lib/debugobjects.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Generic infrastructure for lifetime debugging of objects.
   4  *
   5  * Copyright (C) 2008, Thomas Gleixner <tglx@linutronix.de>
   6  */
   7
   8 #define pr_fmt(fmt) "ODEBUG: " fmt
   9
  10 #include <linux/debugobjects.h>
  11 #include <linux/interrupt.h>
  12 #include <linux/sched.h>
  13 #include <linux/sched/task_stack.h>
  14 #include <linux/seq_file.h>
  15 #include <linux/debugfs.h>
  16 #include <linux/slab.h>
  17 #include <linux/hash.h>
  18 #include <linux/kmemleak.h>
  19 #include <linux/cpu.h>
  20
  21 #define ODEBUG_HASH_BITS        14
  22 #define ODEBUG_HASH_SIZE        (1 << ODEBUG_HASH_BITS)
  23
  24 #define ODEBUG_POOL_SIZE        1024
  25 #define ODEBUG_POOL_MIN_LEVEL   256
  26 #define ODEBUG_POOL_PERCPU_SIZE 64
  27 #define ODEBUG_BATCH_SIZE       16
  28
  29 #define ODEBUG_CHUNK_SHIFT      PAGE_SHIFT
  30 #define ODEBUG_CHUNK_SIZE       (1 << ODEBUG_CHUNK_SHIFT)
  31 #define ODEBUG_CHUNK_MASK       (~(ODEBUG_CHUNK_SIZE - 1))
  32
  33 /*
  34  * We limit the freeing of debug objects via workqueue at a maximum
  35  * frequency of 10Hz and about 1024 objects for each freeing operation.
  36  * So it is freeing at most 10k debug objects per second.
  37  */
  38 #define ODEBUG_FREE_WORK_MAX    1024
  39 #define ODEBUG_FREE_WORK_DELAY  DIV_ROUND_UP(HZ, 10)
  40
  41 struct debug_bucket {
  42         struct hlist_head       list;
  43         raw_spinlock_t          lock;
  44 };
  45
  46 /*
  47  * Debug object percpu free list
  48  * Access is protected by disabling irq
  49  */
  50 struct debug_percpu_free {
  51         struct hlist_head       free_objs;
  52         int                     obj_free;
  53 };
  54
  55 static DEFINE_PER_CPU(struct debug_percpu_free, percpu_obj_pool);
  56
  57 static struct debug_bucket      obj_hash[ODEBUG_HASH_SIZE];
  58
  59 static struct debug_obj         obj_static_pool[ODEBUG_POOL_SIZE] __initdata;
  60
  61 static DEFINE_RAW_SPINLOCK(pool_lock);
  62
  63 static HLIST_HEAD(obj_pool);
  64 static HLIST_HEAD(obj_to_free);
  65
  66 /*
  67  * Because of the presence of percpu free pools, obj_pool_free will
  68  * under-count those in the percpu free pools. Similarly, obj_pool_used
  69  * will over-count those in the percpu free pools. Adjustments will be
  70  * made at debug_stats_show(). Both obj_pool_min_free and obj_pool_max_used
  71  * can be off.
  72  */
  73 static int                      obj_pool_min_free = ODEBUG_POOL_SIZE;
  74 static int                      obj_pool_free = ODEBUG_POOL_SIZE;
  75 static int                      obj_pool_used;
  76 static int                      obj_pool_max_used;
  77 static bool                     obj_freeing;
  78 /* The number of objs on the global free list */
  79 static int                      obj_nr_tofree;
  80
  81 static int                      debug_objects_maxchain __read_mostly;
  82 static int __maybe_unused       debug_objects_maxchecked __read_mostly;
  83 static int                      debug_objects_fixups __read_mostly;
  84 static int                      debug_objects_warnings __read_mostly;
  85 static int                      debug_objects_enabled __read_mostly
  86                                 = CONFIG_DEBUG_OBJECTS_ENABLE_DEFAULT;
  87 static int                      debug_objects_pool_size __read_mostly
  88                                 = ODEBUG_POOL_SIZE;
  89 static int                      debug_objects_pool_min_level __read_mostly
  90                                 = ODEBUG_POOL_MIN_LEVEL;
  91 static const struct debug_obj_descr *descr_test  __read_mostly;
  92 static struct kmem_cache        *obj_cache __read_mostly;
  93
  94 /*
  95  * Track numbers of kmem_cache_alloc()/free() calls done.
  96  */
  97 static int                      debug_objects_allocated;
  98 static int                      debug_objects_freed;
  99
 100 static void free_obj_work(struct work_struct *work);
 101 static DECLARE_DELAYED_WORK(debug_obj_work, free_obj_work);
 102
 103 static int __init enable_object_debug(char *str)
 104 {
 105         debug_objects_enabled = 1;
 106         return 0;
 107 }
 108
 109 static int __init disable_object_debug(char *str)
 110 {
 111         debug_objects_enabled = 0;
 112         return 0;
 113 }
 114
 115 early_param("debug_objects", enable_object_debug);
 116 early_param("no_debug_objects", disable_object_debug);
 117
 118 static const char *obj_states[ODEBUG_STATE_MAX] = {
 119         [ODEBUG_STATE_NONE]             = "none",
 120         [ODEBUG_STATE_INIT]             = "initialized",
 121         [ODEBUG_STATE_INACTIVE]         = "inactive",
 122         [ODEBUG_STATE_ACTIVE]           = "active",
 123         [ODEBUG_STATE_DESTROYED]        = "destroyed",
 124         [ODEBUG_STATE_NOTAVAILABLE]     = "not available",
 125 };
 126
 127 static void fill_pool(void)
 128 {
 129         gfp_t gfp = GFP_ATOMIC | __GFP_NORETRY | __GFP_NOWARN;
 130         struct debug_obj *obj;
 131         unsigned long flags;
 132
 133         if (likely(READ_ONCE(obj_pool_free) >= debug_objects_pool_min_level))
 134                 return;
 135
 136         /*
 137          * Reuse objs from the global free list; they will be reinitialized
 138          * when allocating.
 139          *
 140          * Both obj_nr_tofree and obj_pool_free are checked locklessly; the
 141          * READ_ONCE()s pair with the WRITE_ONCE()s in pool_lock critical
 142          * sections.
 143          */
 144         while (READ_ONCE(obj_nr_tofree) && (READ_ONCE(obj_pool_free) < obj_pool_min_free)) {
 145                 raw_spin_lock_irqsave(&pool_lock, flags);
 146                 /*
 147                  * Recheck with the lock held as the worker thread might have
 148                  * won the race and freed the global free list already.
