 for (;;) { 528 void *entry = xa_entry_locked(xas->xa, node, offset); 529 530 if (node->shift && xa_is_node(entry)) { 531 node = xa_to_node(entry); 532 offset = 0; 533 continue; 534 } 535 if (entry) 536 RCU_INIT_POINTER(node->slots[offset], XA_RETRY_ENTRY); 537 offset++; 538 while (offset == XA_CHUNK_SIZE) { 539 struct xa_node *parent; 540 541 parent = xa_parent_locked(xas->xa, node); 542 offset = node->offset + 1; 543 node->count = 0; 544 node->nr_values = 0; 545 xas_update(xas, node); 546 xa_node_free(node); 547 if (node == top) 548 return; 549 node = parent; 550 } 551 } 552 } 553 554 /* 555 * xas_expand adds nodes to the head of the tree until it has reached 556 * sufficient height to be able to contain @xas->xa_index 557 */ 558 static int xas_expand(struct xa_state *xas, void *head) 559 { 560 struct xarray *xa = xas->xa; 561 struct xa_node *node = NULL; 562 unsigned int shift = 0; 563 unsigned long max = xas_max(xas); 564 565 if (!head) { 566 if (max == 0) 567 return 0; 568 while ((max >> shift) >= XA_CHUNK_SIZE) 569 shift += XA_CHUNK_SHIFT; 570 return shift + XA_CHUNK_SHIFT; 571 } else if (xa_is_node(head)) { 572 node = xa_to_node(head); 573 shift = node->shift + XA_CHUNK_SHIFT; 574 } 575 xas->xa_node = NULL; 576 577 while (max > max_index(head)) { 578 xa_mark_t mark = 0; 579 580 XA_NODE_BUG_ON(node, shift > BITS_PER_LONG); 581 node = xas_alloc(xas, shift); 582 if (!node) 583 return -ENOMEM; 584 585 node->count = 1; 586 if (xa_is_value(head)) 587 node->nr_values = 1; 588 RCU_INIT_POINTER(node->slots[0], head); 589 590 /* Propagate the aggregated mark info to the new child */ 591 for (;;) { 592 if (xa_track_free(xa) && mark == XA_FREE_MARK) { 593 node_mark_all(node, XA_FREE_MARK); 594 if (!xa_marked(xa, XA_FREE_MARK)) { 595 node_clear_mark(node, 0, XA_FREE_MARK); 596 xa_mark_set(xa, XA_FREE_MARK); 597 } 598 } else if (xa_marked(xa, mark)) { 599 node_set_mark(node, 0, mark); 600 } 601 if (mark == XA_MARK_MAX) 602 break; 603 mark_inc(mark); 604 } 605 606 /* 607 * Now that the new node is fully initialised, we can add 608 * it to the tree 609 */ 610 if (xa_is_node(head)) { 611 xa_to_node(head)->offset = 0; 612 rcu_assign_pointer(xa_to_node(head)->parent, node); 613 } 614 head = xa_mk_node(node); 615 rcu_assign_pointer(xa->xa_head, head); 616 xas_update(xas, node); 617 618 shift += XA_CHUNK_SHIFT; 619 } 620 621 xas->xa_node = node; 622 return shift; 623 } 624 625 /* 626 * xas_create() - Create a slot to store an entry in. 627 * @xas: XArray operation state. 628 * @allow_root: %true if we can store the entry in the root directly 629 * 630 * Most users will not need to call this function directly, as it is called 631 * by xas_store(). It is useful for doing conditional store operations 632 * (see the xa_cmpxchg() implementation for an example). 633 * 634 * Return: If the slot already existed, returns the contents of this slot. 635 * If the slot was newly created, returns %NULL. If it failed to create the 636 * slot, returns %NULL and indicates the error in @xas. 637 */ 638 static void *xas_create(struct xa_state *xas, bool allow_root) 639 { 640 struct xarray *xa = xas->xa; 641 void *entry; 642 void __rcu **slot; 643 struct xa_node *node = xas->xa_node; 644 int shift; 645 unsigned int order = xas->xa_shift; 646 647 if (xas_top(node)) { 648 entry = xa_head_locked(xa); 649 xas->xa_node = NULL; 650 if (!entry && xa_zero_busy(xa)) 651 entry = XA_ZERO_ENTRY; 652 shift = xas_expand(xas, entry); 653 if (shift < 0) 654 return NULL; 655 if (!shift && !allow_root) 656 shift = XA_CHUNK_SHIFT; 657 entry = xa_head_locked(xa); 658 slot = &xa->xa_head; 659 } else if (xas_error(xas)) { 660 return NULL; 661 } else if (node) { 662 unsigned int offset = xas->xa_offset; 663 664 shift = node->shift; 665 entry = xa_entry_locked(xa, node, offset); 666 slot = &node->slots[offset]; 667 } else { 668 shift = 0; 669 entry = xa_head_locked(xa); 670 slot = &xa->xa_head; 671 } 672 673 while (shift > order) { 674 shift -= XA_CHUNK_SHIFT; 675 if (!entry) { 676 node = xas_alloc(xas, shift); 677 if (!node) 678 break; 679 if (xa_track_free(xa)) 680 node_mark_all(node, XA_FREE_MARK); 681 rcu_assign_pointer(*slot, xa_mk_node(node)); 682 } else if (xa_is_node(entry)) { 683 node = xa_to_node(entry); 684 } else { 685 break; 686 } 687 entry = xas_descend(xas, node); 688 slot = &node->slots[xas->xa_offset]; 689 } 690 691 return entry; 692 } 693 694 /** 695 * xas_create_range() - Ensure that stores to this range will succeed 696 * @xas: XArray operation state. 697 * 698 * Creates all of the slots in the range covered by @xas. Sets @xas to 699 * create single-index entries and positions it at the beginning of the 700 * range. This is for the benefit of users which have not yet been 701 * converted to use multi-index entries. 702 */ 703 void xas_create_range(struct xa_state *xas) 704 { 705 unsigned long index = xas->xa_index; 706 unsigned char shift = xas->xa_shift; 707 unsigned char sibs = xas->xa_sibs; 708 709 xas->xa_index |= ((sibs + 1UL) << shift) - 1; 710 if (xas_is_node(xas) && xas->xa_node->shift == xas->xa_shift) 711 xas->xa_offset |= sibs; 712 xas->xa_shift = 0; 713 xas->xa_sibs = 0; 714 715 for (;;) { 716 xas_create(xas, true); 717 if (xas_error(xas)) 718 goto restore; 719 if (xas->xa_index <= (index | XA_CHUNK_MASK)) 720 goto success; 721 xas->xa_index -= XA_CHUNK_SIZE; 722 723 for (;;) { 724 struct xa_node *node = xas->xa_node; 725 xas->xa_node = xa_parent_locked(xas->xa, node); 726 xas->xa_offset = node->offset - 1; 727 if (node->offset != 0) 728 break; 729 } 730 } 731 732 restore: 733 xas->xa_shift = shift; 734 xas->xa_sibs = sibs; 735 xas->xa_index = index; 736 return; 737 success: 738 xas->xa_index = index; 739 if (xas->xa_node) 740 xas_set_offset(xas); 741 } 742 EXPORT_SYMBOL_GPL(xas_create_range); 743 744 static void update_node(struct xa_state *xas, struct xa_node *node, 745 int count, int values) 746 { 747 if (!node || (!count && !values)) 748 return; 749 750 node->count += count; 751 node->nr_values += values; 752 XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE); 753 XA_NODE_BUG_ON(node, node->nr_values > XA_CHUNK_SIZE); 754 xas_update(xas, node); 755 if (count < 0) 756 xas_delete_node(xas); 757 } 758 759 /** 760 * xas_store() - Store this entry in the XArray. 761 * @xas: XArray operation state. 762 * @entry: New entry. 763 * 764 * If @xas is operating on a multi-index entry, the entry returned by this 765 * function is essentially meaningless (it may be an internal entry or it 766 * may be %NULL, even if there are non-NULL entries at some of the indices 767 * covered by the range). This is not a problem for any current users, 768 * and can be changed if needed. 