Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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sys/vm/vm_radix.c
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1 /* 2 * Copyright (c) 2013 EMC Corp. 3 * Copyright (c) 2011 Jeffrey Roberson <jeff@freebsd.org> 4 * Copyright (c) 2008 Mayur Shardul <mayur.shardul@gmail.com> 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 * 28 */ 29 30 /* 31 * Path-compressed radix trie implementation. 32 * The following code is not generalized into a general purpose library 33 * because there are way too many parameters embedded that should really 34 * be decided by the library consumers. At the same time, consumers 35 * of this code must achieve highest possible performance. 36 * 37 * The implementation takes into account the following rationale: 38 * - Size of the nodes should be as small as possible but still big enough 39 * to avoid a large maximum depth for the trie. This is a balance 40 * between the necessity to not wire too much physical memory for the nodes 41 * and the necessity to avoid too much cache pollution during the trie 42 * operations. 43 * - There is not a huge bias toward the number of lookup operations over 44 * the number of insert and remove operations. This basically implies 45 * that optimizations supposedly helping one operation but hurting the 46 * other might be carefully evaluated. 47 * - On average not many nodes are expected to be fully populated, hence 48 * level compression may just complicate things. 49 */ 50 51 #include <sys/cdefs.h> 52 __FBSDID("$FreeBSD$"); 53 54 #include "opt_ddb.h" 55 56 #include <sys/param.h> 57 #include <sys/systm.h> 58 #include <sys/kernel.h> 59 #include <sys/vmmeter.h> 60 61 #include <vm/uma.h> 62 #include <vm/vm.h> 63 #include <vm/vm_param.h> 64 #include <vm/vm_page.h> 65 #include <vm/vm_radix.h> 66 67 #ifdef DDB 68 #include <ddb/ddb.h> 69 #endif 70 71 /* 72 * These widths should allow the pointers to a node's children to fit within 73 * a single cache line. The extra levels from a narrow width should not be 74 * a problem thanks to path compression. 75 */ 76 #ifdef __LP64__ 77 #define VM_RADIX_WIDTH 4 78 #else 79 #define VM_RADIX_WIDTH 3 80 #endif 81 82 #define VM_RADIX_COUNT (1 << VM_RADIX_WIDTH) 83 #define VM_RADIX_MASK (VM_RADIX_COUNT - 1) 84 #define VM_RADIX_LIMIT \ 85 (howmany(sizeof(vm_pindex_t) * NBBY, VM_RADIX_WIDTH) - 1) 86 87 /* Flag bits stored in node pointers. */ 88 #define VM_RADIX_ISLEAF 0x1 89 #define VM_RADIX_FLAGS 0x1 90 #define VM_RADIX_PAD VM_RADIX_FLAGS 91 92 /* Returns one unit associated with specified level. */ 93 #define VM_RADIX_UNITLEVEL(lev) \ 94 ((vm_pindex_t)1 << ((lev) * VM_RADIX_WIDTH)) 95 96 struct vm_radix_node { 97 vm_pindex_t rn_owner; /* Owner of record. */ 98 uint16_t rn_count; /* Valid children. */ 99 uint16_t rn_clev; /* Current level. */ 100 void *rn_child[VM_RADIX_COUNT]; /* Child nodes. */ 101 }; 102 103 static uma_zone_t vm_radix_node_zone; 104 105 /* 106 * Allocate a radix node. 107 */ 108 static __inline struct vm_radix_node * 109 vm_radix_node_get(vm_pindex_t owner, uint16_t count, uint16_t clevel) 110 { 111 struct vm_radix_node *rnode; 112 113 rnode = uma_zalloc(vm_radix_node_zone, M_NOWAIT | M_ZERO); 114 if (rnode == NULL) 115 return (NULL); 116 rnode->rn_owner = owner; 117 rnode->rn_count = count; 118 rnode->rn_clev = clevel; 119 return (rnode); 120 } 121 122 /* 123 * Free radix node. 124 */ 125 static __inline void 126 vm_radix_node_put(struct vm_radix_node *rnode) 127 { 128 129 uma_zfree(vm_radix_node_zone, rnode); 130 } 131 132 /* 133 * Return the position in the array for a given level. 