 149                  */
 150                 while (obj_nr_tofree && (obj_pool_free < obj_pool_min_free)) {
 151                         obj = hlist_entry(obj_to_free.first, typeof(*obj), node);
 152                         hlist_del(&obj->node);
 153                         WRITE_ONCE(obj_nr_tofree, obj_nr_tofree - 1);
 154                         hlist_add_head(&obj->node, &obj_pool);
 155                         WRITE_ONCE(obj_pool_free, obj_pool_free + 1);
 156                 }
 157                 raw_spin_unlock_irqrestore(&pool_lock, flags);
 158         }
 159
 160         if (unlikely(!obj_cache))
 161                 return;
 162
 163         while (READ_ONCE(obj_pool_free) < debug_objects_pool_min_level) {
 164                 struct debug_obj *new[ODEBUG_BATCH_SIZE];
 165                 int cnt;
 166
 167                 for (cnt = 0; cnt < ODEBUG_BATCH_SIZE; cnt++) {
 168                         new[cnt] = kmem_cache_zalloc(obj_cache, gfp);
 169                         if (!new[cnt])
 170                                 break;
 171                 }
 172                 if (!cnt)
 173                         return;
 174
 175                 raw_spin_lock_irqsave(&pool_lock, flags);
 176                 while (cnt) {
 177                         hlist_add_head(&new[--cnt]->node, &obj_pool);
 178                         debug_objects_allocated++;
 179                         WRITE_ONCE(obj_pool_free, obj_pool_free + 1);
 180                 }
 181                 raw_spin_unlock_irqrestore(&pool_lock, flags);
 182         }
 183 }
 184
 185 /*
 186  * Lookup an object in the hash bucket.
 187  */
 188 static struct debug_obj *lookup_object(void *addr, struct debug_bucket *b)
 189 {
 190         struct debug_obj *obj;
 191         int cnt = 0;
 192
 193         hlist_for_each_entry(obj, &b->list, node) {
 194                 cnt++;
 195                 if (obj->object == addr)
 196                         return obj;
 197         }
 198         if (cnt > debug_objects_maxchain)
 199                 debug_objects_maxchain = cnt;
 200
 201         return NULL;
 202 }
 203
 204 /*
 205  * Allocate a new object from the hlist
 206  */
 207 static struct debug_obj *__alloc_object(struct hlist_head *list)
 208 {
 209         struct debug_obj *obj = NULL;
 210
 211         if (list->first) {
 212                 obj = hlist_entry(list->first, typeof(*obj), node);
 213                 hlist_del(&obj->node);
 214         }
 215
 216         return obj;
 217 }
 218
 219 /*
 220  * Allocate a new object. If the pool is empty, switch off the debugger.
 221  * Must be called with interrupts disabled.
 222  */
 223 static struct debug_obj *
 224 alloc_object(void *addr, struct debug_bucket *b, const struct debug_obj_descr *descr)
 225 {
 226         struct debug_percpu_free *percpu_pool = this_cpu_ptr(&percpu_obj_pool);
 227         struct debug_obj *obj;
 228
 229         if (likely(obj_cache)) {
 230                 obj = __alloc_object(&percpu_pool->free_objs);
 231                 if (obj) {
 232                         percpu_pool->obj_free--;
 233                         goto init_obj;
 234                 }
 235         }
 236
 237         raw_spin_lock(&pool_lock);
 238         obj = __alloc_object(&obj_pool);
 239         if (obj) {
 240                 obj_pool_used++;
 241                 WRITE_ONCE(obj_pool_free, obj_pool_free - 1);
 242
 243                 /*
 244                  * Looking ahead, allocate one batch of debug objects and
 245                  * put them into the percpu free pool.
 246                  */
 247                 if (likely(obj_cache)) {
 248                         int i;
 249
 250                         for (i = 0; i < ODEBUG_BATCH_SIZE; i++) {
 251                                 struct debug_obj *obj2;
 252
 253                                 obj2 = __alloc_object(&obj_pool);
 254                                 if (!obj2)
 255                                         break;
 256                                 hlist_add_head(&obj2->node,
 257                                                &percpu_pool->free_objs);
 258                                 percpu_pool->obj_free++;
 259                                 obj_pool_used++;
 260                                 WRITE_ONCE(obj_pool_free, obj_pool_free - 1);
 261                         }
 262                 }
 263
 264                 if (obj_pool_used > obj_pool_max_used)
 265                         obj_pool_max_used = obj_pool_used;
 266
 267                 if (obj_pool_free < obj_pool_min_free)
 268                         obj_pool_min_free = obj_pool_free;
 269         }
 270         raw_spin_unlock(&pool_lock);
 271
 272 init_obj:
 273         if (obj) {
 274                 obj->object = addr;
 275                 obj->descr  = descr;
 276                 obj->state  = ODEBUG_STATE_NONE;
 277                 obj->astate = 0;
 278                 hlist_add_head(&obj->node, &b->list);
 279         }
 280         return obj;
 281 }
 282
 283 /*
 284  * workqueue function to free objects.
 285  *
 286  * To reduce contention on the global pool_lock, the actual freeing of
 287  * debug objects will be delayed if the pool_lock is busy.
 288  */
 289 static void free_obj_work(struct work_struct *work)
 290 {
 291         struct hlist_node *tmp;
 292         struct debug_obj *obj;
 293         unsigned long flags;
 294         HLIST_HEAD(tofree);
 295
 296         WRITE_ONCE(obj_freeing, false);
 297         if (!raw_spin_trylock_irqsave(&pool_lock, flags))
 298                 return;
 299
 300         if (obj_pool_free >= debug_objects_pool_size)
 301                 goto free_objs;
 302
 303         /*
 304          * The objs on the pool list might be allocated before the work is
 305          * run, so recheck if pool list it full or not, if not fill pool
 306          * list from the global free list. As it is likely that a workload
 307          * may be gearing up to use more and more objects, don't free any
 308          * of them until the next round.
 309          */
 310         while (obj_nr_tofree && obj_pool_free < debug_objects_pool_size) {
 311                 obj = hlist_entry(obj_to_free.first, typeof(*obj), node);
 312                 hlist_del(&obj->node);
 313                 hlist_add_head(&obj->node, &obj_pool);
 314                 WRITE_ONCE(obj_pool_free, obj_pool_free + 1);
 315                 WRITE_ONCE(obj_nr_tofree, obj_nr_tofree - 1);
 316         }
 317         raw_spin_unlock_irqrestore(&pool_lock, flags);
 318         return;
 319
 320 free_objs:
 321         /*
 322          * Pool list is already full and there are still objs on the free
 323          * list. Move remaining free objs to a temporary list to free the
 324          * memory outside the pool_lock held region.