769 * 770 * Return: The old entry at this index. 771 */ 772 void *xas_store(struct xa_state *xas, void *entry) 773 { 774 struct xa_node *node; 775 void __rcu **slot = &xas->xa->xa_head; 776 unsigned int offset, max; 777 int count = 0; 778 int values = 0; 779 void *first, *next; 780 bool value = xa_is_value(entry); 781 782 if (entry) { 783 bool allow_root = !xa_is_node(entry) && !xa_is_zero(entry); 784 first = xas_create(xas, allow_root); 785 } else { 786 first = xas_load(xas); 787 } 788 789 if (xas_invalid(xas)) 790 return first; 791 node = xas->xa_node; 792 if (node && (xas->xa_shift < node->shift)) 793 xas->xa_sibs = 0; 794 if ((first == entry) && !xas->xa_sibs) 795 return first; 796 797 next = first; 798 offset = xas->xa_offset; 799 max = xas->xa_offset + xas->xa_sibs; 800 if (node) { 801 slot = &node->slots[offset]; 802 if (xas->xa_sibs) 803 xas_squash_marks(xas); 804 } 805 if (!entry) 806 xas_init_marks(xas); 807 808 for (;;) { 809 /* 810 * Must clear the marks before setting the entry to NULL, 811 * otherwise xas_for_each_marked may find a NULL entry and 812 * stop early. rcu_assign_pointer contains a release barrier 813 * so the mark clearing will appear to happen before the 814 * entry is set to NULL. 815 */ 816 rcu_assign_pointer(*slot, entry); 817 if (xa_is_node(next) && (!node || node->shift)) 818 xas_free_nodes(xas, xa_to_node(next)); 819 if (!node) 820 break; 821 count += !next - !entry; 822 values += !xa_is_value(first) - !value; 823 if (entry) { 824 if (offset == max) 825 break; 826 if (!xa_is_sibling(entry)) 827 entry = xa_mk_sibling(xas->xa_offset); 828 } else { 829 if (offset == XA_CHUNK_MASK) 830 break; 831 } 832 next = xa_entry_locked(xas->xa, node, ++offset); 833 if (!xa_is_sibling(next)) { 834 if (!entry && (offset > max)) 835 break; 836 first = next; 837 } 838 slot++; 839 } 840 841 update_node(xas, node, count, values); 842 return first; 843 } 844 EXPORT_SYMBOL_GPL(xas_store); 845 846 /** 847 * xas_get_mark() - Returns the state of this mark. 848 * @xas: XArray operation state. 849 * @mark: Mark number. 850 * 851 * Return: true if the mark is set, false if the mark is clear or @xas 852 * is in an error state. 853 */ 854 bool xas_get_mark(const struct xa_state *xas, xa_mark_t mark) 855 { 856 if (xas_invalid(xas)) 857 return false; 858 if (!xas->xa_node) 859 return xa_marked(xas->xa, mark); 860 return node_get_mark(xas->xa_node, xas->xa_offset, mark); 861 } 862 EXPORT_SYMBOL_GPL(xas_get_mark); 863 864 /** 865 * xas_set_mark() - Sets the mark on this entry and its parents. 866 * @xas: XArray operation state. 867 * @mark: Mark number. 868 * 869 * Sets the specified mark on this entry, and walks up the tree setting it 870 * on all the ancestor entries. Does nothing if @xas has not been walked to 871 * an entry, or is in an error state. 872 */ 873 void xas_set_mark(const struct xa_state *xas, xa_mark_t mark) 874 { 875 struct xa_node *node = xas->xa_node; 876 unsigned int offset = xas->xa_offset; 877 878 if (xas_invalid(xas)) 879 return; 880 881 while (node) { 882 if (node_set_mark(node, offset, mark)) 883 return; 884 offset = node->offset; 885 node = xa_parent_locked(xas->xa, node); 886 } 887 888 if (!xa_marked(xas->xa, mark)) 889 xa_mark_set(xas->xa, mark); 890 } 891 EXPORT_SYMBOL_GPL(xas_set_mark); 892 893 /** 894 * xas_clear_mark() - Clears the mark on this entry and its parents. 895 * @xas: XArray operation state. 896 * @mark: Mark number. 897 * 898 * Clears the specified mark on this entry, and walks back to the head 899 * attempting to clear it on all the ancestor entries. Does nothing if 900 * @xas has not been walked to an entry, or is in an error state. 901 */ 902 void xas_clear_mark(const struct xa_state *xas, xa_mark_t mark) 903 { 904 struct xa_node *node = xas->xa_node; 905 unsigned int offset = xas->xa_offset; 906 907 if (xas_invalid(xas)) 908 return; 909 910 while (node) { 911 if (!node_clear_mark(node, offset, mark)) 912 return; 913 if (node_any_mark(node, mark)) 914 return; 915 916 offset = node->offset; 917 node = xa_parent_locked(xas->xa, node); 918 } 919 920 if (xa_marked(xas->xa, mark)) 921 xa_mark_clear(xas->xa, mark); 922 } 923 EXPORT_SYMBOL_GPL(xas_clear_mark); 924 925 /** 926 * xas_init_marks() - Initialise all marks for the entry 927 * @xas: Array operations state. 928 * 929 * Initialise all marks for the entry specified by @xas. If we're tracking 930 * free entries with a mark, we need to set it on all entries. All other 931 * marks are cleared. 932 * 933 * This implementation is not as efficient as it could be; we may walk 934 * up the tree multiple times. 935 */ 936 void xas_init_marks(const struct xa_state *xas) 937 { 938 xa_mark_t mark = 0; 939 940 for (;;) { 941 if (xa_track_free(xas->xa) && mark == XA_FREE_MARK) 942 xas_set_mark(xas, mark); 943 else 944 xas_clear_mark(xas, mark); 945 if (mark == XA_MARK_MAX) 946 break; 947 mark_inc(mark); 948 } 949 } 950 EXPORT_SYMBOL_GPL(xas_init_marks); 951 952 #ifdef CONFIG_XARRAY_MULTI 953 static unsigned int node_get_marks(struct xa_node *node, unsigned int offset) 954 { 955 unsigned int marks = 0; 956 xa_mark_t mark = XA_MARK_0; 957 958 for (;;) { 959 if (node_get_mark(node, offset, mark)) 960 marks |= 1 << (__force unsigned int)mark; 961 if (mark == XA_MARK_MAX) 962 break; 963 mark_inc(mark); 964 } 965 966 return marks; 967 } 968 969 static void node_set_marks(struct xa_node *node, unsigned int offset, 970 struct xa_node *child, unsigned int marks) 971 { 972 xa_mark_t mark = XA_MARK_0; 973 974 for (;;) { 975 if (marks & (1 << (__force unsigned int)mark)) { 976 node_set_mark(node, offset, mark); 977 if (child) 978 node_mark_all(child, mark); 979 } 980 if (mark == XA_MARK_MAX) 981 break; 982 mark_inc(mark); 983 } 984 } 985 986 /** 987 * xas_split_alloc() - Allocate memory for splitting an entry. 988 * @xas: XArray operation state. 989 * @entry: New entry which will be stored in the array. 990 * @order: Current entry order. 991 * @gfp: Memory allocation flags. 992 * 993 * This function should be called before calling xas_split(). 994 * If necessary, it will allocate new nodes (and fill them with @entry) 995 * to prepare for the upcoming split of an entry of @order size into 996 * entries of the order stored in the @xas. 997 * 998 * Context: May sleep if @gfp flags permit. 