| 1 | /* |
| 2 | * 2002-10-18 written by Jim Houston jim.houston@ccur.com |
| 3 | * Copyright (C) 2002 by Concurrent Computer Corporation |
| 4 | * Distributed under the GNU GPL license version 2. |
| 5 | * |
| 6 | * Modified by George Anzinger to reuse immediately and to use |
| 7 | * find bit instructions. Also removed _irq on spinlocks. |
| 8 | * |
| 9 | * Modified by Nadia Derbey to make it RCU safe. |
| 10 | * |
| 11 | * Small id to pointer translation service. |
| 12 | * |
| 13 | * It uses a radix tree like structure as a sparse array indexed |
| 14 | * by the id to obtain the pointer. The bitmap makes allocating |
| 15 | * a new id quick. |
| 16 | * |
| 17 | * You call it to allocate an id (an int) an associate with that id a |
| 18 | * pointer or what ever, we treat it as a (void *). You can pass this |
| 19 | * id to a user for him to pass back at a later time. You then pass |
| 20 | * that id to this code and it returns your pointer. |
| 21 | |
| 22 | * You can release ids at any time. When all ids are released, most of |
| 23 | * the memory is returned (we keep IDR_FREE_MAX) in a local pool so we |
| 24 | * don't need to go to the memory "store" during an id allocate, just |
| 25 | * so you don't need to be too concerned about locking and conflicts |
| 26 | * with the slab allocator. |
| 27 | */ |
| 28 | |
| 29 | #ifndef TEST // to test in user space... |
| 30 | #include <linux/slab.h> |
| 31 | #include <linux/init.h> |
| 32 | #include <linux/export.h> |
| 33 | #endif |
| 34 | #include <linux/err.h> |
| 35 | #include <linux/string.h> |
| 36 | #include <linux/idr.h> |
| 37 | #include <linux/spinlock.h> |
| 38 | |
| 39 | static struct kmem_cache *idr_layer_cache; |
| 40 | static DEFINE_SPINLOCK(simple_ida_lock); |
| 41 | |
| 42 | static struct idr_layer *get_from_free_list(struct idr *idp) |
| 43 | { |
| 44 | struct idr_layer *p; |
| 45 | unsigned long flags; |
| 46 | |
| 47 | spin_lock_irqsave(&idp->lock, flags); |
| 48 | if ((p = idp->id_free)) { |
| 49 | idp->id_free = p->ary[0]; |
| 50 | idp->id_free_cnt--; |
| 51 | p->ary[0] = NULL; |
| 52 | } |
| 53 | spin_unlock_irqrestore(&idp->lock, flags); |
| 54 | return(p); |
| 55 | } |
| 56 | |
| 57 | static void idr_layer_rcu_free(struct rcu_head *head) |
| 58 | { |
| 59 | struct idr_layer *layer; |
| 60 | |
| 61 | layer = container_of(head, struct idr_layer, rcu_head); |
| 62 | kmem_cache_free(idr_layer_cache, layer); |
| 63 | } |
| 64 | |
| 65 | static inline void free_layer(struct idr_layer *p) |
| 66 | { |
| 67 | call_rcu(&p->rcu_head, idr_layer_rcu_free); |
| 68 | } |
| 69 | |
| 70 | /* only called when idp->lock is held */ |
| 71 | static void __move_to_free_list(struct idr *idp, struct idr_layer *p) |
| 72 | { |
| 73 | p->ary[0] = idp->id_free; |
| 74 | idp->id_free = p; |
| 75 | idp->id_free_cnt++; |
| 76 | } |
| 77 | |
| 78 | static void move_to_free_list(struct idr *idp, struct idr_layer *p) |
| 79 | { |
| 80 | unsigned long flags; |
| 81 | |
| 82 | /* |
| 83 | * Depends on the return element being zeroed. |
| 84 | */ |
| 85 | spin_lock_irqsave(&idp->lock, flags); |
| 86 | __move_to_free_list(idp, p); |
| 87 | spin_unlock_irqrestore(&idp->lock, flags); |
| 88 | } |
| 89 | |
| 90 | static void idr_mark_full(struct idr_layer **pa, int id) |
| 91 | { |
| 92 | struct idr_layer *p = pa[0]; |
| 93 | int l = 0; |
| 94 | |
| 95 | __set_bit(id & IDR_MASK, &p->bitmap); |
| 96 | /* |
| 97 | * If this layer is full mark the bit in the layer above to |
| 98 | * show that this part of the radix tree is full. This may |
| 99 | * complete the layer above and require walking up the radix |
| 100 | * tree. |
| 101 | */ |
| 102 | while (p->bitmap == IDR_FULL) { |
| 103 | if (!(p = pa[++l])) |
| 104 | break; |
| 105 | id = id >> IDR_BITS; |
| 106 | __set_bit((id & IDR_MASK), &p->bitmap); |
| 107 | } |
| 108 | } |
| 109 | |
| 110 | /** |
| 111 | * idr_pre_get - reserve resources for idr allocation |
| 112 | * @idp: idr handle |
| 113 | * @gfp_mask: memory allocation flags |
| 114 | * |
| 115 | * This function should be called prior to calling the idr_get_new* functions. |
