2 * tracing_map - lock-free map for tracing
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
14 * Copyright (C) 2015 Tom Zanussi <tom.zanussi@linux.intel.com>
16 * tracing_map implementation inspired by lock-free map algorithms
17 * originated by Dr. Cliff Click:
19 * http://www.azulsystems.com/blog/cliff/2007-03-26-non-blocking-hashtable
20 * http://www.azulsystems.com/events/javaone_2007/2007_LockFreeHash.pdf
23 #include <linux/vmalloc.h>
24 #include <linux/jhash.h>
25 #include <linux/slab.h>
26 #include <linux/sort.h>
28 #include "tracing_map.h"
32 * NOTE: For a detailed description of the data structures used by
33 * these functions (such as tracing_map_elt) please see the overview
34 * of tracing_map data structures at the beginning of tracing_map.h.
38 * tracing_map_update_sum - Add a value to a tracing_map_elt's sum field
39 * @elt: The tracing_map_elt
40 * @i: The index of the given sum associated with the tracing_map_elt
41 * @n: The value to add to the sum
43 * Add n to sum i associated with the specified tracing_map_elt
44 * instance. The index i is the index returned by the call to
45 * tracing_map_add_sum_field() when the tracing map was set up.
47 void tracing_map_update_sum(struct tracing_map_elt *elt, unsigned int i, u64 n)
49 atomic64_add(n, &elt->fields[i].sum);
53 * tracing_map_read_sum - Return the value of a tracing_map_elt's sum field
54 * @elt: The tracing_map_elt
55 * @i: The index of the given sum associated with the tracing_map_elt
57 * Retrieve the value of the sum i associated with the specified
58 * tracing_map_elt instance. The index i is the index returned by the
59 * call to tracing_map_add_sum_field() when the tracing map was set
62 * Return: The sum associated with field i for elt.
64 u64 tracing_map_read_sum(struct tracing_map_elt *elt, unsigned int i)
66 return (u64)atomic64_read(&elt->fields[i].sum);
69 int tracing_map_cmp_string(void *val_a, void *val_b)
77 int tracing_map_cmp_none(void *val_a, void *val_b)
82 static int tracing_map_cmp_atomic64(void *val_a, void *val_b)
84 u64 a = atomic64_read((atomic64_t *)val_a);
85 u64 b = atomic64_read((atomic64_t *)val_b);
87 return (a > b) ? 1 : ((a < b) ? -1 : 0);
90 #define DEFINE_TRACING_MAP_CMP_FN(type) \
91 static int tracing_map_cmp_##type(void *val_a, void *val_b) \
93 type a = *(type *)val_a; \
94 type b = *(type *)val_b; \
96 return (a > b) ? 1 : ((a < b) ? -1 : 0); \
99 DEFINE_TRACING_MAP_CMP_FN(s64);
100 DEFINE_TRACING_MAP_CMP_FN(u64);
101 DEFINE_TRACING_MAP_CMP_FN(s32);
102 DEFINE_TRACING_MAP_CMP_FN(u32);
103 DEFINE_TRACING_MAP_CMP_FN(s16);
104 DEFINE_TRACING_MAP_CMP_FN(u16);
105 DEFINE_TRACING_MAP_CMP_FN(s8);
106 DEFINE_TRACING_MAP_CMP_FN(u8);
108 tracing_map_cmp_fn_t tracing_map_cmp_num(int field_size,
111 tracing_map_cmp_fn_t fn = tracing_map_cmp_none;
113 switch (field_size) {
116 fn = tracing_map_cmp_s64;
118 fn = tracing_map_cmp_u64;
122 fn = tracing_map_cmp_s32;
124 fn = tracing_map_cmp_u32;
128 fn = tracing_map_cmp_s16;
130 fn = tracing_map_cmp_u16;
134 fn = tracing_map_cmp_s8;
136 fn = tracing_map_cmp_u8;
143 static int tracing_map_add_field(struct tracing_map *map,
144 tracing_map_cmp_fn_t cmp_fn)
148 if (map->n_fields < TRACING_MAP_FIELDS_MAX) {
150 map->fields[map->n_fields++].cmp_fn = cmp_fn;
157 * tracing_map_add_sum_field - Add a field describing a tracing_map sum
158 * @map: The tracing_map
160 * Add a sum field to the key and return the index identifying it in
161 * the map and associated tracing_map_elts. This is the index used
162 * for instance to update a sum for a particular tracing_map_elt using
163 * tracing_map_update_sum() or reading it via tracing_map_read_sum().
