ia64/linux-2.6.18-xen.hg

annotate lib/prio_tree.c @ 847:ad4d307bf9ce

net sfc: Update sfc and sfc_resource driver to latest release

...and update sfc_netfront, sfc_netback, sfc_netutil for any API changes

sfc_netback: Fix asymmetric use of SFC buffer table alloc and free
sfc_netback: Clean up if no SFC accel device found
sfc_netback: Gracefully handle case where page grant fails
sfc_netback: Disable net acceleration if the physical link goes down
sfc_netfront: Less verbose error messages, more verbose counters for
rx discard errors
sfc_netfront: Gracefully handle case where SFC netfront fails during
initialisation

Signed-off-by: Kieran Mansley <kmansley@solarflare.com>
author Keir Fraser <keir.fraser@citrix.com>
date Tue Mar 31 11:59:10 2009 +0100 (2009-03-31)
parents 831230e53067
children
rev   line source
ian@0 1 /*
ian@0 2 * lib/prio_tree.c - priority search tree
ian@0 3 *
ian@0 4 * Copyright (C) 2004, Rajesh Venkatasubramanian <vrajesh@umich.edu>
ian@0 5 *
ian@0 6 * This file is released under the GPL v2.
ian@0 7 *
ian@0 8 * Based on the radix priority search tree proposed by Edward M. McCreight
ian@0 9 * SIAM Journal of Computing, vol. 14, no.2, pages 257-276, May 1985
ian@0 10 *
ian@0 11 * 02Feb2004 Initial version
ian@0 12 */
ian@0 13
ian@0 14 #include <linux/init.h>
ian@0 15 #include <linux/mm.h>
ian@0 16 #include <linux/prio_tree.h>
ian@0 17
ian@0 18 /*
ian@0 19 * A clever mix of heap and radix trees forms a radix priority search tree (PST)
ian@0 20 * which is useful for storing intervals, e.g, we can consider a vma as a closed
ian@0 21 * interval of file pages [offset_begin, offset_end], and store all vmas that
ian@0 22 * map a file in a PST. Then, using the PST, we can answer a stabbing query,
ian@0 23 * i.e., selecting a set of stored intervals (vmas) that overlap with (map) a
ian@0 24 * given input interval X (a set of consecutive file pages), in "O(log n + m)"
ian@0 25 * time where 'log n' is the height of the PST, and 'm' is the number of stored
ian@0 26 * intervals (vmas) that overlap (map) with the input interval X (the set of
ian@0 27 * consecutive file pages).
ian@0 28 *
ian@0 29 * In our implementation, we store closed intervals of the form [radix_index,
ian@0 30 * heap_index]. We assume that always radix_index <= heap_index. McCreight's PST
ian@0 31 * is designed for storing intervals with unique radix indices, i.e., each
ian@0 32 * interval have different radix_index. However, this limitation can be easily
ian@0 33 * overcome by using the size, i.e., heap_index - radix_index, as part of the
ian@0 34 * index, so we index the tree using [(radix_index,size), heap_index].
ian@0 35 *
ian@0 36 * When the above-mentioned indexing scheme is used, theoretically, in a 32 bit
ian@0 37 * machine, the maximum height of a PST can be 64. We can use a balanced version
ian@0 38 * of the priority search tree to optimize the tree height, but the balanced
ian@0 39 * tree proposed by McCreight is too complex and memory-hungry for our purpose.
