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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * tracing_map - lock-free map for tracing
4 *
5 * Copyright (C) 2015 Tom Zanussi <tom.zanussi@linux.intel.com>
6 *
7 * tracing_map implementation inspired by lock-free map algorithms
8 * originated by Dr. Cliff Click:
9 *
10 * http://www.azulsystems.com/blog/cliff/2007-03-26-non-blocking-hashtable
11 * http://www.azulsystems.com/events/javaone_2007/2007_LockFreeHash.pdf
12 */
13
14#include <linux/vmalloc.h>
15#include <linux/jhash.h>
16#include <linux/slab.h>
17#include <linux/sort.h>
18#include <linux/kmemleak.h>
19
20#include "tracing_map.h"
21#include "trace.h"
22
23/*
24 * NOTE: For a detailed description of the data structures used by
25 * these functions (such as tracing_map_elt) please see the overview
26 * of tracing_map data structures at the beginning of tracing_map.h.
27 */
28
29/**
30 * tracing_map_update_sum - Add a value to a tracing_map_elt's sum field
31 * @elt: The tracing_map_elt
32 * @i: The index of the given sum associated with the tracing_map_elt
33 * @n: The value to add to the sum
34 *
35 * Add n to sum i associated with the specified tracing_map_elt
36 * instance. The index i is the index returned by the call to
37 * tracing_map_add_sum_field() when the tracing map was set up.
38 */
39void tracing_map_update_sum(struct tracing_map_elt *elt, unsigned int i, u64 n)
40{
41 atomic64_add(n, &elt->fields[i].sum);
42}
43
44/**
45 * tracing_map_read_sum - Return the value of a tracing_map_elt's sum field
46 * @elt: The tracing_map_elt
47 * @i: The index of the given sum associated with the tracing_map_elt
48 *
49 * Retrieve the value of the sum i associated with the specified
50 * tracing_map_elt instance. The index i is the index returned by the
51 * call to tracing_map_add_sum_field() when the tracing map was set
52 * up.
53 *
54 * Return: The sum associated with field i for elt.
55 */
56u64 tracing_map_read_sum(struct tracing_map_elt *elt, unsigned int i)
57{
58 return (u64)atomic64_read(&elt->fields[i].sum);
59}
60
61/**
62 * tracing_map_set_var - Assign a tracing_map_elt's variable field
63 * @elt: The tracing_map_elt
64 * @i: The index of the given variable associated with the tracing_map_elt
65 * @n: The value to assign
66 *
67 * Assign n to variable i associated with the specified tracing_map_elt
68 * instance. The index i is the index returned by the call to
69 * tracing_map_add_var() when the tracing map was set up.
70 */
71void tracing_map_set_var(struct tracing_map_elt *elt, unsigned int i, u64 n)
72{
73 atomic64_set(&elt->vars[i], n);
74 elt->var_set[i] = true;
75}
76
77/**
78 * tracing_map_var_set - Return whether or not a variable has been set
79 * @elt: The tracing_map_elt
80 * @i: The index of the given variable associated with the tracing_map_elt
81 *
82 * Return true if the variable has been set, false otherwise. The
83 * index i is the index returned by the call to tracing_map_add_var()
84 * when the tracing map was set up.
85 */
86bool tracing_map_var_set(struct tracing_map_elt *elt, unsigned int i)
87{
88 return elt->var_set[i];
89}
90
91/**
92 * tracing_map_read_var - Return the value of a tracing_map_elt's variable field
93 * @elt: The tracing_map_elt
94 * @i: The index of the given variable associated with the tracing_map_elt
95 *
96 * Retrieve the value of the variable i associated with the specified
97 * tracing_map_elt instance. The index i is the index returned by the
98 * call to tracing_map_add_var() when the tracing map was set
99 * up.
100 *
101 * Return: The variable value associated with field i for elt.
102 */
103u64 tracing_map_read_var(struct tracing_map_elt *elt, unsigned int i)
104{
105 return (u64)atomic64_read(&elt->vars[i]);
106}
107
108/**
109 * tracing_map_read_var_once - Return and reset a tracing_map_elt's variable field
110 * @elt: The tracing_map_elt
111 * @i: The index of the given variable associated with the tracing_map_elt
112 *
113 * Retrieve the value of the variable i associated with the specified
114 * tracing_map_elt instance, and reset the variable to the 'not set'
115 * state. The index i is the index returned by the call to
116 * tracing_map_add_var() when the tracing map was set up. The reset
117 * essentially makes the variable a read-once variable if it's only
118 * accessed using this function.
119 *
120 * Return: The variable value associated with field i for elt.