999 */ 1000 void xas_split_alloc(struct xa_state *xas, void *entry, unsigned int order, 1001 gfp_t gfp) 1002 { 1003 unsigned int sibs = (1 << (order % XA_CHUNK_SHIFT)) - 1; 1004 unsigned int mask = xas->xa_sibs; 1005 1006 /* XXX: no support for splitting really large entries yet */ 1007 if (WARN_ON(xas->xa_shift + 2 * XA_CHUNK_SHIFT < order)) 1008 goto nomem; 1009 if (xas->xa_shift + XA_CHUNK_SHIFT > order) 1010 return; 1011 1012 do { 1013 unsigned int i; 1014 void *sibling = NULL; 1015 struct xa_node *node; 1016 1017 node = kmem_cache_alloc(radix_tree_node_cachep, gfp); 1018 if (!node) 1019 goto nomem; 1020 node->array = xas->xa; 1021 for (i = 0; i < XA_CHUNK_SIZE; i++) { 1022 if ((i & mask) == 0) { 1023 RCU_INIT_POINTER(node->slots[i], entry); 1024 sibling = xa_mk_sibling(i); 1025 } else { 1026 RCU_INIT_POINTER(node->slots[i], sibling); 1027 } 1028 } 1029 RCU_INIT_POINTER(node->parent, xas->xa_alloc); 1030 xas->xa_alloc = node; 1031 } while (sibs-- > 0); 1032 1033 return; 1034 nomem: 1035 xas_destroy(xas); 1036 xas_set_err(xas, -ENOMEM); 1037 } 1038 EXPORT_SYMBOL_GPL(xas_split_alloc); 1039 1040 /** 1041 * xas_split() - Split a multi-index entry into smaller entries. 1042 * @xas: XArray operation state. 1043 * @entry: New entry to store in the array. 1044 * @order: Current entry order. 1045 * 1046 * The size of the new entries is set in @xas. The value in @entry is 1047 * copied to all the replacement entries. 1048 * 1049 * Context: Any context. The caller should hold the xa_lock. 1050 */ 1051 void xas_split(struct xa_state *xas, void *entry, unsigned int order) 1052 { 1053 unsigned int sibs = (1 << (order % XA_CHUNK_SHIFT)) - 1; 1054 unsigned int offset, marks; 1055 struct xa_node *node; 1056 void *curr = xas_load(xas); 1057 int values = 0; 1058 1059 node = xas->xa_node; 1060 if (xas_top(node)) 1061 return; 1062 1063 marks = node_get_marks(node, xas->xa_offset); 1064 1065 offset = xas->xa_offset + sibs; 1066 do { 1067 if (xas->xa_shift < node->shift) { 1068 struct xa_node *child = xas->xa_alloc; 1069 1070 xas->xa_alloc = rcu_dereference_raw(child->parent); 1071 child->shift = node->shift - XA_CHUNK_SHIFT; 1072 child->offset = offset; 1073 child->count = XA_CHUNK_SIZE; 1074 child->nr_values = xa_is_value(entry) ? 1075 XA_CHUNK_SIZE : 0; 1076 RCU_INIT_POINTER(child->parent, node); 1077 node_set_marks(node, offset, child, marks); 1078 rcu_assign_pointer(node->slots[offset], 1079 xa_mk_node(child)); 1080 if (xa_is_value(curr)) 1081 values--; 1082 } else { 1083 unsigned int canon = offset - xas->xa_sibs; 1084 1085 node_set_marks(node, canon, NULL, marks); 1086 rcu_assign_pointer(node->slots[canon], entry); 1087 while (offset > canon) 1088 rcu_assign_pointer(node->slots[offset--], 1089 xa_mk_sibling(canon)); 1090 values += (xa_is_value(entry) - xa_is_value(curr)) * 1091 (xas->xa_sibs + 1); 1092 } 1093 } while (offset-- > xas->xa_offset); 1094 1095 node->nr_values += values; 1096 } 1097 EXPORT_SYMBOL_GPL(xas_split); 1098 #endif 1099 1100 /** 1101 * xas_pause() - Pause a walk to drop a lock. 1102 * @xas: XArray operation state. 1103 * 1104 * Some users need to pause a walk and drop the lock they're holding in 1105 * order to yield to a higher priority thread or carry out an operation 1106 * on an entry. Those users should call this function before they drop 1107 * the lock. It resets the @xas to be suitable for the next iteration 1108 * of the loop after the user has reacquired the lock. If most entries 1109 * found during a walk require you to call xas_pause(), the xa_for_each() 1110 * iterator may be more appropriate. 1111 * 1112 * Note that xas_pause() only works for forward iteration. If a user needs 1113 * to pause a reverse iteration, we will need a xas_pause_rev(). 1114 */ 1115 void xas_pause(struct xa_state *xas) 1116 { 1117 struct xa_node *node = xas->xa_node; 1118 1119 if (xas_invalid(xas)) 1120 return; 1121 1122 xas->xa_node = XAS_RESTART; 1123 if (node) { 1124 unsigned long offset = xas->xa_offset; 1125 while (++offset < XA_CHUNK_SIZE) { 1126 if (!xa_is_sibling(xa_entry(xas->xa, node, offset))) 1127 break; 1128 } 1129 xas->xa_index += (offset - xas->xa_offset) << node->shift; 1130 if (xas->xa_index == 0) 1131 xas->xa_node = XAS_BOUNDS; 1132 } else { 1133 xas->xa_index++; 1134 } 1135 } 1136 EXPORT_SYMBOL_GPL(xas_pause); 1137 1138 /* 1139 * __xas_prev() - Find the previous entry in the XArray. 1140 * @xas: XArray operation state. 1141 * 1142 * Helper function for xas_prev() which handles all the complex cases 1143 * out of line. 1144 */ 1145 void *__xas_prev(struct xa_state *xas) 1146 { 1147 void *entry; 1148 1149 if (!xas_frozen(xas->xa_node)) 1150 xas->xa_index--; 1151 if (!xas->xa_node) 1152 return set_bounds(xas); 1153 if (xas_not_node(xas->xa_node)) 1154 return xas_load(xas); 1155 1156 if (xas->xa_offset != get_offset(xas->xa_index, xas->xa_node)) 1157 xas->xa_offset--; 1158 1159 while (xas->xa_offset == 255) { 1160 xas->xa_offset = xas->xa_node->offset - 1; 1161 xas->xa_node = xa_parent(xas->xa, xas->xa_node); 1162 if (!xas->xa_node) 1163 return set_bounds(xas); 1164 } 1165 1166 for (;;) { 1167 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset); 1168 if (!xa_is_node(entry)) 1169 return entry; 1170 1171 xas->xa_node = xa_to_node(entry); 1172 xas_set_offset(xas); 1173 } 1174 } 1175 EXPORT_SYMBOL_GPL(__xas_prev); 1176 1177 /* 1178 * __xas_next() - Find the next entry in the XArray. 1179 * @xas: XArray operation state. 1180 * 1181 * Helper function for xas_next() which handles all the complex cases 1182 * out of line. 1183 */ 1184 void *__xas_next(struct xa_state *xas) 1185 { 1186 void *entry; 1187 1188 if (!xas_frozen(xas->xa_node)) 1189 xas->xa_index++; 1190 if (!xas->xa_node) 1191 return set_bounds(xas); 1192 if (xas_not_node(xas->xa_node)) 1193 return xas_load(xas); 1194 1195 if (xas->xa_offset != get_offset(xas->xa_index, xas->xa_node)) 1196 xas->xa_offset++; 1197 1198 while (xas->xa_offset == XA_CHUNK_SIZE) { 1199 xas->xa_offset = xas->xa_node->offset + 1; 1200 xas->xa_node = xa_parent(xas->xa, xas->xa_node); 1201 if (!xas->xa_node) 1202 return set_bounds(xas); 1203 } 1204 1205 for (;;) { 1206 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset); 1207 if (!xa_is_node(entry)) 1208 return entry; 1209 1210 xas->xa_node = xa_to_node(entry); 1211 xas_set_offset(xas); 1212 } 1213 } 1214 EXPORT_SYMBOL_GPL(__xas_next); 1215 1216 /** 1217 * xas_find() - Find the next present entry in the XArray. 1218 * @xas: XArray operation state. 1219 * @max: Highest index to return. 