lib/objagg.c

   1 // SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
   2 /* Copyright (c) 2018 Mellanox Technologies. All rights reserved */
   3
   4 #include <linux/module.h>
   5 #include <linux/slab.h>
   6 #include <linux/rhashtable.h>
   7 #include <linux/list.h>
   8 #include <linux/sort.h>
   9 #include <linux/objagg.h>
  10
  11 #define CREATE_TRACE_POINTS
  12 #include <trace/events/objagg.h>
  13
  14 struct objagg {
  15         const struct objagg_ops *ops;
  16         void *priv;
  17         struct rhashtable obj_ht;
  18         struct rhashtable_params ht_params;
  19         struct list_head obj_list;
  20         unsigned int obj_count;
  21 };
  22
  23 struct objagg_obj {
  24         struct rhash_head ht_node; /* member of objagg->obj_ht */
  25         struct list_head list; /* member of objagg->obj_list */
  26         struct objagg_obj *parent; /* if the object is nested, this
  27                                     * holds pointer to parent, otherwise NULL
  28                                     */
  29         union {
  30                 void *delta_priv; /* user delta private */
  31                 void *root_priv; /* user root private */
  32         };
  33         unsigned int refcount; /* counts number of users of this object
  34                                 * including nested objects
  35                                 */
  36         struct objagg_obj_stats stats;
  37         unsigned long obj[0];
  38 };
  39
  40 static unsigned int objagg_obj_ref_inc(struct objagg_obj *objagg_obj)
  41 {
  42         return ++objagg_obj->refcount;
  43 }
  44
  45 static unsigned int objagg_obj_ref_dec(struct objagg_obj *objagg_obj)
  46 {
  47         return --objagg_obj->refcount;
  48 }
  49
  50 static void objagg_obj_stats_inc(struct objagg_obj *objagg_obj)
  51 {
  52         objagg_obj->stats.user_count++;
  53         objagg_obj->stats.delta_user_count++;
  54         if (objagg_obj->parent)
  55                 objagg_obj->parent->stats.delta_user_count++;
  56 }
  57
  58 static void objagg_obj_stats_dec(struct objagg_obj *objagg_obj)
  59 {
  60         objagg_obj->stats.user_count--;
  61         objagg_obj->stats.delta_user_count--;
  62         if (objagg_obj->parent)
  63                 objagg_obj->parent->stats.delta_user_count--;
  64 }
  65
  66 static bool objagg_obj_is_root(const struct objagg_obj *objagg_obj)
  67 {
  68         /* Nesting is not supported, so we can use ->parent
  69          * to figure out if the object is root.
  70          */
  71         return !objagg_obj->parent;
  72 }
  73
  74 /**
  75  * objagg_obj_root_priv - obtains root private for an object
  76  * @objagg_obj: objagg object instance
  77  *
  78  * Note: all locking must be provided by the caller.
  79  *
  80  * Either the object is root itself when the private is returned
  81  * directly, or the parent is root and its private is returned
  82  * instead.
  83  *
  84  * Returns a user private root pointer.
  85  */
  86 const void *objagg_obj_root_priv(const struct objagg_obj *objagg_obj)
  87 {
  88         if (objagg_obj_is_root(objagg_obj))
  89                 return objagg_obj->root_priv;
  90         WARN_ON(!objagg_obj_is_root(objagg_obj->parent));
  91         return objagg_obj->parent->root_priv;
  92 }
  93 EXPORT_SYMBOL(objagg_obj_root_priv);
  94
  95 /**
  96  * objagg_obj_delta_priv - obtains delta private for an object
  97  * @objagg_obj: objagg object instance
  98  *
  99  * Note: all locking must be provided by the caller.
 100  *
 101  * Returns user private delta pointer or NULL in case the passed
 102  * object is root.
 103  */
 104 const void *objagg_obj_delta_priv(const struct objagg_obj *objagg_obj)
 105 {
 106         if (objagg_obj_is_root(objagg_obj))
 107                 return NULL;
 108         return objagg_obj->delta_priv;
 109 }
 110 EXPORT_SYMBOL(objagg_obj_delta_priv);
 111
 112 /**
 113  * objagg_obj_raw - obtains object user private pointer
 114  * @objagg_obj: objagg object instance
 115  *
 116  * Note: all locking must be provided by the caller.