 325          */
 326         if (obj_nr_tofree) {
 327                 hlist_move_list(&obj_to_free, &tofree);
 328                 debug_objects_freed += obj_nr_tofree;
 329                 WRITE_ONCE(obj_nr_tofree, 0);
 330         }
 331         raw_spin_unlock_irqrestore(&pool_lock, flags);
 332
 333         hlist_for_each_entry_safe(obj, tmp, &tofree, node) {
 334                 hlist_del(&obj->node);
 335                 kmem_cache_free(obj_cache, obj);
 336         }
 337 }
 338
 339 static void __free_object(struct debug_obj *obj)
 340 {
 341         struct debug_obj *objs[ODEBUG_BATCH_SIZE];
 342         struct debug_percpu_free *percpu_pool;
 343         int lookahead_count = 0;
 344         unsigned long flags;
 345         bool work;
 346
 347         local_irq_save(flags);
 348         if (!obj_cache)
 349                 goto free_to_obj_pool;
 350
 351         /*
 352          * Try to free it into the percpu pool first.
 353          */
 354         percpu_pool = this_cpu_ptr(&percpu_obj_pool);
 355         if (percpu_pool->obj_free < ODEBUG_POOL_PERCPU_SIZE) {
 356                 hlist_add_head(&obj->node, &percpu_pool->free_objs);
 357                 percpu_pool->obj_free++;
 358                 local_irq_restore(flags);
 359                 return;
 360         }
 361
 362         /*
 363          * As the percpu pool is full, look ahead and pull out a batch
 364          * of objects from the percpu pool and free them as well.
 365          */
 366         for (; lookahead_count < ODEBUG_BATCH_SIZE; lookahead_count++) {
 367                 objs[lookahead_count] = __alloc_object(&percpu_pool->free_objs);
 368                 if (!objs[lookahead_count])
 369                         break;
 370                 percpu_pool->obj_free--;
 371         }
 372
 373 free_to_obj_pool:
 374         raw_spin_lock(&pool_lock);
 375         work = (obj_pool_free > debug_objects_pool_size) && obj_cache &&
 376                (obj_nr_tofree < ODEBUG_FREE_WORK_MAX);
 377         obj_pool_used--;
 378
 379         if (work) {
 380                 WRITE_ONCE(obj_nr_tofree, obj_nr_tofree + 1);
 381                 hlist_add_head(&obj->node, &obj_to_free);
 382                 if (lookahead_count) {
 383                         WRITE_ONCE(obj_nr_tofree, obj_nr_tofree + lookahead_count);
 384                         obj_pool_used -= lookahead_count;
 385                         while (lookahead_count) {
 386                                 hlist_add_head(&objs[--lookahead_count]->node,
 387                                                &obj_to_free);
 388                         }
 389                 }
 390
 391                 if ((obj_pool_free > debug_objects_pool_size) &&
 392                     (obj_nr_tofree < ODEBUG_FREE_WORK_MAX)) {
 393                         int i;
 394
 395                         /*
 396                          * Free one more batch of objects from obj_pool.
 397                          */
 398                         for (i = 0; i < ODEBUG_BATCH_SIZE; i++) {
 399                                 obj = __alloc_object(&obj_pool);
 400                                 hlist_add_head(&obj->node, &obj_to_free);
 401                                 WRITE_ONCE(obj_pool_free, obj_pool_free - 1);
 402                                 WRITE_ONCE(obj_nr_tofree, obj_nr_tofree + 1);
 403                         }
 404                 }
 405         } else {
 406                 WRITE_ONCE(obj_pool_free, obj_pool_free + 1);
 407                 hlist_add_head(&obj->node, &obj_pool);
 408                 if (lookahead_count) {
 409                         WRITE_ONCE(obj_pool_free, obj_pool_free + lookahead_count);
 410                         obj_pool_used -= lookahead_count;
 411                         while (lookahead_count) {
 412                                 hlist_add_head(&objs[--lookahead_count]->node,
 413                                                &obj_pool);
 414                         }
 415                 }
 416         }
 417         raw_spin_unlock(&pool_lock);
 418         local_irq_restore(flags);
 419 }
 420
 421 /*
 422  * Put the object back into the pool and schedule work to free objects
 423  * if necessary.
 424  */
 425 static void free_object(struct debug_obj *obj)
 426 {
 427         __free_object(obj);
 428         if (!READ_ONCE(obj_freeing) && READ_ONCE(obj_nr_tofree)) {
 429                 WRITE_ONCE(obj_freeing, true);
 430                 schedule_delayed_work(&debug_obj_work, ODEBUG_FREE_WORK_DELAY);
 431         }
 432 }
 433
 434 #ifdef CONFIG_HOTPLUG_CPU
 435 static int object_cpu_offline(unsigned int cpu)
 436 {
 437         struct debug_percpu_free *percpu_pool;
 438         struct hlist_node *tmp;
 439         struct debug_obj *obj;
 440
 441         /* Remote access is safe as the CPU is dead already */
 442         percpu_pool = per_cpu_ptr(&percpu_obj_pool, cpu);
 443         hlist_for_each_entry_safe(obj, tmp, &percpu_pool->free_objs, node) {
 444                 hlist_del(&obj->node);
 445                 kmem_cache_free(obj_cache, obj);
 446         }
 447         percpu_pool->obj_free = 0;
 448
 449         return 0;
 450 }
 451 #endif
 452
 453 /*
 454  * We run out of memory. That means we probably have tons of objects
 455  * allocated.
 456  */
 457 static void debug_objects_oom(void)
 458 {
 459         struct debug_bucket *db = obj_hash;
 460         struct hlist_node *tmp;
 461         HLIST_HEAD(freelist);
 462         struct debug_obj *obj;
 463         unsigned long flags;
 464         int i;
 465
 466         pr_warn("Out of memory. ODEBUG disabled\n");
 467
 468         for (i = 0; i < ODEBUG_HASH_SIZE; i++, db++) {
 469                 raw_spin_lock_irqsave(&db->lock, flags);
 470                 hlist_move_list(&db->list, &freelist);
 471                 raw_spin_unlock_irqrestore(&db->lock, flags);
 472
 473                 /* Now free them */
 474                 hlist_for_each_entry_safe(obj, tmp, &freelist, node) {
 475                         hlist_del(&obj->node);
 476                         free_object(obj);
 477                 }
 478         }
 479 }
 480
 481 /*
 482  * We use the pfn of the address for the hash. That way we can check
 483  * for freed objects simply by checking the affected bucket.
 484  */
 485 static struct debug_bucket *get_bucket(unsigned long addr)
 486 {
 487         unsigned long hash;
 488
 489         hash = hash_long((addr >> ODEBUG_CHUNK_SHIFT), ODEBUG_HASH_BITS);
 490         return &obj_hash[hash];
 491 }
 492
 493 static void debug_print_object(struct debug_obj *obj, char *msg)
 494 {
 495         const struct debug_obj_descr *descr = obj->descr;
 496         static int limit;
 497
 498         if (limit < 5 && descr != descr_test) {
 499                 void *hint = descr->debug_hint ?