1220 * 1221 * If the @xas has not yet been walked to an entry, return the entry 1222 * which has an index >= xas.xa_index. If it has been walked, the entry 1223 * currently being pointed at has been processed, and so we move to the 1224 * next entry. 1225 * 1226 * If no entry is found and the array is smaller than @max, the iterator 1227 * is set to the smallest index not yet in the array. This allows @xas 1228 * to be immediately passed to xas_store(). 1229 * 1230 * Return: The entry, if found, otherwise %NULL. 1231 */ 1232 void *xas_find(struct xa_state *xas, unsigned long max) 1233 { 1234 void *entry; 1235 1236 if (xas_error(xas) || xas->xa_node == XAS_BOUNDS) 1237 return NULL; 1238 if (xas->xa_index > max) 1239 return set_bounds(xas); 1240 1241 if (!xas->xa_node) { 1242 xas->xa_index = 1; 1243 return set_bounds(xas); 1244 } else if (xas->xa_node == XAS_RESTART) { 1245 entry = xas_load(xas); 1246 if (entry || xas_not_node(xas->xa_node)) 1247 return entry; 1248 } else if (!xas->xa_node->shift && 1249 xas->xa_offset != (xas->xa_index & XA_CHUNK_MASK)) { 1250 xas->xa_offset = ((xas->xa_index - 1) & XA_CHUNK_MASK) + 1; 1251 } 1252 1253 xas_advance(xas); 1254 1255 while (xas->xa_node && (xas->xa_index <= max)) { 1256 if (unlikely(xas->xa_offset == XA_CHUNK_SIZE)) { 1257 xas->xa_offset = xas->xa_node->offset + 1; 1258 xas->xa_node = xa_parent(xas->xa, xas->xa_node); 1259 continue; 1260 } 1261 1262 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset); 1263 if (xa_is_node(entry)) { 1264 xas->xa_node = xa_to_node(entry); 1265 xas->xa_offset = 0; 1266 continue; 1267 } 1268 if (entry && !xa_is_sibling(entry)) 1269 return entry; 1270 1271 xas_advance(xas); 1272 } 1273 1274 if (!xas->xa_node) 1275 xas->xa_node = XAS_BOUNDS; 1276 return NULL; 1277 } 1278 EXPORT_SYMBOL_GPL(xas_find); 1279 1280 /** 1281 * xas_find_marked() - Find the next marked entry in the XArray. 1282 * @xas: XArray operation state. 1283 * @max: Highest index to return. 1284 * @mark: Mark number to search for. 1285 * 1286 * If the @xas has not yet been walked to an entry, return the marked entry 1287 * which has an index >= xas.xa_index. If it has been walked, the entry 1288 * currently being pointed at has been processed, and so we return the 1289 * first marked entry with an index > xas.xa_index. 1290 * 1291 * If no marked entry is found and the array is smaller than @max, @xas is 1292 * set to the bounds state and xas->xa_index is set to the smallest index 1293 * not yet in the array. This allows @xas to be immediately passed to 1294 * xas_store(). 1295 * 1296 * If no entry is found before @max is reached, @xas is set to the restart 1297 * state. 1298 * 1299 * Return: The entry, if found, otherwise %NULL. 1300 */ 1301 void *xas_find_marked(struct xa_state *xas, unsigned long max, xa_mark_t mark) 1302 { 1303 bool advance = true; 1304 unsigned int offset; 1305 void *entry; 1306 1307 if (xas_error(xas)) 1308 return NULL; 1309 if (xas->xa_index > max) 1310 goto max; 1311 1312 if (!xas->xa_node) { 1313 xas->xa_index = 1; 1314 goto out; 1315 } else if (xas_top(xas->xa_node)) { 1316 advance = false; 1317 entry = xa_head(xas->xa); 1318 xas->xa_node = NULL; 1319 if (xas->xa_index > max_index(entry)) 1320 goto out; 1321 if (!xa_is_node(entry)) { 1322 if (xa_marked(xas->xa, mark)) 1323 return entry; 1324 xas->xa_index = 1; 1325 goto out; 1326 } 1327 xas->xa_node = xa_to_node(entry); 1328 xas->xa_offset = xas->xa_index >> xas->xa_node->shift; 1329 } 1330 1331 while (xas->xa_index <= max) { 1332 if (unlikely(xas->xa_offset == XA_CHUNK_SIZE)) { 1333 xas->xa_offset = xas->xa_node->offset + 1; 1334 xas->xa_node = xa_parent(xas->xa, xas->xa_node); 1335 if (!xas->xa_node) 1336 break; 1337 advance = false; 1338 continue; 1339 } 1340 1341 if (!advance) { 1342 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset); 1343 if (xa_is_sibling(entry)) { 1344 xas->xa_offset = xa_to_sibling(entry); 1345 xas_move_index(xas, xas->xa_offset); 1346 } 1347 } 1348 1349 offset = xas_find_chunk(xas, advance, mark); 1350 if (offset > xas->xa_offset) { 1351 advance = false; 1352 xas_move_index(xas, offset); 1353 /* Mind the wrap */ 1354 if ((xas->xa_index - 1) >= max) 1355 goto max; 1356 xas->xa_offset = offset; 1357 if (offset == XA_CHUNK_SIZE) 1358 continue; 1359 } 1360 1361 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset); 1362 if (!entry && !(xa_track_free(xas->xa) && mark == XA_FREE_MARK)) 1363 continue; 1364 if (!xa_is_node(entry)) 1365 return entry; 1366 xas->xa_node = xa_to_node(entry); 1367 xas_set_offset(xas); 1368 } 1369 1370 out: 1371 if (xas->xa_index > max) 1372 goto max; 1373 return set_bounds(xas); 1374 max: 1375 xas->xa_node = XAS_RESTART; 1376 return NULL; 1377 } 1378 EXPORT_SYMBOL_GPL(xas_find_marked); 1379 1380 /** 1381 * xas_find_conflict() - Find the next present entry in a range. 1382 * @xas: XArray operation state. 1383 * 1384 * The @xas describes both a range and a position within that range. 1385 * 1386 * Context: Any context. Expects xa_lock to be held. 1387 * Return: The next entry in the range covered by @xas or %NULL. 1388 */ 1389 void *xas_find_conflict(struct xa_state *xas) 1390 { 1391 void *curr; 1392 1393 if (xas_error(xas)) 1394 return NULL; 1395 1396 if (!xas->xa_node) 1397 return NULL; 1398 1399 if (xas_top(xas->xa_node)) { 1400 curr = xas_start(xas); 1401 if (!curr) 1402 return NULL; 1403 while (xa_is_node(curr)) { 1404 struct xa_node *node = xa_to_node(curr); 1405 curr = xas_descend(xas, node); 1406 } 1407 if (curr) 1408 return curr; 1409 } 1410 1411 if (xas->xa_node->shift > xas->xa_shift) 1412 return NULL; 1413 1414 for (;;) { 1415 if (xas->xa_node->shift == xas->xa_shift) { 1416 if ((xas->xa_offset & xas->xa_sibs) == xas->xa_sibs) 1417 break; 1418 } else if (xas->xa_offset == XA_CHUNK_MASK) { 1419 xas->xa_offset = xas->xa_node->offset; 1420 xas->xa_node = xa_parent_locked(xas->xa, xas->xa_node); 1421 if (!xas->xa_node) 1422 break; 1423 continue; 1424 } 1425 curr = xa_entry_locked(xas->xa, xas->xa_node, ++xas->xa_offset); 1426 if (xa_is_sibling(curr)) 1427 continue; 1428 while (xa_is_node(curr)) { 1429 xas->xa_node = xa_to_node(curr); 1430 xas->xa_offset = 0; 1431 curr = xa_entry_locked(xas->xa, xas->xa_node, 0); 1432 } 1433 if (curr) 1434 return curr; 1435 } 1436 xas->xa_offset -= xas->xa_sibs; 1437 return NULL; 1438 } 1439 EXPORT_SYMBOL_GPL(xas_find_conflict); 1440 1441 /** 1442 * xa_load() - Load an entry from an XArray. 1443 * @xa: XArray. 1444 * @index: index into array. 