tracing_map.c 27.8 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165
/*
 * tracing_map - lock-free map for tracing
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * Copyright (C) 2015 Tom Zanussi <tom.zanussi@linux.intel.com>
 *
 * tracing_map implementation inspired by lock-free map algorithms
 * originated by Dr. Cliff Click:
 *
 * http://www.azulsystems.com/blog/cliff/2007-03-26-non-blocking-hashtable
 * http://www.azulsystems.com/events/javaone_2007/2007_LockFreeHash.pdf
 */

#include <linux/vmalloc.h>
#include <linux/jhash.h>
#include <linux/slab.h>
#include <linux/sort.h>

#include "tracing_map.h"
#include "trace.h"

/*
 * NOTE: For a detailed description of the data structures used by
 * these functions (such as tracing_map_elt) please see the overview
 * of tracing_map data structures at the beginning of tracing_map.h.
 */

/**
 * tracing_map_update_sum - Add a value to a tracing_map_elt's sum field
 * @elt: The tracing_map_elt
 * @i: The index of the given sum associated with the tracing_map_elt
 * @n: The value to add to the sum
 *
 * Add n to sum i associated with the specified tracing_map_elt
 * instance.  The index i is the index returned by the call to
 * tracing_map_add_sum_field() when the tracing map was set up.
 */
void tracing_map_update_sum(struct tracing_map_elt *elt, unsigned int i, u64 n)
{
	atomic64_add(n, &elt->fields[i].sum);
}

/**
 * tracing_map_read_sum - Return the value of a tracing_map_elt's sum field
 * @elt: The tracing_map_elt
 * @i: The index of the given sum associated with the tracing_map_elt
 *
 * Retrieve the value of the sum i associated with the specified
 * tracing_map_elt instance.  The index i is the index returned by the
 * call to tracing_map_add_sum_field() when the tracing map was set
 * up.
 *
 * Return: The sum associated with field i for elt.
 */
u64 tracing_map_read_sum(struct tracing_map_elt *elt, unsigned int i)
{
	return (u64)atomic64_read(&elt->fields[i].sum);
}

int tracing_map_cmp_string(void *val_a, void *val_b)
{
	char *a = val_a;
	char *b = val_b;

	return strcmp(a, b);
}

int tracing_map_cmp_none(void *val_a, void *val_b)
{
	return 0;
}

static int tracing_map_cmp_atomic64(void *val_a, void *val_b)
{
	u64 a = atomic64_read((atomic64_t *)val_a);
	u64 b = atomic64_read((atomic64_t *)val_b);

	return (a > b) ? 1 : ((a < b) ? -1 : 0);
}

#define DEFINE_TRACING_MAP_CMP_FN(type)					\
static int tracing_map_cmp_##type(void *val_a, void *val_b)		\
{									\
	type a = *(type *)val_a;					\
	type b = *(type *)val_b;					\
									\
	return (a > b) ? 1 : ((a < b) ? -1 : 0);			\
}

DEFINE_TRACING_MAP_CMP_FN(s64);
DEFINE_TRACING_MAP_CMP_FN(u64);
DEFINE_TRACING_MAP_CMP_FN(s32);
DEFINE_TRACING_MAP_CMP_FN(u32);
DEFINE_TRACING_MAP_CMP_FN(s16);
DEFINE_TRACING_MAP_CMP_FN(u16);
DEFINE_TRACING_MAP_CMP_FN(s8);
DEFINE_TRACING_MAP_CMP_FN(u8);

tracing_map_cmp_fn_t tracing_map_cmp_num(int field_size,
					 int field_is_signed)
{
	tracing_map_cmp_fn_t fn = tracing_map_cmp_none;

	switch (field_size) {
	case 8:
		if (field_is_signed)
			fn = tracing_map_cmp_s64;
		else
			fn = tracing_map_cmp_u64;
		break;
	case 4:
		if (field_is_signed)
			fn = tracing_map_cmp_s32;
		else
			fn = tracing_map_cmp_u32;
		break;
	case 2:
		if (field_is_signed)
			fn = tracing_map_cmp_s16;
		else
			fn = tracing_map_cmp_u16;
		break;
	case 1:
		if (field_is_signed)
			fn = tracing_map_cmp_s8;
		else
			fn = tracing_map_cmp_u8;
		break;
	}

