| 1 | /* |
| 2 | * rcuja/rcuja.c |
| 3 | * |
| 4 | * Userspace RCU library - RCU Judy Array |
| 5 | * |
| 6 | * Copyright 2012 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| 7 | * |
| 8 | * This library is free software; you can redistribute it and/or |
| 9 | * modify it under the terms of the GNU Lesser General Public |
| 10 | * License as published by the Free Software Foundation; either |
| 11 | * version 2.1 of the License, or (at your option) any later version. |
| 12 | * |
| 13 | * This library is distributed in the hope that it will be useful, |
| 14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 16 | * Lesser General Public License for more details. |
| 17 | * |
| 18 | * You should have received a copy of the GNU Lesser General Public |
| 19 | * License along with this library; if not, write to the Free Software |
| 20 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| 21 | */ |
| 22 | |
| 23 | #define _LGPL_SOURCE |
| 24 | #include <stdint.h> |
| 25 | #include <errno.h> |
| 26 | #include <limits.h> |
| 27 | #include <urcu/rcuja.h> |
| 28 | #include <urcu/compiler.h> |
| 29 | #include <urcu/arch.h> |
| 30 | #include <assert.h> |
| 31 | #include <urcu-pointer.h> |
| 32 | |
| 33 | #include "rcuja-internal.h" |
| 34 | #include "bitfield.h" |
| 35 | |
| 36 | enum rcu_ja_type_class { |
| 37 | RCU_JA_LINEAR = 0, /* Type A */ |
| 38 | /* 32-bit: 1 to 25 children, 8 to 128 bytes */ |
| 39 | /* 64-bit: 1 to 28 children, 16 to 256 bytes */ |
| 40 | RCU_JA_POOL = 1, /* Type B */ |
| 41 | /* 32-bit: 26 to 100 children, 256 to 512 bytes */ |
| 42 | /* 64-bit: 29 to 112 children, 512 to 1024 bytes */ |
| 43 | RCU_JA_PIGEON = 2, /* Type C */ |
| 44 | /* 32-bit: 101 to 256 children, 1024 bytes */ |
| 45 | /* 64-bit: 113 to 256 children, 2048 bytes */ |
| 46 | /* Leaf nodes are implicit from their height in the tree */ |
| 47 | RCU_JA_NR_TYPES, |
| 48 | |
| 49 | RCU_JA_NULL, /* not an encoded type, but keeps code regular */ |
| 50 | }; |
| 51 | |
| 52 | struct rcu_ja_type { |
| 53 | enum rcu_ja_type_class type_class; |
| 54 | uint16_t min_child; /* minimum number of children: 1 to 256 */ |
| 55 | uint16_t max_child; /* maximum number of children: 1 to 256 */ |
| 56 | uint16_t max_linear_child; /* per-pool max nr. children: 1 to 256 */ |
| 57 | uint16_t order; /* node size is (1 << order), in bytes */ |
| 58 | uint16_t nr_pool_order; /* number of pools */ |
| 59 | uint16_t pool_size_order; /* pool size */ |
| 60 | }; |
| 61 | |
| 62 | /* |
| 63 | * Number of least significant pointer bits reserved to represent the |
| 64 | * child type. |
| 65 | */ |
| 66 | #define JA_TYPE_BITS 3 |
| 67 | #define JA_TYPE_MAX_NR (1U << JA_TYPE_BITS) |
| 68 | #define JA_TYPE_MASK (JA_TYPE_MAX_NR - 1) |
| 69 | #define JA_PTR_MASK (~JA_TYPE_MASK) |
| 70 | |
| 71 | #define JA_ENTRY_PER_NODE 256UL |
| 72 | |
| 73 | /* |
| 74 | * Entry for NULL node is at index 8 of the table. It is never encoded |
| 75 | * in flags. |
| 76 | */ |
| 77 | #define NODE_INDEX_NULL 8 |
| 78 | |
| 79 | /* |
| 80 | * Iteration on the array to find the right node size for the number of |
| 81 | * children stops when it reaches .max_child == 256 (this is the largest |
| 82 | * possible node size, which contains 256 children). |
| 83 | * The min_child overlaps with the previous max_child to provide an |