 117  *
 118  * Returns user private pointer as was passed to objagg_obj_get() by "obj" arg.
 119  */
 120 const void *objagg_obj_raw(const struct objagg_obj *objagg_obj)
 121 {
 122         return objagg_obj->obj;
 123 }
 124 EXPORT_SYMBOL(objagg_obj_raw);
 125
 126 static struct objagg_obj *objagg_obj_lookup(struct objagg *objagg, void *obj)
 127 {
 128         return rhashtable_lookup_fast(&objagg->obj_ht, obj, objagg->ht_params);
 129 }
 130
 131 static int objagg_obj_parent_assign(struct objagg *objagg,
 132                                     struct objagg_obj *objagg_obj,
 133                                     struct objagg_obj *parent)
 134 {
 135         void *delta_priv;
 136
 137         delta_priv = objagg->ops->delta_create(objagg->priv, parent->obj,
 138                                                objagg_obj->obj);
 139         if (IS_ERR(delta_priv))
 140                 return PTR_ERR(delta_priv);
 141
 142         /* User returned a delta private, that means that
 143          * our object can be aggregated into the parent.
 144          */
 145         objagg_obj->parent = parent;
 146         objagg_obj->delta_priv = delta_priv;
 147         objagg_obj_ref_inc(objagg_obj->parent);
 148         trace_objagg_obj_parent_assign(objagg, objagg_obj,
 149                                        parent,
 150                                        parent->refcount);
 151         return 0;
 152 }
 153
 154 static int objagg_obj_parent_lookup_assign(struct objagg *objagg,
 155                                            struct objagg_obj *objagg_obj)
 156 {
 157         struct objagg_obj *objagg_obj_cur;
 158         int err;
 159
 160         list_for_each_entry(objagg_obj_cur, &objagg->obj_list, list) {
 161                 /* Nesting is not supported. In case the object
 162                  * is not root, it cannot be assigned as parent.
 163                  */
 164                 if (!objagg_obj_is_root(objagg_obj_cur))
 165                         continue;
 166                 err = objagg_obj_parent_assign(objagg, objagg_obj,
 167                                                objagg_obj_cur);
 168                 if (!err)
 169                         return 0;
 170         }
 171         return -ENOENT;
 172 }
 173
 174 static void __objagg_obj_put(struct objagg *objagg,
 175                              struct objagg_obj *objagg_obj);
 176
 177 static void objagg_obj_parent_unassign(struct objagg *objagg,
 178                                        struct objagg_obj *objagg_obj)
 179 {
 180         trace_objagg_obj_parent_unassign(objagg, objagg_obj,
 181                                          objagg_obj->parent,
 182                                          objagg_obj->parent->refcount);
 183         objagg->ops->delta_destroy(objagg->priv, objagg_obj->delta_priv);
 184         __objagg_obj_put(objagg, objagg_obj->parent);
 185 }
 186
 187 static int objagg_obj_root_create(struct objagg *objagg,
 188                                   struct objagg_obj *objagg_obj)
 189 {
 190         objagg_obj->root_priv = objagg->ops->root_create(objagg->priv,
 191                                                          objagg_obj->obj);
 192         if (IS_ERR(objagg_obj->root_priv))
 193                 return PTR_ERR(objagg_obj->root_priv);
 194
 195         trace_objagg_obj_root_create(objagg, objagg_obj);
 196         return 0;
 197 }
 198
 199 static void objagg_obj_root_destroy(struct objagg *objagg,
 200                                     struct objagg_obj *objagg_obj)
 201 {
 202         trace_objagg_obj_root_destroy(objagg, objagg_obj);
 203         objagg->ops->root_destroy(objagg->priv, objagg_obj->root_priv);
 204 }
 205