1445 * 1446 * Context: Any context. Takes and releases the RCU lock. 1447 * Return: The entry at @index in @xa. 1448 */ 1449 void *xa_load(struct xarray *xa, unsigned long index) 1450 { 1451 XA_STATE(xas, xa, index); 1452 void *entry; 1453 1454 rcu_read_lock(); 1455 do { 1456 entry = xas_load(&xas); 1457 if (xa_is_zero(entry)) 1458 entry = NULL; 1459 } while (xas_retry(&xas, entry)); 1460 rcu_read_unlock(); 1461 1462 return entry; 1463 } 1464 EXPORT_SYMBOL(xa_load); 1465 1466 static void *xas_result(struct xa_state *xas, void *curr) 1467 { 1468 if (xa_is_zero(curr)) 1469 return NULL; 1470 if (xas_error(xas)) 1471 curr = xas->xa_node; 1472 return curr; 1473 } 1474 1475 /** 1476 * __xa_erase() - Erase this entry from the XArray while locked. 1477 * @xa: XArray. 1478 * @index: Index into array. 1479 * 1480 * After this function returns, loading from @index will return %NULL. 1481 * If the index is part of a multi-index entry, all indices will be erased 1482 * and none of the entries will be part of a multi-index entry. 1483 * 1484 * Context: Any context. Expects xa_lock to be held on entry. 1485 * Return: The entry which used to be at this index. 1486 */ 1487 void *__xa_erase(struct xarray *xa, unsigned long index) 1488 { 1489 XA_STATE(xas, xa, index); 1490 return xas_result(&xas, xas_store(&xas, NULL)); 1491 } 1492 EXPORT_SYMBOL(__xa_erase); 1493 1494 /** 1495 * xa_erase() - Erase this entry from the XArray. 1496 * @xa: XArray. 1497 * @index: Index of entry. 1498 * 1499 * After this function returns, loading from @index will return %NULL. 1500 * If the index is part of a multi-index entry, all indices will be erased 1501 * and none of the entries will be part of a multi-index entry. 1502 * 1503 * Context: Any context. Takes and releases the xa_lock. 1504 * Return: The entry which used to be at this index. 1505 */ 1506 void *xa_erase(struct xarray *xa, unsigned long index) 1507 { 1508 void *entry; 1509 1510 xa_lock(xa); 1511 entry = __xa_erase(xa, index); 1512 xa_unlock(xa); 1513 1514 return entry; 1515 } 1516 EXPORT_SYMBOL(xa_erase); 1517 1518 /** 1519 * __xa_store() - Store this entry in the XArray. 1520 * @xa: XArray. 1521 * @index: Index into array. 1522 * @entry: New entry. 1523 * @gfp: Memory allocation flags. 1524 * 1525 * You must already be holding the xa_lock when calling this function. 1526 * It will drop the lock if needed to allocate memory, and then reacquire 1527 * it afterwards. 1528 * 1529 * Context: Any context. Expects xa_lock to be held on entry. May 1530 * release and reacquire xa_lock if @gfp flags permit. 1531 * Return: The old entry at this index or xa_err() if an error happened. 1532 */ 1533 void *__xa_store(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp) 1534 { 1535 XA_STATE(xas, xa, index); 1536 void *curr; 1537 1538 if (WARN_ON_ONCE(xa_is_advanced(entry))) 1539 return XA_ERROR(-EINVAL); 1540 if (xa_track_free(xa) && !entry) 1541 entry = XA_ZERO_ENTRY; 1542 1543 do { 1544 curr = xas_store(&xas, entry); 1545 if (xa_track_free(xa)) 1546 xas_clear_mark(&xas, XA_FREE_MARK); 1547 } while (__xas_nomem(&xas, gfp)); 1548 1549 return xas_result(&xas, curr); 1550 } 1551 EXPORT_SYMBOL(__xa_store); 1552 1553 /** 1554 * xa_store() - Store this entry in the XArray. 1555 * @xa: XArray. 1556 * @index: Index into array. 1557 * @entry: New entry. 1558 * @gfp: Memory allocation flags. 1559 * 1560 * After this function returns, loads from this index will return @entry. 1561 * Storing into an existing multi-index entry updates the entry of every index. 1562 * The marks associated with @index are unaffected unless @entry is %NULL. 1563 * 1564 * Context: Any context. Takes and releases the xa_lock. 1565 * May sleep if the @gfp flags permit. 1566 * Return: The old entry at this index on success, xa_err(-EINVAL) if @entry 1567 * cannot be stored in an XArray, or xa_err(-ENOMEM) if memory allocation 1568 * failed. 1569 */ 1570 void *xa_store(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp) 1571 { 1572 void *curr; 1573 1574 xa_lock(xa); 1575 curr = __xa_store(xa, index, entry, gfp); 1576 xa_unlock(xa); 1577 1578 return curr; 1579 } 1580 EXPORT_SYMBOL(xa_store); 1581 1582 /** 1583 * __xa_cmpxchg() - Store this entry in the XArray. 1584 * @xa: XArray. 1585 * @index: Index into array. 1586 * @old: Old value to test against. 1587 * @entry: New entry. 1588 * @gfp: Memory allocation flags. 1589 * 1590 * You must already be holding the xa_lock when calling this function. 1591 * It will drop the lock if needed to allocate memory, and then reacquire 1592 * it afterwards. 1593 * 1594 * Context: Any context. Expects xa_lock to be held on entry. May 1595 * release and reacquire xa_lock if @gfp flags permit. 1596 * Return: The old entry at this index or xa_err() if an error happened. 1597 */ 1598 void *__xa_cmpxchg(struct xarray *xa, unsigned long index, 1599 void *old, void *entry, gfp_t gfp) 1600 { 1601 XA_STATE(xas, xa, index); 1602 void *curr; 1603 1604 if (WARN_ON_ONCE(xa_is_advanced(entry))) 1605 return XA_ERROR(-EINVAL); 1606 1607 do { 1608 curr = xas_load(&xas); 1609 if (curr == old) { 1610 xas_store(&xas, entry); 1611 if (xa_track_free(xa) && entry && !curr) 1612 xas_clear_mark(&xas, XA_FREE_MARK); 1613 } 1614 } while (__xas_nomem(&xas, gfp)); 1615 1616 return xas_result(&xas, curr); 1617 } 1618 EXPORT_SYMBOL(__xa_cmpxchg); 1619 1620 /** 1621 * __xa_insert() - Store this entry in the XArray if no entry is present. 1622 * @xa: XArray. 1623 * @index: Index into array. 1624 * @entry: New entry. 1625 * @gfp: Memory allocation flags. 1626 * 1627 * Inserting a NULL entry will store a reserved entry (like xa_reserve()) 1628 * if no entry is present. Inserting will fail if a reserved entry is 1629 * present, even though loading from this index will return NULL. 1630 * 1631 * Context: Any context. Expects xa_lock to be held on entry. May 1632 * release and reacquire xa_lock if @gfp flags permit. 1633 * Return: 0 if the store succeeded. -EBUSY if another entry was present. 1634 * -ENOMEM if memory could not be allocated. 