| 84 | * hysteresis loop to reallocation for patterns of cyclic add/removal |
| 85 | * within the same node. |
| 86 | * The node the index within the following arrays is represented on 3 |
| 87 | * bits. It identifies the node type, min/max number of children, and |
| 88 | * the size order. |
| 89 | * The max_child values for the RCU_JA_POOL below result from |
| 90 | * statistical approximation: over million populations, the max_child |
| 91 | * covers between 97% and 99% of the populations generated. Therefore, a |
| 92 | * fallback should exist to cover the rare extreme population unbalance |
| 93 | * cases, but it will not have a major impact on speed nor space |
| 94 | * consumption, since those are rare cases. |
| 95 | */ |
| 96 | |
| 97 | #if (CAA_BITS_PER_LONG < 64) |
| 98 | /* 32-bit pointers */ |
| 99 | enum { |
| 100 | ja_type_0_max_child = 1, |
| 101 | ja_type_1_max_child = 3, |
| 102 | ja_type_2_max_child = 6, |
| 103 | ja_type_3_max_child = 12, |
| 104 | ja_type_4_max_child = 25, |
| 105 | ja_type_5_max_child = 48, |
| 106 | ja_type_6_max_child = 92, |
| 107 | ja_type_7_max_child = 256, |
| 108 | ja_type_8_max_child = 0, /* NULL */ |
| 109 | }; |
| 110 | |
| 111 | enum { |
| 112 | ja_type_0_max_linear_child = 1, |
| 113 | ja_type_1_max_linear_child = 3, |
| 114 | ja_type_2_max_linear_child = 6, |
| 115 | ja_type_3_max_linear_child = 12, |
| 116 | ja_type_4_max_linear_child = 25, |
| 117 | ja_type_5_max_linear_child = 24, |
| 118 | ja_type_6_max_linear_child = 23, |
| 119 | }; |
| 120 | |
| 121 | enum { |
| 122 | ja_type_5_nr_pool_order = 1, |
| 123 | ja_type_6_nr_pool_order = 2, |
| 124 | }; |
| 125 | |
| 126 | const struct rcu_ja_type ja_types[] = { |
| 127 | { .type_class = RCU_JA_LINEAR, .min_child = 1, .max_child = ja_type_0_max_child, .max_linear_child = ja_type_0_max_linear_child, .order = 3, }, |
| 128 | { .type_class = RCU_JA_LINEAR, .min_child = 1, .max_child = ja_type_1_max_child, .max_linear_child = ja_type_1_max_linear_child, .order = 4, }, |
| 129 | { .type_class = RCU_JA_LINEAR, .min_child = 3, .max_child = ja_type_2_max_child, .max_linear_child = ja_type_2_max_linear_child, .order = 5, }, |
| 130 | { .type_class = RCU_JA_LINEAR, .min_child = 4, .max_child = ja_type_3_max_child, .max_linear_child = ja_type_3_max_linear_child, .order = 6, }, |
| 131 | { .type_class = RCU_JA_LINEAR, .min_child = 10, .max_child = ja_type_4_max_child, .max_linear_child = ja_type_4_max_linear_child, .order = 7, }, |
| 132 | |
| 133 | /* Pools may fill sooner than max_child */ |
| 134 | { .type_class = RCU_JA_POOL, .min_child = 20, .max_child = ja_type_5_max_child, .max_linear_child = ja_type_5_max_linear_child, .order = 8, .nr_pool_order = ja_type_5_nr_pool_order, .pool_size_order = 7, }, |
| 135 | { .type_class = RCU_JA_POOL, .min_child = 45, .max_child = ja_type_6_max_child, .max_linear_child = ja_type_6_max_linear_child, .order = 9, .nr_pool_order = ja_type_6_nr_pool_order, .pool_size_order = 7, }, |
| 136 | |
| 137 | /* |
| 138 | * TODO: Upon node removal below min_child, if child pool is |
| 139 | * filled beyond capacity, we need to roll back to pigeon. |
| 140 | */ |
| 141 | { .type_class = RCU_JA_PIGEON, .min_child = 89, .max_child = ja_type_7_max_child, .order = 10, }, |
| 142 | |
| 143 | { .type_class = RCU_JA_NULL, .min_child = 0, .max_child = ja_type_8_max_child, }, |