134 */ 135 static __inline int 136 vm_radix_slot(vm_pindex_t index, uint16_t level) 137 { 138 139 return ((index >> (level * VM_RADIX_WIDTH)) & VM_RADIX_MASK); 140 } 141 142 /* Trims the key after the specified level. */ 143 static __inline vm_pindex_t 144 vm_radix_trimkey(vm_pindex_t index, uint16_t level) 145 { 146 vm_pindex_t ret; 147 148 ret = index; 149 if (level > 0) { 150 ret >>= level * VM_RADIX_WIDTH; 151 ret <<= level * VM_RADIX_WIDTH; 152 } 153 return (ret); 154 } 155 156 /* 157 * Get the root node for a radix tree. 158 */ 159 static __inline struct vm_radix_node * 160 vm_radix_getroot(struct vm_radix *rtree) 161 { 162 163 return ((struct vm_radix_node *)rtree->rt_root); 164 } 165 166 /* 167 * Set the root node for a radix tree. 168 */ 169 static __inline void 170 vm_radix_setroot(struct vm_radix *rtree, struct vm_radix_node *rnode) 171 { 172 173 rtree->rt_root = (uintptr_t)rnode; 174 } 175 176 /* 177 * Returns TRUE if the specified radix node is a leaf and FALSE otherwise. 178 */ 179 static __inline boolean_t 180 vm_radix_isleaf(struct vm_radix_node *rnode) 181 { 182 183 return (((uintptr_t)rnode & VM_RADIX_ISLEAF) != 0); 184 } 185 186 /* 187 * Returns the associated page extracted from rnode. 188 */ 189 static __inline vm_page_t 190 vm_radix_topage(struct vm_radix_node *rnode) 191 { 192 193 return ((vm_page_t)((uintptr_t)rnode & ~VM_RADIX_FLAGS)); 194 } 195 196 /* 197 * Adds the page as a child of the provided node. 198 */ 199 static __inline void 200 vm_radix_addpage(struct vm_radix_node *rnode, vm_pindex_t index, uint16_t clev, 201 vm_page_t page) 202 { 203 int slot; 204 205 slot = vm_radix_slot(index, clev); 206 rnode->rn_child[slot] = (void *)((uintptr_t)page | VM_RADIX_ISLEAF); 207 } 208 209 /* 210 * Returns the slot where two keys differ. 211 * It cannot accept 2 equal keys. 212 */ 213 static __inline uint16_t 214 vm_radix_keydiff(vm_pindex_t index1, vm_pindex_t index2) 215 { 216 uint16_t clev; 217 218 KASSERT(index1 != index2, ("%s: passing the same key value %jx", 219 __func__, (uintmax_t)index1)); 220 221 index1 ^= index2; 222 for (clev = VM_RADIX_LIMIT;; clev--) 223 if (vm_radix_slot(index1, clev) != 0) 224 return (clev); 225 } 226 227 /* 228 * Returns TRUE if it can be determined that key does not belong to the 229 * specified rnode. Otherwise, returns FALSE. 230 */ 231 static __inline boolean_t 232 vm_radix_keybarr(struct vm_radix_node *rnode, vm_pindex_t idx) 233 { 234 235 if (rnode->rn_clev < VM_RADIX_LIMIT) { 236 idx = vm_radix_trimkey(idx, rnode->rn_clev + 1); 237 return (idx != rnode->rn_owner); 238 } 239 return (FALSE); 240 } 241 242 /* 243 * Internal helper for vm_radix_reclaim_allnodes(). 244 * This function is recursive. 245 */ 246 static void 247 vm_radix_reclaim_allnodes_int(struct vm_radix_node *rnode) 248 { 249 int slot; 250 251 KASSERT(rnode->rn_count <= VM_RADIX_COUNT, 252 ("vm_radix_reclaim_allnodes_int: bad count in rnode %p", rnode)); 253 for (slot = 0; rnode->rn_count != 0; slot++) { 254 if (rnode->rn_child[slot] == NULL) 255 continue; 256 if (!vm_radix_isleaf(rnode->rn_child[slot])) 257 vm_radix_reclaim_allnodes_int(rnode->rn_child[slot]); 258 rnode->rn_child[slot] = NULL; 259 rnode->rn_count--; 260 } 261 vm_radix_node_put(rnode); 262 } 263 264 #ifdef INVARIANTS 265 /* 266 * Radix node zone destructor. 