| 116 | * It preallocates enough memory to satisfy the worst possible allocation. The |
| 117 | * caller should pass in GFP_KERNEL if possible. This of course requires that |
| 118 | * no spinning locks be held. |
| 119 | * |
| 120 | * If the system is REALLY out of memory this function returns %0, |
| 121 | * otherwise %1. |
| 122 | */ |
| 123 | int idr_pre_get(struct idr *idp, gfp_t gfp_mask) |
| 124 | { |
| 125 | while (idp->id_free_cnt < IDR_FREE_MAX) { |
| 126 | struct idr_layer *new; |
| 127 | new = kmem_cache_zalloc(idr_layer_cache, gfp_mask); |
| 128 | if (new == NULL) |
| 129 | return (0); |
| 130 | move_to_free_list(idp, new); |
| 131 | } |
| 132 | return 1; |
| 133 | } |
| 134 | EXPORT_SYMBOL(idr_pre_get); |
| 135 | |
| 136 | static int sub_alloc(struct idr *idp, int *starting_id, struct idr_layer **pa) |
| 137 | { |
| 138 | int n, m, sh; |
| 139 | struct idr_layer *p, *new; |
| 140 | int l, id, oid; |
| 141 | unsigned long bm; |
| 142 | |
| 143 | id = *starting_id; |
| 144 | restart: |
| 145 | p = idp->top; |
| 146 | l = idp->layers; |
| 147 | pa[l--] = NULL; |
| 148 | while (1) { |
| 149 | /* |
| 150 | * We run around this while until we reach the leaf node... |
| 151 | */ |
| 152 | n = (id >> (IDR_BITS*l)) & IDR_MASK; |
| 153 | bm = ~p->bitmap; |
| 154 | m = find_next_bit(&bm, IDR_SIZE, n); |
| 155 | if (m == IDR_SIZE) { |
| 156 | /* no space available go back to previous layer. */ |
| 157 | l++; |
| 158 | oid = id; |
| 159 | id = (id | ((1 << (IDR_BITS * l)) - 1)) + 1; |
| 160 | |
| 161 | /* if already at the top layer, we need to grow */ |
| 162 | if (id >= 1 << (idp->layers * IDR_BITS)) { |
| 163 | *starting_id = id; |
| 164 | return IDR_NEED_TO_GROW; |
| 165 | } |
| 166 | p = pa[l]; |
| 167 | BUG_ON(!p); |
| 168 | |
| 169 | /* If we need to go up one layer, continue the |
| 170 | * loop; otherwise, restart from the top. |
| 171 | */ |
| 172 | sh = IDR_BITS * (l + 1); |
| 173 | if (oid >> sh == id >> sh) |
| 174 | continue; |
| 175 | else |
| 176 | goto restart; |
| 177 | } |
| 178 | if (m != n) { |
| 179 | sh = IDR_BITS*l; |
| 180 | id = ((id >> sh) ^ n ^ m) << sh; |
| 181 | } |
| 182 | if ((id >= MAX_ID_BIT) || (id < 0)) |
| 183 | return IDR_NOMORE_SPACE; |
| 184 | if (l == 0) |
| 185 | break; |
| 186 | /* |
| 187 | * Create the layer below if it is missing. |
| 188 | */ |
| 189 | if (!p->ary[m]) { |
| 190 | new = get_from_free_list(idp); |
| 191 | if (!new) |
| 192 | return -1; |
| 193 | new->layer = l-1; |
| 194 | rcu_assign_pointer(p->ary[m], new); |
| 195 | p->count++; |
| 196 | } |
| 197 | pa[l--] = p; |
| 198 | p = p->ary[m]; |
| 199 | } |
| 200 | |
| 201 | pa[l] = p; |
| 202 | return id; |
| 203 | } |
| 204 | |
| 205 | static int idr_get_empty_slot(struct idr *idp, int starting_id, |
| 206 | struct idr_layer **pa) |
| 207 | { |
| 208 | struct idr_layer *p, *new; |
| 209 | int layers, v, id; |
| 210 | unsigned long flags; |
| 211 | |
| 212 | id = starting_id; |
| 213 | build_up: |
| 214 | p = idp->top; |
| 215 | layers = idp->layers; |
| 216 | if (unlikely(!p)) { |
| 217 | if (!(p = get_from_free_list(idp))) |
| 218 | return -1; |
| 219 | p->layer = 0; |
| 220 | layers = 1; |
| 221 | } |
| 222 | /* |
| 223 | * Add a new layer to the top of the tree if the requested |
| 224 | * id is larger than the currently allocated space. |
| 225 | */ |
| 226 | while ((layers < (MAX_LEVEL - 1)) && (id >= (1 << (layers*IDR_BITS)))) { |
| 227 | layers++; |
| 228 | if (!p->count) { |
| 229 | /* special case: if the tree is currently empty, |
| 230 | * then we grow the tree by moving the top node |
| 231 | * upwards. |
| 232 | */ |
| 233 | p->layer++; |
| 234 | continue; |
| 235 | } |
| 236 | if (!(new = get_from_free_list(idp))) { |
| 237 | /* |
| 238 | * The allocation failed. If we built part of |
| 239 | * the structure tear it down. |
| 240 | */ |
| 241 | spin_lock_irqsave(&idp->lock, flags); |
| 242 | for (new = p; p && p != idp->top; new = p) { |
| 243 | p = p->ary[0]; |
| 244 | new->ary[0] = NULL; |
| 245 | new->bitmap = new->count = 0; |
| 246 | __move_to_free_list(idp, new); |
| 247 | } |