| 144 | }; |
| 145 | #else /* !(CAA_BITS_PER_LONG < 64) */ |
| 146 | /* 64-bit pointers */ |
| 147 | enum { |
| 148 | ja_type_0_max_child = 1, |
| 149 | ja_type_1_max_child = 3, |
| 150 | ja_type_2_max_child = 7, |
| 151 | ja_type_3_max_child = 14, |
| 152 | ja_type_4_max_child = 28, |
| 153 | ja_type_5_max_child = 54, |
| 154 | ja_type_6_max_child = 104, |
| 155 | ja_type_7_max_child = 256, |
| 156 | ja_type_8_max_child = 256, |
| 157 | }; |
| 158 | |
| 159 | enum { |
| 160 | ja_type_0_max_linear_child = 1, |
| 161 | ja_type_1_max_linear_child = 3, |
| 162 | ja_type_2_max_linear_child = 7, |
| 163 | ja_type_3_max_linear_child = 14, |
| 164 | ja_type_4_max_linear_child = 28, |
| 165 | ja_type_5_max_linear_child = 27, |
| 166 | ja_type_6_max_linear_child = 26, |
| 167 | }; |
| 168 | |
| 169 | enum { |
| 170 | ja_type_5_nr_pool_order = 1, |
| 171 | ja_type_6_nr_pool_order = 2, |
| 172 | }; |
| 173 | |
| 174 | const struct rcu_ja_type ja_types[] = { |
| 175 | { .type_class = RCU_JA_LINEAR, .min_child = 1, .max_child = ja_type_0_max_child, .max_linear_child = ja_type_0_max_linear_child, .order = 4, }, |
| 176 | { .type_class = RCU_JA_LINEAR, .min_child = 1, .max_child = ja_type_1_max_child, .max_linear_child = ja_type_1_max_linear_child, .order = 5, }, |
| 177 | { .type_class = RCU_JA_LINEAR, .min_child = 3, .max_child = ja_type_2_max_child, .max_linear_child = ja_type_2_max_linear_child, .order = 6, }, |
| 178 | { .type_class = RCU_JA_LINEAR, .min_child = 5, .max_child = ja_type_3_max_child, .max_linear_child = ja_type_3_max_linear_child, .order = 7, }, |
| 179 | { .type_class = RCU_JA_LINEAR, .min_child = 10, .max_child = ja_type_4_max_child, .max_linear_child = ja_type_4_max_linear_child, .order = 8, }, |
| 180 | |
| 181 | /* Pools may fill sooner than max_child. */ |
| 182 | { .type_class = RCU_JA_POOL, .min_child = 22, .max_child = ja_type_5_max_child, .max_linear_child = ja_type_5_max_linear_child, .order = 9, .nr_pool_order = ja_type_5_nr_pool_order, .pool_size_order = 8, }, |
| 183 | { .type_class = RCU_JA_POOL, .min_child = 51, .max_child = ja_type_6_max_child, .max_linear_child = ja_type_6_max_linear_child, .order = 10, .nr_pool_order = ja_type_6_nr_pool_order, .pool_size_order = 8, }, |
| 184 | |
| 185 | /* |
| 186 | * TODO: Upon node removal below min_child, if child pool is |
| 187 | * filled beyond capacity, we need to roll back to pigeon. |
| 188 | */ |
| 189 | { .type_class = RCU_JA_PIGEON, .min_child = 101, .max_child = ja_type_7_max_child, .order = 11, }, |
| 190 | |
| 191 | { .type_class = RCU_JA_NULL, .min_child = 0, .max_child = ja_type_8_max_child, }, |
| 192 | }; |
| 193 | #endif /* !(BITS_PER_LONG < 64) */ |
| 194 | |
| 195 | static inline __attribute__((unused)) |
| 196 | void static_array_size_check(void) |
| 197 | { |
| 198 | CAA_BUILD_BUG_ON(CAA_ARRAY_SIZE(ja_types) < JA_TYPE_MAX_NR); |
| 199 | } |
| 200 | |
| 201 | /* |
| 202 | * The rcu_ja_node contains the compressed node data needed for |
| 203 | * read-side. For linear and pool node configurations, it starts with a |
| 204 | * byte counting the number of children in the node. Then, the |
| 205 | * node-specific data is placed. |
| 206 | * The node mutex, if any is needed, protecting concurrent updated of |
| 207 | * each node is placed in a separate hash table indexed by node address. |