267 */ 268 static void 269 vm_radix_node_zone_dtor(void *mem, int size __unused, void *arg __unused) 270 { 271 struct vm_radix_node *rnode; 272 int slot; 273 274 rnode = mem; 275 KASSERT(rnode->rn_count == 0, 276 ("vm_radix_node_put: rnode %p has %d children", rnode, 277 rnode->rn_count)); 278 for (slot = 0; slot < VM_RADIX_COUNT; slot++) 279 KASSERT(rnode->rn_child[slot] == NULL, 280 ("vm_radix_node_put: rnode %p has a child", rnode)); 281 } 282 #endif 283 284 #ifndef UMA_MD_SMALL_ALLOC 285 /* 286 * Reserve the KVA necessary to satisfy the node allocation. 287 * This is mandatory in architectures not supporting direct 288 * mapping as they will need otherwise to carve into the kernel maps for 289 * every node allocation, resulting into deadlocks for consumers already 290 * working with kernel maps. 291 */ 292 static void 293 vm_radix_reserve_kva(void *arg __unused) 294 { 295 296 /* 297 * Calculate the number of reserved nodes, discounting the pages that 298 * are needed to store them. 299 */ 300 if (!uma_zone_reserve_kva(vm_radix_node_zone, 301 ((vm_paddr_t)cnt.v_page_count * PAGE_SIZE) / (PAGE_SIZE + 302 sizeof(struct vm_radix_node)))) 303 panic("%s: unable to reserve KVA", __func__); 304 } 305 SYSINIT(vm_radix_reserve_kva, SI_SUB_KMEM, SI_ORDER_SECOND, 306 vm_radix_reserve_kva, NULL); 307 #endif 308 309 /* 310 * Initialize the UMA slab zone. 311 * Until vm_radix_prealloc() is called, the zone will be served by the 312 * UMA boot-time pre-allocated pool of pages. 313 */ 314 void 315 vm_radix_init(void) 316 { 317 318 vm_radix_node_zone = uma_zcreate("RADIX NODE", 319 sizeof(struct vm_radix_node), NULL, 320 #ifdef INVARIANTS 321 vm_radix_node_zone_dtor, 322 #else 323 NULL, 324 #endif 325 NULL, NULL, VM_RADIX_PAD, UMA_ZONE_VM); 326 } 327 328 /* 329 * Inserts the key-value pair into the trie. 330 * Panics if the key already exists. 331 */ 332 int 333 vm_radix_insert(struct vm_radix *rtree, vm_page_t page) 334 { 335 vm_pindex_t index, newind; 336 void **parentp; 337 struct vm_radix_node *rnode, *tmp; 338 vm_page_t m; 339 int slot; 340 uint16_t clev; 341 342 index = page->pindex; 343 344 restart: 345 346 /* 347 * The owner of record for root is not really important because it 348 * will never be used. 349 */ 350 rnode = vm_radix_getroot(rtree); 351 if (rnode == NULL) { 352 rtree->rt_root = (uintptr_t)page | VM_RADIX_ISLEAF; 353 return (0); 354 } 355 parentp = (void **)&rtree->rt_root; 356 for (;;) { 357 if (vm_radix_isleaf(rnode)) { 358 m = vm_radix_topage(rnode); 359 if (m->pindex == index) 360 panic("%s: key %jx is already present", 361 __func__, (uintmax_t)index); 362 clev = vm_radix_keydiff(m->pindex, index); 363 364 /* 365 * During node allocation the trie that is being 366 * walked can be modified because of recursing radix 367 * trie operations. 368 * If this is the case, the recursing functions signal 369 * such situation and the insert operation must 370 * start from scratch again. 371 * The freed radix node will then be in the UMA 372 * caches very likely to avoid the same situation 373 * to happen. 