| 248 | spin_unlock_irqrestore(&idp->lock, flags); |
| 249 | return -1; |
| 250 | } |
| 251 | new->ary[0] = p; |
| 252 | new->count = 1; |
| 253 | new->layer = layers-1; |
| 254 | if (p->bitmap == IDR_FULL) |
| 255 | __set_bit(0, &new->bitmap); |
| 256 | p = new; |
| 257 | } |
| 258 | rcu_assign_pointer(idp->top, p); |
| 259 | idp->layers = layers; |
| 260 | v = sub_alloc(idp, &id, pa); |
| 261 | if (v == IDR_NEED_TO_GROW) |
| 262 | goto build_up; |
| 263 | return(v); |
| 264 | } |
| 265 | |
| 266 | static int idr_get_new_above_int(struct idr *idp, void *ptr, int starting_id) |
| 267 | { |
| 268 | struct idr_layer *pa[MAX_LEVEL]; |
| 269 | int id; |
| 270 | |
| 271 | id = idr_get_empty_slot(idp, starting_id, pa); |
| 272 | if (id >= 0) { |
| 273 | /* |
| 274 | * Successfully found an empty slot. Install the user |
| 275 | * pointer and mark the slot full. |
| 276 | */ |
| 277 | rcu_assign_pointer(pa[0]->ary[id & IDR_MASK], |
| 278 | (struct idr_layer *)ptr); |
| 279 | pa[0]->count++; |
| 280 | idr_mark_full(pa, id); |
| 281 | } |
| 282 | |
| 283 | return id; |
| 284 | } |
| 285 | |
| 286 | /** |
| 287 | * idr_get_new_above - allocate new idr entry above or equal to a start id |
| 288 | * @idp: idr handle |
| 289 | * @ptr: pointer you want associated with the id |
| 290 | * @starting_id: id to start search at |
| 291 | * @id: pointer to the allocated handle |
| 292 | * |
| 293 | * This is the allocate id function. It should be called with any |
| 294 | * required locks. |
| 295 | * |
| 296 | * If allocation from IDR's private freelist fails, idr_get_new_above() will |
| 297 | * return %-EAGAIN. The caller should retry the idr_pre_get() call to refill |
| 298 | * IDR's preallocation and then retry the idr_get_new_above() call. |
| 299 | * |
| 300 | * If the idr is full idr_get_new_above() will return %-ENOSPC. |
| 301 | * |
| 302 | * @id returns a value in the range @starting_id ... %0x7fffffff |
| 303 | */ |
| 304 | int idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id) |
| 305 | { |
| 306 | int rv; |
| 307 | |
| 308 | rv = idr_get_new_above_int(idp, ptr, starting_id); |
| 309 | /* |
| 310 | * This is a cheap hack until the IDR code can be fixed to |
| 311 | * return proper error values. |
| 312 | */ |
| 313 | if (rv < 0) |
| 314 | return _idr_rc_to_errno(rv); |
| 315 | *id = rv; |
| 316 | return 0; |
| 317 | } |
| 318 | EXPORT_SYMBOL(idr_get_new_above); |
| 319 | |
| 320 | /** |
| 321 | * idr_get_new - allocate new idr entry |
| 322 | * @idp: idr handle |
| 323 | * @ptr: pointer you want associated with the id |
| 324 | * @id: pointer to the allocated handle |
| 325 | * |
| 326 | * If allocation from IDR's private freelist fails, idr_get_new_above() will |
| 327 | * return %-EAGAIN. The caller should retry the idr_pre_get() call to refill |
| 328 | * IDR's preallocation and then retry the idr_get_new_above() call. |
| 329 | * |
| 330 | * If the idr is full idr_get_new_above() will return %-ENOSPC. |
| 331 | * |
| 332 | * @id returns a value in the range %0 ... %0x7fffffff |
| 333 | */ |
| 334 | int idr_get_new(struct idr *idp, void *ptr, int *id) |
| 335 | { |
| 336 | int rv; |
| 337 | |
| 338 | rv = idr_get_new_above_int(idp, ptr, 0); |
| 339 | /* |
| 340 | * This is a cheap hack until the IDR code can be fixed to |
| 341 | * return proper error values. |
| 342 | */ |
| 343 | if (rv < 0) |
| 344 | return _idr_rc_to_errno(rv); |
| 345 | *id = rv; |
| 346 | return 0; |
| 347 | } |
| 348 | EXPORT_SYMBOL(idr_get_new); |
| 349 | |
| 350 | static void idr_remove_warning(int id) |
| 351 | { |
| 352 | printk(KERN_WARNING |
| 353 | "idr_remove called for id=%d which is not allocated.\n", id); |
| 354 | dump_stack(); |
| 355 | } |
| 356 | |
| 357 | static void sub_remove(struct idr *idp, int shift, int id) |
| 358 | { |
| 359 | struct idr_layer *p = idp->top; |
| 360 | struct idr_layer **pa[MAX_LEVEL]; |
| 361 | struct idr_layer ***paa = &pa[0]; |
| 362 | struct idr_layer *to_free; |
| 363 | int n; |
| 364 | |
| 365 | *paa = NULL; |
| 366 | *++paa = &idp->top; |
| 367 | |
| 368 | while ((shift > 0) && p) { |
| 369 | n = (id >> shift) & IDR_MASK; |