1635 */ 1636 int __xa_insert(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp) 1637 { 1638 XA_STATE(xas, xa, index); 1639 void *curr; 1640 1641 if (WARN_ON_ONCE(xa_is_advanced(entry))) 1642 return -EINVAL; 1643 if (!entry) 1644 entry = XA_ZERO_ENTRY; 1645 1646 do { 1647 curr = xas_load(&xas); 1648 if (!curr) { 1649 xas_store(&xas, entry); 1650 if (xa_track_free(xa)) 1651 xas_clear_mark(&xas, XA_FREE_MARK); 1652 } else { 1653 xas_set_err(&xas, -EBUSY); 1654 } 1655 } while (__xas_nomem(&xas, gfp)); 1656 1657 return xas_error(&xas); 1658 } 1659 EXPORT_SYMBOL(__xa_insert); 1660 1661 #ifdef CONFIG_XARRAY_MULTI 1662 static void xas_set_range(struct xa_state *xas, unsigned long first, 1663 unsigned long last) 1664 { 1665 unsigned int shift = 0; 1666 unsigned long sibs = last - first; 1667 unsigned int offset = XA_CHUNK_MASK; 1668 1669 xas_set(xas, first); 1670 1671 while ((first & XA_CHUNK_MASK) == 0) { 1672 if (sibs < XA_CHUNK_MASK) 1673 break; 1674 if ((sibs == XA_CHUNK_MASK) && (offset < XA_CHUNK_MASK)) 1675 break; 1676 shift += XA_CHUNK_SHIFT; 1677 if (offset == XA_CHUNK_MASK) 1678 offset = sibs & XA_CHUNK_MASK; 1679 sibs >>= XA_CHUNK_SHIFT; 1680 first >>= XA_CHUNK_SHIFT; 1681 } 1682 1683 offset = first & XA_CHUNK_MASK; 1684 if (offset + sibs > XA_CHUNK_MASK) 1685 sibs = XA_CHUNK_MASK - offset; 1686 if ((((first + sibs + 1) << shift) - 1) > last) 1687 sibs -= 1; 1688 1689 xas->xa_shift = shift; 1690 xas->xa_sibs = sibs; 1691 } 1692 1693 /** 1694 * xa_store_range() - Store this entry at a range of indices in the XArray. 1695 * @xa: XArray. 1696 * @first: First index to affect. 1697 * @last: Last index to affect. 1698 * @entry: New entry. 1699 * @gfp: Memory allocation flags. 1700 * 1701 * After this function returns, loads from any index between @first and @last, 1702 * inclusive will return @entry. 1703 * Storing into an existing multi-index entry updates the entry of every index. 1704 * The marks associated with @index are unaffected unless @entry is %NULL. 1705 * 1706 * Context: Process context. Takes and releases the xa_lock. May sleep 1707 * if the @gfp flags permit. 1708 * Return: %NULL on success, xa_err(-EINVAL) if @entry cannot be stored in 1709 * an XArray, or xa_err(-ENOMEM) if memory allocation failed. 1710 */ 1711 void *xa_store_range(struct xarray *xa, unsigned long first, 1712 unsigned long last, void *entry, gfp_t gfp) 1713 { 1714 XA_STATE(xas, xa, 0); 1715 1716 if (WARN_ON_ONCE(xa_is_internal(entry))) 1717 return XA_ERROR(-EINVAL); 1718 if (last < first) 1719 return XA_ERROR(-EINVAL); 1720 1721 do { 1722 xas_lock(&xas); 1723 if (entry) { 1724 unsigned int order = BITS_PER_LONG; 1725 if (last + 1) 1726 order = __ffs(last + 1); 1727 xas_set_order(&xas, last, order); 1728 xas_create(&xas, true); 1729 if (xas_error(&xas)) 1730 goto unlock; 1731 } 1732 do { 1733 xas_set_range(&xas, first, last); 1734 xas_store(&xas, entry); 1735 if (xas_error(&xas)) 1736 goto unlock; 1737 first += xas_size(&xas); 1738 } while (first <= last); 1739 unlock: 1740 xas_unlock(&xas); 1741 } while (xas_nomem(&xas, gfp)); 1742 1743 return xas_result(&xas, NULL); 1744 } 1745 EXPORT_SYMBOL(xa_store_range); 1746 1747 /** 1748 * xa_get_order() - Get the order of an entry. 1749 * @xa: XArray. 1750 * @index: Index of the entry. 1751 * 1752 * Return: A number between 0 and 63 indicating the order of the entry. 1753 */ 1754 int xa_get_order(struct xarray *xa, unsigned long index) 1755 { 1756 XA_STATE(xas, xa, index); 1757 void *entry; 1758 int order = 0; 1759 1760 rcu_read_lock(); 1761 entry = xas_load(&xas); 1762 1763 if (!entry) 1764 goto unlock; 1765 1766 if (!xas.xa_node) 1767 goto unlock; 1768 1769 for (;;) { 1770 unsigned int slot = xas.xa_offset + (1 << order); 1771 1772 if (slot >= XA_CHUNK_SIZE) 1773 break; 1774 if (!xa_is_sibling(xas.xa_node->slots[slot])) 1775 break; 1776 order++; 1777 } 1778 1779 order += xas.xa_node->shift; 1780 unlock: 1781 rcu_read_unlock(); 1782 1783 return order; 1784 } 1785 EXPORT_SYMBOL(xa_get_order); 1786 #endif /* CONFIG_XARRAY_MULTI */ 1787 1788 /** 1789 * __xa_alloc() - Find somewhere to store this entry in the XArray. 1790 * @xa: XArray. 1791 * @id: Pointer to ID. 1792 * @limit: Range for allocated ID. 1793 * @entry: New entry. 1794 * @gfp: Memory allocation flags. 1795 * 1796 * Finds an empty entry in @xa between @limit.min and @limit.max, 1797 * stores the index into the @id pointer, then stores the entry at 1798 * that index. A concurrent lookup will not see an uninitialised @id. 1799 * 1800 * Context: Any context. Expects xa_lock to be held on entry. May 1801 * release and reacquire xa_lock if @gfp flags permit. 1802 * Return: 0 on success, -ENOMEM if memory could not be allocated or 1803 * -EBUSY if there are no free entries in @limit. 1804 */ 1805 int __xa_alloc(struct xarray *xa, u32 *id, void *entry, 1806 struct xa_limit limit, gfp_t gfp) 1807 { 1808 XA_STATE(xas, xa, 0); 1809 1810 if (WARN_ON_ONCE(xa_is_advanced(entry))) 1811 return -EINVAL; 1812 if (WARN_ON_ONCE(!xa_track_free(xa))) 1813 return -EINVAL; 1814 1815 if (!entry) 1816 entry = XA_ZERO_ENTRY; 1817 1818 do { 1819 xas.xa_index = limit.min; 1820 xas_find_marked(&xas, limit.max, XA_FREE_MARK); 1821 if (xas.xa_node == XAS_RESTART) 1822 xas_set_err(&xas, -EBUSY); 1823 else 1824 *id = xas.xa_index; 1825 xas_store(&xas, entry); 1826 xas_clear_mark(&xas, XA_FREE_MARK); 1827 } while (__xas_nomem(&xas, gfp)); 1828 1829 return xas_error(&xas); 1830 } 1831 EXPORT_SYMBOL(__xa_alloc); 1832 1833 /** 1834 * __xa_alloc_cyclic() - Find somewhere to store this entry in the XArray. 1835 * @xa: XArray. 1836 * @id: Pointer to ID. 1837 * @entry: New entry. 1838 * @limit: Range of allocated ID. 1839 * @next: Pointer to next ID to allocate. 1840 * @gfp: Memory allocation flags. 1841 * 1842 * Finds an empty entry in @xa between @limit.min and @limit.max, 1843 * stores the index into the @id pointer, then stores the entry at 1844 * that index. A concurrent lookup will not see an uninitialised @id. 1845 * The search for an empty entry will start at @next and will wrap 1846 * around if necessary. 1847 * 1848 * Context: Any context. Expects xa_lock to be held on entry. May 1849 * release and reacquire xa_lock if @gfp flags permit. 1850 * Return: 0 if the allocation succeeded without wrapping. 1 if the 1851 * allocation succeeded after wrapping, -ENOMEM if memory could not be 1852 * allocated or -EBUSY if there are no free entries in @limit. 1853 */ 1854 int __xa_alloc_cyclic(struct xarray *xa, u32 *id, void *entry, 1855 struct xa_limit limit, u32 *next, gfp_t gfp) 1856 { 1857 u32 min = limit.min; 1858 int ret; 1859 1860 limit.min = max(min, *next); 1861 ret = __xa_alloc(xa, id, entry, limit, gfp); 1862 if ((xa->xa_flags & XA_FLAGS_ALLOC_WRAPPED) && ret == 0) { 1863 xa->xa_flags &= ~XA_FLAGS_ALLOC_WRAPPED; 1864 ret = 1; 1865 } 1866 1867 if (ret < 0 && limit.min > min) { 1868 limit.min = min; 1869 ret = __xa_alloc(xa, id, entry, limit, gfp); 1870 if (ret == 0) 1871 ret = 1; 1872 } 1873 1874 if (ret >= 0) { 1875 *next = *id + 1; 1876 if (*next == 0) 1877 xa->xa_flags |= XA_FLAGS_ALLOC_WRAPPED; 1878 } 1879 return ret; 1880 } 1881 EXPORT_SYMBOL(__xa_alloc_cyclic); 1882 1883 /** 1884 * __xa_set_mark() - Set this mark on this entry while locked. 