 500                         descr->debug_hint(obj->object) : NULL;
 501                 limit++;
 502                 WARN(1, KERN_ERR "ODEBUG: %s %s (active state %u) "
 503                                  "object type: %s hint: %pS\n",
 504                         msg, obj_states[obj->state], obj->astate,
 505                         descr->name, hint);
 506         }
 507         debug_objects_warnings++;
 508 }
 509
 510 /*
 511  * Try to repair the damage, so we have a better chance to get useful
 512  * debug output.
 513  */
 514 static bool
 515 debug_object_fixup(bool (*fixup)(void *addr, enum debug_obj_state state),
 516                    void * addr, enum debug_obj_state state)
 517 {
 518         if (fixup && fixup(addr, state)) {
 519                 debug_objects_fixups++;
 520                 return true;
 521         }
 522         return false;
 523 }
 524
 525 static void debug_object_is_on_stack(void *addr, int onstack)
 526 {
 527         int is_on_stack;
 528         static int limit;
 529
 530         if (limit > 4)
 531                 return;
 532
 533         is_on_stack = object_is_on_stack(addr);
 534         if (is_on_stack == onstack)
 535                 return;
 536
 537         limit++;
 538         if (is_on_stack)
 539                 pr_warn("object %p is on stack %p, but NOT annotated.\n", addr,
 540                          task_stack_page(current));
 541         else
 542                 pr_warn("object %p is NOT on stack %p, but annotated.\n", addr,
 543                          task_stack_page(current));
 544
 545         WARN_ON(1);
 546 }
 547
 548 static void
 549 __debug_object_init(void *addr, const struct debug_obj_descr *descr, int onstack)
 550 {
 551         enum debug_obj_state state;
 552         bool check_stack = false;
 553         struct debug_bucket *db;
 554         struct debug_obj *obj;
 555         unsigned long flags;
 556
 557         /*
 558          * On RT enabled kernels the pool refill must happen in preemptible
 559          * context:
 560          */
 561         if (!IS_ENABLED(CONFIG_PREEMPT_RT) || preemptible())
 562                 fill_pool();
 563
 564         db = get_bucket((unsigned long) addr);
 565
 566         raw_spin_lock_irqsave(&db->lock, flags);
 567
 568         obj = lookup_object(addr, db);
 569         if (!obj) {
 570                 obj = alloc_object(addr, db, descr);
 571                 if (!obj) {
 572                         debug_objects_enabled = 0;
 573                         raw_spin_unlock_irqrestore(&db->lock, flags);
 574                         debug_objects_oom();
 575                         return;
 576                 }
 577                 check_stack = true;
 578         }
 579
 580         switch (obj->state) {
 581         case ODEBUG_STATE_NONE:
 582         case ODEBUG_STATE_INIT:
 583         case ODEBUG_STATE_INACTIVE:
 584                 obj->state = ODEBUG_STATE_INIT;
 585                 break;
 586
 587         case ODEBUG_STATE_ACTIVE:
 588                 state = obj->state;
 589                 raw_spin_unlock_irqrestore(&db->lock, flags);
 590                 debug_print_object(obj, "init");
 591                 debug_object_fixup(descr->fixup_init, addr, state);
 592                 return;
 593
 594         case ODEBUG_STATE_DESTROYED:
 595                 raw_spin_unlock_irqrestore(&db->lock, flags);
 596                 debug_print_object(obj, "init");
 597                 return;
 598         default:
 599                 break;
 600         }
 601
 602         raw_spin_unlock_irqrestore(&db->lock, flags);
 603         if (check_stack)
 604                 debug_object_is_on_stack(addr, onstack);
 605 }
 606
 607 /**
 608  * debug_object_init - debug checks when an object is initialized
 609  * @addr:       address of the object
 610  * @descr:      pointer to an object specific debug description structure
 611  */
 612 void debug_object_init(void *addr, const struct debug_obj_descr *descr)
 613 {
 614         if (!debug_objects_enabled)
 615                 return;
 616
 617         __debug_object_init(addr, descr, 0);
 618 }
 619 EXPORT_SYMBOL_GPL(debug_object_init);
 620
 621 /**
 622  * debug_object_init_on_stack - debug checks when an object on stack is
 623  *                              initialized
 624  * @addr:       address of the object
 625  * @descr:      pointer to an object specific debug description structure
 626  */
 627 void debug_object_init_on_stack(void *addr, const struct debug_obj_descr *descr)
 628 {
 629         if (!debug_objects_enabled)
 630                 return;
 631
 632         __debug_object_init(addr, descr, 1);
 633 }
 634 EXPORT_SYMBOL_GPL(debug_object_init_on_stack);
 635
 636 /**
 637  * debug_object_activate - debug checks when an object is activated
 638  * @addr:       address of the object
 639  * @descr:      pointer to an object specific debug description structure
 640  * Returns 0 for success, -EINVAL for check failed.
 641  */
 642 int debug_object_activate(void *addr, const struct debug_obj_descr *descr)
 643 {
 644         enum debug_obj_state state;
 645         struct debug_bucket *db;
 646         struct debug_obj *obj;
 647         unsigned long flags;
 648         int ret;
 649         struct debug_obj o = { .object = addr,
 650                                .state = ODEBUG_STATE_NOTAVAILABLE,
 651                                .descr = descr };
 652
 653         if (!debug_objects_enabled)
 654                 return 0;
 655
 656         db = get_bucket((unsigned long) addr);
 657
 658         raw_spin_lock_irqsave(&db->lock, flags);
 659
 660         obj = lookup_object(addr, db);
 661         if (obj) {
 662                 bool print_object = false;
 663
 664                 switch (obj->state) {
 665                 case ODEBUG_STATE_INIT:
 666                 case ODEBUG_STATE_INACTIVE:
 667                         obj->state = ODEBUG_STATE_ACTIVE;
 668                         ret = 0;
 669                         break;
 670
 671                 case ODEBUG_STATE_ACTIVE:
 672                         state = obj->state;
 673                         raw_spin_unlock_irqrestore(&db->lock, flags);
 674                         debug_print_object(obj, "activate");
 675                         ret = debug_object_fixup(descr->fixup_activate, addr, state);
 676                         return ret ? 0 : -EINVAL;
 677
 678                 case ODEBUG_STATE_DESTROYED:
 679                         print_object = true;
 680                         ret = -EINVAL;
 681                         break;
 682                 default:
 683                         ret = 0;
 684                         break;
 685                 }
 686                 raw_spin_unlock_irqrestore(&db->lock, flags);
 687                 if (print_object)
 688                         debug_print_object(obj, "activate");
 689                 return ret;
 690         }
 691
 692         raw_spin_unlock_irqrestore(&db->lock, flags);
 693
 694         /*
 695          * We are here when a static object is activated. We
 696          * let the type specific code confirm whether this is
 697          * true or not. if true, we just make sure that the
 698          * static object is tracked in the object tracker. If
 699          * not, this must be a bug, so we try to fix it up.