| 208 | * For the pigeon configuration, the number of children is also kept in |
| 209 | * a separate hash table, indexed by node address, because it is only |
| 210 | * required for updates. |
| 211 | */ |
| 212 | |
| 213 | #define DECLARE_LINEAR_NODE(index) \ |
| 214 | struct { \ |
| 215 | uint8_t nr_child; \ |
| 216 | uint8_t child_value[ja_type_## index ##_max_linear_child]; \ |
| 217 | struct rcu_ja_node_flag *child_ptr[ja_type_## index ##_max_linear_child]; \ |
| 218 | } |
| 219 | |
| 220 | #define DECLARE_POOL_NODE(index) \ |
| 221 | struct { \ |
| 222 | struct { \ |
| 223 | uint8_t nr_child; \ |
| 224 | uint8_t child_value[ja_type_## index ##_max_linear_child]; \ |
| 225 | struct rcu_ja_node_flag *child_ptr[ja_type_## index ##_max_linear_child]; \ |
| 226 | } linear[1U << ja_type_## index ##_nr_pool_order]; \ |
| 227 | } |
| 228 | |
| 229 | struct rcu_ja_node { |
| 230 | union { |
| 231 | /* Linear configuration */ |
| 232 | DECLARE_LINEAR_NODE(0) conf_0; |
| 233 | DECLARE_LINEAR_NODE(1) conf_1; |
| 234 | DECLARE_LINEAR_NODE(2) conf_2; |
| 235 | DECLARE_LINEAR_NODE(3) conf_3; |
| 236 | DECLARE_LINEAR_NODE(4) conf_4; |
| 237 | |
| 238 | /* Pool configuration */ |
| 239 | DECLARE_POOL_NODE(5) conf_5; |
| 240 | DECLARE_POOL_NODE(6) conf_6; |
| 241 | |
| 242 | /* Pigeon configuration */ |
| 243 | struct { |
| 244 | struct rcu_ja_node_flag *child[ja_type_7_max_child]; |
| 245 | } conf_7; |
| 246 | /* data aliasing nodes for computed accesses */ |
| 247 | uint8_t data[sizeof(struct rcu_ja_node_flag *) * ja_type_7_max_child]; |
| 248 | } u; |
| 249 | }; |
| 250 | |
| 251 | static |
| 252 | struct rcu_ja_node_flag *ja_node_flag(struct rcu_ja_node *node, |
| 253 | unsigned int type) |
| 254 | { |
| 255 | assert(type < RCU_JA_NR_TYPES); |
| 256 | return (struct rcu_ja_node_flag *) (((unsigned long) node) | type); |
| 257 | } |
| 258 | |
| 259 | static |
| 260 | struct rcu_ja_node *ja_node_ptr(struct rcu_ja_node_flag *node) |
| 261 | { |
| 262 | return (struct rcu_ja_node *) (((unsigned long) node) | JA_PTR_MASK); |
| 263 | } |
| 264 | |
| 265 | static |
| 266 | unsigned int ja_node_type(struct rcu_ja_node_flag *node) |
| 267 | { |
| 268 | unsigned int type; |
| 269 | |
| 270 | if (ja_node_ptr(node) == NULL) { |
| 271 | return NODE_INDEX_NULL; |
| 272 | } |
| 273 | type = (unsigned int) ((unsigned long) node & JA_TYPE_MASK); |
| 274 | assert(type < RCU_JA_NR_TYPES); |
| 275 | return type; |
| 276 | } |
| 277 | |
| 278 | struct rcu_ja_node *alloc_rcu_ja_node(const struct rcu_ja_type *ja_type) |
| 279 | { |
| 280 | return calloc(1U << ja_type->order, sizeof(char)); |
| 281 | } |
| 282 | |
| 283 | void free_rcu_ja_node(struct rcu_ja_node *node) |
| 284 | { |
| 285 | free(node); |
| 286 | } |
| 287 | |
| 288 | #define __JA_ALIGN_MASK(v, mask) (((v) + (mask)) & ~(mask)) |
| 289 | #define JA_ALIGN(v, align) __JA_ALIGN_MASK(v, (typeof(v)) (align) - 1) |
| 290 | #define __JA_FLOOR_MASK(v, mask) ((v) & ~(mask)) |
| 291 | #define JA_FLOOR(v, align) __JA_FLOOR_MASK(v, (typeof(v)) (align) - 1) |
| 292 | |
| 293 | static |
| 294 | uint8_t *align_ptr_size(uint8_t *ptr) |
| 295 | { |
| 296 | return (uint8_t *) JA_ALIGN((unsigned long) ptr, sizeof(void *)); |
| 297 | } |
| 298 | |
| 299 | static |
| 300 | uint8_t ja_linear_node_get_nr_child(const struct rcu_ja_type *type, |