1885 * @xa: XArray. 1886 * @index: Index of entry. 1887 * @mark: Mark number. 1888 * 1889 * Attempting to set a mark on a %NULL entry does not succeed. 1890 * 1891 * Context: Any context. Expects xa_lock to be held on entry. 1892 */ 1893 void __xa_set_mark(struct xarray *xa, unsigned long index, xa_mark_t mark) 1894 { 1895 XA_STATE(xas, xa, index); 1896 void *entry = xas_load(&xas); 1897 1898 if (entry) 1899 xas_set_mark(&xas, mark); 1900 } 1901 EXPORT_SYMBOL(__xa_set_mark); 1902 1903 /** 1904 * __xa_clear_mark() - Clear this mark on this entry while locked. 1905 * @xa: XArray. 1906 * @index: Index of entry. 1907 * @mark: Mark number. 1908 * 1909 * Context: Any context. Expects xa_lock to be held on entry. 1910 */ 1911 void __xa_clear_mark(struct xarray *xa, unsigned long index, xa_mark_t mark) 1912 { 1913 XA_STATE(xas, xa, index); 1914 void *entry = xas_load(&xas); 1915 1916 if (entry) 1917 xas_clear_mark(&xas, mark); 1918 } 1919 EXPORT_SYMBOL(__xa_clear_mark); 1920 1921 /** 1922 * xa_get_mark() - Inquire whether this mark is set on this entry. 1923 * @xa: XArray. 1924 * @index: Index of entry. 1925 * @mark: Mark number. 1926 * 1927 * This function uses the RCU read lock, so the result may be out of date 1928 * by the time it returns. If you need the result to be stable, use a lock. 1929 * 1930 * Context: Any context. Takes and releases the RCU lock. 1931 * Return: True if the entry at @index has this mark set, false if it doesn't. 1932 */ 1933 bool xa_get_mark(struct xarray *xa, unsigned long index, xa_mark_t mark) 1934 { 1935 XA_STATE(xas, xa, index); 1936 void *entry; 1937 1938 rcu_read_lock(); 1939 entry = xas_start(&xas); 1940 while (xas_get_mark(&xas, mark)) { 1941 if (!xa_is_node(entry)) 1942 goto found; 1943 entry = xas_descend(&xas, xa_to_node(entry)); 1944 } 1945 rcu_read_unlock(); 1946 return false; 1947 found: 1948 rcu_read_unlock(); 1949 return true; 1950 } 1951 EXPORT_SYMBOL(xa_get_mark); 1952 1953 /** 1954 * xa_set_mark() - Set this mark on this entry. 1955 * @xa: XArray. 1956 * @index: Index of entry. 1957 * @mark: Mark number. 1958 * 1959 * Attempting to set a mark on a %NULL entry does not succeed. 1960 * 1961 * Context: Process context. Takes and releases the xa_lock. 1962 */ 1963 void xa_set_mark(struct xarray *xa, unsigned long index, xa_mark_t mark) 1964 { 1965 xa_lock(xa); 1966 __xa_set_mark(xa, index, mark); 1967 xa_unlock(xa); 1968 } 1969 EXPORT_SYMBOL(xa_set_mark); 1970 1971 /** 1972 * xa_clear_mark() - Clear this mark on this entry. 1973 * @xa: XArray. 1974 * @index: Index of entry. 1975 * @mark: Mark number. 1976 * 1977 * Clearing a mark always succeeds. 1978 * 1979 * Context: Process context. Takes and releases the xa_lock. 1980 */ 1981 void xa_clear_mark(struct xarray *xa, unsigned long index, xa_mark_t mark) 1982 { 1983 xa_lock(xa); 1984 __xa_clear_mark(xa, index, mark); 1985 xa_unlock(xa); 1986 } 1987 EXPORT_SYMBOL(xa_clear_mark); 1988 1989 /** 1990 * xa_find() - Search the XArray for an entry. 1991 * @xa: XArray. 1992 * @indexp: Pointer to an index. 1993 * @max: Maximum index to search to. 1994 * @filter: Selection criterion. 1995 * 1996 * Finds the entry in @xa which matches the @filter, and has the lowest 1997 * index that is at least @indexp and no more than @max. 1998 * If an entry is found, @indexp is updated to be the index of the entry. 1999 * This function is protected by the RCU read lock, so it may not find 2000 * entries which are being simultaneously added. It will not return an 2001 * %XA_RETRY_ENTRY; if you need to see retry entries, use xas_find(). 2002 * 2003 * Context: Any context. Takes and releases the RCU lock. 2004 * Return: The entry, if found, otherwise %NULL. 2005 */ 2006 void *xa_find(struct xarray *xa, unsigned long *indexp, 2007 unsigned long max, xa_mark_t filter) 2008 { 2009 XA_STATE(xas, xa, *indexp); 2010 void *entry; 2011 2012 rcu_read_lock(); 2013 do { 2014 if ((__force unsigned int)filter < XA_MAX_MARKS) 2015 entry = xas_find_marked(&xas, max, filter); 2016 else 2017 entry = xas_find(&xas, max); 2018 } while (xas_retry(&xas, entry)); 2019 rcu_read_unlock(); 2020 2021 if (entry) 2022 *indexp = xas.xa_index; 2023 return entry; 2024 } 2025 EXPORT_SYMBOL(xa_find); 2026 2027 static bool xas_sibling(struct xa_state *xas) 2028 { 2029 struct xa_node *node = xas->xa_node; 2030 unsigned long mask; 2031 2032 if (!IS_ENABLED(CONFIG_XARRAY_MULTI) || !node) 2033 return false; 2034 mask = (XA_CHUNK_SIZE << node->shift) - 1; 2035 return (xas->xa_index & mask) > 2036 ((unsigned long)xas->xa_offset << node->shift); 2037 } 2038 2039 /** 2040 * xa_find_after() - Search the XArray for a present entry. 2041 * @xa: XArray. 2042 * @indexp: Pointer to an index. 2043 * @max: Maximum index to search to. 2044 * @filter: Selection criterion. 2045 * 2046 * Finds the entry in @xa which matches the @filter and has the lowest 2047 * index that is above @indexp and no more than @max. 2048 * If an entry is found, @indexp is updated to be the index of the entry. 2049 * This function is protected by the RCU read lock, so it may miss entries 2050 * which are being simultaneously added. It will not return an 2051 * %XA_RETRY_ENTRY; if you need to see retry entries, use xas_find(). 2052 * 2053 * Context: Any context. Takes and releases the RCU lock. 2054 * Return: The pointer, if found, otherwise %NULL. 2055 */ 2056 void *xa_find_after(struct xarray *xa, unsigned long *indexp, 2057 unsigned long max, xa_mark_t filter) 2058 { 2059 XA_STATE(xas, xa, *indexp + 1); 2060 void *entry; 2061 2062 if (xas.xa_index == 0) 2063 return NULL; 2064 2065 rcu_read_lock(); 2066 for (;;) { 2067 if ((__force unsigned int)filter < XA_MAX_MARKS) 2068 entry = xas_find_marked(&xas, max, filter); 2069 else 2070 entry = xas_find(&xas, max); 2071 2072 if (xas_invalid(&xas)) 2073 break; 2074 if (xas_sibling(&xas)) 2075 continue; 2076 if (!xas_retry(&xas, entry)) 2077 break; 2078 } 2079 rcu_read_unlock(); 2080 2081 if (entry) 2082 *indexp = xas.xa_index; 2083 return entry; 2084 } 2085 EXPORT_SYMBOL(xa_find_after); 2086 2087 static unsigned int xas_extract_present(struct xa_state *xas, void **dst, 2088 unsigned long max, unsigned int n) 2089 { 2090 void *entry; 2091 unsigned int i = 0; 2092 2093 rcu_read_lock(); 2094 xas_for_each(xas, entry, max) { 2095 if (xas_retry(xas, entry)) 2096 continue; 2097 dst[i++] = entry; 2098 if (i == n) 2099 break; 2100 } 2101 rcu_read_unlock(); 2102 2103 return i; 2104 } 2105 2106 static unsigned int xas_extract_marked(struct xa_state *xas, void **dst, 2107 unsigned long max, unsigned int n, xa_mark_t mark) 2108 { 2109 void *entry; 2110 unsigned int i = 0; 2111 2112 rcu_read_lock(); 2113 xas_for_each_marked(xas, entry, max, mark) { 2114 if (xas_retry(xas, entry)) 2115 continue; 2116 dst[i++] = entry; 2117 if (i == n) 2118 break; 2119 } 2120 rcu_read_unlock(); 2121 2122 return i; 2123 } 2124 2125 /** 2126 * xa_extract() - Copy selected entries from the XArray into a normal array. 