165 * Return: The index identifying the field in the map and associated
166 * tracing_map_elts, or -EINVAL on error.
168 int tracing_map_add_sum_field(struct tracing_map *map)
170 return tracing_map_add_field(map, tracing_map_cmp_atomic64);
174 * tracing_map_add_key_field - Add a field describing a tracing_map key
175 * @map: The tracing_map
176 * @offset: The offset within the key
177 * @cmp_fn: The comparison function that will be used to sort on the key
179 * Let the map know there is a key and that if it's used as a sort key
182 * A key can be a subset of a compound key; for that purpose, the
183 * offset param is used to describe where within the the compound key
184 * the key referenced by this key field resides.
186 * Return: The index identifying the field in the map and associated
187 * tracing_map_elts, or -EINVAL on error.
189 int tracing_map_add_key_field(struct tracing_map *map,
191 tracing_map_cmp_fn_t cmp_fn)
194 int idx = tracing_map_add_field(map, cmp_fn);
199 map->fields[idx].offset = offset;
201 map->key_idx[map->n_keys++] = idx;
206 void tracing_map_array_clear(struct tracing_map_array *a)
213 for (i = 0; i < a->n_pages; i++)
214 memset(a->pages[i], 0, PAGE_SIZE);
217 void tracing_map_array_free(struct tracing_map_array *a)
229 for (i = 0; i < a->n_pages; i++) {
232 free_page((unsigned long)a->pages[i]);
236 struct tracing_map_array *tracing_map_array_alloc(unsigned int n_elts,
237 unsigned int entry_size)
239 struct tracing_map_array *a;
242 a = kzalloc(sizeof(*a), GFP_KERNEL);
246 a->entry_size_shift = fls(roundup_pow_of_two(entry_size) - 1);
247 a->entries_per_page = PAGE_SIZE / (1 << a->entry_size_shift);
248 a->n_pages = n_elts / a->entries_per_page;
251 a->entry_shift = fls(a->entries_per_page) - 1;
252 a->entry_mask = (1 << a->entry_shift) - 1;
254 a->pages = kcalloc(a->n_pages, sizeof(void *), GFP_KERNEL);
258 for (i = 0; i < a->n_pages; i++) {
259 a->pages[i] = (void *)get_zeroed_page(GFP_KERNEL);
266 tracing_map_array_free(a);
272 static void tracing_map_elt_clear(struct tracing_map_elt *elt)
276 for (i = 0; i < elt->map->n_fields; i++)
277 if (elt->fields[i].cmp_fn == tracing_map_cmp_atomic64)
278 atomic64_set(&elt->fields[i].sum, 0);
280 if (elt->map->ops && elt->map->ops->elt_clear)
281 elt->map->ops->elt_clear(elt);
284 static void tracing_map_elt_init_fields(struct tracing_map_elt *elt)
288 tracing_map_elt_clear(elt);
290 for (i = 0; i < elt->map->n_fields; i++) {
291 elt->fields[i].cmp_fn = elt->map->fields[i].cmp_fn;
293 if (elt->fields[i].cmp_fn != tracing_map_cmp_atomic64)
294 elt->fields[i].offset = elt->map->fields[i].offset;
298 static void tracing_map_elt_free(struct tracing_map_elt *elt)
303 if (elt->map->ops && elt->map->ops->elt_free)
304 elt->map->ops->elt_free(elt);
310 static struct tracing_map_elt *tracing_map_elt_alloc(struct tracing_map *map)
312 struct tracing_map_elt *elt;
315 elt = kzalloc(sizeof(*elt), GFP_KERNEL);
317 return ERR_PTR(-ENOMEM);
321 elt->key = kzalloc(map->key_size, GFP_KERNEL);
327 elt->fields = kcalloc(map->n_fields, sizeof(*elt->fields), GFP_KERNEL);
333 tracing_map_elt_init_fields(elt);
335 if (map->ops && map->ops->elt_alloc) {
336 err = map->ops->elt_alloc(elt);
342 tracing_map_elt_free(elt);
347 static struct tracing_map_elt *get_free_elt(struct tracing_map *map)
349 struct tracing_map_elt *elt = NULL;
352 idx = atomic_inc_return(&map->next_elt);