374 */ 375 rtree->rt_flags |= RT_INSERT_INPROG; 376 tmp = vm_radix_node_get(vm_radix_trimkey(index, 377 clev + 1), 2, clev); 378 rtree->rt_flags &= ~RT_INSERT_INPROG; 379 if (tmp == NULL) { 380 rtree->rt_flags &= ~RT_TRIE_MODIFIED; 381 return (ENOMEM); 382 } 383 if ((rtree->rt_flags & RT_TRIE_MODIFIED) != 0) { 384 rtree->rt_flags &= ~RT_TRIE_MODIFIED; 385 tmp->rn_count = 0; 386 vm_radix_node_put(tmp); 387 goto restart; 388 } 389 *parentp = tmp; 390 vm_radix_addpage(tmp, index, clev, page); 391 vm_radix_addpage(tmp, m->pindex, clev, m); 392 return (0); 393 } else if (vm_radix_keybarr(rnode, index)) 394 break; 395 slot = vm_radix_slot(index, rnode->rn_clev); 396 if (rnode->rn_child[slot] == NULL) { 397 rnode->rn_count++; 398 vm_radix_addpage(rnode, index, rnode->rn_clev, page); 399 return (0); 400 } 401 parentp = &rnode->rn_child[slot]; 402 rnode = rnode->rn_child[slot]; 403 } 404 405 /* 406 * A new node is needed because the right insertion level is reached. 407 * Setup the new intermediate node and add the 2 children: the 408 * new object and the older edge. 409 */ 410 newind = rnode->rn_owner; 411 clev = vm_radix_keydiff(newind, index); 412 413 /* See the comments above. */ 414 rtree->rt_flags |= RT_INSERT_INPROG; 415 tmp = vm_radix_node_get(vm_radix_trimkey(index, clev + 1), 2, clev); 416 rtree->rt_flags &= ~RT_INSERT_INPROG; 417 if (tmp == NULL) { 418 rtree->rt_flags &= ~RT_TRIE_MODIFIED; 419 return (ENOMEM); 420 } 421 if ((rtree->rt_flags & RT_TRIE_MODIFIED) != 0) { 422 rtree->rt_flags &= ~RT_TRIE_MODIFIED; 423 tmp->rn_count = 0; 424 vm_radix_node_put(tmp); 425 goto restart; 426 } 427 *parentp = tmp; 428 vm_radix_addpage(tmp, index, clev, page); 429 slot = vm_radix_slot(newind, clev); 430 tmp->rn_child[slot] = rnode; 431 return (0); 432 } 433 434 /* 435 * Returns TRUE if the specified radix tree contains a single leaf and FALSE 436 * otherwise. 437 */ 438 boolean_t 439 vm_radix_is_singleton(struct vm_radix *rtree) 440 { 441 struct vm_radix_node *rnode; 442 443 rnode = vm_radix_getroot(rtree); 444 if (rnode == NULL) 445 return (FALSE); 446 return (vm_radix_isleaf(rnode)); 447 } 448 449 /* 450 * Returns the value stored at the index. If the index is not present, 451 * NULL is returned. 452 */ 453 vm_page_t 454 vm_radix_lookup(struct vm_radix *rtree, vm_pindex_t index) 455 { 456 struct vm_radix_node *rnode; 457 vm_page_t m; 458 int slot; 459 460 rnode = vm_radix_getroot(rtree); 461 while (rnode != NULL) { 462 if (vm_radix_isleaf(rnode)) { 463 m = vm_radix_topage(rnode); 464 if (m->pindex == index) 465 return (m); 466 else 467 break; 468 } else if (vm_radix_keybarr(rnode, index)) 469 break; 470 slot = vm_radix_slot(index, rnode->rn_clev); 471 rnode = rnode->rn_child[slot]; 472 } 473 return (NULL); 474 } 475 476 /* 477 * Look up the nearest entry at a position bigger than or equal to index. 478 */ 479 vm_page_t 480 vm_radix_lookup_ge(struct vm_radix *rtree, vm_pindex_t index) 481 { 482 struct vm_radix_node *stack[VM_RADIX_LIMIT]; 483 vm_pindex_t inc; 484 vm_page_t m; 485 struct vm_radix_node *child, *rnode; 486 #ifdef INVARIANTS 487 int loops = 0; 488 #endif 489 int slot, tos; 490 491 rnode = vm_radix_getroot(rtree); 492 if (rnode == NULL) 493 return (NULL); 494 else if (vm_radix_isleaf(rnode)) { 495 m = vm_radix_topage(rnode); 496 if (m->pindex >= index) 497 return (m); 498 else 499 return (NULL); 500 } 501 tos = 0; 502 for (;;) { 503 /* 504 * If the keys differ before the current bisection node, 505 * then the search key might rollback to the earliest 506 * available bisection node or to the smallest key 507 * in the current node (if the owner is bigger than the 508 * search key). 