ian@0 40 */
ian@0 41
ian@0 42 /*
ian@0 43 * The following macros are used for implementing prio_tree for i_mmap
ian@0 44 */
ian@0 45
ian@0 46 #define RADIX_INDEX(vma) ((vma)->vm_pgoff)
ian@0 47 #define VMA_SIZE(vma) (((vma)->vm_end - (vma)->vm_start) >> PAGE_SHIFT)
ian@0 48 /* avoid overflow */
ian@0 49 #define HEAP_INDEX(vma) ((vma)->vm_pgoff + (VMA_SIZE(vma) - 1))
ian@0 50
ian@0 51
ian@0 52 static void get_index(const struct prio_tree_root *root,
ian@0 53 const struct prio_tree_node *node,
ian@0 54 unsigned long *radix, unsigned long *heap)
ian@0 55 {
ian@0 56 if (root->raw) {
ian@0 57 struct vm_area_struct *vma = prio_tree_entry(
ian@0 58 node, struct vm_area_struct, shared.prio_tree_node);
ian@0 59
ian@0 60 *radix = RADIX_INDEX(vma);
ian@0 61 *heap = HEAP_INDEX(vma);
ian@0 62 }
ian@0 63 else {
ian@0 64 *radix = node->start;
ian@0 65 *heap = node->last;
ian@0 66 }
ian@0 67 }
ian@0 68
ian@0 69 static unsigned long index_bits_to_maxindex[BITS_PER_LONG];
ian@0 70
ian@0 71 void __init prio_tree_init(void)
ian@0 72 {
ian@0 73 unsigned int i;
ian@0 74
ian@0 75 for (i = 0; i < ARRAY_SIZE(index_bits_to_maxindex) - 1; i++)
ian@0 76 index_bits_to_maxindex[i] = (1UL << (i + 1)) - 1;
ian@0 77 index_bits_to_maxindex[ARRAY_SIZE(index_bits_to_maxindex) - 1] = ~0UL;
ian@0 78 }
ian@0 79
ian@0 80 /*
ian@0 81 * Maximum heap_index that can be stored in a PST with index_bits bits
ian@0 82 */
ian@0 83 static inline unsigned long prio_tree_maxindex(unsigned int bits)
ian@0 84 {
ian@0 85 return index_bits_to_maxindex[bits - 1];
ian@0 86 }
ian@0 87
ian@0 88 /*
ian@0 89 * Extend a priority search tree so that it can store a node with heap_index
ian@0 90 * max_heap_index. In the worst case, this algorithm takes O((log n)^2).
ian@0 91 * However, this function is used rarely and the common case performance is
ian@0 92 * not bad.
ian@0 93 */
ian@0 94 static struct prio_tree_node *prio_tree_expand(struct prio_tree_root *root,
ian@0 95 struct prio_tree_node *node, unsigned long max_heap_index)
ian@0 96 {
ian@0 97 struct prio_tree_node *first = NULL, *prev, *last = NULL;
ian@0 98
ian@0 99 if (max_heap_index > prio_tree_maxindex(root->index_bits))
ian@0 100 root->index_bits++;
ian@0 101
ian@0 102 while (max_heap_index > prio_tree_maxindex(root->index_bits)) {
ian@0 103 root->index_bits++;
ian@0 104
ian@0 105 if (prio_tree_empty(root))
ian@0 106 continue;
ian@0 107
ian@0 108 if (first == NULL) {
ian@0 109 first = root->prio_tree_node;
ian@0 110 prio_tree_remove(root, root->prio_tree_node);
ian@0 111 INIT_PRIO_TREE_NODE(first);
ian@0 112 last = first;
ian@0 113 } else {
ian@0 114 prev = last;
ian@0 115 last = root->prio_tree_node;
ian@0 116 prio_tree_remove(root, root->prio_tree_node);
ian@0 117 INIT_PRIO_TREE_NODE(last);
ian@0 118 prev->left = last;
ian@0 119 last->parent = prev;
ian@0 120 }
ian@0 121 }
ian@0 122
ian@0 123 INIT_PRIO_TREE_NODE(node);
ian@0 124
ian@0 125 if (first) {
ian@0 126 node->left = first;
ian@0 127 first->parent = node;
ian@0 128 } else
ian@0 129 last = node;
ian@0 130
ian@0 131 if (!prio_tree_empty(root)) {
ian@0 132 last->left = root->prio_tree_node;
ian@0 133 last->left->parent = last;
ian@0 134 }
ian@0 135
ian@0 136 root->prio_tree_node = node;
ian@0 137 return node;
ian@0 138 }
ian@0 139
ian@0 140 /*
ian@0 141 * Replace a prio_tree_node with a new node and return the old node
ian@0 142 */
ian@0 143 struct prio_tree_node *prio_tree_replace(struct prio_tree_root *root,
ian@0 144 struct prio_tree_node *old, struct prio_tree_node *node)
ian@0 145 {
ian@0 146 INIT_PRIO_TREE_NODE(node);
ian@0 147
ian@0 148 if (prio_tree_root(old)) {
ian@0 149 BUG_ON(root->prio_tree_node != old);
ian@0 150 /*
ian@0 151 * We can reduce root->index_bits here. However, it is complex
ian@0 152 * and does not help much to improve performance (IMO).