353 if (idx < map->max_elts) {
354 elt = *(TRACING_MAP_ELT(map->elts, idx));
355 if (map->ops && map->ops->elt_init)
356 map->ops->elt_init(elt);
362 static void tracing_map_free_elts(struct tracing_map *map)
369 for (i = 0; i < map->max_elts; i++)
370 tracing_map_elt_free(*(TRACING_MAP_ELT(map->elts, i)));
372 tracing_map_array_free(map->elts);
375 static int tracing_map_alloc_elts(struct tracing_map *map)
379 map->elts = tracing_map_array_alloc(map->max_elts,
380 sizeof(struct tracing_map_elt *));
384 for (i = 0; i < map->max_elts; i++) {
385 *(TRACING_MAP_ELT(map->elts, i)) = tracing_map_elt_alloc(map);
386 if (!(*(TRACING_MAP_ELT(map->elts, i)))) {
387 tracing_map_free_elts(map);
396 static inline bool keys_match(void *key, void *test_key, unsigned key_size)
400 if (memcmp(key, test_key, key_size))
406 static inline struct tracing_map_elt *
407 __tracing_map_insert(struct tracing_map *map, void *key, bool lookup_only)
409 u32 idx, key_hash, test_key;
410 struct tracing_map_entry *entry;
412 key_hash = jhash(key, map->key_size, 0);
415 idx = key_hash >> (32 - (map->map_bits + 1));
418 idx &= (map->map_size - 1);
419 entry = TRACING_MAP_ENTRY(map->map, idx);
420 test_key = entry->key;
422 if (test_key && test_key == key_hash && entry->val &&
423 keys_match(key, entry->val->key, map->key_size)) {
424 atomic64_inc(&map->hits);
432 if (!cmpxchg(&entry->key, 0, key_hash)) {
433 struct tracing_map_elt *elt;
435 elt = get_free_elt(map);
437 atomic64_inc(&map->drops);
442 memcpy(elt->key, key, map->key_size);
444 atomic64_inc(&map->hits);
457 * tracing_map_insert - Insert key and/or retrieve val from a tracing_map
458 * @map: The tracing_map to insert into
459 * @key: The key to insert
461 * Inserts a key into a tracing_map and creates and returns a new
462 * tracing_map_elt for it, or if the key has already been inserted by
463 * a previous call, returns the tracing_map_elt already associated
464 * with it. When the map was created, the number of elements to be
465 * allocated for the map was specified (internally maintained as
466 * 'max_elts' in struct tracing_map), and that number of
467 * tracing_map_elts was created by tracing_map_init(). This is the
468 * pre-allocated pool of tracing_map_elts that tracing_map_insert()
469 * will allocate from when adding new keys. Once that pool is
470 * exhausted, tracing_map_insert() is useless and will return NULL to
471 * signal that state. There are two user-visible tracing_map
472 * variables, 'hits' and 'drops', which are updated by this function.
473 * Every time an element is either successfully inserted or retrieved,
474 * the 'hits' value is incrememented. Every time an element insertion
475 * fails, the 'drops' value is incremented.
477 * This is a lock-free tracing map insertion function implementing a
478 * modified form of Cliff Click's basic insertion algorithm. It
479 * requires the table size be a power of two. To prevent any
480 * possibility of an infinite loop we always make the internal table
481 * size double the size of the requested table size (max_elts * 2).
482 * Likewise, we never reuse a slot or resize or delete elements - when
483 * we've reached max_elts entries, we simply return NULL once we've
484 * run out of entries. Readers can at any point in time traverse the
485 * tracing map and safely access the key/val pairs.