| 370 | __clear_bit(n, &p->bitmap); |
| 371 | *++paa = &p->ary[n]; |
| 372 | p = p->ary[n]; |
| 373 | shift -= IDR_BITS; |
| 374 | } |
| 375 | n = id & IDR_MASK; |
| 376 | if (likely(p != NULL && test_bit(n, &p->bitmap))){ |
| 377 | __clear_bit(n, &p->bitmap); |
| 378 | rcu_assign_pointer(p->ary[n], NULL); |
| 379 | to_free = NULL; |
| 380 | while(*paa && ! --((**paa)->count)){ |
| 381 | if (to_free) |
| 382 | free_layer(to_free); |
| 383 | to_free = **paa; |
| 384 | **paa-- = NULL; |
| 385 | } |
| 386 | if (!*paa) |
| 387 | idp->layers = 0; |
| 388 | if (to_free) |
| 389 | free_layer(to_free); |
| 390 | } else |
| 391 | idr_remove_warning(id); |
| 392 | } |
| 393 | |
| 394 | /** |
| 395 | * idr_remove - remove the given id and free its slot |
| 396 | * @idp: idr handle |
| 397 | * @id: unique key |
| 398 | */ |
| 399 | void idr_remove(struct idr *idp, int id) |
| 400 | { |
| 401 | struct idr_layer *p; |
| 402 | struct idr_layer *to_free; |
| 403 | |
| 404 | /* Mask off upper bits we don't use for the search. */ |
| 405 | id &= MAX_ID_MASK; |
| 406 | |
| 407 | sub_remove(idp, (idp->layers - 1) * IDR_BITS, id); |
| 408 | if (idp->top && idp->top->count == 1 && (idp->layers > 1) && |
| 409 | idp->top->ary[0]) { |
| 410 | /* |
| 411 | * Single child at leftmost slot: we can shrink the tree. |
| 412 | * This level is not needed anymore since when layers are |
| 413 | * inserted, they are inserted at the top of the existing |
| 414 | * tree. |
| 415 | */ |
| 416 | to_free = idp->top; |
| 417 | p = idp->top->ary[0]; |
| 418 | rcu_assign_pointer(idp->top, p); |
| 419 | --idp->layers; |
| 420 | to_free->bitmap = to_free->count = 0; |
| 421 | free_layer(to_free); |
| 422 | } |
| 423 | while (idp->id_free_cnt >= IDR_FREE_MAX) { |
| 424 | p = get_from_free_list(idp); |
| 425 | /* |
| 426 | * Note: we don't call the rcu callback here, since the only |
| 427 | * layers that fall into the freelist are those that have been |
| 428 | * preallocated. |
| 429 | */ |
| 430 | kmem_cache_free(idr_layer_cache, p); |
| 431 | } |
| 432 | return; |
| 433 | } |
| 434 | EXPORT_SYMBOL(idr_remove); |
| 435 | |
| 436 | /** |
| 437 | * idr_remove_all - remove all ids from the given idr tree |
| 438 | * @idp: idr handle |
| 439 | * |
| 440 | * idr_destroy() only frees up unused, cached idp_layers, but this |
| 441 | * function will remove all id mappings and leave all idp_layers |
| 442 | * unused. |
| 443 | * |
| 444 | * A typical clean-up sequence for objects stored in an idr tree will |
| 445 | * use idr_for_each() to free all objects, if necessay, then |
| 446 | * idr_remove_all() to remove all ids, and idr_destroy() to free |
| 447 | * up the cached idr_layers. |
| 448 | */ |
| 449 | void idr_remove_all(struct idr *idp) |
| 450 | { |
| 451 | int n, id, max; |
| 452 | int bt_mask; |
| 453 | struct idr_layer *p; |
| 454 | struct idr_layer *pa[MAX_LEVEL]; |
| 455 | struct idr_layer **paa = &pa[0]; |
| 456 | |
| 457 | n = idp->layers * IDR_BITS; |
| 458 | p = idp->top; |
| 459 | rcu_assign_pointer(idp->top, NULL); |
| 460 | max = 1 << n; |
| 461 | |
| 462 | id = 0; |
| 463 | while (id < max) { |
| 464 | while (n > IDR_BITS && p) { |
| 465 | n -= IDR_BITS; |
| 466 | *paa++ = p; |
| 467 | p = p->ary[(id >> n) & IDR_MASK]; |
| 468 | } |
| 469 | |
| 470 | bt_mask = id; |
| 471 | id += 1 << n; |
| 472 | /* Get the highest bit that the above add changed from 0->1. */ |
| 473 | while (n < fls(id ^ bt_mask)) { |
| 474 | if (p) |
| 475 | free_layer(p); |
| 476 | n += IDR_BITS; |
| 477 | p = *--paa; |
| 478 | } |
| 479 | } |
| 480 | idp->layers = 0; |
| 481 | } |
| 482 | EXPORT_SYMBOL(idr_remove_all); |
| 483 | |
| 484 | /** |
| 485 | * idr_destroy - release all cached layers within an idr tree |
| 486 | * @idp: idr handle |
| 487 | */ |
| 488 | void idr_destroy(struct idr *idp) |
| 489 | { |
| 490 | while (idp->id_free_cnt) { |
| 491 | struct idr_layer *p = get_from_free_list(idp); |
| 492 | kmem_cache_free(idr_layer_cache, p); |
| 493 | } |
| 494 | } |
| 495 | EXPORT_SYMBOL(idr_destroy); |
| 496 | |
| 497 | /** |
| 498 | * idr_find - return pointer for given id |