	return fn;
}

static int tracing_map_add_field(struct tracing_map *map,
				 tracing_map_cmp_fn_t cmp_fn)
{
	int ret = -EINVAL;

	if (map->n_fields < TRACING_MAP_FIELDS_MAX) {
		ret = map->n_fields;
		map->fields[map->n_fields++].cmp_fn = cmp_fn;
	}

	return ret;
}

/**
 * tracing_map_add_sum_field - Add a field describing a tracing_map sum
 * @map: The tracing_map
 *
 * Add a sum field to the key and return the index identifying it in
 * the map and associated tracing_map_elts.  This is the index used
 * for instance to update a sum for a particular tracing_map_elt using
 * tracing_map_update_sum() or reading it via tracing_map_read_sum().
 *
 * Return: The index identifying the field in the map and associated
166
 * tracing_map_elts, or -EINVAL on error.
167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186
 */
int tracing_map_add_sum_field(struct tracing_map *map)
{
	return tracing_map_add_field(map, tracing_map_cmp_atomic64);
}

/**
 * tracing_map_add_key_field - Add a field describing a tracing_map key
 * @map: The tracing_map
 * @offset: The offset within the key
 * @cmp_fn: The comparison function that will be used to sort on the key
 *
 * Let the map know there is a key and that if it's used as a sort key
 * to use cmp_fn.
 *
 * A key can be a subset of a compound key; for that purpose, the
 * offset param is used to describe where within the the compound key
 * the key referenced by this key field resides.
 *
 * Return: The index identifying the field in the map and associated
187
 * tracing_map_elts, or -EINVAL on error.
188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223
 */
int tracing_map_add_key_field(struct tracing_map *map,
			      unsigned int offset,
			      tracing_map_cmp_fn_t cmp_fn)

{
	int idx = tracing_map_add_field(map, cmp_fn);

	if (idx < 0)
		return idx;

	map->fields[idx].offset = offset;

	map->key_idx[map->n_keys++] = idx;

	return idx;
}

void tracing_map_array_clear(struct tracing_map_array *a)
{
	unsigned int i;

	if (!a->pages)
		return;

	for (i = 0; i < a->n_pages; i++)
		memset(a->pages[i], 0, PAGE_SIZE);
}

void tracing_map_array_free(struct tracing_map_array *a)
{
	unsigned int i;

	if (!a)
		return;

224 225
	if (!a->pages)
		goto free;
226 227 228 229 230 231

	for (i = 0; i < a->n_pages; i++) {
		if (!a->pages[i])
			break;
		free_page((unsigned long)a->pages[i]);
	}
232 233 234 235 236

	kfree(a->pages);

 free:
	kfree(a);
237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371
}

struct tracing_map_array *tracing_map_array_alloc(unsigned int n_elts,
						  unsigned int entry_size)
{
	struct tracing_map_array *a;
	unsigned int i;

	a = kzalloc(sizeof(*a), GFP_KERNEL);
	if (!a)
		return NULL;

	a->entry_size_shift = fls(roundup_pow_of_two(entry_size) - 1);
	a->entries_per_page = PAGE_SIZE / (1 << a->entry_size_shift);
	a->n_pages = n_elts / a->entries_per_page;
	if (!a->n_pages)
		a->n_pages = 1;
	a->entry_shift = fls(a->entries_per_page) - 1;
	a->entry_mask = (1 << a->entry_shift) - 1;

	a->pages = kcalloc(a->n_pages, sizeof(void *), GFP_KERNEL);
	if (!a->pages)
		goto free;

	for (i = 0; i < a->n_pages; i++) {
		a->pages[i] = (void *)get_zeroed_page(GFP_KERNEL);
		if (!a->pages[i])
			goto free;
	}
 out:
	return a;
 free:
	tracing_map_array_free(a);
	a = NULL;

	goto out;
}

static void tracing_map_elt_clear(struct tracing_map_elt *elt)
{
	unsigned i;

