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>
27 #include <linux/kmemleak.h>
29 #include "tracing_map.h"
33 * NOTE: For a detailed description of the data structures used by
34 * these functions (such as tracing_map_elt) please see the overview
35 * of tracing_map data structures at the beginning of tracing_map.h.
39 * tracing_map_update_sum - Add a value to a tracing_map_elt's sum field
40 * @elt: The tracing_map_elt
41 * @i: The index of the given sum associated with the tracing_map_elt
42 * @n: The value to add to the sum
44 * Add n to sum i associated with the specified tracing_map_elt
45 * instance. The index i is the index returned by the call to
46 * tracing_map_add_sum_field() when the tracing map was set up.
48 void tracing_map_update_sum(struct tracing_map_elt *elt, unsigned int i, u64 n)
50 atomic64_add(n, &elt->fields[i].sum);
54 * tracing_map_read_sum - Return the value of a tracing_map_elt's sum field
55 * @elt: The tracing_map_elt
56 * @i: The index of the given sum associated with the tracing_map_elt
58 * Retrieve the value of the sum i associated with the specified
59 * tracing_map_elt instance. The index i is the index returned by the
60 * call to tracing_map_add_sum_field() when the tracing map was set
63 * Return: The sum associated with field i for elt.
65 u64 tracing_map_read_sum(struct tracing_map_elt *elt, unsigned int i)
67 return (u64)atomic64_read(&elt->fields[i].sum);
70 int tracing_map_cmp_string(void *val_a, void *val_b)
78 int tracing_map_cmp_none(void *val_a, void *val_b)
83 static int tracing_map_cmp_atomic64(void *val_a, void *val_b)
85 u64 a = atomic64_read((atomic64_t *)val_a);
86 u64 b = atomic64_read((atomic64_t *)val_b);
88 return (a > b) ? 1 : ((a < b) ? -1 : 0);
91 #define DEFINE_TRACING_MAP_CMP_FN(type) \
92 static int tracing_map_cmp_##type(void *val_a, void *val_b) \
94 type a = (type)(*(u64 *)val_a); \
95 type b = (type)(*(u64 *)val_b); \
97 return (a > b) ? 1 : ((a < b) ? -1 : 0); \
100 DEFINE_TRACING_MAP_CMP_FN(s64);
101 DEFINE_TRACING_MAP_CMP_FN(u64);
102 DEFINE_TRACING_MAP_CMP_FN(s32);
103 DEFINE_TRACING_MAP_CMP_FN(u32);
104 DEFINE_TRACING_MAP_CMP_FN(s16);
105 DEFINE_TRACING_MAP_CMP_FN(u16);
106 DEFINE_TRACING_MAP_CMP_FN(s8);
107 DEFINE_TRACING_MAP_CMP_FN(u8);
109 tracing_map_cmp_fn_t tracing_map_cmp_num(int field_size,
112 tracing_map_cmp_fn_t fn = tracing_map_cmp_none;
114 switch (field_size) {
117 fn = tracing_map_cmp_s64;
119 fn = tracing_map_cmp_u64;
123 fn = tracing_map_cmp_s32;
125 fn = tracing_map_cmp_u32;
129 fn = tracing_map_cmp_s16;
131 fn = tracing_map_cmp_u16;
135 fn = tracing_map_cmp_s8;
137 fn = tracing_map_cmp_u8;
144 static int tracing_map_add_field(struct tracing_map *map,
145 tracing_map_cmp_fn_t cmp_fn)
149 if (map->n_fields < TRACING_MAP_FIELDS_MAX) {
151 map->fields[map->n_fields++].cmp_fn = cmp_fn;
158 * tracing_map_add_sum_field - Add a field describing a tracing_map sum
159 * @map: The tracing_map
161 * Add a sum field to the key and return the index identifying it in
162 * the map and associated tracing_map_elts. This is the index used
163 * for instance to update a sum for a particular tracing_map_elt using
164 * tracing_map_update_sum() or reading it via tracing_map_read_sum().
166 * Return: The index identifying the field in the map and associated
167 * tracing_map_elts, or -EINVAL on error.