 206 static int objagg_obj_init(struct objagg *objagg,
 207                            struct objagg_obj *objagg_obj)
 208 {
 209         int err;
 210
 211         /* Try to find if the object can be aggregated under an existing one. */
 212         err = objagg_obj_parent_lookup_assign(objagg, objagg_obj);
 213         if (!err)
 214                 return 0;
 215         /* If aggregation is not possible, make the object a root. */
 216         return objagg_obj_root_create(objagg, objagg_obj);
 217 }
 218
 219 static void objagg_obj_fini(struct objagg *objagg,
 220                             struct objagg_obj *objagg_obj)
 221 {
 222         if (!objagg_obj_is_root(objagg_obj))
 223                 objagg_obj_parent_unassign(objagg, objagg_obj);
 224         else
 225                 objagg_obj_root_destroy(objagg, objagg_obj);
 226 }
 227
 228 static struct objagg_obj *objagg_obj_create(struct objagg *objagg, void *obj)
 229 {
 230         struct objagg_obj *objagg_obj;
 231         int err;
 232
 233         objagg_obj = kzalloc(sizeof(*objagg_obj) + objagg->ops->obj_size,
 234                              GFP_KERNEL);
 235         if (!objagg_obj)
 236                 return ERR_PTR(-ENOMEM);
 237         objagg_obj_ref_inc(objagg_obj);
 238         memcpy(objagg_obj->obj, obj, objagg->ops->obj_size);
 239
 240         err = objagg_obj_init(objagg, objagg_obj);
 241         if (err)
 242                 goto err_obj_init;
 243
 244         err = rhashtable_insert_fast(&objagg->obj_ht, &objagg_obj->ht_node,
 245                                      objagg->ht_params);
 246         if (err)
 247                 goto err_ht_insert;
 248         list_add(&objagg_obj->list, &objagg->obj_list);
 249         objagg->obj_count++;
 250         trace_objagg_obj_create(objagg, objagg_obj);
 251
 252         return objagg_obj;
 253
 254 err_ht_insert:
 255         objagg_obj_fini(objagg, objagg_obj);
 256 err_obj_init:
 257         kfree(objagg_obj);
 258         return ERR_PTR(err);
 259 }
 260
 261 static struct objagg_obj *__objagg_obj_get(struct objagg *objagg, void *obj)
 262 {
 263         struct objagg_obj *objagg_obj;
 264
 265         /* First, try to find the object exactly as user passed it,
 266          * perhaps it is already in use.
 267          */
 268         objagg_obj = objagg_obj_lookup(objagg, obj);
 269         if (objagg_obj) {
 270                 objagg_obj_ref_inc(objagg_obj);
 271                 return objagg_obj;
 272         }
 273
 274         return objagg_obj_create(objagg, obj);
 275 }
 276
 277 /**
 278  * objagg_obj_get - gets an object within objagg instance
 279  * @objagg:     objagg instance
 280  * @obj:        user-specific private object pointer
 281  *
 282  * Note: all locking must be provided by the caller.
 283  *
 284  * Size of the "obj" memory is specified in "objagg->ops".
 285  *
 286  * There are 3 main options this function wraps:
 287  * 1) The object according to "obj" already exist. In that case
 288  *    the reference counter is incrementes and the object is returned.
 289  * 2) The object does not exist, but it can be aggregated within
 290  *    another object. In that case, user ops->delta_create() is called
 291  *    to obtain delta data and a new object is created with returned
 292  *    user-delta private pointer.
 293  * 3) The object does not exist and cannot be aggregated into
 294  *    any of the existing objects. In that case, user ops->root_create()
 295  *    is called to create the root and a new object is created with
 296  *    returned user-root private pointer.
 297  *
 298  * Returns a pointer to objagg object instance in case of success,
 299  * otherwise it returns pointer error using ERR_PTR macro.