 700          */
 701         if (descr->is_static_object && descr->is_static_object(addr)) {
 702                 /* track this static object */
 703                 debug_object_init(addr, descr);
 704                 debug_object_activate(addr, descr);
 705         } else {
 706                 debug_print_object(&o, "activate");
 707                 ret = debug_object_fixup(descr->fixup_activate, addr,
 708                                         ODEBUG_STATE_NOTAVAILABLE);
 709                 return ret ? 0 : -EINVAL;
 710         }
 711         return 0;
 712 }
 713 EXPORT_SYMBOL_GPL(debug_object_activate);
 714
 715 /**
 716  * debug_object_deactivate - debug checks when an object is deactivated
 717  * @addr:       address of the object
 718  * @descr:      pointer to an object specific debug description structure
 719  */
 720 void debug_object_deactivate(void *addr, const struct debug_obj_descr *descr)
 721 {
 722         struct debug_bucket *db;
 723         struct debug_obj *obj;
 724         unsigned long flags;
 725         bool print_object = false;
 726
 727         if (!debug_objects_enabled)
 728                 return;
 729
 730         db = get_bucket((unsigned long) addr);
 731
 732         raw_spin_lock_irqsave(&db->lock, flags);
 733
 734         obj = lookup_object(addr, db);
 735         if (obj) {
 736                 switch (obj->state) {
 737                 case ODEBUG_STATE_INIT:
 738                 case ODEBUG_STATE_INACTIVE:
 739                 case ODEBUG_STATE_ACTIVE:
 740                         if (!obj->astate)
 741                                 obj->state = ODEBUG_STATE_INACTIVE;
 742                         else
 743                                 print_object = true;
 744                         break;
 745
 746                 case ODEBUG_STATE_DESTROYED:
 747                         print_object = true;
 748                         break;
 749                 default:
 750                         break;
 751                 }
 752         }
 753
 754         raw_spin_unlock_irqrestore(&db->lock, flags);
 755         if (!obj) {
 756                 struct debug_obj o = { .object = addr,
 757                                        .state = ODEBUG_STATE_NOTAVAILABLE,
 758                                        .descr = descr };
 759
 760                 debug_print_object(&o, "deactivate");
 761         } else if (print_object) {
 762                 debug_print_object(obj, "deactivate");
 763         }
 764 }
 765 EXPORT_SYMBOL_GPL(debug_object_deactivate);
 766
 767 /**
 768  * debug_object_destroy - debug checks when an object is destroyed
 769  * @addr:       address of the object
 770  * @descr:      pointer to an object specific debug description structure
 771  */
 772 void debug_object_destroy(void *addr, const struct debug_obj_descr *descr)
 773 {
 774         enum debug_obj_state state;
 775         struct debug_bucket *db;
 776         struct debug_obj *obj;
 777         unsigned long flags;
 778         bool print_object = false;
 779
 780         if (!debug_objects_enabled)
 781                 return;
 782
 783         db = get_bucket((unsigned long) addr);
 784
 785         raw_spin_lock_irqsave(&db->lock, flags);
 786
 787         obj = lookup_object(addr, db);
 788         if (!obj)
 789                 goto out_unlock;
 790
 791         switch (obj->state) {
 792         case ODEBUG_STATE_NONE:
 793         case ODEBUG_STATE_INIT:
 794         case ODEBUG_STATE_INACTIVE:
 795                 obj->state = ODEBUG_STATE_DESTROYED;
 796                 break;
 797         case ODEBUG_STATE_ACTIVE:
 798                 state = obj->state;
 799                 raw_spin_unlock_irqrestore(&db->lock, flags);
 800                 debug_print_object(obj, "destroy");
 801                 debug_object_fixup(descr->fixup_destroy, addr, state);
 802                 return;
 803
 804         case ODEBUG_STATE_DESTROYED:
 805                 print_object = true;
 806                 break;
 807         default:
 808                 break;
 809         }
 810 out_unlock:
 811         raw_spin_unlock_irqrestore(&db->lock, flags);
 812         if (print_object)
 813                 debug_print_object(obj, "destroy");
 814 }
 815 EXPORT_SYMBOL_GPL(debug_object_destroy);
 816
 817 /**
 818  * debug_object_free - debug checks when an object is freed
 819  * @addr:       address of the object
 820  * @descr:      pointer to an object specific debug description structure
 821  */
 822 void debug_object_free(void *addr, const struct debug_obj_descr *descr)
 823 {
 824         enum debug_obj_state state;
 825         struct debug_bucket *db;
 826         struct debug_obj *obj;
 827         unsigned long flags;
 828
 829         if (!debug_objects_enabled)
 830                 return;
 831
 832         db = get_bucket((unsigned long) addr);
 833
 834         raw_spin_lock_irqsave(&db->lock, flags);
 835
 836         obj = lookup_object(addr, db);
 837         if (!obj)
 838                 goto out_unlock;
 839
 840         switch (obj->state) {
 841         case ODEBUG_STATE_ACTIVE:
 842                 state = obj->state;
 843                 raw_spin_unlock_irqrestore(&db->lock, flags);
 844                 debug_print_object(obj, "free");
 845                 debug_object_fixup(descr->fixup_free, addr, state);
 846                 return;
 847         default:
 848                 hlist_del(&obj->node);
 849                 raw_spin_unlock_irqrestore(&db->lock, flags);
 850                 free_object(obj);
 851                 return;
 852         }
 853 out_unlock:
 854         raw_spin_unlock_irqrestore(&db->lock, flags);
 855 }
 856 EXPORT_SYMBOL_GPL(debug_object_free);
 857
 858 /**
 859  * debug_object_assert_init - debug checks when object should be init-ed
 860  * @addr:       address of the object
 861  * @descr:      pointer to an object specific debug description structure
 862  */
 863 void debug_object_assert_init(void *addr, const struct debug_obj_descr *descr)
 864 {
 865         struct debug_bucket *db;
 866         struct debug_obj *obj;
 867         unsigned long flags;
 868
 869         if (!debug_objects_enabled)
 870                 return;
 871
 872         db = get_bucket((unsigned long) addr);
 873
 874         raw_spin_lock_irqsave(&db->lock, flags);
 875
 876         obj = lookup_object(addr, db);
 877         if (!obj) {
 878                 struct debug_obj o = { .object = addr,
 879                                        .state = ODEBUG_STATE_NOTAVAILABLE,
 880                                        .descr = descr };
 881
 882                 raw_spin_unlock_irqrestore(&db->lock, flags);
 883                 /*
 884                  * Maybe the object is static, and we let the type specific
 885                  * code confirm. Track this static object if true, else invoke
 886                  * fixup.