	for (i = 0; i < elt->map->n_fields; i++)
		if (elt->fields[i].cmp_fn == tracing_map_cmp_atomic64)
			atomic64_set(&elt->fields[i].sum, 0);

	if (elt->map->ops && elt->map->ops->elt_clear)
		elt->map->ops->elt_clear(elt);
}

static void tracing_map_elt_init_fields(struct tracing_map_elt *elt)
{
	unsigned int i;

	tracing_map_elt_clear(elt);

	for (i = 0; i < elt->map->n_fields; i++) {
		elt->fields[i].cmp_fn = elt->map->fields[i].cmp_fn;

		if (elt->fields[i].cmp_fn != tracing_map_cmp_atomic64)
			elt->fields[i].offset = elt->map->fields[i].offset;
	}
}

static void tracing_map_elt_free(struct tracing_map_elt *elt)
{
	if (!elt)
		return;

	if (elt->map->ops && elt->map->ops->elt_free)
		elt->map->ops->elt_free(elt);
	kfree(elt->fields);
	kfree(elt->key);
	kfree(elt);
}

static struct tracing_map_elt *tracing_map_elt_alloc(struct tracing_map *map)
{
	struct tracing_map_elt *elt;
	int err = 0;

	elt = kzalloc(sizeof(*elt), GFP_KERNEL);
	if (!elt)
		return ERR_PTR(-ENOMEM);

	elt->map = map;

	elt->key = kzalloc(map->key_size, GFP_KERNEL);
	if (!elt->key) {
		err = -ENOMEM;
		goto free;
	}

	elt->fields = kcalloc(map->n_fields, sizeof(*elt->fields), GFP_KERNEL);
	if (!elt->fields) {
		err = -ENOMEM;
		goto free;
	}

	tracing_map_elt_init_fields(elt);

	if (map->ops && map->ops->elt_alloc) {
		err = map->ops->elt_alloc(elt);
		if (err)
			goto free;
	}
	return elt;
 free:
	tracing_map_elt_free(elt);

	return ERR_PTR(err);
}

static struct tracing_map_elt *get_free_elt(struct tracing_map *map)
{
	struct tracing_map_elt *elt = NULL;
	int idx;

	idx = atomic_inc_return(&map->next_elt);
	if (idx < map->max_elts) {
		elt = *(TRACING_MAP_ELT(map->elts, idx));
		if (map->ops && map->ops->elt_init)
			map->ops->elt_init(elt);
	}

	return elt;
}

static void tracing_map_free_elts(struct tracing_map *map)
{
	unsigned int i;

	if (!map->elts)
		return;

372
	for (i = 0; i < map->max_elts; i++) {
373
		tracing_map_elt_free(*(TRACING_MAP_ELT(map->elts, i)));
374 375
		*(TRACING_MAP_ELT(map->elts, i)) = NULL;
	}
376 377

	tracing_map_array_free(map->elts);
378
	map->elts = NULL;
379 380 381 382 383 384 385 386 387 388 389 390 391
}

static int tracing_map_alloc_elts(struct tracing_map *map)
{
	unsigned int i;

	map->elts = tracing_map_array_alloc(map->max_elts,
					    sizeof(struct tracing_map_elt *));
	if (!map->elts)
		return -ENOMEM;

	for (i = 0; i < map->max_elts; i++) {
		*(TRACING_MAP_ELT(map->elts, i)) = tracing_map_elt_alloc(map);
392 393
		if (IS_ERR(*(TRACING_MAP_ELT(map->elts, i)))) {
			*(TRACING_MAP_ELT(map->elts, i)) = NULL;
394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823
			tracing_map_free_elts(map);

			return -ENOMEM;
		}
	}

	return 0;
}

static inline bool keys_match(void *key, void *test_key, unsigned key_size)
{
	bool match = true;

	if (memcmp(key, test_key, key_size))
		match = false;

	return match;
}

static inline struct tracing_map_elt *
__tracing_map_insert(struct tracing_map *map, void *key, bool lookup_only)
{
	u32 idx, key_hash, test_key;
	struct tracing_map_entry *entry;

	key_hash = jhash(key, map->key_size, 0);
	if (key_hash == 0)
		key_hash = 1;
	idx = key_hash >> (32 - (map->map_bits + 1));