 300  */
 301 struct objagg_obj *objagg_obj_get(struct objagg *objagg, void *obj)
 302 {
 303         struct objagg_obj *objagg_obj;
 304
 305         objagg_obj = __objagg_obj_get(objagg, obj);
 306         if (IS_ERR(objagg_obj))
 307                 return objagg_obj;
 308         objagg_obj_stats_inc(objagg_obj);
 309         trace_objagg_obj_get(objagg, objagg_obj, objagg_obj->refcount);
 310         return objagg_obj;
 311 }
 312 EXPORT_SYMBOL(objagg_obj_get);
 313
 314 static void objagg_obj_destroy(struct objagg *objagg,
 315                                struct objagg_obj *objagg_obj)
 316 {
 317         trace_objagg_obj_destroy(objagg, objagg_obj);
 318         --objagg->obj_count;
 319         list_del(&objagg_obj->list);
 320         rhashtable_remove_fast(&objagg->obj_ht, &objagg_obj->ht_node,
 321                                objagg->ht_params);
 322         objagg_obj_fini(objagg, objagg_obj);
 323         kfree(objagg_obj);
 324 }
 325
 326 static void __objagg_obj_put(struct objagg *objagg,
 327                              struct objagg_obj *objagg_obj)
 328 {
 329         if (!objagg_obj_ref_dec(objagg_obj))
 330                 objagg_obj_destroy(objagg, objagg_obj);
 331 }
 332
 333 /**
 334  * objagg_obj_put - puts an object within objagg instance
 335  * @objagg:     objagg instance
 336  * @objagg_obj: objagg object instance
 337  *
 338  * Note: all locking must be provided by the caller.
 339  *
 340  * Symmetric to objagg_obj_get().
 341  */
 342 void objagg_obj_put(struct objagg *objagg, struct objagg_obj *objagg_obj)
 343 {
 344         trace_objagg_obj_put(objagg, objagg_obj, objagg_obj->refcount);
 345         objagg_obj_stats_dec(objagg_obj);
 346         __objagg_obj_put(objagg, objagg_obj);
 347 }
 348 EXPORT_SYMBOL(objagg_obj_put);
 349
 350 /**
 351  * objagg_create - creates a new objagg instance
 352  * @ops:        user-specific callbacks
 353  * @priv:       pointer to a private data passed to the ops
 354  *
 355  * Note: all locking must be provided by the caller.
 356  *
 357  * The purpose of the library is to provide an infrastructure to
 358  * aggregate user-specified objects. Library does not care about the type
 359  * of the object. User fills-up ops which take care of the specific
 360  * user object manipulation.
 361  *
 362  * As a very stupid example, consider integer numbers. For example
 363  * number 8 as a root object. That can aggregate number 9 with delta 1,
 364  * number 10 with delta 2, etc. This example is implemented as
 365  * a part of a testing module in test_objagg.c file.
 366  *
 367  * Each objagg instance contains multiple trees. Each tree node is
 368  * represented by "an object". In the current implementation there can be
 369  * only roots and leafs nodes. Leaf nodes are called deltas.
 370  * But in general, this can be easily extended for intermediate nodes.
 371  * In that extension, a delta would be associated with all non-root
 372  * nodes.
 373  *
 374  * Returns a pointer to newly created objagg instance in case of success,
 375  * otherwise it returns pointer error using ERR_PTR macro.
 376  */
 377 struct objagg *objagg_create(const struct objagg_ops *ops, void *priv)
 378 {
 379         struct objagg *objagg;
 380         int err;
 381
 382         if (WARN_ON(!ops || !ops->root_create || !ops->root_destroy ||
 383                     !ops->delta_create || !ops->delta_destroy))
 384                 return ERR_PTR(-EINVAL);
 385         objagg = kzalloc(sizeof(*objagg), GFP_KERNEL);
 386         if (!objagg)
 387                 return ERR_PTR(-ENOMEM);
 388         objagg->ops = ops;
 389         objagg->priv = priv;
 390         INIT_LIST_HEAD(&objagg->obj_list);
 391
 392         objagg->ht_params.key_len = ops->obj_size;
 393         objagg->ht_params.key_offset = offsetof(struct objagg_obj, obj);
 394         objagg->ht_params.head_offset = offsetof(struct objagg_obj, ht_node);
 395
 396         err = rhashtable_init(&objagg->obj_ht, &objagg->ht_params);
 397         if (err)
 398                 goto err_rhashtable_init;
 399
 400         trace_objagg_create(objagg);
 401         return objagg;
 402
 403 err_rhashtable_init:
 404         kfree(objagg);
 405         return ERR_PTR(err);
 406 }
 407 EXPORT_SYMBOL(objagg_create);
 408
 409 /**
 410  * objagg_destroy - destroys a new objagg instance
 411  * @objagg:     objagg instance
 412  *
 413  * Note: all locking must be provided by the caller.