2127 * @xa: The source XArray to copy from. 2128 * @dst: The buffer to copy entries into. 2129 * @start: The first index in the XArray eligible to be selected. 2130 * @max: The last index in the XArray eligible to be selected. 2131 * @n: The maximum number of entries to copy. 2132 * @filter: Selection criterion. 2133 * 2134 * Copies up to @n entries that match @filter from the XArray. The 2135 * copied entries will have indices between @start and @max, inclusive. 2136 * 2137 * The @filter may be an XArray mark value, in which case entries which are 2138 * marked with that mark will be copied. It may also be %XA_PRESENT, in 2139 * which case all entries which are not %NULL will be copied. 2140 * 2141 * The entries returned may not represent a snapshot of the XArray at a 2142 * moment in time. For example, if another thread stores to index 5, then 2143 * index 10, calling xa_extract() may return the old contents of index 5 2144 * and the new contents of index 10. Indices not modified while this 2145 * function is running will not be skipped. 2146 * 2147 * If you need stronger guarantees, holding the xa_lock across calls to this 2148 * function will prevent concurrent modification. 2149 * 2150 * Context: Any context. Takes and releases the RCU lock. 2151 * Return: The number of entries copied. 2152 */ 2153 unsigned int xa_extract(struct xarray *xa, void **dst, unsigned long start, 2154 unsigned long max, unsigned int n, xa_mark_t filter) 2155 { 2156 XA_STATE(xas, xa, start); 2157 2158 if (!n) 2159 return 0; 2160 2161 if ((__force unsigned int)filter < XA_MAX_MARKS) 2162 return xas_extract_marked(&xas, dst, max, n, filter); 2163 return xas_extract_present(&xas, dst, max, n); 2164 } 2165 EXPORT_SYMBOL(xa_extract); 2166 2167 /** 2168 * xa_delete_node() - Private interface for workingset code. 2169 * @node: Node to be removed from the tree. 2170 * @update: Function to call to update ancestor nodes. 2171 * 2172 * Context: xa_lock must be held on entry and will not be released. 2173 */ 2174 void xa_delete_node(struct xa_node *node, xa_update_node_t update) 2175 { 2176 struct xa_state xas = { 2177 .xa = node->array, 2178 .xa_index = (unsigned long)node->offset << 2179 (node->shift + XA_CHUNK_SHIFT), 2180 .xa_shift = node->shift + XA_CHUNK_SHIFT, 2181 .xa_offset = node->offset, 2182 .xa_node = xa_parent_locked(node->array, node), 2183 .xa_update = update, 2184 }; 2185 2186 xas_store(&xas, NULL); 2187 } 2188 EXPORT_SYMBOL_GPL(xa_delete_node); /* For the benefit of the test suite */ 2189 2190 /** 2191 * xa_destroy() - Free all internal data structures. 2192 * @xa: XArray. 2193 * 2194 * After calling this function, the XArray is empty and has freed all memory 2195 * allocated for its internal data structures. You are responsible for 2196 * freeing the objects referenced by the XArray. 2197 * 2198 * Context: Any context. Takes and releases the xa_lock, interrupt-safe. 2199 */ 2200 void xa_destroy(struct xarray *xa) 2201 { 2202 XA_STATE(xas, xa, 0); 2203 unsigned long flags; 2204 void *entry; 2205 2206 xas.xa_node = NULL; 2207 xas_lock_irqsave(&xas, flags); 2208 entry = xa_head_locked(xa); 2209 RCU_INIT_POINTER(xa->xa_head, NULL); 2210 xas_init_marks(&xas); 2211 if (xa_zero_busy(xa)) 2212 xa_mark_clear(xa, XA_FREE_MARK); 2213 /* lockdep checks we're still holding the lock in xas_free_nodes() */ 2214 if (xa_is_node(entry)) 2215 xas_free_nodes(&xas, xa_to_node(entry)); 2216 xas_unlock_irqrestore(&xas, flags); 2217 } 2218 EXPORT_SYMBOL(xa_destroy); 2219 2220 #ifdef XA_DEBUG 2221 void xa_dump_node(const struct xa_node *node) 2222 { 2223 unsigned i, j; 2224 2225 if (!node) 2226 return; 2227 if ((unsigned long)node & 3) { 2228 pr_cont("node %px\n", node); 2229 return; 2230 } 2231 2232 pr_cont("node %px %s %d parent %px shift %d count %d values %d " 2233 "array %px list %px %px marks", 2234 node, node->parent ? "offset" : "max", node->offset, 2235 node->parent, node->shift, node->count, node->nr_values, 2236 node->array, node->private_list.prev, node->private_list.next); 2237 for (i = 0; i < XA_MAX_MARKS; i++) 2238 for (j = 0; j < XA_MARK_LONGS; j++) 2239 pr_cont(" %lx", node->marks[i][j]); 2240 pr_cont("\n"); 2241 } 2242 2243 void xa_dump_index(unsigned long index, unsigned int shift) 2244 { 2245 if (!shift) 2246 pr_info("%lu: ", index); 2247 else if (shift >= BITS_PER_LONG) 2248 pr_info("0-%lu: ", ~0UL); 2249 else 2250 pr_info("%lu-%lu: ", index, index | ((1UL << shift) - 1)); 2251 } 2252 2253 void xa_dump_entry(const void *entry, unsigned long index, unsigned long shift) 2254 { 2255 if (!entry) 2256 return; 2257 2258 xa_dump_index(index, shift); 2259 2260 if (xa_is_node(entry)) { 2261 if (shift == 0) { 2262 pr_cont("%px\n", entry); 2263 } else { 2264 unsigned long i; 2265 struct xa_node *node = xa_to_node(entry); 2266 xa_dump_node(node); 2267 for (i = 0; i < XA_CHUNK_SIZE; i++) 2268 xa_dump_entry(node->slots[i], 2269 index + (i << node->shift), node->shift); 2270 } 2271 } else if (xa_is_value(entry)) 2272 pr_cont("value %ld (0x%lx) [%px]\n", xa_to_value(entry), 2273 xa_to_value(entry), entry); 2274 else if (!xa_is_internal(entry)) 2275 pr_cont("%px\n", entry); 2276 else if (xa_is_retry(entry)) 2277 pr_cont("retry (%ld)\n", xa_to_internal(entry)); 2278 else if (xa_is_sibling(entry)) 2279 pr_cont("sibling (slot %ld)\n", xa_to_sibling(entry)); 2280 else if (xa_is_zero(entry)) 2281 pr_cont("zero (%ld)\n", xa_to_internal(entry)); 2282 else 2283 pr_cont("UNKNOWN ENTRY (%px)\n", entry); 2284 } 2285 2286 void xa_dump(const struct xarray *xa) 2287 { 2288 void *entry = xa->xa_head; 2289 unsigned int shift = 0; 2290 2291 pr_info("xarray: %px head %px flags %x marks %d %d %d\n", xa, entry, 2292 xa->xa_flags, xa_marked(xa, XA_MARK_0), 2293 xa_marked(xa, XA_MARK_1), xa_marked(xa, XA_MARK_2)); 2294 if (xa_is_node(entry)) 2295 shift = xa_to_node(entry)->shift + XA_CHUNK_SHIFT; 2296 xa_dump_entry(entry, 0, shift); 2297 } 2298 #endif 2299