	while (1) {
		idx &= (map->map_size - 1);
		entry = TRACING_MAP_ENTRY(map->map, idx);
		test_key = entry->key;

		if (test_key && test_key == key_hash && entry->val &&
		    keys_match(key, entry->val->key, map->key_size)) {
			atomic64_inc(&map->hits);
			return entry->val;
		}

		if (!test_key) {
			if (lookup_only)
				break;

			if (!cmpxchg(&entry->key, 0, key_hash)) {
				struct tracing_map_elt *elt;

				elt = get_free_elt(map);
				if (!elt) {
					atomic64_inc(&map->drops);
					entry->key = 0;
					break;
				}

				memcpy(elt->key, key, map->key_size);
				entry->val = elt;
				atomic64_inc(&map->hits);

				return entry->val;
			}
		}

		idx++;
	}

	return NULL;
}

/**
 * tracing_map_insert - Insert key and/or retrieve val from a tracing_map
 * @map: The tracing_map to insert into
 * @key: The key to insert
 *
 * Inserts a key into a tracing_map and creates and returns a new
 * tracing_map_elt for it, or if the key has already been inserted by
 * a previous call, returns the tracing_map_elt already associated
 * with it.  When the map was created, the number of elements to be
 * allocated for the map was specified (internally maintained as
 * 'max_elts' in struct tracing_map), and that number of
 * tracing_map_elts was created by tracing_map_init().  This is the
 * pre-allocated pool of tracing_map_elts that tracing_map_insert()
 * will allocate from when adding new keys.  Once that pool is
 * exhausted, tracing_map_insert() is useless and will return NULL to
 * signal that state.  There are two user-visible tracing_map
 * variables, 'hits' and 'drops', which are updated by this function.
 * Every time an element is either successfully inserted or retrieved,
 * the 'hits' value is incrememented.  Every time an element insertion
 * fails, the 'drops' value is incremented.
 *
 * This is a lock-free tracing map insertion function implementing a
 * modified form of Cliff Click's basic insertion algorithm.  It
 * requires the table size be a power of two.  To prevent any
 * possibility of an infinite loop we always make the internal table
 * size double the size of the requested table size (max_elts * 2).
 * Likewise, we never reuse a slot or resize or delete elements - when
 * we've reached max_elts entries, we simply return NULL once we've
 * run out of entries.  Readers can at any point in time traverse the
 * tracing map and safely access the key/val pairs.
 *
 * Return: the tracing_map_elt pointer val associated with the key.
 * If this was a newly inserted key, the val will be a newly allocated
 * and associated tracing_map_elt pointer val.  If the key wasn't
 * found and the pool of tracing_map_elts has been exhausted, NULL is
 * returned and no further insertions will succeed.
 */
struct tracing_map_elt *tracing_map_insert(struct tracing_map *map, void *key)
{
	return __tracing_map_insert(map, key, false);
}

/**
 * tracing_map_lookup - Retrieve val from a tracing_map
 * @map: The tracing_map to perform the lookup on
 * @key: The key to look up
 *
 * Looks up key in tracing_map and if found returns the matching
 * tracing_map_elt.  This is a lock-free lookup; see
 * tracing_map_insert() for details on tracing_map and how it works.
 * Every time an element is retrieved, the 'hits' value is
 * incrememented.  There is one user-visible tracing_map variable,
 * 'hits', which is updated by this function.  Every time an element
 * is successfully retrieved, the 'hits' value is incrememented.  The
 * 'drops' value is never updated by this function.
 *
 * Return: the tracing_map_elt pointer val associated with the key.
 * If the key wasn't found, NULL is returned.
 */
struct tracing_map_elt *tracing_map_lookup(struct tracing_map *map, void *key)
{
	return __tracing_map_insert(map, key, true);
}