| 499 | * @idp: idr handle |
| 500 | * @id: lookup key |
| 501 | * |
| 502 | * Return the pointer given the id it has been registered with. A %NULL |
| 503 | * return indicates that @id is not valid or you passed %NULL in |
| 504 | * idr_get_new(). |
| 505 | * |
| 506 | * This function can be called under rcu_read_lock(), given that the leaf |
| 507 | * pointers lifetimes are correctly managed. |
| 508 | */ |
| 509 | void *idr_find(struct idr *idp, int id) |
| 510 | { |
| 511 | int n; |
| 512 | struct idr_layer *p; |
| 513 | |
| 514 | p = rcu_dereference_raw(idp->top); |
| 515 | if (!p) |
| 516 | return NULL; |
| 517 | n = (p->layer+1) * IDR_BITS; |
| 518 | |
| 519 | /* Mask off upper bits we don't use for the search. */ |
| 520 | id &= MAX_ID_MASK; |
| 521 | |
| 522 | if (id >= (1 << n)) |
| 523 | return NULL; |
| 524 | BUG_ON(n == 0); |
| 525 | |
| 526 | while (n > 0 && p) { |
| 527 | n -= IDR_BITS; |
| 528 | BUG_ON(n != p->layer*IDR_BITS); |
| 529 | p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]); |
| 530 | } |
| 531 | return((void *)p); |
| 532 | } |
| 533 | EXPORT_SYMBOL(idr_find); |
| 534 | |
| 535 | /** |
| 536 | * idr_for_each - iterate through all stored pointers |
| 537 | * @idp: idr handle |
| 538 | * @fn: function to be called for each pointer |
| 539 | * @data: data passed back to callback function |
| 540 | * |
| 541 | * Iterate over the pointers registered with the given idr. The |
| 542 | * callback function will be called for each pointer currently |
| 543 | * registered, passing the id, the pointer and the data pointer passed |
| 544 | * to this function. It is not safe to modify the idr tree while in |
| 545 | * the callback, so functions such as idr_get_new and idr_remove are |
| 546 | * not allowed. |
| 547 | * |
| 548 | * We check the return of @fn each time. If it returns anything other |
| 549 | * than %0, we break out and return that value. |
| 550 | * |
| 551 | * The caller must serialize idr_for_each() vs idr_get_new() and idr_remove(). |
| 552 | */ |
| 553 | int idr_for_each(struct idr *idp, |
| 554 | int (*fn)(int id, void *p, void *data), void *data) |
| 555 | { |
| 556 | int n, id, max, error = 0; |
| 557 | struct idr_layer *p; |
| 558 | struct idr_layer *pa[MAX_LEVEL]; |
| 559 | struct idr_layer **paa = &pa[0]; |
| 560 | |
| 561 | n = idp->layers * IDR_BITS; |
| 562 | p = rcu_dereference_raw(idp->top); |
| 563 | max = 1 << n; |
| 564 | |
| 565 | id = 0; |
| 566 | while (id < max) { |
| 567 | while (n > 0 && p) { |
| 568 | n -= IDR_BITS; |
| 569 | *paa++ = p; |
| 570 | p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]); |
| 571 | } |
| 572 | |
| 573 | if (p) { |
| 574 | error = fn(id, (void *)p, data); |
| 575 | if (error) |
| 576 | break; |
| 577 | } |
| 578 | |
| 579 | id += 1 << n; |
| 580 | while (n < fls(id)) { |
| 581 | n += IDR_BITS; |
| 582 | p = *--paa; |
| 583 | } |
| 584 | } |
| 585 | |
| 586 | return error; |
| 587 | } |
| 588 | EXPORT_SYMBOL(idr_for_each); |
| 589 | |
| 590 | /** |
| 591 | * idr_get_next - lookup next object of id to given id. |
| 592 | * @idp: idr handle |
| 593 | * @nextidp: pointer to lookup key |
| 594 | * |
| 595 | * Returns pointer to registered object with id, which is next number to |
| 596 | * given id. After being looked up, *@nextidp will be updated for the next |
| 597 | * iteration. |
| 598 | * |
| 599 | * This function can be called under rcu_read_lock(), given that the leaf |
| 600 | * pointers lifetimes are correctly managed. |
| 601 | */ |
| 602 | void *idr_get_next(struct idr *idp, int *nextidp) |
| 603 | { |
| 604 | struct idr_layer *p, *pa[MAX_LEVEL]; |
| 605 | struct idr_layer **paa = &pa[0]; |
| 606 | int id = *nextidp; |
| 607 | int n, max; |
| 608 | |
| 609 | /* find first ent */ |
| 610 | p = rcu_dereference_raw(idp->top); |
| 611 | if (!p) |
| 612 | return NULL; |
| 613 | n = (p->layer + 1) * IDR_BITS; |
| 614 | max = 1 << n; |
| 615 | |
| 616 | while (id < max) { |
| 617 | while (n > 0 && p) { |
| 618 | n -= IDR_BITS; |
| 619 | *paa++ = p; |
| 620 | p = rcu_dereference_raw(p->ary[(id >> n) & IDR_MASK]); |