509 */ 510 if (vm_radix_keybarr(rnode, index)) { 511 if (index > rnode->rn_owner) { 512 ascend: 513 KASSERT(++loops < 1000, 514 ("vm_radix_lookup_ge: too many loops")); 515 516 /* 517 * Pop nodes from the stack until either the 518 * stack is empty or a node that could have a 519 * matching descendant is found. 520 */ 521 do { 522 if (tos == 0) 523 return (NULL); 524 rnode = stack[--tos]; 525 } while (vm_radix_slot(index, 526 rnode->rn_clev) == (VM_RADIX_COUNT - 1)); 527 528 /* 529 * The following computation cannot overflow 530 * because index's slot at the current level 531 * is less than VM_RADIX_COUNT - 1. 532 */ 533 index = vm_radix_trimkey(index, 534 rnode->rn_clev); 535 index += VM_RADIX_UNITLEVEL(rnode->rn_clev); 536 } else 537 index = rnode->rn_owner; 538 KASSERT(!vm_radix_keybarr(rnode, index), 539 ("vm_radix_lookup_ge: keybarr failed")); 540 } 541 slot = vm_radix_slot(index, rnode->rn_clev); 542 child = rnode->rn_child[slot]; 543 if (vm_radix_isleaf(child)) { 544 m = vm_radix_topage(child); 545 if (m->pindex >= index) 546 return (m); 547 } else if (child != NULL) 548 goto descend; 549 550 /* 551 * Look for an available edge or page within the current 552 * bisection node. 553 */ 554 if (slot < (VM_RADIX_COUNT - 1)) { 555 inc = VM_RADIX_UNITLEVEL(rnode->rn_clev); 556 index = vm_radix_trimkey(index, rnode->rn_clev); 557 do { 558 index += inc; 559 slot++; 560 child = rnode->rn_child[slot]; 561 if (vm_radix_isleaf(child)) { 562 m = vm_radix_topage(child); 563 if (m->pindex >= index) 564 return (m); 565 } else if (child != NULL) 566 goto descend; 567 } while (slot < (VM_RADIX_COUNT - 1)); 568 } 569 KASSERT(child == NULL || vm_radix_isleaf(child), 570 ("vm_radix_lookup_ge: child is radix node")); 571 572 /* 573 * If a page or edge bigger than the search slot is not found 574 * in the current node, ascend to the next higher-level node. 575 */ 576 goto ascend; 577 descend: 578 KASSERT(rnode->rn_clev > 0, 579 ("vm_radix_lookup_ge: pushing leaf's parent")); 580 KASSERT(tos < VM_RADIX_LIMIT, 581 ("vm_radix_lookup_ge: stack overflow")); 582 stack[tos++] = rnode; 583 rnode = child; 584 } 585 } 586 587 /* 588 * Look up the nearest entry at a position less than or equal to index. 589 */ 590 vm_page_t 591 vm_radix_lookup_le(struct vm_radix *rtree, vm_pindex_t index) 592 { 593 struct vm_radix_node *stack[VM_RADIX_LIMIT]; 594 vm_pindex_t inc; 595 vm_page_t m; 596 struct vm_radix_node *child, *rnode; 597 #ifdef INVARIANTS 598 int loops = 0; 599 #endif 600 int slot, tos; 601 602 rnode = vm_radix_getroot(rtree); 603 if (rnode == NULL) 604 return (NULL); 605 else if (vm_radix_isleaf(rnode)) { 606 m = vm_radix_topage(rnode); 607 if (m->pindex <= index) 608 return (m); 609 else 610 return (NULL); 611 } 612 tos = 0; 613 for (;;) { 614 /* 615 * If the keys differ before the current bisection node, 616 * then the search key might rollback to the earliest 617 * available bisection node or to the largest key 618 * in the current node (if the owner is smaller than the 619 * search key). 