ian@0 153 */
ian@0 154 node->parent = node;
ian@0 155 root->prio_tree_node = node;
ian@0 156 } else {
ian@0 157 node->parent = old->parent;
ian@0 158 if (old->parent->left == old)
ian@0 159 old->parent->left = node;
ian@0 160 else
ian@0 161 old->parent->right = node;
ian@0 162 }
ian@0 163
ian@0 164 if (!prio_tree_left_empty(old)) {
ian@0 165 node->left = old->left;
ian@0 166 old->left->parent = node;
ian@0 167 }
ian@0 168
ian@0 169 if (!prio_tree_right_empty(old)) {
ian@0 170 node->right = old->right;
ian@0 171 old->right->parent = node;
ian@0 172 }
ian@0 173
ian@0 174 return old;
ian@0 175 }
ian@0 176
ian@0 177 /*
ian@0 178 * Insert a prio_tree_node @node into a radix priority search tree @root. The
ian@0 179 * algorithm typically takes O(log n) time where 'log n' is the number of bits
ian@0 180 * required to represent the maximum heap_index. In the worst case, the algo
ian@0 181 * can take O((log n)^2) - check prio_tree_expand.
ian@0 182 *
ian@0 183 * If a prior node with same radix_index and heap_index is already found in
ian@0 184 * the tree, then returns the address of the prior node. Otherwise, inserts
ian@0 185 * @node into the tree and returns @node.
ian@0 186 */
ian@0 187 struct prio_tree_node *prio_tree_insert(struct prio_tree_root *root,
ian@0 188 struct prio_tree_node *node)
ian@0 189 {
ian@0 190 struct prio_tree_node *cur, *res = node;
ian@0 191 unsigned long radix_index, heap_index;
ian@0 192 unsigned long r_index, h_index, index, mask;
ian@0 193 int size_flag = 0;
ian@0 194
ian@0 195 get_index(root, node, &radix_index, &heap_index);
ian@0 196
ian@0 197 if (prio_tree_empty(root) ||
ian@0 198 heap_index > prio_tree_maxindex(root->index_bits))
ian@0 199 return prio_tree_expand(root, node, heap_index);
ian@0 200
ian@0 201 cur = root->prio_tree_node;
ian@0 202 mask = 1UL << (root->index_bits - 1);
ian@0 203
ian@0 204 while (mask) {
ian@0 205 get_index(root, cur, &r_index, &h_index);
ian@0 206
ian@0 207 if (r_index == radix_index && h_index == heap_index)
ian@0 208 return cur;
ian@0 209
ian@0 210 if (h_index < heap_index ||
ian@0 211 (h_index == heap_index && r_index > radix_index)) {
ian@0 212 struct prio_tree_node *tmp = node;
ian@0 213 node = prio_tree_replace(root, cur, node);
ian@0 214 cur = tmp;
ian@0 215 /* swap indices */
ian@0 216 index = r_index;
ian@0 217 r_index = radix_index;
ian@0 218 radix_index = index;
ian@0 219 index = h_index;
ian@0 220 h_index = heap_index;
ian@0 221 heap_index = index;
ian@0 222 }
ian@0 223
ian@0 224 if (size_flag)
ian@0 225 index = heap_index - radix_index;
ian@0 226 else
ian@0 227 index = radix_index;
ian@0 228
ian@0 229 if (index & mask) {
ian@0 230 if (prio_tree_right_empty(cur)) {
ian@0 231 INIT_PRIO_TREE_NODE(node);
ian@0 232 cur->right = node;
ian@0 233 node->parent = cur;
ian@0 234 return res;
ian@0 235 } else
ian@0 236 cur = cur->right;
ian@0 237 } else {
ian@0 238 if (prio_tree_left_empty(cur)) {
ian@0 239 INIT_PRIO_TREE_NODE(node);
ian@0 240 cur->left = node;
ian@0 241 node->parent = cur;
ian@0 242 return res;
ian@0 243 } else
ian@0 244 cur = cur->left;
ian@0 245 }
ian@0 246
ian@0 247 mask >>= 1;
ian@0 248
ian@0 249 if (!mask) {
ian@0 250 mask = 1UL << (BITS_PER_LONG - 1);
ian@0 251 size_flag = 1;
ian@0 252 }
ian@0 253 }
ian@0 254 /* Should not reach here */
ian@0 255 BUG();
ian@0 256 return NULL;
ian@0 257 }
ian@0 258
ian@0 259 /*
ian@0 260 * Remove a prio_tree_node @node from a radix priority search tree @root. The
ian@0 261 * algorithm takes O(log n) time where 'log n' is the number of bits required
ian@0 262 * to represent the maximum heap_index.