| 621 | } |
| 622 | |
| 623 | if (p) { |
| 624 | *nextidp = id; |
| 625 | return p; |
| 626 | } |
| 627 | |
| 628 | id += 1 << n; |
| 629 | while (n < fls(id)) { |
| 630 | n += IDR_BITS; |
| 631 | p = *--paa; |
| 632 | } |
| 633 | } |
| 634 | return NULL; |
| 635 | } |
| 636 | EXPORT_SYMBOL(idr_get_next); |
| 637 | |
| 638 | |
| 639 | /** |
| 640 | * idr_replace - replace pointer for given id |
| 641 | * @idp: idr handle |
| 642 | * @ptr: pointer you want associated with the id |
| 643 | * @id: lookup key |
| 644 | * |
| 645 | * Replace the pointer registered with an id and return the old value. |
| 646 | * A %-ENOENT return indicates that @id was not found. |
| 647 | * A %-EINVAL return indicates that @id was not within valid constraints. |
| 648 | * |
| 649 | * The caller must serialize with writers. |
| 650 | */ |
| 651 | void *idr_replace(struct idr *idp, void *ptr, int id) |
| 652 | { |
| 653 | int n; |
| 654 | struct idr_layer *p, *old_p; |
| 655 | |
| 656 | p = idp->top; |
| 657 | if (!p) |
| 658 | return ERR_PTR(-EINVAL); |
| 659 | |
| 660 | n = (p->layer+1) * IDR_BITS; |
| 661 | |
| 662 | id &= MAX_ID_MASK; |
| 663 | |
| 664 | if (id >= (1 << n)) |
| 665 | return ERR_PTR(-EINVAL); |
| 666 | |
| 667 | n -= IDR_BITS; |
| 668 | while ((n > 0) && p) { |
| 669 | p = p->ary[(id >> n) & IDR_MASK]; |
| 670 | n -= IDR_BITS; |
| 671 | } |
| 672 | |
| 673 | n = id & IDR_MASK; |
| 674 | if (unlikely(p == NULL || !test_bit(n, &p->bitmap))) |
| 675 | return ERR_PTR(-ENOENT); |
| 676 | |
| 677 | old_p = p->ary[n]; |
| 678 | rcu_assign_pointer(p->ary[n], ptr); |
| 679 | |
| 680 | return old_p; |
| 681 | } |
| 682 | EXPORT_SYMBOL(idr_replace); |
| 683 | |
| 684 | void __init idr_init_cache(void) |
| 685 | { |
| 686 | idr_layer_cache = kmem_cache_create("idr_layer_cache", |
| 687 | sizeof(struct idr_layer), 0, SLAB_PANIC, NULL); |
| 688 | } |
| 689 | |
| 690 | /** |
| 691 | * idr_init - initialize idr handle |
| 692 | * @idp: idr handle |
| 693 | * |
| 694 | * This function is use to set up the handle (@idp) that you will pass |
| 695 | * to the rest of the functions. |
| 696 | */ |
| 697 | void idr_init(struct idr *idp) |
| 698 | { |
| 699 | memset(idp, 0, sizeof(struct idr)); |
| 700 | spin_lock_init(&idp->lock); |
| 701 | } |
| 702 | EXPORT_SYMBOL(idr_init); |
| 703 | |
| 704 | |
| 705 | /** |
| 706 | * DOC: IDA description |
| 707 | * IDA - IDR based ID allocator |
| 708 | * |
| 709 | * This is id allocator without id -> pointer translation. Memory |
| 710 | * usage is much lower than full blown idr because each id only |
| 711 | * occupies a bit. ida uses a custom leaf node which contains |
| 712 | * IDA_BITMAP_BITS slots. |
| 713 | * |
| 714 | * 2007-04-25 written by Tejun Heo <htejun@gmail.com> |
| 715 | */ |
| 716 | |
| 717 | static void free_bitmap(struct ida *ida, struct ida_bitmap *bitmap) |
| 718 | { |
| 719 | unsigned long flags; |
| 720 | |
| 721 | if (!ida->free_bitmap) { |
| 722 | spin_lock_irqsave(&ida->idr.lock, flags); |
| 723 | if (!ida->free_bitmap) { |
| 724 | ida->free_bitmap = bitmap; |
| 725 | bitmap = NULL; |
| 726 | } |
| 727 | spin_unlock_irqrestore(&ida->idr.lock, flags); |
| 728 | } |
| 729 | |
| 730 | kfree(bitmap); |
| 731 | } |
| 732 | |
| 733 | /** |
| 734 | * ida_pre_get - reserve resources for ida allocation |
| 735 | * @ida: ida handle |
| 736 | * @gfp_mask: memory allocation flag |
| 737 | * |
| 738 | * This function should be called prior to locking and calling the |
| 739 | * following function. It preallocates enough memory to satisfy the |
| 740 | * worst possible allocation. |
| 741 | * |
| 742 | * If the system is REALLY out of memory this function returns %0, |
| 743 | * otherwise %1. |
| 744 | */ |
| 745 | int ida_pre_get(struct ida *ida, gfp_t gfp_mask) |
| 746 | { |
| 747 | /* allocate idr_layers */ |
| 748 | if (!idr_pre_get(&ida->idr, gfp_mask)) |
| 749 | return 0; |
| 750 | |
| 751 | /* allocate free_bitmap */ |
| 752 | if (!ida->free_bitmap) { |
| 753 | struct ida_bitmap *bitmap; |
| 754 | |
| 755 | bitmap = kmalloc(sizeof(struct ida_bitmap), gfp_mask); |
| 756 | if (!bitmap) |