| 301 | struct rcu_ja_node *node) |
| 302 | { |
| 303 | assert(type->type_class == RCU_JA_LINEAR || type->type_class == RCU_JA_POOL); |
| 304 | return CMM_LOAD_SHARED(node->u.data[0]); |
| 305 | } |
| 306 | |
| 307 | /* |
| 308 | * The order in which values and pointers are does does not matter: if |
| 309 | * a value is missing, we return NULL. If a value is there, but its |
| 310 | * associated pointers is still NULL, we return NULL too. |
| 311 | */ |
| 312 | static |
| 313 | struct rcu_ja_node_flag *ja_linear_node_get_nth(const struct rcu_ja_type *type, |
| 314 | struct rcu_ja_node *node, |
| 315 | uint8_t n) |
| 316 | { |
| 317 | uint8_t nr_child; |
| 318 | uint8_t *values; |
| 319 | struct rcu_ja_node_flag **pointers; |
| 320 | struct rcu_ja_node_flag *ptr; |
| 321 | unsigned int i; |
| 322 | |
| 323 | assert(type->type_class == RCU_JA_LINEAR || type->type_class == RCU_JA_POOL); |
| 324 | |
| 325 | nr_child = ja_linear_node_get_nr_child(type, node); |
| 326 | cmm_smp_rmb(); /* read nr_child before values and pointers */ |
| 327 | assert(nr_child <= type->max_linear_child); |
| 328 | assert(type->type_class != RCU_JA_LINEAR || nr_child >= type->min_child); |
| 329 | |
| 330 | values = &node->u.data[1]; |
| 331 | for (i = 0; i < nr_child; i++) { |
| 332 | if (CMM_LOAD_SHARED(values[i]) == n) |
| 333 | break; |
| 334 | } |
| 335 | if (i >= nr_child) |
| 336 | return NULL; |
| 337 | pointers = (struct rcu_ja_node_flag **) align_ptr_size(&values[type->max_linear_child]); |
| 338 | ptr = rcu_dereference(pointers[i]); |
| 339 | assert(ja_node_ptr(ptr) != NULL); |
| 340 | return ptr; |
| 341 | } |
| 342 | |
| 343 | static |
| 344 | struct rcu_ja_node_flag *ja_linear_node_get_ith_pos(const struct rcu_ja_type *type, |
| 345 | struct rcu_ja_node *node, |
| 346 | uint8_t i, |
| 347 | uint8_t *v, |
| 348 | struct rcu_ja_node_flag **iter) |
| 349 | { |
| 350 | uint8_t *values; |
| 351 | struct rcu_ja_node_flag **pointers; |
| 352 | |
| 353 | assert(type->type_class == RCU_JA_LINEAR || type->type_class == RCU_JA_POOL); |
| 354 | assert(i < ja_linear_node_get_nr_child(type, node)); |
| 355 | |
| 356 | values = &node->u.data[1]; |
| 357 | *v = values[i]; |
| 358 | pointers = (struct rcu_ja_node_flag **) align_ptr_size(&values[type->max_linear_child]); |
| 359 | *iter = pointers[i]; |
| 360 | } |
| 361 | |
| 362 | static |
| 363 | struct rcu_ja_node_flag *ja_pool_node_get_nth(const struct rcu_ja_type *type, |
| 364 | struct rcu_ja_node *node, |
| 365 | uint8_t n) |
| 366 | { |
| 367 | struct rcu_ja_node *linear; |
| 368 | |
| 369 | assert(type->type_class == RCU_JA_POOL); |
| 370 | /* |
| 371 | * TODO: currently, we select the pool by highest bits. We |
| 372 | * should support various encodings. |
| 373 | */ |
| 374 | linear = (struct rcu_ja_node *) |
| 375 | &node->u.data[((unsigned long) n >> (CHAR_BIT - type->nr_pool_order)) << type->pool_size_order]; |
| 376 | return ja_linear_node_get_nth(type, linear, n); |
| 377 | } |
| 378 | |
| 379 | static |
| 380 | struct rcu_ja_node *ja_pool_node_get_ith_pool(const struct rcu_ja_type *type, |
| 381 | struct rcu_ja_node *node, |
| 382 | uint8_t i) |
| 383 | { |
| 384 | assert(type->type_class == RCU_JA_POOL); |
| 385 | return (struct rcu_ja_node *) |
| 386 | &node->u.data[(unsigned int) i << type->pool_size_order]; |