ian@0 263 */
ian@0 264 void prio_tree_remove(struct prio_tree_root *root, struct prio_tree_node *node)
ian@0 265 {
ian@0 266 struct prio_tree_node *cur;
ian@0 267 unsigned long r_index, h_index_right, h_index_left;
ian@0 268
ian@0 269 cur = node;
ian@0 270
ian@0 271 while (!prio_tree_left_empty(cur) || !prio_tree_right_empty(cur)) {
ian@0 272 if (!prio_tree_left_empty(cur))
ian@0 273 get_index(root, cur->left, &r_index, &h_index_left);
ian@0 274 else {
ian@0 275 cur = cur->right;
ian@0 276 continue;
ian@0 277 }
ian@0 278
ian@0 279 if (!prio_tree_right_empty(cur))
ian@0 280 get_index(root, cur->right, &r_index, &h_index_right);
ian@0 281 else {
ian@0 282 cur = cur->left;
ian@0 283 continue;
ian@0 284 }
ian@0 285
ian@0 286 /* both h_index_left and h_index_right cannot be 0 */
ian@0 287 if (h_index_left >= h_index_right)
ian@0 288 cur = cur->left;
ian@0 289 else
ian@0 290 cur = cur->right;
ian@0 291 }
ian@0 292
ian@0 293 if (prio_tree_root(cur)) {
ian@0 294 BUG_ON(root->prio_tree_node != cur);
ian@0 295 __INIT_PRIO_TREE_ROOT(root, root->raw);
ian@0 296 return;
ian@0 297 }
ian@0 298
ian@0 299 if (cur->parent->right == cur)
ian@0 300 cur->parent->right = cur->parent;
ian@0 301 else
ian@0 302 cur->parent->left = cur->parent;
ian@0 303
ian@0 304 while (cur != node)
ian@0 305 cur = prio_tree_replace(root, cur->parent, cur);
ian@0 306 }
ian@0 307
ian@0 308 /*
ian@0 309 * Following functions help to enumerate all prio_tree_nodes in the tree that
ian@0 310 * overlap with the input interval X [radix_index, heap_index]. The enumeration
ian@0 311 * takes O(log n + m) time where 'log n' is the height of the tree (which is
ian@0 312 * proportional to # of bits required to represent the maximum heap_index) and
ian@0 313 * 'm' is the number of prio_tree_nodes that overlap the interval X.
ian@0 314 */
ian@0 315
ian@0 316 static struct prio_tree_node *prio_tree_left(struct prio_tree_iter *iter,
ian@0 317 unsigned long *r_index, unsigned long *h_index)
ian@0 318 {
ian@0 319 if (prio_tree_left_empty(iter->cur))
ian@0 320 return NULL;
ian@0 321
ian@0 322 get_index(iter->root, iter->cur->left, r_index, h_index);
ian@0 323
ian@0 324 if (iter->r_index <= *h_index) {
ian@0 325 iter->cur = iter->cur->left;
ian@0 326 iter->mask >>= 1;
ian@0 327 if (iter->mask) {
ian@0 328 if (iter->size_level)
ian@0 329 iter->size_level++;
ian@0 330 } else {
ian@0 331 if (iter->size_level) {
ian@0 332 BUG_ON(!prio_tree_left_empty(iter->cur));
ian@0 333 BUG_ON(!prio_tree_right_empty(iter->cur));
ian@0 334 iter->size_level++;
ian@0 335 iter->mask = ULONG_MAX;
ian@0 336 } else {
ian@0 337 iter->size_level = 1;
ian@0 338 iter->mask = 1UL << (BITS_PER_LONG - 1);
ian@0 339 }
ian@0 340 }
ian@0 341 return iter->cur;
ian@0 342 }
ian@0 343
ian@0 344 return NULL;
ian@0 345 }
ian@0 346
ian@0 347 static struct prio_tree_node *prio_tree_right(struct prio_tree_iter *iter,
ian@0 348 unsigned long *r_index, unsigned long *h_index)
ian@0 349 {
ian@0 350 unsigned long value;
ian@0 351
ian@0 352 if (prio_tree_right_empty(iter->cur))
ian@0 353 return NULL;
ian@0 354
ian@0 355 if (iter->size_level)
ian@0 356 value = iter->value;
ian@0 357 else
ian@0 358 value = iter->value | iter->mask;
ian@0 359
ian@0 360 if (iter->h_index < value)
ian@0 361 return NULL;
ian@0 362
ian@0 363 get_index(iter->root, iter->cur->right, r_index, h_index);
ian@0 364
ian@0 365 if (iter->r_index <= *h_index) {
ian@0 366 iter->cur = iter->cur->right;
ian@0 367 iter->mask >>= 1;
ian@0 368 iter->value = value;