487 * Return: the tracing_map_elt pointer val associated with the key.
488 * If this was a newly inserted key, the val will be a newly allocated
489 * and associated tracing_map_elt pointer val. If the key wasn't
490 * found and the pool of tracing_map_elts has been exhausted, NULL is
491 * returned and no further insertions will succeed.
493 struct tracing_map_elt *tracing_map_insert(struct tracing_map *map, void *key)
495 return __tracing_map_insert(map, key, false);
499 * tracing_map_lookup - Retrieve val from a tracing_map
500 * @map: The tracing_map to perform the lookup on
501 * @key: The key to look up
503 * Looks up key in tracing_map and if found returns the matching
504 * tracing_map_elt. This is a lock-free lookup; see
505 * tracing_map_insert() for details on tracing_map and how it works.
506 * Every time an element is retrieved, the 'hits' value is
507 * incrememented. There is one user-visible tracing_map variable,
508 * 'hits', which is updated by this function. Every time an element
509 * is successfully retrieved, the 'hits' value is incrememented. The
510 * 'drops' value is never updated by this function.
512 * Return: the tracing_map_elt pointer val associated with the key.
513 * If the key wasn't found, NULL is returned.
515 struct tracing_map_elt *tracing_map_lookup(struct tracing_map *map, void *key)
517 return __tracing_map_insert(map, key, true);
521 * tracing_map_destroy - Destroy a tracing_map
522 * @map: The tracing_map to destroy
524 * Frees a tracing_map along with its associated array of
527 * Callers should make sure there are no readers or writers actively
528 * reading or inserting into the map before calling this.
530 void tracing_map_destroy(struct tracing_map *map)
535 tracing_map_free_elts(map);
537 tracing_map_array_free(map->map);
542 * tracing_map_clear - Clear a tracing_map
543 * @map: The tracing_map to clear
545 * Resets the tracing map to a cleared or initial state. The
546 * tracing_map_elts are all cleared, and the array of struct
547 * tracing_map_entry is reset to an initialized state.
549 * Callers should make sure there are no writers actively inserting
550 * into the map before calling this.
552 void tracing_map_clear(struct tracing_map *map)
556 atomic_set(&map->next_elt, -1);
557 atomic64_set(&map->hits, 0);
558 atomic64_set(&map->drops, 0);
560 tracing_map_array_clear(map->map);
562 for (i = 0; i < map->max_elts; i++)
563 tracing_map_elt_clear(*(TRACING_MAP_ELT(map->elts, i)));
566 static void set_sort_key(struct tracing_map *map,
567 struct tracing_map_sort_key *sort_key)
569 map->sort_key = *sort_key;
573 * tracing_map_create - Create a lock-free map and element pool
574 * @map_bits: The size of the map (2 ** map_bits)
575 * @key_size: The size of the key for the map in bytes
576 * @ops: Optional client-defined tracing_map_ops instance
577 * @private_data: Client data associated with the map
579 * Creates and sets up a map to contain 2 ** map_bits number of
580 * elements (internally maintained as 'max_elts' in struct
581 * tracing_map). Before using, map fields should be added to the map
582 * with tracing_map_add_sum_field() and tracing_map_add_key_field().
583 * tracing_map_init() should then be called to allocate the array of
584 * tracing_map_elts, in order to avoid allocating anything in the map
585 * insertion path. The user-specified map size reflects the maximum
586 * number of elements that can be contained in the table requested by
587 * the user - internally we double that in order to keep the table
588 * sparse and keep collisions manageable.
590 * A tracing_map is a special-purpose map designed to aggregate or
591 * 'sum' one or more values associated with a specific object of type
592 * tracing_map_elt, which is attached by the map to a given key.
594 * tracing_map_create() sets up the map itself, and provides
595 * operations for inserting tracing_map_elts, but doesn't allocate the
596 * tracing_map_elts themselves, or provide a means for describing the
597 * keys or sums associated with the tracing_map_elts. All
598 * tracing_map_elts for a given map have the same set of sums and
599 * keys, which are defined by the client using the functions
600 * tracing_map_add_key_field() and tracing_map_add_sum_field(). Once
601 * the fields are defined, the pool of elements allocated for the map
602 * can be created, which occurs when the client code calls
603 * tracing_map_init().