| 387 | } |
| 388 | |
| 389 | static |
| 390 | struct rcu_ja_node_flag *ja_pigeon_node_get_nth(const struct rcu_ja_type *type, |
| 391 | struct rcu_ja_node *node, |
| 392 | uint8_t n) |
| 393 | { |
| 394 | assert(type->type_class == RCU_JA_PIGEON); |
| 395 | return rcu_dereference(((struct rcu_ja_node_flag **) node->u.data)[n]); |
| 396 | } |
| 397 | |
| 398 | /* |
| 399 | * ja_node_get_nth: get nth item from a node. |
| 400 | * node_flag is already rcu_dereference'd. |
| 401 | */ |
| 402 | static |
| 403 | struct rcu_ja_node_flag *ja_node_get_nth(struct rcu_ja_node_flag *node_flag, |
| 404 | uint8_t n) |
| 405 | { |
| 406 | unsigned int type_index; |
| 407 | struct rcu_ja_node *node; |
| 408 | const struct rcu_ja_type *type; |
| 409 | |
| 410 | node = ja_node_ptr(node_flag); |
| 411 | assert(node != NULL); |
| 412 | type_index = ja_node_type(node_flag); |
| 413 | type = &ja_types[type_index]; |
| 414 | |
| 415 | switch (type->type_class) { |
| 416 | case RCU_JA_LINEAR: |
| 417 | return ja_linear_node_get_nth(type, node, n); |
| 418 | case RCU_JA_POOL: |
| 419 | return ja_pool_node_get_nth(type, node, n); |
| 420 | case RCU_JA_PIGEON: |
| 421 | return ja_pigeon_node_get_nth(type, node, n); |
| 422 | default: |
| 423 | assert(0); |
| 424 | return (void *) -1UL; |
| 425 | } |
| 426 | } |
| 427 | |
| 428 | static |
| 429 | unsigned int ja_get_nr_child(struct rcu_ja_shadow_node *shadow_node) |
| 430 | { |
| 431 | return shadow_node->nr_child; |
| 432 | } |
| 433 | |
| 434 | static |
| 435 | int ja_linear_node_set_nth(const struct rcu_ja_type *type, |
| 436 | struct rcu_ja_node *node, |
| 437 | struct rcu_ja_shadow_node *shadow_node, |
| 438 | uint8_t n, |
| 439 | struct rcu_ja_node_flag *child_node_flag) |
| 440 | { |
| 441 | uint8_t nr_child; |
| 442 | uint8_t *values, *nr_child_ptr; |
| 443 | struct rcu_ja_node_flag **pointers; |
| 444 | unsigned int i; |
| 445 | |
| 446 | assert(type->type_class == RCU_JA_LINEAR || type->type_class == RCU_JA_POOL); |
| 447 | |
| 448 | nr_child_ptr = &node->u.data[0]; |
| 449 | nr_child = *nr_child_ptr; |
| 450 | assert(nr_child <= type->max_linear_child); |
| 451 | assert(type->type_class != RCU_JA_LINEAR || nr_child >= type->min_child); |
| 452 | |
| 453 | values = &node->u.data[1]; |
| 454 | for (i = 0; i < nr_child; i++) { |
| 455 | if (values[i] == n) |
| 456 | return -EEXIST; |
| 457 | } |
| 458 | if (nr_child >= type->max_linear_child) { |
| 459 | /* No space left in this node type */ |
| 460 | return -ENOSPC; |
| 461 | } |
| 462 | pointers = (struct rcu_ja_node_flag **) align_ptr_size(&values[type->max_linear_child]); |
| 463 | assert(pointers[nr_child] == NULL); |
| 464 | rcu_assign_pointer(pointers[nr_child], child_node_flag); |
| 465 | CMM_STORE_SHARED(values[nr_child], n); |
| 466 | cmm_smp_wmb(); /* write value and pointer before nr_child */ |
| 467 | CMM_STORE_SHARED(*nr_child_ptr, nr_child + 1); |
| 468 | shadow_node->nr_child++; |
| 469 | return 0; |
| 470 | } |
| 471 | |
| 472 | static |
| 473 | int ja_pool_node_set_nth(const struct rcu_ja_type *type, |
| 474 | struct rcu_ja_node *node, |
| 475 | struct rcu_ja_shadow_node *shadow_node, |
| 476 | uint8_t n, |
| 477 | struct rcu_ja_node_flag *child_node_flag) |
| 478 | { |
| 479 | struct rcu_ja_node *linear; |
| 480 | |