620 */ 621 if (vm_radix_keybarr(rnode, index)) { 622 if (index > rnode->rn_owner) { 623 index = rnode->rn_owner + VM_RADIX_COUNT * 624 VM_RADIX_UNITLEVEL(rnode->rn_clev); 625 } else { 626 ascend: 627 KASSERT(++loops < 1000, 628 ("vm_radix_lookup_le: too many loops")); 629 630 /* 631 * Pop nodes from the stack until either the 632 * stack is empty or a node that could have a 633 * matching descendant is found. 634 */ 635 do { 636 if (tos == 0) 637 return (NULL); 638 rnode = stack[--tos]; 639 } while (vm_radix_slot(index, 640 rnode->rn_clev) == 0); 641 642 /* 643 * The following computation cannot overflow 644 * because index's slot at the current level 645 * is greater than 0. 646 */ 647 index = vm_radix_trimkey(index, 648 rnode->rn_clev); 649 } 650 index--; 651 KASSERT(!vm_radix_keybarr(rnode, index), 652 ("vm_radix_lookup_le: keybarr failed")); 653 } 654 slot = vm_radix_slot(index, rnode->rn_clev); 655 child = rnode->rn_child[slot]; 656 if (vm_radix_isleaf(child)) { 657 m = vm_radix_topage(child); 658 if (m->pindex <= index) 659 return (m); 660 } else if (child != NULL) 661 goto descend; 662 663 /* 664 * Look for an available edge or page within the current 665 * bisection node. 666 */ 667 if (slot > 0) { 668 inc = VM_RADIX_UNITLEVEL(rnode->rn_clev); 669 index |= inc - 1; 670 do { 671 index -= inc; 672 slot--; 673 child = rnode->rn_child[slot]; 674 if (vm_radix_isleaf(child)) { 675 m = vm_radix_topage(child); 676 if (m->pindex <= index) 677 return (m); 678 } else if (child != NULL) 679 goto descend; 680 } while (slot > 0); 681 } 682 KASSERT(child == NULL || vm_radix_isleaf(child), 683 ("vm_radix_lookup_le: child is radix node")); 684 685 /* 686 * If a page or edge smaller than the search slot is not found 687 * in the current node, ascend to the next higher-level node. 688 */ 689 goto ascend; 690 descend: 691 KASSERT(rnode->rn_clev > 0, 692 ("vm_radix_lookup_le: pushing leaf's parent")); 693 KASSERT(tos < VM_RADIX_LIMIT, 694 ("vm_radix_lookup_le: stack overflow")); 695 stack[tos++] = rnode; 696 rnode = child; 697 } 698 } 699 700 /* 701 * Remove the specified index from the tree. 702 * Panics if the key is not present. 703 */ 704 void 705 vm_radix_remove(struct vm_radix *rtree, vm_pindex_t index) 706 { 707 struct vm_radix_node *rnode, *parent; 708 vm_page_t m; 709 int i, slot; 710 711 /* 712 * Detect if a page is going to be removed from a trie which is 713 * already undergoing another trie operation. 714 * Right now this is only possible for vm_radix_remove() recursing 715 * into vm_radix_insert(). 716 * If this is the case, the caller must be notified about this 717 * situation. It will also takecare to update the RT_TRIE_MODIFIED 718 * accordingly. 719 * The RT_TRIE_MODIFIED bit is set here because the remove operation 720 * will always succeed. 721 */ 722 if ((rtree->rt_flags & RT_INSERT_INPROG) != 0) 723 rtree->rt_flags |= RT_TRIE_MODIFIED; 724 725 rnode = vm_radix_getroot(rtree); 726 if (vm_radix_isleaf(rnode)) { 727 m = vm_radix_topage(rnode); 728 if (m->pindex != index) 729 panic("%s: invalid key found", __func__); 730 vm_radix_setroot(rtree, NULL); 731 return; 732 } 733 parent = NULL; 734 for (;;) { 735 if (rnode == NULL) 736 panic("vm_radix_remove: impossible to locate the key"); 737 slot = vm_radix_slot(index, rnode->rn_clev); 738 if (vm_radix_isleaf(rnode->rn_child[slot])) { 739 m = vm_radix_topage(rnode->rn_child[slot]); 740 if (m->pindex != index) 741 panic("%s: invalid key found", __func__); 