 887                  */
 888                 if (descr->is_static_object && descr->is_static_object(addr)) {
 889                         /* Track this static object */
 890                         debug_object_init(addr, descr);
 891                 } else {
 892                         debug_print_object(&o, "assert_init");
 893                         debug_object_fixup(descr->fixup_assert_init, addr,
 894                                            ODEBUG_STATE_NOTAVAILABLE);
 895                 }
 896                 return;
 897         }
 898
 899         raw_spin_unlock_irqrestore(&db->lock, flags);
 900 }
 901 EXPORT_SYMBOL_GPL(debug_object_assert_init);
 902
 903 /**
 904  * debug_object_active_state - debug checks object usage state machine
 905  * @addr:       address of the object
 906  * @descr:      pointer to an object specific debug description structure
 907  * @expect:     expected state
 908  * @next:       state to move to if expected state is found
 909  */
 910 void
 911 debug_object_active_state(void *addr, const struct debug_obj_descr *descr,
 912                           unsigned int expect, unsigned int next)
 913 {
 914         struct debug_bucket *db;
 915         struct debug_obj *obj;
 916         unsigned long flags;
 917         bool print_object = false;
 918
 919         if (!debug_objects_enabled)
 920                 return;
 921
 922         db = get_bucket((unsigned long) addr);
 923
 924         raw_spin_lock_irqsave(&db->lock, flags);
 925
 926         obj = lookup_object(addr, db);
 927         if (obj) {
 928                 switch (obj->state) {
 929                 case ODEBUG_STATE_ACTIVE:
 930                         if (obj->astate == expect)
 931                                 obj->astate = next;
 932                         else
 933                                 print_object = true;
 934                         break;
 935
 936                 default:
 937                         print_object = true;
 938                         break;
 939                 }
 940         }
 941
 942         raw_spin_unlock_irqrestore(&db->lock, flags);
 943         if (!obj) {
 944                 struct debug_obj o = { .object = addr,
 945                                        .state = ODEBUG_STATE_NOTAVAILABLE,
 946                                        .descr = descr };
 947
 948                 debug_print_object(&o, "active_state");
 949         } else if (print_object) {
 950                 debug_print_object(obj, "active_state");
 951         }
 952 }
 953 EXPORT_SYMBOL_GPL(debug_object_active_state);
 954
 955 #ifdef CONFIG_DEBUG_OBJECTS_FREE
 956 static void __debug_check_no_obj_freed(const void *address, unsigned long size)
 957 {
 958         unsigned long flags, oaddr, saddr, eaddr, paddr, chunks;
 959         const struct debug_obj_descr *descr;
 960         enum debug_obj_state state;
 961         struct debug_bucket *db;
 962         struct hlist_node *tmp;
 963         struct debug_obj *obj;
 964         int cnt, objs_checked = 0;
 965
 966         saddr = (unsigned long) address;
 967         eaddr = saddr + size;
 968         paddr = saddr & ODEBUG_CHUNK_MASK;
 969         chunks = ((eaddr - paddr) + (ODEBUG_CHUNK_SIZE - 1));
 970         chunks >>= ODEBUG_CHUNK_SHIFT;
 971
 972         for (;chunks > 0; chunks--, paddr += ODEBUG_CHUNK_SIZE) {
 973                 db = get_bucket(paddr);
 974
 975 repeat:
 976                 cnt = 0;
 977                 raw_spin_lock_irqsave(&db->lock, flags);
 978                 hlist_for_each_entry_safe(obj, tmp, &db->list, node) {
 979                         cnt++;
 980                         oaddr = (unsigned long) obj->object;
 981                         if (oaddr < saddr || oaddr >= eaddr)
 982                                 continue;
 983
 984                         switch (obj->state) {
 985                         case ODEBUG_STATE_ACTIVE:
 986                                 descr = obj->descr;
 987                                 state = obj->state;
 988                                 raw_spin_unlock_irqrestore(&db->lock, flags);
 989                                 debug_print_object(obj, "free");
 990                                 debug_object_fixup(descr->fixup_free,
 991                                                    (void *) oaddr, state);
 992                                 goto repeat;
 993                         default:
 994                                 hlist_del(&obj->node);
 995                                 __free_object(obj);
 996                                 break;
 997                         }
 998                 }
 999                 raw_spin_unlock_irqrestore(&db->lock, flags);
1000
1001                 if (cnt > debug_objects_maxchain)
1002                         debug_objects_maxchain = cnt;
1003
1004                 objs_checked += cnt;
1005         }
1006
1007         if (objs_checked > debug_objects_maxchecked)
1008                 debug_objects_maxchecked = objs_checked;
1009
1010         /* Schedule work to actually kmem_cache_free() objects */
1011         if (!READ_ONCE(obj_freeing) && READ_ONCE(obj_nr_tofree)) {
1012                 WRITE_ONCE(obj_freeing, true);
1013                 schedule_delayed_work(&debug_obj_work, ODEBUG_FREE_WORK_DELAY);
1014         }
1015 }
1016
1017 void debug_check_no_obj_freed(const void *address, unsigned long size)
1018 {
1019         if (debug_objects_enabled)
1020                 __debug_check_no_obj_freed(address, size);
1021 }
1022 #endif
1023
1024 #ifdef CONFIG_DEBUG_FS
1025
1026 static int debug_stats_show(struct seq_file *m, void *v)
1027 {
1028         int cpu, obj_percpu_free = 0;
1029
1030         for_each_possible_cpu(cpu)
1031                 obj_percpu_free += per_cpu(percpu_obj_pool.obj_free, cpu);
1032
1033         seq_printf(m, "max_chain     :%d\n", debug_objects_maxchain);
1034         seq_printf(m, "max_checked   :%d\n", debug_objects_maxchecked);
1035         seq_printf(m, "warnings      :%d\n", debug_objects_warnings);
1036         seq_printf(m, "fixups        :%d\n", debug_objects_fixups);
1037         seq_printf(m, "pool_free     :%d\n", READ_ONCE(obj_pool_free) + obj_percpu_free);
1038         seq_printf(m, "pool_pcp_free :%d\n", obj_percpu_free);
1039         seq_printf(m, "pool_min_free :%d\n", obj_pool_min_free);
1040         seq_printf(m, "pool_used     :%d\n", obj_pool_used - obj_percpu_free);
1041         seq_printf(m, "pool_max_used :%d\n", obj_pool_max_used);
1042         seq_printf(m, "on_free_list  :%d\n", READ_ONCE(obj_nr_tofree));
1043         seq_printf(m, "objs_allocated:%d\n", debug_objects_allocated);