| 481 | assert(type->type_class == RCU_JA_POOL); |
| 482 | linear = (struct rcu_ja_node *) |
| 483 | &node->u.data[((unsigned long) n >> (CHAR_BIT - type->nr_pool_order)) << type->pool_size_order]; |
| 484 | return ja_linear_node_set_nth(type, linear, shadow_node, |
| 485 | n, child_node_flag); |
| 486 | } |
| 487 | |
| 488 | static |
| 489 | int ja_pigeon_node_set_nth(const struct rcu_ja_type *type, |
| 490 | struct rcu_ja_node *node, |
| 491 | struct rcu_ja_shadow_node *shadow_node, |
| 492 | uint8_t n, |
| 493 | struct rcu_ja_node_flag *child_node_flag) |
| 494 | { |
| 495 | struct rcu_ja_node_flag **ptr; |
| 496 | |
| 497 | assert(type->type_class == RCU_JA_PIGEON); |
| 498 | ptr = &((struct rcu_ja_node_flag **) node->u.data)[n]; |
| 499 | if (*ptr != NULL) |
| 500 | return -EEXIST; |
| 501 | rcu_assign_pointer(*ptr, child_node_flag); |
| 502 | shadow_node->nr_child++; |
| 503 | return 0; |
| 504 | } |
| 505 | |
| 506 | /* |
| 507 | * _ja_node_set_nth: set nth item within a node. Return an error |
| 508 | * (negative error value) if it is already there. |
| 509 | * TODO: exclusive access on node. |
| 510 | */ |
| 511 | static |
| 512 | int _ja_node_set_nth(const struct rcu_ja_type *type, |
| 513 | struct rcu_ja_node *node, |
| 514 | struct rcu_ja_shadow_node *shadow_node, |
| 515 | uint8_t n, |
| 516 | struct rcu_ja_node_flag *child_node_flag) |
| 517 | { |
| 518 | switch (type->type_class) { |
| 519 | case RCU_JA_LINEAR: |
| 520 | return ja_linear_node_set_nth(type, node, shadow_node, n, |
| 521 | child_node_flag); |
| 522 | case RCU_JA_POOL: |
| 523 | return ja_pool_node_set_nth(type, node, shadow_node, n, |
| 524 | child_node_flag); |
| 525 | case RCU_JA_PIGEON: |
| 526 | return ja_pigeon_node_set_nth(type, node, shadow_node, n, |
| 527 | child_node_flag); |
| 528 | case RCU_JA_NULL: |
| 529 | return -ENOSPC; |
| 530 | default: |
| 531 | assert(0); |
| 532 | return -EINVAL; |
| 533 | } |
| 534 | |
| 535 | return 0; |
| 536 | } |
| 537 | |
| 538 | /* |
| 539 | * ja_node_recompact_add: recompact a node, adding a new child. |
| 540 | * TODO: for pool type, take selection bit(s) into account. |
| 541 | */ |
| 542 | static |
| 543 | int ja_node_recompact_add(struct rcu_ja *ja, |
| 544 | unsigned int old_type_index, |
| 545 | const struct rcu_ja_type *old_type, |
| 546 | struct rcu_ja_node *old_node, |
| 547 | struct rcu_ja_shadow_node **shadow_node, |
| 548 | struct rcu_ja_node_flag **old_node_flag, uint8_t n, |
| 549 | struct rcu_ja_node_flag *child_node_flag) |
| 550 | { |
| 551 | unsigned int new_type_index; |
| 552 | struct rcu_ja_node *new_node; |
| 553 | const struct rcu_ja_type *new_type; |
| 554 | struct rcu_ja_node_flag *new_node_flag; |
| 555 | int ret; |
| 556 | |
| 557 | if (*shadow_node == NULL) { |
| 558 | new_type_index = 0; |
| 559 | } else { |
| 560 | new_type_index = old_type_index + 1; |
| 561 | } |
| 562 | new_type = &ja_types[new_type_index]; |
| 563 | new_node = alloc_rcu_ja_node(new_type); |
| 564 | if (!new_node) |
| 565 | return -ENOMEM; |
| 566 | new_node_flag = ja_node_flag(new_node, new_type_index); |
| 567 | |
| 568 | ret = rcuja_shadow_set(ja->ht, new_node, *shadow_node); |
| 569 | if (ret) |
| 570 | return ret; |
| 571 | |
| 572 | if (*shadow_node == NULL) { |
| 573 | *shadow_node = rcuja_shadow_lookup_lock(ja->ht, new_node); |
| 574 | assert(*shadow_node); |