ian@0 369 if (iter->mask) {
ian@0 370 if (iter->size_level)
ian@0 371 iter->size_level++;
ian@0 372 } else {
ian@0 373 if (iter->size_level) {
ian@0 374 BUG_ON(!prio_tree_left_empty(iter->cur));
ian@0 375 BUG_ON(!prio_tree_right_empty(iter->cur));
ian@0 376 iter->size_level++;
ian@0 377 iter->mask = ULONG_MAX;
ian@0 378 } else {
ian@0 379 iter->size_level = 1;
ian@0 380 iter->mask = 1UL << (BITS_PER_LONG - 1);
ian@0 381 }
ian@0 382 }
ian@0 383 return iter->cur;
ian@0 384 }
ian@0 385
ian@0 386 return NULL;
ian@0 387 }
ian@0 388
ian@0 389 static struct prio_tree_node *prio_tree_parent(struct prio_tree_iter *iter)
ian@0 390 {
ian@0 391 iter->cur = iter->cur->parent;
ian@0 392 if (iter->mask == ULONG_MAX)
ian@0 393 iter->mask = 1UL;
ian@0 394 else if (iter->size_level == 1)
ian@0 395 iter->mask = 1UL;
ian@0 396 else
ian@0 397 iter->mask <<= 1;
ian@0 398 if (iter->size_level)
ian@0 399 iter->size_level--;
ian@0 400 if (!iter->size_level && (iter->value & iter->mask))
ian@0 401 iter->value ^= iter->mask;
ian@0 402 return iter->cur;
ian@0 403 }
ian@0 404
ian@0 405 static inline int overlap(struct prio_tree_iter *iter,
ian@0 406 unsigned long r_index, unsigned long h_index)
ian@0 407 {
ian@0 408 return iter->h_index >= r_index && iter->r_index <= h_index;
ian@0 409 }
ian@0 410
ian@0 411 /*
ian@0 412 * prio_tree_first:
ian@0 413 *
ian@0 414 * Get the first prio_tree_node that overlaps with the interval [radix_index,
ian@0 415 * heap_index]. Note that always radix_index <= heap_index. We do a pre-order
ian@0 416 * traversal of the tree.
ian@0 417 */
ian@0 418 static struct prio_tree_node *prio_tree_first(struct prio_tree_iter *iter)
ian@0 419 {
ian@0 420 struct prio_tree_root *root;
ian@0 421 unsigned long r_index, h_index;
ian@0 422
ian@0 423 INIT_PRIO_TREE_ITER(iter);
ian@0 424
ian@0 425 root = iter->root;
ian@0 426 if (prio_tree_empty(root))
ian@0 427 return NULL;
ian@0 428
ian@0 429 get_index(root, root->prio_tree_node, &r_index, &h_index);
ian@0 430
ian@0 431 if (iter->r_index > h_index)
ian@0 432 return NULL;
ian@0 433
ian@0 434 iter->mask = 1UL << (root->index_bits - 1);
ian@0 435 iter->cur = root->prio_tree_node;
ian@0 436
ian@0 437 while (1) {
ian@0 438 if (overlap(iter, r_index, h_index))
ian@0 439 return iter->cur;
ian@0 440
ian@0 441 if (prio_tree_left(iter, &r_index, &h_index))
ian@0 442 continue;
ian@0 443
ian@0 444 if (prio_tree_right(iter, &r_index, &h_index))
ian@0 445 continue;
ian@0 446
ian@0 447 break;
ian@0 448 }
ian@0 449 return NULL;
ian@0 450 }
ian@0 451
ian@0 452 /*
ian@0 453 * prio_tree_next:
ian@0 454 *
ian@0 455 * Get the next prio_tree_node that overlaps with the input interval in iter
ian@0 456 */
ian@0 457 struct prio_tree_node *prio_tree_next(struct prio_tree_iter *iter)
ian@0 458 {
ian@0 459 unsigned long r_index, h_index;
ian@0 460
ian@0 461 if (iter->cur == NULL)
ian@0 462 return prio_tree_first(iter);
ian@0 463
ian@0 464 repeat:
ian@0 465 while (prio_tree_left(iter, &r_index, &h_index))
ian@0 466 if (overlap(iter, r_index, h_index))
ian@0 467 return iter->cur;
ian@0 468
ian@0 469 while (!prio_tree_right(iter, &r_index, &h_index)) {
ian@0 470 while (!prio_tree_root(iter->cur) &&
ian@0 471 iter->cur->parent->right == iter->cur)
ian@0 472 prio_tree_parent(iter);
ian@0 473
ian@0 474 if (prio_tree_root(iter->cur))
ian@0 475 return NULL;
ian@0 476
ian@0 477 prio_tree_parent(iter);
ian@0 478 }
ian@0 479
ian@0 480 if (overlap(iter, r_index, h_index))
ian@0 481 return iter->cur;
ian@0 482
ian@0 483 goto repeat;
ian@0 484 }