169 int tracing_map_add_sum_field(struct tracing_map *map)
171 return tracing_map_add_field(map, tracing_map_cmp_atomic64);
175 * tracing_map_add_key_field - Add a field describing a tracing_map key
176 * @map: The tracing_map
177 * @offset: The offset within the key
178 * @cmp_fn: The comparison function that will be used to sort on the key
180 * Let the map know there is a key and that if it's used as a sort key
183 * A key can be a subset of a compound key; for that purpose, the
184 * offset param is used to describe where within the the compound key
185 * the key referenced by this key field resides.
187 * Return: The index identifying the field in the map and associated
188 * tracing_map_elts, or -EINVAL on error.
190 int tracing_map_add_key_field(struct tracing_map *map,
192 tracing_map_cmp_fn_t cmp_fn)
195 int idx = tracing_map_add_field(map, cmp_fn);
200 map->fields[idx].offset = offset;
202 map->key_idx[map->n_keys++] = idx;
207 void tracing_map_array_clear(struct tracing_map_array *a)
214 for (i = 0; i < a->n_pages; i++)
215 memset(a->pages[i], 0, PAGE_SIZE);
218 void tracing_map_array_free(struct tracing_map_array *a)
228 for (i = 0; i < a->n_pages; i++) {
231 kmemleak_free(a->pages[i]);
232 free_page((unsigned long)a->pages[i]);
241 struct tracing_map_array *tracing_map_array_alloc(unsigned int n_elts,
242 unsigned int entry_size)
244 struct tracing_map_array *a;
247 a = kzalloc(sizeof(*a), GFP_KERNEL);
251 a->entry_size_shift = fls(roundup_pow_of_two(entry_size) - 1);
252 a->entries_per_page = PAGE_SIZE / (1 << a->entry_size_shift);
253 a->n_pages = n_elts / a->entries_per_page;
256 a->entry_shift = fls(a->entries_per_page) - 1;
257 a->entry_mask = (1 << a->entry_shift) - 1;
259 a->pages = kcalloc(a->n_pages, sizeof(void *), GFP_KERNEL);
263 for (i = 0; i < a->n_pages; i++) {
264 a->pages[i] = (void *)get_zeroed_page(GFP_KERNEL);
267 kmemleak_alloc(a->pages[i], PAGE_SIZE, 1, GFP_KERNEL);
272 tracing_map_array_free(a);
278 static void tracing_map_elt_clear(struct tracing_map_elt *elt)
282 for (i = 0; i < elt->map->n_fields; i++)
283 if (elt->fields[i].cmp_fn == tracing_map_cmp_atomic64)
284 atomic64_set(&elt->fields[i].sum, 0);
286 if (elt->map->ops && elt->map->ops->elt_clear)
287 elt->map->ops->elt_clear(elt);
290 static void tracing_map_elt_init_fields(struct tracing_map_elt *elt)
294 tracing_map_elt_clear(elt);
296 for (i = 0; i < elt->map->n_fields; i++) {
297 elt->fields[i].cmp_fn = elt->map->fields[i].cmp_fn;
299 if (elt->fields[i].cmp_fn != tracing_map_cmp_atomic64)
300 elt->fields[i].offset = elt->map->fields[i].offset;
304 static void tracing_map_elt_free(struct tracing_map_elt *elt)
309 if (elt->map->ops && elt->map->ops->elt_free)
310 elt->map->ops->elt_free(elt);
316 static struct tracing_map_elt *tracing_map_elt_alloc(struct tracing_map *map)
318 struct tracing_map_elt *elt;
321 elt = kzalloc(sizeof(*elt), GFP_KERNEL);
323 return ERR_PTR(-ENOMEM);
327 elt->key = kzalloc(map->key_size, GFP_KERNEL);
333 elt->fields = kcalloc(map->n_fields, sizeof(*elt->fields), GFP_KERNEL);
339 tracing_map_elt_init_fields(elt);
341 if (map->ops && map->ops->elt_alloc) {
342 err = map->ops->elt_alloc(elt);
348 tracing_map_elt_free(elt);
353 static struct tracing_map_elt *get_free_elt(struct tracing_map *map)
355 struct tracing_map_elt *elt = NULL;
358 idx = atomic_inc_return(&map->next_elt);
359 if (idx < map->max_elts) {
360 elt = *(TRACING_MAP_ELT(map->elts, idx));
361 if (map->ops && map->ops->elt_init)
362 map->ops->elt_init(elt);
368 static void tracing_map_free_elts(struct tracing_map *map)