| 575 | } |
| 576 | |
| 577 | /* |
| 578 | * We need to clear nr_child, because it will be re-incremented |
| 579 | * by _ja_node_set_nth(). |
| 580 | */ |
| 581 | (*shadow_node)->nr_child = 0; |
| 582 | |
| 583 | assert(old_type->type_class != RCU_JA_PIGEON); |
| 584 | switch (old_type->type_class) { |
| 585 | case RCU_JA_LINEAR: |
| 586 | { |
| 587 | uint8_t nr_child = |
| 588 | ja_linear_node_get_nr_child(old_type, old_node); |
| 589 | unsigned int i; |
| 590 | |
| 591 | for (i = 0; i < nr_child; i++) { |
| 592 | struct rcu_ja_node_flag *iter; |
| 593 | uint8_t v; |
| 594 | |
| 595 | ja_linear_node_get_ith_pos(old_type, old_node, i, &v, &iter); |
| 596 | if (!iter) |
| 597 | continue; |
| 598 | ret = _ja_node_set_nth(new_type, new_node, *shadow_node, |
| 599 | v, iter); |
| 600 | assert(!ret); |
| 601 | } |
| 602 | break; |
| 603 | } |
| 604 | case RCU_JA_POOL: |
| 605 | { |
| 606 | unsigned int pool_nr; |
| 607 | |
| 608 | for (pool_nr = 0; pool_nr < (1U << old_type->nr_pool_order); pool_nr++) { |
| 609 | struct rcu_ja_node *pool = |
| 610 | ja_pool_node_get_ith_pool(old_type, |
| 611 | old_node, pool_nr); |
| 612 | uint8_t nr_child = |
| 613 | ja_linear_node_get_nr_child(old_type, pool); |
| 614 | unsigned int j; |
| 615 | |
| 616 | for (j = 0; j < nr_child; j++) { |
| 617 | struct rcu_ja_node_flag *iter; |
| 618 | uint8_t v; |
| 619 | |
| 620 | ja_linear_node_get_ith_pos(old_type, pool, |
| 621 | j, &v, &iter); |
| 622 | if (!iter) |
| 623 | continue; |
| 624 | ret = _ja_node_set_nth(new_type, new_node, *shadow_node, |
| 625 | v, iter); |
| 626 | assert(!ret); |
| 627 | } |
| 628 | } |
| 629 | break; |
| 630 | } |
| 631 | case RCU_JA_PIGEON: |
| 632 | default: |
| 633 | assert(0); |
| 634 | return -EINVAL; |
| 635 | } |
| 636 | |
| 637 | /* add node */ |
| 638 | ret = _ja_node_set_nth(new_type, new_node, *shadow_node, |
| 639 | n, child_node_flag); |
| 640 | assert(!ret); |
| 641 | /* Replace the old node with the new recompacted one */ |
| 642 | rcu_assign_pointer(*old_node_flag, new_node_flag); |
| 643 | ret = rcuja_shadow_clear(ja->ht, old_node, |
| 644 | RCUJA_SHADOW_CLEAR_FREE_NODE); |
| 645 | assert(!ret); |
| 646 | return 0; |
| 647 | } |
| 648 | |
| 649 | static |
| 650 | int ja_node_set_nth(struct rcu_ja *ja, |
| 651 | struct rcu_ja_node_flag **node_flag, uint8_t n, |
| 652 | struct rcu_ja_node_flag *child_node_flag) |
| 653 | { |
| 654 | int ret; |
| 655 | unsigned int type_index; |
| 656 | const struct rcu_ja_type *type; |
| 657 | struct rcu_ja_node *node; |
| 658 | struct rcu_ja_shadow_node *shadow_node = NULL; |
| 659 | |
| 660 | node = ja_node_ptr(*node_flag); |
| 661 | type_index = ja_node_type(*node_flag); |
| 662 | type = &ja_types[type_index]; |
| 663 | if (node != NULL) { |
| 664 | shadow_node = rcuja_shadow_lookup_lock(ja->ht, node); |
| 665 | assert(shadow_node); |
| 666 | } |
| 667 | ret = _ja_node_set_nth(type, node, shadow_node, |
| 668 | n, child_node_flag); |
| 669 | if (ret == -ENOSPC) { |
| 670 | /* Not enough space in node, need to recompact. */ |
| 671 | ret = ja_node_recompact_add(ja, type_index, type, node, |
| 672 | &shadow_node, node_flag, n, child_node_flag); |
| 673 | /* recompact always leave shadow_node locked */ |
| 674 | } |
| 675 | rcuja_shadow_unlock(shadow_node); |
| 676 | return ret; |
| 677 | } |