| 757 | return 0; |
| 758 | |
| 759 | free_bitmap(ida, bitmap); |
| 760 | } |
| 761 | |
| 762 | return 1; |
| 763 | } |
| 764 | EXPORT_SYMBOL(ida_pre_get); |
| 765 | |
| 766 | /** |
| 767 | * ida_get_new_above - allocate new ID above or equal to a start id |
| 768 | * @ida: ida handle |
| 769 | * @starting_id: id to start search at |
| 770 | * @p_id: pointer to the allocated handle |
| 771 | * |
| 772 | * Allocate new ID above or equal to @starting_id. It should be called |
| 773 | * with any required locks. |
| 774 | * |
| 775 | * If memory is required, it will return %-EAGAIN, you should unlock |
| 776 | * and go back to the ida_pre_get() call. If the ida is full, it will |
| 777 | * return %-ENOSPC. |
| 778 | * |
| 779 | * @p_id returns a value in the range @starting_id ... %0x7fffffff. |
| 780 | */ |
| 781 | int ida_get_new_above(struct ida *ida, int starting_id, int *p_id) |
| 782 | { |
| 783 | struct idr_layer *pa[MAX_LEVEL]; |
| 784 | struct ida_bitmap *bitmap; |
| 785 | unsigned long flags; |
| 786 | int idr_id = starting_id / IDA_BITMAP_BITS; |
| 787 | int offset = starting_id % IDA_BITMAP_BITS; |
| 788 | int t, id; |
| 789 | |
| 790 | restart: |
| 791 | /* get vacant slot */ |
| 792 | t = idr_get_empty_slot(&ida->idr, idr_id, pa); |
| 793 | if (t < 0) |
| 794 | return _idr_rc_to_errno(t); |
| 795 | |
| 796 | if (t * IDA_BITMAP_BITS >= MAX_ID_BIT) |
| 797 | return -ENOSPC; |
| 798 | |
| 799 | if (t != idr_id) |
| 800 | offset = 0; |
| 801 | idr_id = t; |
| 802 | |
| 803 | /* if bitmap isn't there, create a new one */ |
| 804 | bitmap = (void *)pa[0]->ary[idr_id & IDR_MASK]; |
| 805 | if (!bitmap) { |
| 806 | spin_lock_irqsave(&ida->idr.lock, flags); |
| 807 | bitmap = ida->free_bitmap; |
| 808 | ida->free_bitmap = NULL; |
| 809 | spin_unlock_irqrestore(&ida->idr.lock, flags); |
| 810 | |
| 811 | if (!bitmap) |
| 812 | return -EAGAIN; |
| 813 | |
| 814 | memset(bitmap, 0, sizeof(struct ida_bitmap)); |
| 815 | rcu_assign_pointer(pa[0]->ary[idr_id & IDR_MASK], |
| 816 | (void *)bitmap); |
| 817 | pa[0]->count++; |
| 818 | } |
| 819 | |
| 820 | /* lookup for empty slot */ |
| 821 | t = find_next_zero_bit(bitmap->bitmap, IDA_BITMAP_BITS, offset); |
| 822 | if (t == IDA_BITMAP_BITS) { |
| 823 | /* no empty slot after offset, continue to the next chunk */ |
| 824 | idr_id++; |
| 825 | offset = 0; |
| 826 | goto restart; |
| 827 | } |
| 828 | |
| 829 | id = idr_id * IDA_BITMAP_BITS + t; |
| 830 | if (id >= MAX_ID_BIT) |
| 831 | return -ENOSPC; |
| 832 | |
| 833 | __set_bit(t, bitmap->bitmap); |
| 834 | if (++bitmap->nr_busy == IDA_BITMAP_BITS) |
| 835 | idr_mark_full(pa, idr_id); |
| 836 | |
| 837 | *p_id = id; |
| 838 | |
| 839 | /* Each leaf node can handle nearly a thousand slots and the |
| 840 | * whole idea of ida is to have small memory foot print. |
| 841 | * Throw away extra resources one by one after each successful |
| 842 | * allocation. |
| 843 | */ |
| 844 | if (ida->idr.id_free_cnt || ida->free_bitmap) { |
| 845 | struct idr_layer *p = get_from_free_list(&ida->idr); |
| 846 | if (p) |
| 847 | kmem_cache_free(idr_layer_cache, p); |
| 848 | } |
| 849 | |
| 850 | return 0; |
| 851 | } |
| 852 | EXPORT_SYMBOL(ida_get_new_above); |
| 853 | |
| 854 | /** |
| 855 | * ida_get_new - allocate new ID |
| 856 | * @ida: idr handle |
| 857 | * @p_id: pointer to the allocated handle |
| 858 | * |
| 859 | * Allocate new ID. It should be called with any required locks. |
| 860 | * |
| 861 | * If memory is required, it will return %-EAGAIN, you should unlock |
| 862 | * and go back to the idr_pre_get() call. If the idr is full, it will |
| 863 | * return %-ENOSPC. |
| 864 | * |
| 865 | * @p_id returns a value in the range %0 ... %0x7fffffff. |
| 866 | */ |
| 867 | int ida_get_new(struct ida *ida, int *p_id) |
| 868 | { |
| 869 | return ida_get_new_above(ida, 0, p_id); |
| 870 | } |
| 871 | EXPORT_SYMBOL(ida_get_new); |
| 872 | |
| 873 | /** |
| 874 | * ida_remove - remove the given ID |
| 875 | * @ida: ida handle |
| 876 | * @id: ID to free |
| 877 | */ |
| 878 | void ida_remove(struct ida *ida, int id) |
| 879 | { |