/**
 * tracing_map_destroy - Destroy a tracing_map
 * @map: The tracing_map to destroy
 *
 * Frees a tracing_map along with its associated array of
 * tracing_map_elts.
 *
 * Callers should make sure there are no readers or writers actively
 * reading or inserting into the map before calling this.
 */
void tracing_map_destroy(struct tracing_map *map)
{
	if (!map)
		return;

	tracing_map_free_elts(map);

	tracing_map_array_free(map->map);
	kfree(map);
}

/**
 * tracing_map_clear - Clear a tracing_map
 * @map: The tracing_map to clear
 *
 * Resets the tracing map to a cleared or initial state.  The
 * tracing_map_elts are all cleared, and the array of struct
 * tracing_map_entry is reset to an initialized state.
 *
 * Callers should make sure there are no writers actively inserting
 * into the map before calling this.
 */
void tracing_map_clear(struct tracing_map *map)
{
	unsigned int i;

	atomic_set(&map->next_elt, -1);
	atomic64_set(&map->hits, 0);
	atomic64_set(&map->drops, 0);

	tracing_map_array_clear(map->map);

	for (i = 0; i < map->max_elts; i++)
		tracing_map_elt_clear(*(TRACING_MAP_ELT(map->elts, i)));
}

static void set_sort_key(struct tracing_map *map,
			 struct tracing_map_sort_key *sort_key)
{
	map->sort_key = *sort_key;
}

/**
 * tracing_map_create - Create a lock-free map and element pool
 * @map_bits: The size of the map (2 ** map_bits)
 * @key_size: The size of the key for the map in bytes
 * @ops: Optional client-defined tracing_map_ops instance
 * @private_data: Client data associated with the map
 *
 * Creates and sets up a map to contain 2 ** map_bits number of
 * elements (internally maintained as 'max_elts' in struct
 * tracing_map).  Before using, map fields should be added to the map
 * with tracing_map_add_sum_field() and tracing_map_add_key_field().
 * tracing_map_init() should then be called to allocate the array of
 * tracing_map_elts, in order to avoid allocating anything in the map
 * insertion path.  The user-specified map size reflects the maximum
 * number of elements that can be contained in the table requested by
 * the user - internally we double that in order to keep the table
 * sparse and keep collisions manageable.
 *
 * A tracing_map is a special-purpose map designed to aggregate or
 * 'sum' one or more values associated with a specific object of type
 * tracing_map_elt, which is attached by the map to a given key.
 *
 * tracing_map_create() sets up the map itself, and provides
 * operations for inserting tracing_map_elts, but doesn't allocate the
 * tracing_map_elts themselves, or provide a means for describing the
 * keys or sums associated with the tracing_map_elts.  All
 * tracing_map_elts for a given map have the same set of sums and
 * keys, which are defined by the client using the functions
 * tracing_map_add_key_field() and tracing_map_add_sum_field().  Once
 * the fields are defined, the pool of elements allocated for the map
 * can be created, which occurs when the client code calls
 * tracing_map_init().
 *
 * When tracing_map_init() returns, tracing_map_elt elements can be
 * inserted into the map using tracing_map_insert().  When called,
 * tracing_map_insert() grabs a free tracing_map_elt from the pool, or
 * finds an existing match in the map and in either case returns it.
 * The client can then use tracing_map_update_sum() and
 * tracing_map_read_sum() to update or read a given sum field for the
 * tracing_map_elt.
 *
 * The client can at any point retrieve and traverse the current set
 * of inserted tracing_map_elts in a tracing_map, via
 * tracing_map_sort_entries().  Sorting can be done on any field,
 * including keys.
 *
 * See tracing_map.h for a description of tracing_map_ops.
 *
 * Return: the tracing_map pointer if successful, ERR_PTR if not.
 */
struct tracing_map *tracing_map_create(unsigned int map_bits,
				       unsigned int key_size,
				       const struct tracing_map_ops *ops,
				       void *private_data)
{
	struct tracing_map *map;
	unsigned int i;

	if (map_bits < TRACING_MAP_BITS_MIN ||
	    map_bits > TRACING_MAP_BITS_MAX)
		return ERR_PTR(-EINVAL);

	map = kzalloc(sizeof(*map), GFP_KERNEL);
	if (!map)
		return ERR_PTR(-ENOMEM);

	map->map_bits = map_bits;
	map->max_elts = (1 << map_bits);
	atomic_set(&map->next_elt, -1);

	map->map_size = (1 << (map_bits + 1));
	map->ops = ops;

	map->private_data = private_data;