605 * When tracing_map_init() returns, tracing_map_elt elements can be
606 * inserted into the map using tracing_map_insert(). When called,
607 * tracing_map_insert() grabs a free tracing_map_elt from the pool, or
608 * finds an existing match in the map and in either case returns it.
609 * The client can then use tracing_map_update_sum() and
610 * tracing_map_read_sum() to update or read a given sum field for the
613 * The client can at any point retrieve and traverse the current set
614 * of inserted tracing_map_elts in a tracing_map, via
615 * tracing_map_sort_entries(). Sorting can be done on any field,
618 * See tracing_map.h for a description of tracing_map_ops.
620 * Return: the tracing_map pointer if successful, ERR_PTR if not.
622 struct tracing_map *tracing_map_create(unsigned int map_bits,
623 unsigned int key_size,
624 const struct tracing_map_ops *ops,
627 struct tracing_map *map;
630 if (map_bits < TRACING_MAP_BITS_MIN ||
631 map_bits > TRACING_MAP_BITS_MAX)
632 return ERR_PTR(-EINVAL);
634 map = kzalloc(sizeof(*map), GFP_KERNEL);
636 return ERR_PTR(-ENOMEM);
638 map->map_bits = map_bits;
639 map->max_elts = (1 << map_bits);
640 atomic_set(&map->next_elt, -1);
642 map->map_size = (1 << (map_bits + 1));
645 map->private_data = private_data;
647 map->map = tracing_map_array_alloc(map->map_size,
648 sizeof(struct tracing_map_entry));
652 map->key_size = key_size;
653 for (i = 0; i < TRACING_MAP_KEYS_MAX; i++)
654 map->key_idx[i] = -1;
658 tracing_map_destroy(map);
659 map = ERR_PTR(-ENOMEM);
665 * tracing_map_init - Allocate and clear a map's tracing_map_elts
666 * @map: The tracing_map to initialize
668 * Allocates a clears a pool of tracing_map_elts equal to the
669 * user-specified size of 2 ** map_bits (internally maintained as
670 * 'max_elts' in struct tracing_map). Before using, the map fields
671 * should be added to the map with tracing_map_add_sum_field() and
672 * tracing_map_add_key_field(). tracing_map_init() should then be
673 * called to allocate the array of tracing_map_elts, in order to avoid
674 * allocating anything in the map insertion path. The user-specified
675 * map size reflects the max number of elements requested by the user
676 * - internally we double that in order to keep the table sparse and
677 * keep collisions manageable.
679 * See tracing_map.h for a description of tracing_map_ops.
681 * Return: the tracing_map pointer if successful, ERR_PTR if not.
683 int tracing_map_init(struct tracing_map *map)
687 if (map->n_fields < 2)
688 return -EINVAL; /* need at least 1 key and 1 val */
690 err = tracing_map_alloc_elts(map);
694 tracing_map_clear(map);
699 static int cmp_entries_dup(const struct tracing_map_sort_entry **a,
700 const struct tracing_map_sort_entry **b)
704 if (memcmp((*a)->key, (*b)->key, (*a)->elt->map->key_size))
710 static int cmp_entries_sum(const struct tracing_map_sort_entry **a,
711 const struct tracing_map_sort_entry **b)
713 const struct tracing_map_elt *elt_a, *elt_b;
714 struct tracing_map_sort_key *sort_key;
715 struct tracing_map_field *field;
716 tracing_map_cmp_fn_t cmp_fn;
723 sort_key = &elt_a->map->sort_key;
725 field = &elt_a->fields[sort_key->field_idx];
726 cmp_fn = field->cmp_fn;
728 val_a = &elt_a->fields[sort_key->field_idx].sum;
729 val_b = &elt_b->fields[sort_key->field_idx].sum;
731 ret = cmp_fn(val_a, val_b);
732 if (sort_key->descending)
738 static int cmp_entries_key(const struct tracing_map_sort_entry **a,
739 const struct tracing_map_sort_entry **b)
741 const struct tracing_map_elt *elt_a, *elt_b;
742 struct tracing_map_sort_key *sort_key;
743 struct tracing_map_field *field;
744 tracing_map_cmp_fn_t cmp_fn;
751 sort_key = &elt_a->map->sort_key;
753 field = &elt_a->fields[sort_key->field_idx];
755 cmp_fn = field->cmp_fn;
757 val_a = elt_a->key + field->offset;
758 val_b = elt_b->key + field->offset;
760 ret = cmp_fn(val_a, val_b);
761 if (sort_key->descending)
767 static void destroy_sort_entry(struct tracing_map_sort_entry *entry)
772 if (entry->elt_copied)
773 tracing_map_elt_free(entry->elt);
779 * tracing_map_destroy_sort_entries - Destroy an array of sort entries
780 * @entries: The entries to destroy
781 * @n_entries: The number of entries in the array
783 * Destroy the elements returned by a tracing_map_sort_entries() call.