375 for (i = 0; i < map->max_elts; i++) {
376 tracing_map_elt_free(*(TRACING_MAP_ELT(map->elts, i)));
377 *(TRACING_MAP_ELT(map->elts, i)) = NULL;
380 tracing_map_array_free(map->elts);
384 static int tracing_map_alloc_elts(struct tracing_map *map)
388 map->elts = tracing_map_array_alloc(map->max_elts,
389 sizeof(struct tracing_map_elt *));
393 for (i = 0; i < map->max_elts; i++) {
394 *(TRACING_MAP_ELT(map->elts, i)) = tracing_map_elt_alloc(map);
395 if (IS_ERR(*(TRACING_MAP_ELT(map->elts, i)))) {
396 *(TRACING_MAP_ELT(map->elts, i)) = NULL;
397 tracing_map_free_elts(map);
406 static inline bool keys_match(void *key, void *test_key, unsigned key_size)
410 if (memcmp(key, test_key, key_size))
416 static inline struct tracing_map_elt *
417 __tracing_map_insert(struct tracing_map *map, void *key, bool lookup_only)
419 u32 idx, key_hash, test_key;
420 struct tracing_map_entry *entry;
422 key_hash = jhash(key, map->key_size, 0);
425 idx = key_hash >> (32 - (map->map_bits + 1));
428 idx &= (map->map_size - 1);
429 entry = TRACING_MAP_ENTRY(map->map, idx);
430 test_key = entry->key;
432 if (test_key && test_key == key_hash && entry->val &&
433 keys_match(key, entry->val->key, map->key_size)) {
434 atomic64_inc(&map->hits);
442 if (!cmpxchg(&entry->key, 0, key_hash)) {
443 struct tracing_map_elt *elt;
445 elt = get_free_elt(map);
447 atomic64_inc(&map->drops);
452 memcpy(elt->key, key, map->key_size);
454 atomic64_inc(&map->hits);
467 * tracing_map_insert - Insert key and/or retrieve val from a tracing_map
468 * @map: The tracing_map to insert into
469 * @key: The key to insert
471 * Inserts a key into a tracing_map and creates and returns a new
472 * tracing_map_elt for it, or if the key has already been inserted by
473 * a previous call, returns the tracing_map_elt already associated
474 * with it. When the map was created, the number of elements to be
475 * allocated for the map was specified (internally maintained as
476 * 'max_elts' in struct tracing_map), and that number of
477 * tracing_map_elts was created by tracing_map_init(). This is the
478 * pre-allocated pool of tracing_map_elts that tracing_map_insert()
479 * will allocate from when adding new keys. Once that pool is
480 * exhausted, tracing_map_insert() is useless and will return NULL to
481 * signal that state. There are two user-visible tracing_map
482 * variables, 'hits' and 'drops', which are updated by this function.
483 * Every time an element is either successfully inserted or retrieved,
484 * the 'hits' value is incrememented. Every time an element insertion
485 * fails, the 'drops' value is incremented.
487 * This is a lock-free tracing map insertion function implementing a
488 * modified form of Cliff Click's basic insertion algorithm. It
489 * requires the table size be a power of two. To prevent any
490 * possibility of an infinite loop we always make the internal table
491 * size double the size of the requested table size (max_elts * 2).
492 * Likewise, we never reuse a slot or resize or delete elements - when
493 * we've reached max_elts entries, we simply return NULL once we've
494 * run out of entries. Readers can at any point in time traverse the
495 * tracing map and safely access the key/val pairs.
497 * Return: the tracing_map_elt pointer val associated with the key.
498 * If this was a newly inserted key, the val will be a newly allocated
499 * and associated tracing_map_elt pointer val. If the key wasn't
500 * found and the pool of tracing_map_elts has been exhausted, NULL is
501 * returned and no further insertions will succeed.