	map->map = tracing_map_array_alloc(map->map_size,
					   sizeof(struct tracing_map_entry));
	if (!map->map)
		goto free;

	map->key_size = key_size;
	for (i = 0; i < TRACING_MAP_KEYS_MAX; i++)
		map->key_idx[i] = -1;
 out:
	return map;
 free:
	tracing_map_destroy(map);
	map = ERR_PTR(-ENOMEM);

	goto out;
}

/**
 * tracing_map_init - Allocate and clear a map's tracing_map_elts
 * @map: The tracing_map to initialize
 *
 * Allocates a clears a pool of tracing_map_elts equal to the
 * user-specified size of 2 ** map_bits (internally maintained as
 * 'max_elts' in struct tracing_map).  Before using, the map fields
 * should be added to the map with tracing_map_add_sum_field() and
 * tracing_map_add_key_field().  tracing_map_init() should then be
 * called to allocate the array of tracing_map_elts, in order to avoid
 * allocating anything in the map insertion path.  The user-specified
 * map size reflects the max number of elements requested by the user
 * - internally we double that in order to keep the table sparse and
 * keep collisions manageable.
 *
 * See tracing_map.h for a description of tracing_map_ops.
 *
 * Return: the tracing_map pointer if successful, ERR_PTR if not.
 */
int tracing_map_init(struct tracing_map *map)
{
	int err;

	if (map->n_fields < 2)
		return -EINVAL; /* need at least 1 key and 1 val */

	err = tracing_map_alloc_elts(map);
	if (err)
		return err;

	tracing_map_clear(map);

	return err;
}

static int cmp_entries_dup(const struct tracing_map_sort_entry **a,
			   const struct tracing_map_sort_entry **b)
{
	int ret = 0;

	if (memcmp((*a)->key, (*b)->key, (*a)->elt->map->key_size))
		ret = 1;

	return ret;
}

static int cmp_entries_sum(const struct tracing_map_sort_entry **a,
			   const struct tracing_map_sort_entry **b)
{
	const struct tracing_map_elt *elt_a, *elt_b;
	struct tracing_map_sort_key *sort_key;
	struct tracing_map_field *field;
	tracing_map_cmp_fn_t cmp_fn;
	void *val_a, *val_b;
	int ret = 0;

	elt_a = (*a)->elt;
	elt_b = (*b)->elt;

	sort_key = &elt_a->map->sort_key;

	field = &elt_a->fields[sort_key->field_idx];
	cmp_fn = field->cmp_fn;

	val_a = &elt_a->fields[sort_key->field_idx].sum;
	val_b = &elt_b->fields[sort_key->field_idx].sum;

	ret = cmp_fn(val_a, val_b);
	if (sort_key->descending)
		ret = -ret;

	return ret;
}

static int cmp_entries_key(const struct tracing_map_sort_entry **a,
			   const struct tracing_map_sort_entry **b)
{
	const struct tracing_map_elt *elt_a, *elt_b;
	struct tracing_map_sort_key *sort_key;
	struct tracing_map_field *field;
	tracing_map_cmp_fn_t cmp_fn;
	void *val_a, *val_b;
	int ret = 0;

	elt_a = (*a)->elt;
	elt_b = (*b)->elt;

	sort_key = &elt_a->map->sort_key;

	field = &elt_a->fields[sort_key->field_idx];

	cmp_fn = field->cmp_fn;

	val_a = elt_a->key + field->offset;
	val_b = elt_b->key + field->offset;

	ret = cmp_fn(val_a, val_b);
	if (sort_key->descending)
		ret = -ret;

	return ret;
}

static void destroy_sort_entry(struct tracing_map_sort_entry *entry)
{
	if (!entry)
		return;

	if (entry->elt_copied)
		tracing_map_elt_free(entry->elt);

	kfree(entry);
}

/**
 * tracing_map_destroy_sort_entries - Destroy an array of sort entries
 * @entries: The entries to destroy
 * @n_entries: The number of entries in the array
 *
 * Destroy the elements returned by a tracing_map_sort_entries() call.
 */
void tracing_map_destroy_sort_entries(struct tracing_map_sort_entry **entries,
				      unsigned int n_entries)
{
	unsigned int i;