785 void tracing_map_destroy_sort_entries(struct tracing_map_sort_entry **entries,
786 unsigned int n_entries)
790 for (i = 0; i < n_entries; i++)
791 destroy_sort_entry(entries[i]);
796 static struct tracing_map_sort_entry *
797 create_sort_entry(void *key, struct tracing_map_elt *elt)
799 struct tracing_map_sort_entry *sort_entry;
801 sort_entry = kzalloc(sizeof(*sort_entry), GFP_KERNEL);
805 sort_entry->key = key;
806 sort_entry->elt = elt;
811 static struct tracing_map_elt *copy_elt(struct tracing_map_elt *elt)
813 struct tracing_map_elt *dup_elt;
816 dup_elt = tracing_map_elt_alloc(elt->map);
820 if (elt->map->ops && elt->map->ops->elt_copy)
821 elt->map->ops->elt_copy(dup_elt, elt);
823 dup_elt->private_data = elt->private_data;
824 memcpy(dup_elt->key, elt->key, elt->map->key_size);
826 for (i = 0; i < elt->map->n_fields; i++) {
827 atomic64_set(&dup_elt->fields[i].sum,
828 atomic64_read(&elt->fields[i].sum));
829 dup_elt->fields[i].cmp_fn = elt->fields[i].cmp_fn;
835 static int merge_dup(struct tracing_map_sort_entry **sort_entries,
836 unsigned int target, unsigned int dup)
838 struct tracing_map_elt *target_elt, *elt;
839 bool first_dup = (target - dup) == 1;
843 elt = sort_entries[target]->elt;
844 target_elt = copy_elt(elt);
847 sort_entries[target]->elt = target_elt;
848 sort_entries[target]->elt_copied = true;
850 target_elt = sort_entries[target]->elt;
852 elt = sort_entries[dup]->elt;
854 for (i = 0; i < elt->map->n_fields; i++)
855 atomic64_add(atomic64_read(&elt->fields[i].sum),
856 &target_elt->fields[i].sum);
858 sort_entries[dup]->dup = true;
863 static int merge_dups(struct tracing_map_sort_entry **sort_entries,
864 int n_entries, unsigned int key_size)
866 unsigned int dups = 0, total_dups = 0;
873 sort(sort_entries, n_entries, sizeof(struct tracing_map_sort_entry *),
874 (int (*)(const void *, const void *))cmp_entries_dup, NULL);
876 key = sort_entries[0]->key;
877 for (i = 1; i < n_entries; i++) {
878 if (!memcmp(sort_entries[i]->key, key, key_size)) {
879 dups++; total_dups++;
880 err = merge_dup(sort_entries, i - dups, i);
885 key = sort_entries[i]->key;
892 for (i = 0, j = 0; i < n_entries; i++) {
893 if (!sort_entries[i]->dup) {
894 sort_entries[j] = sort_entries[i];
896 sort_entries[i] = NULL;
898 destroy_sort_entry(sort_entries[i]);
899 sort_entries[i] = NULL;
906 static bool is_key(struct tracing_map *map, unsigned int field_idx)
910 for (i = 0; i < map->n_keys; i++)
911 if (map->key_idx[i] == field_idx)
916 static void sort_secondary(struct tracing_map *map,
917 const struct tracing_map_sort_entry **entries,
918 unsigned int n_entries,
919 struct tracing_map_sort_key *primary_key,
920 struct tracing_map_sort_key *secondary_key)
922 int (*primary_fn)(const struct tracing_map_sort_entry **,
923 const struct tracing_map_sort_entry **);
924 int (*secondary_fn)(const struct tracing_map_sort_entry **,
925 const struct tracing_map_sort_entry **);
926 unsigned i, start = 0, n_sub = 1;
928 if (is_key(map, primary_key->field_idx))
929 primary_fn = cmp_entries_key;