503 struct tracing_map_elt *tracing_map_insert(struct tracing_map *map, void *key)
505 return __tracing_map_insert(map, key, false);
509 * tracing_map_lookup - Retrieve val from a tracing_map
510 * @map: The tracing_map to perform the lookup on
511 * @key: The key to look up
513 * Looks up key in tracing_map and if found returns the matching
514 * tracing_map_elt. This is a lock-free lookup; see
515 * tracing_map_insert() for details on tracing_map and how it works.
516 * Every time an element is retrieved, the 'hits' value is
517 * incrememented. There is one user-visible tracing_map variable,
518 * 'hits', which is updated by this function. Every time an element
519 * is successfully retrieved, the 'hits' value is incrememented. The
520 * 'drops' value is never updated by this function.
522 * Return: the tracing_map_elt pointer val associated with the key.
523 * If the key wasn't found, NULL is returned.
525 struct tracing_map_elt *tracing_map_lookup(struct tracing_map *map, void *key)
527 return __tracing_map_insert(map, key, true);
531 * tracing_map_destroy - Destroy a tracing_map
532 * @map: The tracing_map to destroy
534 * Frees a tracing_map along with its associated array of
537 * Callers should make sure there are no readers or writers actively
538 * reading or inserting into the map before calling this.
540 void tracing_map_destroy(struct tracing_map *map)
545 tracing_map_free_elts(map);
547 tracing_map_array_free(map->map);
552 * tracing_map_clear - Clear a tracing_map
553 * @map: The tracing_map to clear
555 * Resets the tracing map to a cleared or initial state. The
556 * tracing_map_elts are all cleared, and the array of struct
557 * tracing_map_entry is reset to an initialized state.
559 * Callers should make sure there are no writers actively inserting
560 * into the map before calling this.
562 void tracing_map_clear(struct tracing_map *map)
566 atomic_set(&map->next_elt, -1);
567 atomic64_set(&map->hits, 0);
568 atomic64_set(&map->drops, 0);
570 tracing_map_array_clear(map->map);
572 for (i = 0; i < map->max_elts; i++)
573 tracing_map_elt_clear(*(TRACING_MAP_ELT(map->elts, i)));
576 static void set_sort_key(struct tracing_map *map,
577 struct tracing_map_sort_key *sort_key)
579 map->sort_key = *sort_key;
583 * tracing_map_create - Create a lock-free map and element pool
584 * @map_bits: The size of the map (2 ** map_bits)
585 * @key_size: The size of the key for the map in bytes
586 * @ops: Optional client-defined tracing_map_ops instance
587 * @private_data: Client data associated with the map
589 * Creates and sets up a map to contain 2 ** map_bits number of
590 * elements (internally maintained as 'max_elts' in struct
591 * tracing_map). Before using, map fields should be added to the map
592 * with tracing_map_add_sum_field() and tracing_map_add_key_field().
593 * tracing_map_init() should then be called to allocate the array of
594 * tracing_map_elts, in order to avoid allocating anything in the map
595 * insertion path. The user-specified map size reflects the maximum
596 * number of elements that can be contained in the table requested by
597 * the user - internally we double that in order to keep the table
598 * sparse and keep collisions manageable.
600 * A tracing_map is a special-purpose map designed to aggregate or
601 * 'sum' one or more values associated with a specific object of type
602 * tracing_map_elt, which is attached by the map to a given key.
604 * tracing_map_create() sets up the map itself, and provides
605 * operations for inserting tracing_map_elts, but doesn't allocate the
606 * tracing_map_elts themselves, or provide a means for describing the
607 * keys or sums associated with the tracing_map_elts. All
608 * tracing_map_elts for a given map have the same set of sums and
609 * keys, which are defined by the client using the functions
610 * tracing_map_add_key_field() and tracing_map_add_sum_field(). Once
611 * the fields are defined, the pool of elements allocated for the map
612 * can be created, which occurs when the client code calls
613 * tracing_map_init().