| 880 | struct idr_layer *p = ida->idr.top; |
| 881 | int shift = (ida->idr.layers - 1) * IDR_BITS; |
| 882 | int idr_id = id / IDA_BITMAP_BITS; |
| 883 | int offset = id % IDA_BITMAP_BITS; |
| 884 | int n; |
| 885 | struct ida_bitmap *bitmap; |
| 886 | |
| 887 | /* clear full bits while looking up the leaf idr_layer */ |
| 888 | while ((shift > 0) && p) { |
| 889 | n = (idr_id >> shift) & IDR_MASK; |
| 890 | __clear_bit(n, &p->bitmap); |
| 891 | p = p->ary[n]; |
| 892 | shift -= IDR_BITS; |
| 893 | } |
| 894 | |
| 895 | if (p == NULL) |
| 896 | goto err; |
| 897 | |
| 898 | n = idr_id & IDR_MASK; |
| 899 | __clear_bit(n, &p->bitmap); |
| 900 | |
| 901 | bitmap = (void *)p->ary[n]; |
| 902 | if (!test_bit(offset, bitmap->bitmap)) |
| 903 | goto err; |
| 904 | |
| 905 | /* update bitmap and remove it if empty */ |
| 906 | __clear_bit(offset, bitmap->bitmap); |
| 907 | if (--bitmap->nr_busy == 0) { |
| 908 | __set_bit(n, &p->bitmap); /* to please idr_remove() */ |
| 909 | idr_remove(&ida->idr, idr_id); |
| 910 | free_bitmap(ida, bitmap); |
| 911 | } |
| 912 | |
| 913 | return; |
| 914 | |
| 915 | err: |
| 916 | printk(KERN_WARNING |
| 917 | "ida_remove called for id=%d which is not allocated.\n", id); |
| 918 | } |
| 919 | EXPORT_SYMBOL(ida_remove); |
| 920 | |
| 921 | /** |
| 922 | * ida_destroy - release all cached layers within an ida tree |
| 923 | * @ida: ida handle |
| 924 | */ |
| 925 | void ida_destroy(struct ida *ida) |
| 926 | { |
| 927 | idr_destroy(&ida->idr); |
| 928 | kfree(ida->free_bitmap); |
| 929 | } |
| 930 | EXPORT_SYMBOL(ida_destroy); |
| 931 | |
| 932 | /** |
| 933 | * ida_simple_get - get a new id. |
| 934 | * @ida: the (initialized) ida. |
| 935 | * @start: the minimum id (inclusive, < 0x8000000) |
| 936 | * @end: the maximum id (exclusive, < 0x8000000 or 0) |
| 937 | * @gfp_mask: memory allocation flags |
| 938 | * |
| 939 | * Allocates an id in the range start <= id < end, or returns -ENOSPC. |
| 940 | * On memory allocation failure, returns -ENOMEM. |
| 941 | * |
| 942 | * Use ida_simple_remove() to get rid of an id. |
| 943 | */ |
| 944 | int ida_simple_get(struct ida *ida, unsigned int start, unsigned int end, |
| 945 | gfp_t gfp_mask) |
| 946 | { |
| 947 | int ret, id; |
| 948 | unsigned int max; |
| 949 | unsigned long flags; |
| 950 | |
| 951 | BUG_ON((int)start < 0); |
| 952 | BUG_ON((int)end < 0); |
| 953 | |
| 954 | if (end == 0) |
| 955 | max = 0x80000000; |
| 956 | else { |
| 957 | BUG_ON(end < start); |
| 958 | max = end - 1; |
| 959 | } |
| 960 | |
| 961 | again: |
| 962 | if (!ida_pre_get(ida, gfp_mask)) |
| 963 | return -ENOMEM; |
| 964 | |
| 965 | spin_lock_irqsave(&simple_ida_lock, flags); |
| 966 | ret = ida_get_new_above(ida, start, &id); |
| 967 | if (!ret) { |
| 968 | if (id > max) { |
| 969 | ida_remove(ida, id); |
| 970 | ret = -ENOSPC; |
| 971 | } else { |
| 972 | ret = id; |
| 973 | } |
| 974 | } |
| 975 | spin_unlock_irqrestore(&simple_ida_lock, flags); |
| 976 | |
| 977 | if (unlikely(ret == -EAGAIN)) |
| 978 | goto again; |
| 979 | |
| 980 | return ret; |
| 981 | } |
| 982 | EXPORT_SYMBOL(ida_simple_get); |
| 983 | |
| 984 | /** |
| 985 | * ida_simple_remove - remove an allocated id. |
| 986 | * @ida: the (initialized) ida. |
| 987 | * @id: the id returned by ida_simple_get. |
| 988 | */ |
| 989 | void ida_simple_remove(struct ida *ida, unsigned int id) |
| 990 | { |
| 991 | unsigned long flags; |
| 992 | |
| 993 | BUG_ON((int)id < 0); |
| 994 | spin_lock_irqsave(&simple_ida_lock, flags); |
| 995 | ida_remove(ida, id); |
| 996 | spin_unlock_irqrestore(&simple_ida_lock, flags); |
| 997 | } |
| 998 | EXPORT_SYMBOL(ida_simple_remove); |
| 999 | |
| 1000 | /** |
| 1001 | * ida_init - initialize ida handle |
| 1002 | * @ida: ida handle |
| 1003 | * |
| 1004 | * This function is use to set up the handle (@ida) that you will pass |
| 1005 | * to the rest of the functions. |
| 1006 | */ |
| 1007 | void ida_init(struct ida *ida) |
| 1008 | { |
| 1009 | memset(ida, 0, sizeof(struct ida)); |
| 1010 | idr_init(&ida->idr); |
| 1011 | |
| 1012 | } |
| 1013 | EXPORT_SYMBOL(ida_init); |