1044         seq_printf(m, "objs_freed    :%d\n", debug_objects_freed);
1045         return 0;
1046 }
1047 DEFINE_SHOW_ATTRIBUTE(debug_stats);
1048
1049 static int __init debug_objects_init_debugfs(void)
1050 {
1051         struct dentry *dbgdir;
1052
1053         if (!debug_objects_enabled)
1054                 return 0;
1055
1056         dbgdir = debugfs_create_dir("debug_objects", NULL);
1057
1058         debugfs_create_file("stats", 0444, dbgdir, NULL, &debug_stats_fops);
1059
1060         return 0;
1061 }
1062 __initcall(debug_objects_init_debugfs);
1063
1064 #else
1065 static inline void debug_objects_init_debugfs(void) { }
1066 #endif
1067
1068 #ifdef CONFIG_DEBUG_OBJECTS_SELFTEST
1069
1070 /* Random data structure for the self test */
1071 struct self_test {
1072         unsigned long   dummy1[6];
1073         int             static_init;
1074         unsigned long   dummy2[3];
1075 };
1076
1077 static __initconst const struct debug_obj_descr descr_type_test;
1078
1079 static bool __init is_static_object(void *addr)
1080 {
1081         struct self_test *obj = addr;
1082
1083         return obj->static_init;
1084 }
1085
1086 /*
1087  * fixup_init is called when:
1088  * - an active object is initialized
1089  */
1090 static bool __init fixup_init(void *addr, enum debug_obj_state state)
1091 {
1092         struct self_test *obj = addr;
1093
1094         switch (state) {
1095         case ODEBUG_STATE_ACTIVE:
1096                 debug_object_deactivate(obj, &descr_type_test);
1097                 debug_object_init(obj, &descr_type_test);
1098                 return true;
1099         default:
1100                 return false;
1101         }
1102 }
1103
1104 /*
1105  * fixup_activate is called when:
1106  * - an active object is activated
1107  * - an unknown non-static object is activated
1108  */
1109 static bool __init fixup_activate(void *addr, enum debug_obj_state state)
1110 {
1111         struct self_test *obj = addr;
1112
1113         switch (state) {
1114         case ODEBUG_STATE_NOTAVAILABLE:
1115                 return true;
1116         case ODEBUG_STATE_ACTIVE:
1117                 debug_object_deactivate(obj, &descr_type_test);
1118                 debug_object_activate(obj, &descr_type_test);
1119                 return true;
1120
1121         default:
1122                 return false;
1123         }
1124 }
1125
1126 /*
1127  * fixup_destroy is called when:
1128  * - an active object is destroyed
1129  */
1130 static bool __init fixup_destroy(void *addr, enum debug_obj_state state)
1131 {
1132         struct self_test *obj = addr;
1133
1134         switch (state) {
1135         case ODEBUG_STATE_ACTIVE:
1136                 debug_object_deactivate(obj, &descr_type_test);
1137                 debug_object_destroy(obj, &descr_type_test);
1138                 return true;
1139         default:
1140                 return false;
1141         }
1142 }
1143
1144 /*
1145  * fixup_free is called when:
1146  * - an active object is freed
1147  */
1148 static bool __init fixup_free(void *addr, enum debug_obj_state state)
1149 {
1150         struct self_test *obj = addr;
1151
1152         switch (state) {
1153         case ODEBUG_STATE_ACTIVE:
1154                 debug_object_deactivate(obj, &descr_type_test);
1155                 debug_object_free(obj, &descr_type_test);
1156                 return true;
1157         default:
1158                 return false;
1159         }
1160 }
1161
1162 static int __init
1163 check_results(void *addr, enum debug_obj_state state, int fixups, int warnings)
1164 {
1165         struct debug_bucket *db;
1166         struct debug_obj *obj;
1167         unsigned long flags;
1168         int res = -EINVAL;
1169
1170         db = get_bucket((unsigned long) addr);
1171
1172         raw_spin_lock_irqsave(&db->lock, flags);
1173
1174         obj = lookup_object(addr, db);
1175         if (!obj && state != ODEBUG_STATE_NONE) {
1176                 WARN(1, KERN_ERR "ODEBUG: selftest object not found\n");
1177                 goto out;
1178         }
1179         if (obj && obj->state != state) {
1180                 WARN(1, KERN_ERR "ODEBUG: selftest wrong state: %d != %d\n",
1181                        obj->state, state);
1182                 goto out;
1183         }
1184         if (fixups != debug_objects_fixups) {
1185                 WARN(1, KERN_ERR "ODEBUG: selftest fixups failed %d != %d\n",
1186                        fixups, debug_objects_fixups);
1187                 goto out;
1188         }
1189         if (warnings != debug_objects_warnings) {
1190                 WARN(1, KERN_ERR "ODEBUG: selftest warnings failed %d != %d\n",
1191                        warnings, debug_objects_warnings);
1192                 goto out;
1193         }
1194         res = 0;
1195 out:
1196         raw_spin_unlock_irqrestore(&db->lock, flags);
1197         if (res)
1198                 debug_objects_enabled = 0;
1199         return res;
1200 }
1201
1202 static __initconst const struct debug_obj_descr descr_type_test = {
1203         .name                   = "selftest",
1204         .is_static_object       = is_static_object,
1205         .fixup_init             = fixup_init,
1206         .fixup_activate         = fixup_activate,
1207         .fixup_destroy          = fixup_destroy,
1208         .fixup_free             = fixup_free,
1209 };
1210
1211 static __initdata struct self_test obj = { .static_init = 0 };
1212
1213 static void __init debug_objects_selftest(void)
1214 {
1215         int fixups, oldfixups, warnings, oldwarnings;
1216         unsigned long flags;
1217
1218         local_irq_save(flags);
1219
1220         fixups = oldfixups = debug_objects_fixups;
1221         warnings = oldwarnings = debug_objects_warnings;
1222         descr_test = &descr_type_test;
1223
1224         debug_object_init(&obj, &descr_type_test);
1225         if (check_results(&obj, ODEBUG_STATE_INIT, fixups, warnings))
1226                 goto out;
1227         debug_object_activate(&obj, &descr_type_test);
1228         if (check_results(&obj, ODEBUG_STATE_ACTIVE, fixups, warnings))
1229                 goto out;
1230         debug_object_activate(&obj, &descr_type_test);
1231         if (check_results(&obj, ODEBUG_STATE_ACTIVE, ++fixups, ++warnings))
1232                 goto out;
1233         debug_object_deactivate(&obj, &descr_type_test);
1234         if (check_results(&obj, ODEBUG_STATE_INACTIVE, fixups, warnings))
1235                 goto out;
1236         debug_object_destroy(&obj, &descr_type_test);
1237         if (check_results(&obj, ODEBUG_STATE_DESTROYED, fixups, warnings))
1238                 goto out;
1239         debug_object_init(&obj, &descr_type_test);