615 * When tracing_map_init() returns, tracing_map_elt elements can be
616 * inserted into the map using tracing_map_insert(). When called,
617 * tracing_map_insert() grabs a free tracing_map_elt from the pool, or
618 * finds an existing match in the map and in either case returns it.
619 * The client can then use tracing_map_update_sum() and
620 * tracing_map_read_sum() to update or read a given sum field for the
623 * The client can at any point retrieve and traverse the current set
624 * of inserted tracing_map_elts in a tracing_map, via
625 * tracing_map_sort_entries(). Sorting can be done on any field,
628 * See tracing_map.h for a description of tracing_map_ops.
630 * Return: the tracing_map pointer if successful, ERR_PTR if not.
632 struct tracing_map *tracing_map_create(unsigned int map_bits,
633 unsigned int key_size,
634 const struct tracing_map_ops *ops,
637 struct tracing_map *map;
640 if (map_bits < TRACING_MAP_BITS_MIN ||
641 map_bits > TRACING_MAP_BITS_MAX)
642 return ERR_PTR(-EINVAL);
644 map = kzalloc(sizeof(*map), GFP_KERNEL);
646 return ERR_PTR(-ENOMEM);
648 map->map_bits = map_bits;
649 map->max_elts = (1 << map_bits);
650 atomic_set(&map->next_elt, -1);
652 map->map_size = (1 << (map_bits + 1));
655 map->private_data = private_data;
657 map->map = tracing_map_array_alloc(map->map_size,
658 sizeof(struct tracing_map_entry));
662 map->key_size = key_size;
663 for (i = 0; i < TRACING_MAP_KEYS_MAX; i++)
664 map->key_idx[i] = -1;
668 tracing_map_destroy(map);
669 map = ERR_PTR(-ENOMEM);
675 * tracing_map_init - Allocate and clear a map's tracing_map_elts
676 * @map: The tracing_map to initialize
678 * Allocates a clears a pool of tracing_map_elts equal to the
679 * user-specified size of 2 ** map_bits (internally maintained as
680 * 'max_elts' in struct tracing_map). Before using, the map fields
681 * should be added to the map with tracing_map_add_sum_field() and
682 * tracing_map_add_key_field(). tracing_map_init() should then be
683 * called to allocate the array of tracing_map_elts, in order to avoid
684 * allocating anything in the map insertion path. The user-specified
685 * map size reflects the max number of elements requested by the user
686 * - internally we double that in order to keep the table sparse and
687 * keep collisions manageable.
689 * See tracing_map.h for a description of tracing_map_ops.
691 * Return: the tracing_map pointer if successful, ERR_PTR if not.
693 int tracing_map_init(struct tracing_map *map)
697 if (map->n_fields < 2)
698 return -EINVAL; /* need at least 1 key and 1 val */
700 err = tracing_map_alloc_elts(map);
704 tracing_map_clear(map);
709 static int cmp_entries_dup(const void *A, const void *B)
711 const struct tracing_map_sort_entry *a, *b;
714 a = *(const struct tracing_map_sort_entry **)A;
715 b = *(const struct tracing_map_sort_entry **)B;
717 if (memcmp(a->key, b->key, a->elt->map->key_size))
723 static int cmp_entries_sum(const void *A, const void *B)
725 const struct tracing_map_elt *elt_a, *elt_b;
726 const struct tracing_map_sort_entry *a, *b;
727 struct tracing_map_sort_key *sort_key;
728 struct tracing_map_field *field;
729 tracing_map_cmp_fn_t cmp_fn;
733 a = *(const struct tracing_map_sort_entry **)A;
734 b = *(const struct tracing_map_sort_entry **)B;
739 sort_key = &elt_a->map->sort_key;
741 field = &elt_a->fields[sort_key->field_idx];
742 cmp_fn = field->cmp_fn;
744 val_a = &elt_a->fields[sort_key->field_idx].sum;
745 val_b = &elt_b->fields[sort_key->field_idx].sum;
747 ret = cmp_fn(val_a, val_b);
748 if (sort_key->descending)
754 static int cmp_entries_key(const void *A, const void *B)
756 const struct tracing_map_elt *elt_a, *elt_b;
757 const struct tracing_map_sort_entry *a, *b;
758 struct tracing_map_sort_key *sort_key;
759 struct tracing_map_field *field;
760 tracing_map_cmp_fn_t cmp_fn;
764 a = *(const struct tracing_map_sort_entry **)A;
765 b = *(const struct tracing_map_sort_entry **)B;
770 sort_key = &elt_a->map->sort_key;
772 field = &elt_a->fields[sort_key->field_idx];
774 cmp_fn = field->cmp_fn;
776 val_a = elt_a->key + field->offset;
777 val_b = elt_b->key + field->offset;
779 ret = cmp_fn(val_a, val_b);
780 if (sort_key->descending)
786 static void destroy_sort_entry(struct tracing_map_sort_entry *entry)
791 if (entry->elt_copied)
792 tracing_map_elt_free(entry->elt);
798 * tracing_map_destroy_sort_entries - Destroy an array of sort entries
799 * @entries: The entries to destroy
800 * @n_entries: The number of entries in the array
802 * Destroy the elements returned by a tracing_map_sort_entries() call.