742 rnode->rn_child[slot] = NULL; 743 rnode->rn_count--; 744 if (rnode->rn_count > 1) 745 break; 746 for (i = 0; i < VM_RADIX_COUNT; i++) 747 if (rnode->rn_child[i] != NULL) 748 break; 749 KASSERT(i != VM_RADIX_COUNT, 750 ("%s: invalid node configuration", __func__)); 751 if (parent == NULL) 752 vm_radix_setroot(rtree, rnode->rn_child[i]); 753 else { 754 slot = vm_radix_slot(index, parent->rn_clev); 755 KASSERT(parent->rn_child[slot] == rnode, 756 ("%s: invalid child value", __func__)); 757 parent->rn_child[slot] = rnode->rn_child[i]; 758 } 759 rnode->rn_count--; 760 rnode->rn_child[i] = NULL; 761 vm_radix_node_put(rnode); 762 break; 763 } 764 parent = rnode; 765 rnode = rnode->rn_child[slot]; 766 } 767 } 768 769 /* 770 * Remove and free all the nodes from the radix tree. 771 * This function is recursive but there is a tight control on it as the 772 * maximum depth of the tree is fixed. 773 */ 774 void 775 vm_radix_reclaim_allnodes(struct vm_radix *rtree) 776 { 777 struct vm_radix_node *root; 778 779 KASSERT((rtree->rt_flags & RT_INSERT_INPROG) == 0, 780 ("vm_radix_reclaim_allnodes: unexpected trie recursion")); 781 782 root = vm_radix_getroot(rtree); 783 if (root == NULL) 784 return; 785 vm_radix_setroot(rtree, NULL); 786 if (!vm_radix_isleaf(root)) 787 vm_radix_reclaim_allnodes_int(root); 788 } 789 790 /* 791 * Replace an existing page in the trie with another one. 792 * Panics if there is not an old page in the trie at the new page's index. 793 */ 794 vm_page_t 795 vm_radix_replace(struct vm_radix *rtree, vm_page_t newpage) 796 { 797 struct vm_radix_node *rnode; 798 vm_page_t m; 799 vm_pindex_t index; 800 int slot; 801 802 index = newpage->pindex; 803 rnode = vm_radix_getroot(rtree); 804 if (rnode == NULL) 805 panic("%s: replacing page on an empty trie", __func__); 806 if (vm_radix_isleaf(rnode)) { 807 m = vm_radix_topage(rnode); 808 if (m->pindex != index) 809 panic("%s: original replacing root key not found", 810 __func__); 811 rtree->rt_root = (uintptr_t)newpage | VM_RADIX_ISLEAF; 812 return (m); 813 } 814 for (;;) { 815 slot = vm_radix_slot(index, rnode->rn_clev); 816 if (vm_radix_isleaf(rnode->rn_child[slot])) { 817 m = vm_radix_topage(rnode->rn_child[slot]); 818 if (m->pindex == index) { 819 rnode->rn_child[slot] = 820 (void *)((uintptr_t)newpage | 821 VM_RADIX_ISLEAF); 822 return (m); 823 } else 824 break; 825 } else if (rnode->rn_child[slot] == NULL || 826 vm_radix_keybarr(rnode->rn_child[slot], index)) 827 break; 828 rnode = rnode->rn_child[slot]; 829 } 830 panic("%s: original replacing page not found", __func__); 831 } 832 833 #ifdef DDB 834 /* 835 * Show details about the given radix node. 836 */ 837 DB_SHOW_COMMAND(radixnode, db_show_radixnode) 838 { 839 struct vm_radix_node *rnode; 840 int i; 841 842 if (!have_addr) 843 return; 844 rnode = (struct vm_radix_node *)addr; 845 db_printf("radixnode %p, owner %jx, children count %u, level %u:\n", 846 (void *)rnode, (uintmax_t)rnode->rn_owner, rnode->rn_count, 847 rnode->rn_clev); 848 for (i = 0; i < VM_RADIX_COUNT; i++) 849 if (rnode->rn_child[i] != NULL) 850 db_printf("slot: %d, val: %p, page: %p, clev: %d\n", 851 i, (void *)rnode->rn_child[i], 852 vm_radix_isleaf(rnode->rn_child[i]) ? 853 vm_radix_topage(rnode->rn_child[i]) : NULL, 854 rnode->rn_clev); 855 } 856 #endif /* DDB */
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