	for (i = 0; i < n_entries; i++)
		destroy_sort_entry(entries[i]);

	vfree(entries);
}

static struct tracing_map_sort_entry *
create_sort_entry(void *key, struct tracing_map_elt *elt)
{
	struct tracing_map_sort_entry *sort_entry;

	sort_entry = kzalloc(sizeof(*sort_entry), GFP_KERNEL);
	if (!sort_entry)
		return NULL;

	sort_entry->key = key;
	sort_entry->elt = elt;

	return sort_entry;
}

static struct tracing_map_elt *copy_elt(struct tracing_map_elt *elt)
{
	struct tracing_map_elt *dup_elt;
	unsigned int i;

	dup_elt = tracing_map_elt_alloc(elt->map);
824
	if (IS_ERR(dup_elt))
825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065
		return NULL;

	if (elt->map->ops && elt->map->ops->elt_copy)
		elt->map->ops->elt_copy(dup_elt, elt);

	dup_elt->private_data = elt->private_data;
	memcpy(dup_elt->key, elt->key, elt->map->key_size);

	for (i = 0; i < elt->map->n_fields; i++) {
		atomic64_set(&dup_elt->fields[i].sum,
			     atomic64_read(&elt->fields[i].sum));
		dup_elt->fields[i].cmp_fn = elt->fields[i].cmp_fn;
	}

	return dup_elt;
}

static int merge_dup(struct tracing_map_sort_entry **sort_entries,
		     unsigned int target, unsigned int dup)
{
	struct tracing_map_elt *target_elt, *elt;
	bool first_dup = (target - dup) == 1;
	int i;

	if (first_dup) {
		elt = sort_entries[target]->elt;
		target_elt = copy_elt(elt);
		if (!target_elt)
			return -ENOMEM;
		sort_entries[target]->elt = target_elt;
		sort_entries[target]->elt_copied = true;
	} else
		target_elt = sort_entries[target]->elt;

	elt = sort_entries[dup]->elt;

	for (i = 0; i < elt->map->n_fields; i++)
		atomic64_add(atomic64_read(&elt->fields[i].sum),
			     &target_elt->fields[i].sum);

	sort_entries[dup]->dup = true;

	return 0;
}

static int merge_dups(struct tracing_map_sort_entry **sort_entries,
		      int n_entries, unsigned int key_size)
{
	unsigned int dups = 0, total_dups = 0;
	int err, i, j;
	void *key;

	if (n_entries < 2)
		return total_dups;

	sort(sort_entries, n_entries, sizeof(struct tracing_map_sort_entry *),
	     (int (*)(const void *, const void *))cmp_entries_dup, NULL);

	key = sort_entries[0]->key;
	for (i = 1; i < n_entries; i++) {
		if (!memcmp(sort_entries[i]->key, key, key_size)) {
			dups++; total_dups++;
			err = merge_dup(sort_entries, i - dups, i);
			if (err)
				return err;
			continue;
		}
		key = sort_entries[i]->key;
		dups = 0;
	}

	if (!total_dups)
		return total_dups;

	for (i = 0, j = 0; i < n_entries; i++) {
		if (!sort_entries[i]->dup) {
			sort_entries[j] = sort_entries[i];
			if (j++ != i)
				sort_entries[i] = NULL;
		} else {
			destroy_sort_entry(sort_entries[i]);
			sort_entries[i] = NULL;
		}
	}

	return total_dups;
}

static bool is_key(struct tracing_map *map, unsigned int field_idx)
{
	unsigned int i;

	for (i = 0; i < map->n_keys; i++)
		if (map->key_idx[i] == field_idx)
			return true;
	return false;
}

static void sort_secondary(struct tracing_map *map,
			   const struct tracing_map_sort_entry **entries,
			   unsigned int n_entries,
			   struct tracing_map_sort_key *primary_key,
			   struct tracing_map_sort_key *secondary_key)
{
	int (*primary_fn)(const struct tracing_map_sort_entry **,
			  const struct tracing_map_sort_entry **);
	int (*secondary_fn)(const struct tracing_map_sort_entry **,
			    const struct tracing_map_sort_entry **);
	unsigned i, start = 0, n_sub = 1;