804 void tracing_map_destroy_sort_entries(struct tracing_map_sort_entry **entries,
805 unsigned int n_entries)
809 for (i = 0; i < n_entries; i++)
810 destroy_sort_entry(entries[i]);
815 static struct tracing_map_sort_entry *
816 create_sort_entry(void *key, struct tracing_map_elt *elt)
818 struct tracing_map_sort_entry *sort_entry;
820 sort_entry = kzalloc(sizeof(*sort_entry), GFP_KERNEL);
824 sort_entry->key = key;
825 sort_entry->elt = elt;
830 static struct tracing_map_elt *copy_elt(struct tracing_map_elt *elt)
832 struct tracing_map_elt *dup_elt;
835 dup_elt = tracing_map_elt_alloc(elt->map);
839 if (elt->map->ops && elt->map->ops->elt_copy)
840 elt->map->ops->elt_copy(dup_elt, elt);
842 dup_elt->private_data = elt->private_data;
843 memcpy(dup_elt->key, elt->key, elt->map->key_size);
845 for (i = 0; i < elt->map->n_fields; i++) {
846 atomic64_set(&dup_elt->fields[i].sum,
847 atomic64_read(&elt->fields[i].sum));
848 dup_elt->fields[i].cmp_fn = elt->fields[i].cmp_fn;
854 static int merge_dup(struct tracing_map_sort_entry **sort_entries,
855 unsigned int target, unsigned int dup)
857 struct tracing_map_elt *target_elt, *elt;
858 bool first_dup = (target - dup) == 1;
862 elt = sort_entries[target]->elt;
863 target_elt = copy_elt(elt);
866 sort_entries[target]->elt = target_elt;
867 sort_entries[target]->elt_copied = true;
869 target_elt = sort_entries[target]->elt;
871 elt = sort_entries[dup]->elt;
873 for (i = 0; i < elt->map->n_fields; i++)
874 atomic64_add(atomic64_read(&elt->fields[i].sum),
875 &target_elt->fields[i].sum);
877 sort_entries[dup]->dup = true;
882 static int merge_dups(struct tracing_map_sort_entry **sort_entries,
883 int n_entries, unsigned int key_size)
885 unsigned int dups = 0, total_dups = 0;
892 sort(sort_entries, n_entries, sizeof(struct tracing_map_sort_entry *),
893 (int (*)(const void *, const void *))cmp_entries_dup, NULL);
895 key = sort_entries[0]->key;
896 for (i = 1; i < n_entries; i++) {
897 if (!memcmp(sort_entries[i]->key, key, key_size)) {
898 dups++; total_dups++;
899 err = merge_dup(sort_entries, i - dups, i);
904 key = sort_entries[i]->key;
911 for (i = 0, j = 0; i < n_entries; i++) {
912 if (!sort_entries[i]->dup) {
913 sort_entries[j] = sort_entries[i];
915 sort_entries[i] = NULL;
917 destroy_sort_entry(sort_entries[i]);
918 sort_entries[i] = NULL;
925 static bool is_key(struct tracing_map *map, unsigned int field_idx)
929 for (i = 0; i < map->n_keys; i++)
930 if (map->key_idx[i] == field_idx)
935 static void sort_secondary(struct tracing_map *map,
936 const struct tracing_map_sort_entry **entries,
937 unsigned int n_entries,
938 struct tracing_map_sort_key *primary_key,
939 struct tracing_map_sort_key *secondary_key)
941 int (*primary_fn)(const void *, const void *);
942 int (*secondary_fn)(const void *, const void *);
943 unsigned i, start = 0, n_sub = 1;
945 if (is_key(map, primary_key->field_idx))
946 primary_fn = cmp_entries_key;
948 primary_fn = cmp_entries_sum;