931 primary_fn = cmp_entries_sum;
933 if (is_key(map, secondary_key->field_idx))
934 secondary_fn = cmp_entries_key;
936 secondary_fn = cmp_entries_sum;
938 for (i = 0; i < n_entries - 1; i++) {
939 const struct tracing_map_sort_entry **a = &entries[i];
940 const struct tracing_map_sort_entry **b = &entries[i + 1];
942 if (primary_fn(a, b) == 0) {
944 if (i < n_entries - 2)
954 set_sort_key(map, secondary_key);
955 sort(&entries[start], n_sub,
956 sizeof(struct tracing_map_sort_entry *),
957 (int (*)(const void *, const void *))secondary_fn, NULL);
958 set_sort_key(map, primary_key);
966 * tracing_map_sort_entries - Sort the current set of tracing_map_elts in a map
967 * @map: The tracing_map
968 * @sort_key: The sort key to use for sorting
969 * @sort_entries: outval: pointer to allocated and sorted array of entries
971 * tracing_map_sort_entries() sorts the current set of entries in the
972 * map and returns the list of tracing_map_sort_entries containing
973 * them to the client in the sort_entries param. The client can
974 * access the struct tracing_map_elt element of interest directly as
975 * the 'elt' field of a returned struct tracing_map_sort_entry object.
977 * The sort_key has only two fields: idx and descending. 'idx' refers
978 * to the index of the field added via tracing_map_add_sum_field() or
979 * tracing_map_add_key_field() when the tracing_map was initialized.
980 * 'descending' is a flag that if set reverses the sort order, which
981 * by default is ascending.
983 * The client should not hold on to the returned array but should use
984 * it and call tracing_map_destroy_sort_entries() when done.
986 * Return: the number of sort_entries in the struct tracing_map_sort_entry
987 * array, negative on error
989 int tracing_map_sort_entries(struct tracing_map *map,
990 struct tracing_map_sort_key *sort_keys,
991 unsigned int n_sort_keys,
992 struct tracing_map_sort_entry ***sort_entries)
994 int (*cmp_entries_fn)(const struct tracing_map_sort_entry **,
995 const struct tracing_map_sort_entry **);
996 struct tracing_map_sort_entry *sort_entry, **entries;
997 int i, n_entries, ret;
999 entries = vmalloc(map->max_elts * sizeof(sort_entry));
1003 for (i = 0, n_entries = 0; i < map->map_size; i++) {
1004 struct tracing_map_entry *entry;
1006 entry = TRACING_MAP_ENTRY(map->map, i);
1008 if (!entry->key || !entry->val)
1011 entries[n_entries] = create_sort_entry(entry->val->key,
1013 if (!entries[n_entries++]) {
1019 if (n_entries == 0) {
1024 if (n_entries == 1) {
1025 *sort_entries = entries;
1029 ret = merge_dups(entries, n_entries, map->key_size);
1034 if (is_key(map, sort_keys[0].field_idx))
1035 cmp_entries_fn = cmp_entries_key;
1037 cmp_entries_fn = cmp_entries_sum;
1039 set_sort_key(map, &sort_keys[0]);
1041 sort(entries, n_entries, sizeof(struct tracing_map_sort_entry *),
1042 (int (*)(const void *, const void *))cmp_entries_fn, NULL);
1044 if (n_sort_keys > 1)
1046 (const struct tracing_map_sort_entry **)entries,
1051 *sort_entries = entries;
1055 tracing_map_destroy_sort_entries(entries, n_entries);