	if (is_key(map, primary_key->field_idx))
		primary_fn = cmp_entries_key;
	else
		primary_fn = cmp_entries_sum;

	if (is_key(map, secondary_key->field_idx))
		secondary_fn = cmp_entries_key;
	else
		secondary_fn = cmp_entries_sum;

	for (i = 0; i < n_entries - 1; i++) {
		const struct tracing_map_sort_entry **a = &entries[i];
		const struct tracing_map_sort_entry **b = &entries[i + 1];

		if (primary_fn(a, b) == 0) {
			n_sub++;
			if (i < n_entries - 2)
				continue;
		}

		if (n_sub < 2) {
			start = i + 1;
			n_sub = 1;
			continue;
		}

		set_sort_key(map, secondary_key);
		sort(&entries[start], n_sub,
		     sizeof(struct tracing_map_sort_entry *),
		     (int (*)(const void *, const void *))secondary_fn, NULL);
		set_sort_key(map, primary_key);

		start = i + 1;
		n_sub = 1;
	}
}

/**
 * tracing_map_sort_entries - Sort the current set of tracing_map_elts in a map
 * @map: The tracing_map
 * @sort_key: The sort key to use for sorting
 * @sort_entries: outval: pointer to allocated and sorted array of entries
 *
 * tracing_map_sort_entries() sorts the current set of entries in the
 * map and returns the list of tracing_map_sort_entries containing
 * them to the client in the sort_entries param.  The client can
 * access the struct tracing_map_elt element of interest directly as
 * the 'elt' field of a returned struct tracing_map_sort_entry object.
 *
 * The sort_key has only two fields: idx and descending.  'idx' refers
 * to the index of the field added via tracing_map_add_sum_field() or
 * tracing_map_add_key_field() when the tracing_map was initialized.
 * 'descending' is a flag that if set reverses the sort order, which
 * by default is ascending.
 *
 * The client should not hold on to the returned array but should use
 * it and call tracing_map_destroy_sort_entries() when done.
 *
 * Return: the number of sort_entries in the struct tracing_map_sort_entry
 * array, negative on error
 */
int tracing_map_sort_entries(struct tracing_map *map,
			     struct tracing_map_sort_key *sort_keys,
			     unsigned int n_sort_keys,
			     struct tracing_map_sort_entry ***sort_entries)
{
	int (*cmp_entries_fn)(const struct tracing_map_sort_entry **,
			      const struct tracing_map_sort_entry **);
	struct tracing_map_sort_entry *sort_entry, **entries;
	int i, n_entries, ret;

	entries = vmalloc(map->max_elts * sizeof(sort_entry));
	if (!entries)
		return -ENOMEM;

	for (i = 0, n_entries = 0; i < map->map_size; i++) {
		struct tracing_map_entry *entry;

		entry = TRACING_MAP_ENTRY(map->map, i);

		if (!entry->key || !entry->val)
			continue;

		entries[n_entries] = create_sort_entry(entry->val->key,
						       entry->val);
		if (!entries[n_entries++]) {
			ret = -ENOMEM;
			goto free;
		}
	}

	if (n_entries == 0) {
		ret = 0;
		goto free;
	}

	if (n_entries == 1) {
		*sort_entries = entries;
		return 1;
	}

	ret = merge_dups(entries, n_entries, map->key_size);
	if (ret < 0)
		goto free;
	n_entries -= ret;

	if (is_key(map, sort_keys[0].field_idx))
		cmp_entries_fn = cmp_entries_key;
	else
		cmp_entries_fn = cmp_entries_sum;

	set_sort_key(map, &sort_keys[0]);

	sort(entries, n_entries, sizeof(struct tracing_map_sort_entry *),
	     (int (*)(const void *, const void *))cmp_entries_fn, NULL);

	if (n_sort_keys > 1)
		sort_secondary(map,
			       (const struct tracing_map_sort_entry **)entries,
			       n_entries,
			       &sort_keys[0],
			       &sort_keys[1]);

	*sort_entries = entries;

	return n_entries;
 free:
	tracing_map_destroy_sort_entries(entries, n_entries);

	return ret;
}