950 if (is_key(map, secondary_key->field_idx))
951 secondary_fn = cmp_entries_key;
953 secondary_fn = cmp_entries_sum;
955 for (i = 0; i < n_entries - 1; i++) {
956 const struct tracing_map_sort_entry **a = &entries[i];
957 const struct tracing_map_sort_entry **b = &entries[i + 1];
959 if (primary_fn(a, b) == 0) {
961 if (i < n_entries - 2)
971 set_sort_key(map, secondary_key);
972 sort(&entries[start], n_sub,
973 sizeof(struct tracing_map_sort_entry *),
974 (int (*)(const void *, const void *))secondary_fn, NULL);
975 set_sort_key(map, primary_key);
983 * tracing_map_sort_entries - Sort the current set of tracing_map_elts in a map
984 * @map: The tracing_map
985 * @sort_key: The sort key to use for sorting
986 * @sort_entries: outval: pointer to allocated and sorted array of entries
988 * tracing_map_sort_entries() sorts the current set of entries in the
989 * map and returns the list of tracing_map_sort_entries containing
990 * them to the client in the sort_entries param. The client can
991 * access the struct tracing_map_elt element of interest directly as
992 * the 'elt' field of a returned struct tracing_map_sort_entry object.
994 * The sort_key has only two fields: idx and descending. 'idx' refers
995 * to the index of the field added via tracing_map_add_sum_field() or
996 * tracing_map_add_key_field() when the tracing_map was initialized.
997 * 'descending' is a flag that if set reverses the sort order, which
998 * by default is ascending.
1000 * The client should not hold on to the returned array but should use
1001 * it and call tracing_map_destroy_sort_entries() when done.
1003 * Return: the number of sort_entries in the struct tracing_map_sort_entry
1004 * array, negative on error
1006 int tracing_map_sort_entries(struct tracing_map *map,
1007 struct tracing_map_sort_key *sort_keys,
1008 unsigned int n_sort_keys,
1009 struct tracing_map_sort_entry ***sort_entries)
1011 int (*cmp_entries_fn)(const void *, const void *);
1012 struct tracing_map_sort_entry *sort_entry, **entries;
1013 int i, n_entries, ret;
1015 entries = vmalloc(map->max_elts * sizeof(sort_entry));
1019 for (i = 0, n_entries = 0; i < map->map_size; i++) {
1020 struct tracing_map_entry *entry;
1022 entry = TRACING_MAP_ENTRY(map->map, i);
1024 if (!entry->key || !entry->val)
1027 entries[n_entries] = create_sort_entry(entry->val->key,
1029 if (!entries[n_entries++]) {
1035 if (n_entries == 0) {
1040 if (n_entries == 1) {
1041 *sort_entries = entries;
1045 ret = merge_dups(entries, n_entries, map->key_size);
1050 if (is_key(map, sort_keys[0].field_idx))
1051 cmp_entries_fn = cmp_entries_key;
1053 cmp_entries_fn = cmp_entries_sum;
1055 set_sort_key(map, &sort_keys[0]);
1057 sort(entries, n_entries, sizeof(struct tracing_map_sort_entry *),
1058 (int (*)(const void *, const void *))cmp_entries_fn, NULL);
1060 if (n_sort_keys > 1)
1062 (const struct tracing_map_sort_entry **)entries,
1067 *sort_entries = entries;
1071 tracing_map_destroy_sort_entries(entries, n_entries);