1240         if (check_results(&obj, ODEBUG_STATE_DESTROYED, fixups, ++warnings))
1241                 goto out;
1242         debug_object_activate(&obj, &descr_type_test);
1243         if (check_results(&obj, ODEBUG_STATE_DESTROYED, fixups, ++warnings))
1244                 goto out;
1245         debug_object_deactivate(&obj, &descr_type_test);
1246         if (check_results(&obj, ODEBUG_STATE_DESTROYED, fixups, ++warnings))
1247                 goto out;
1248         debug_object_free(&obj, &descr_type_test);
1249         if (check_results(&obj, ODEBUG_STATE_NONE, fixups, warnings))
1250                 goto out;
1251
1252         obj.static_init = 1;
1253         debug_object_activate(&obj, &descr_type_test);
1254         if (check_results(&obj, ODEBUG_STATE_ACTIVE, fixups, warnings))
1255                 goto out;
1256         debug_object_init(&obj, &descr_type_test);
1257         if (check_results(&obj, ODEBUG_STATE_INIT, ++fixups, ++warnings))
1258                 goto out;
1259         debug_object_free(&obj, &descr_type_test);
1260         if (check_results(&obj, ODEBUG_STATE_NONE, fixups, warnings))
1261                 goto out;
1262
1263 #ifdef CONFIG_DEBUG_OBJECTS_FREE
1264         debug_object_init(&obj, &descr_type_test);
1265         if (check_results(&obj, ODEBUG_STATE_INIT, fixups, warnings))
1266                 goto out;
1267         debug_object_activate(&obj, &descr_type_test);
1268         if (check_results(&obj, ODEBUG_STATE_ACTIVE, fixups, warnings))
1269                 goto out;
1270         __debug_check_no_obj_freed(&obj, sizeof(obj));
1271         if (check_results(&obj, ODEBUG_STATE_NONE, ++fixups, ++warnings))
1272                 goto out;
1273 #endif
1274         pr_info("selftest passed\n");
1275
1276 out:
1277         debug_objects_fixups = oldfixups;
1278         debug_objects_warnings = oldwarnings;
1279         descr_test = NULL;
1280
1281         local_irq_restore(flags);
1282 }
1283 #else
1284 static inline void debug_objects_selftest(void) { }
1285 #endif
1286
1287 /*
1288  * Called during early boot to initialize the hash buckets and link
1289  * the static object pool objects into the poll list. After this call
1290  * the object tracker is fully operational.
1291  */
1292 void __init debug_objects_early_init(void)
1293 {
1294         int i;
1295
1296         for (i = 0; i < ODEBUG_HASH_SIZE; i++)
1297                 raw_spin_lock_init(&obj_hash[i].lock);
1298
1299         for (i = 0; i < ODEBUG_POOL_SIZE; i++)
1300                 hlist_add_head(&obj_static_pool[i].node, &obj_pool);
1301 }
1302
1303 /*
1304  * Convert the statically allocated objects to dynamic ones:
1305  */
1306 static int __init debug_objects_replace_static_objects(void)
1307 {
1308         struct debug_bucket *db = obj_hash;
1309         struct hlist_node *tmp;
1310         struct debug_obj *obj, *new;
1311         HLIST_HEAD(objects);
1312         int i, cnt = 0;
1313
1314         for (i = 0; i < ODEBUG_POOL_SIZE; i++) {
1315                 obj = kmem_cache_zalloc(obj_cache, GFP_KERNEL);
1316                 if (!obj)
1317                         goto free;
1318                 hlist_add_head(&obj->node, &objects);
1319         }
1320
1321         /*
1322          * debug_objects_mem_init() is now called early that only one CPU is up
1323          * and interrupts have been disabled, so it is safe to replace the
1324          * active object references.
1325          */
1326
1327         /* Remove the statically allocated objects from the pool */
1328         hlist_for_each_entry_safe(obj, tmp, &obj_pool, node)
1329                 hlist_del(&obj->node);
1330         /* Move the allocated objects to the pool */
1331         hlist_move_list(&objects, &obj_pool);
1332
1333         /* Replace the active object references */
1334         for (i = 0; i < ODEBUG_HASH_SIZE; i++, db++) {
1335                 hlist_move_list(&db->list, &objects);
1336
1337                 hlist_for_each_entry(obj, &objects, node) {
1338                         new = hlist_entry(obj_pool.first, typeof(*obj), node);
1339                         hlist_del(&new->node);
1340                         /* copy object data */
1341                         *new = *obj;
1342                         hlist_add_head(&new->node, &db->list);
1343                         cnt++;
1344                 }
1345         }
1346
1347         pr_debug("%d of %d active objects replaced\n",
1348                  cnt, obj_pool_used);
1349         return 0;
1350 free:
1351         hlist_for_each_entry_safe(obj, tmp, &objects, node) {
1352                 hlist_del(&obj->node);
1353                 kmem_cache_free(obj_cache, obj);
1354         }
1355         return -ENOMEM;
1356 }
1357
1358 /*
1359  * Called after the kmem_caches are functional to setup a dedicated
1360  * cache pool, which has the SLAB_DEBUG_OBJECTS flag set. This flag
1361  * prevents that the debug code is called on kmem_cache_free() for the
1362  * debug tracker objects to avoid recursive calls.
1363  */
1364 void __init debug_objects_mem_init(void)
1365 {
1366         int cpu, extras;
1367
1368         if (!debug_objects_enabled)
1369                 return;
1370
1371         /*
1372          * Initialize the percpu object pools
1373          *
1374          * Initialization is not strictly necessary, but was done for
1375          * completeness.
1376          */
1377         for_each_possible_cpu(cpu)
1378                 INIT_HLIST_HEAD(&per_cpu(percpu_obj_pool.free_objs, cpu));
1379
1380         obj_cache = kmem_cache_create("debug_objects_cache",
1381                                       sizeof (struct debug_obj), 0,
1382                                       SLAB_DEBUG_OBJECTS | SLAB_NOLEAKTRACE,
1383                                       NULL);
1384
1385         if (!obj_cache || debug_objects_replace_static_objects()) {
1386                 debug_objects_enabled = 0;
1387                 kmem_cache_destroy(obj_cache);
1388                 pr_warn("out of memory.\n");
1389         } else
1390                 debug_objects_selftest();
1391
1392 #ifdef CONFIG_HOTPLUG_CPU
1393         cpuhp_setup_state_nocalls(CPUHP_DEBUG_OBJ_DEAD, "object:offline", NULL,
1394                                         object_cpu_offline);
1395 #endif
1396
1397         /*
1398          * Increase the thresholds for allocating and freeing objects
1399          * according to the number of possible CPUs available in the system.
1400          */
1401         extras = num_possible_cpus() * ODEBUG_BATCH_SIZE;
1402         debug_objects_pool_size += extras;
1403         debug_objects_pool_min_level += extras;
1404 }