 414  */
 415 void objagg_destroy(struct objagg *objagg)
 416 {
 417         trace_objagg_destroy(objagg);
 418         WARN_ON(!list_empty(&objagg->obj_list));
 419         rhashtable_destroy(&objagg->obj_ht);
 420         kfree(objagg);
 421 }
 422 EXPORT_SYMBOL(objagg_destroy);
 423
 424 static int objagg_stats_info_sort_cmp_func(const void *a, const void *b)
 425 {
 426         const struct objagg_obj_stats_info *stats_info1 = a;
 427         const struct objagg_obj_stats_info *stats_info2 = b;
 428
 429         if (stats_info1->is_root != stats_info2->is_root)
 430                 return stats_info2->is_root - stats_info1->is_root;
 431         if (stats_info1->stats.delta_user_count !=
 432             stats_info2->stats.delta_user_count)
 433                 return stats_info2->stats.delta_user_count -
 434                        stats_info1->stats.delta_user_count;
 435         return stats_info2->stats.user_count - stats_info1->stats.user_count;
 436 }
 437
 438 /**
 439  * objagg_stats_get - obtains stats of the objagg instance
 440  * @objagg:     objagg instance
 441  *
 442  * Note: all locking must be provided by the caller.
 443  *
 444  * The returned structure contains statistics of all object
 445  * currently in use, ordered by following rules:
 446  * 1) Root objects are always on lower indexes than the rest.
 447  * 2) Objects with higher delta user count are always on lower
 448  *    indexes.
 449  * 3) In case more objects have the same delta user count,
 450  *    the objects are ordered by user count.
 451  *
 452  * Returns a pointer to stats instance in case of success,
 453  * otherwise it returns pointer error using ERR_PTR macro.
 454  */
 455 const struct objagg_stats *objagg_stats_get(struct objagg *objagg)
 456 {
 457         struct objagg_stats *objagg_stats;
 458         struct objagg_obj *objagg_obj;
 459         size_t alloc_size;
 460         int i;
 461
 462         alloc_size = sizeof(*objagg_stats) +
 463                      sizeof(objagg_stats->stats_info[0]) * objagg->obj_count;
 464         objagg_stats = kzalloc(alloc_size, GFP_KERNEL);
 465         if (!objagg_stats)
 466                 return ERR_PTR(-ENOMEM);
 467
 468         i = 0;
 469         list_for_each_entry(objagg_obj, &objagg->obj_list, list) {
 470                 memcpy(&objagg_stats->stats_info[i].stats, &objagg_obj->stats,
 471                        sizeof(objagg_stats->stats_info[0].stats));
 472                 objagg_stats->stats_info[i].objagg_obj = objagg_obj;
 473                 objagg_stats->stats_info[i].is_root =
 474                                         objagg_obj_is_root(objagg_obj);
 475                 i++;
 476         }
 477         objagg_stats->stats_info_count = i;
 478
 479         sort(objagg_stats->stats_info, objagg_stats->stats_info_count,
 480              sizeof(struct objagg_obj_stats_info),
 481              objagg_stats_info_sort_cmp_func, NULL);
 482
 483         return objagg_stats;
 484 }
 485 EXPORT_SYMBOL(objagg_stats_get);
 486
 487 /**
 488  * objagg_stats_puts - puts stats of the objagg instance
 489  * @objagg_stats:       objagg instance stats
 490  *
 491  * Note: all locking must be provided by the caller.
 492  */
 493 void objagg_stats_put(const struct objagg_stats *objagg_stats)
 494 {
 495         kfree(objagg_stats);
 496 }
 497 EXPORT_SYMBOL(objagg_stats_put);
 498
 499 MODULE_LICENSE("Dual BSD/GPL");
 500 MODULE_AUTHOR("Jiri Pirko <jiri@mellanox.com>");
 501 MODULE_DESCRIPTION("Object aggregation manager");