121 */
122u64 tracing_map_read_var_once(struct tracing_map_elt *elt, unsigned int i)
123{
124 elt->var_set[i] = false;
125 return (u64)atomic64_read(&elt->vars[i]);
126}
127
128int tracing_map_cmp_string(void *val_a, void *val_b)
129{
130 char *a = val_a;
131 char *b = val_b;
132
133 return strcmp(a, b);
134}
135
136int tracing_map_cmp_none(void *val_a, void *val_b)
137{
138 return 0;
139}
140
141static int tracing_map_cmp_atomic64(void *val_a, void *val_b)
142{
143 u64 a = atomic64_read((atomic64_t *)val_a);
144 u64 b = atomic64_read((atomic64_t *)val_b);
145
146 return (a > b) ? 1 : ((a < b) ? -1 : 0);
147}
148
149#define DEFINE_TRACING_MAP_CMP_FN(type) \
150static int tracing_map_cmp_##type(void *val_a, void *val_b) \
151{ \
152 type a = (type)(*(u64 *)val_a); \
153 type b = (type)(*(u64 *)val_b); \
154 \
155 return (a > b) ? 1 : ((a < b) ? -1 : 0); \
156}
157
158DEFINE_TRACING_MAP_CMP_FN(s64);
159DEFINE_TRACING_MAP_CMP_FN(u64);
160DEFINE_TRACING_MAP_CMP_FN(s32);
161DEFINE_TRACING_MAP_CMP_FN(u32);
162DEFINE_TRACING_MAP_CMP_FN(s16);
163DEFINE_TRACING_MAP_CMP_FN(u16);
164DEFINE_TRACING_MAP_CMP_FN(s8);
165DEFINE_TRACING_MAP_CMP_FN(u8);
166
167tracing_map_cmp_fn_t tracing_map_cmp_num(int field_size,
168 int field_is_signed)
169{
170 tracing_map_cmp_fn_t fn = tracing_map_cmp_none;
171
172 switch (field_size) {
173 case 8:
174 if (field_is_signed)
175 fn = tracing_map_cmp_s64;
176 else
177 fn = tracing_map_cmp_u64;
178 break;
179 case 4:
180 if (field_is_signed)
181 fn = tracing_map_cmp_s32;
182 else
183 fn = tracing_map_cmp_u32;
184 break;
185 case 2:
186 if (field_is_signed)
187 fn = tracing_map_cmp_s16;
188 else
189 fn = tracing_map_cmp_u16;
190 break;
191 case 1:
192 if (field_is_signed)
193 fn = tracing_map_cmp_s8;
194 else
195 fn = tracing_map_cmp_u8;
196 break;
197 }
198
199 return fn;
200}
201
202static int tracing_map_add_field(struct tracing_map *map,
203 tracing_map_cmp_fn_t cmp_fn)
204{
205 int ret = -EINVAL;
206
207 if (map->n_fields < TRACING_MAP_FIELDS_MAX) {
208 ret = map->n_fields;
209 map->fields[map->n_fields++].cmp_fn = cmp_fn;
210 }
211
212 return ret;
213}
214
215/**
216 * tracing_map_add_sum_field - Add a field describing a tracing_map sum
217 * @map: The tracing_map
218 *
219 * Add a sum field to the key and return the index identifying it in
220 * the map and associated tracing_map_elts. This is the index used
221 * for instance to update a sum for a particular tracing_map_elt using
222 * tracing_map_update_sum() or reading it via tracing_map_read_sum().
223 *
224 * Return: The index identifying the field in the map and associated
225 * tracing_map_elts, or -EINVAL on error.
226 */
227int tracing_map_add_sum_field(struct tracing_map *map)
228{
229 return tracing_map_add_field(map, tracing_map_cmp_atomic64);
230}
231
232/**
233 * tracing_map_add_var - Add a field describing a tracing_map var
234 * @map: The tracing_map
235 *
236 * Add a var to the map and return the index identifying it in the map
237 * and associated tracing_map_elts. This is the index used for
238 * instance to update a var for a particular tracing_map_elt using
239 * tracing_map_update_var() or reading it via tracing_map_read_var().
240 *
241 * Return: The index identifying the var in the map and associated
242 * tracing_map_elts, or -EINVAL on error.
243 */
244int tracing_map_add_var(struct tracing_map *map)
245{
246 int ret = -EINVAL;
247
248 if (map->n_vars < TRACING_MAP_VARS_MAX)
249 ret = map->n_vars++;
250
251 return ret;
252}
253
254/**
255 * tracing_map_add_key_field - Add a field describing a tracing_map key
256 * @map: The tracing_map
257 * @offset: The offset within the key
258 * @cmp_fn: The comparison function that will be used to sort on the key
259 *
260 * Let the map know there is a key and that if it's used as a sort key
261 * to use cmp_fn.
262 *
263 * A key can be a subset of a compound key; for that purpose, the
264 * offset param is used to describe where within the compound key
265 * the key referenced by this key field resides.
266 *
267 * Return: The index identifying the field in the map and associated
268 * tracing_map_elts, or -EINVAL on error.
269 */
270int tracing_map_add_key_field(struct tracing_map *map,
271 unsigned int offset,
272 tracing_map_cmp_fn_t cmp_fn)
273
274{
275 int idx = tracing_map_add_field(map, cmp_fn);
276
277 if (idx < 0)
278 return idx;
279
280 map->fields[idx].offset = offset;
281
282 map->key_idx[map->n_keys++] = idx;
283
284 return idx;
285}
286
287static void tracing_map_array_clear(struct tracing_map_array *a)
288{
289 unsigned int i;
290
291 if (!a->pages)
292 return;
293
294 for (i = 0; i < a->n_pages; i++)
295 memset(a->pages[i], 0, PAGE_SIZE);
296}
297
298static void tracing_map_array_free(struct tracing_map_array *a)
299{
300 unsigned int i;
301
302 if (!a)
303 return;
304
305 if (!a->pages)
306 goto free;
307
308 for (i = 0; i < a->n_pages; i++) {
309 if (!a->pages[i])
310 break;
311 kmemleak_free(a->pages[i]);
312 free_page((unsigned long)a->pages[i]);
313 }
314
315 kfree(a->pages);
316
317 free:
318 kfree(a);
319}
320
321static struct tracing_map_array *tracing_map_array_alloc(unsigned int n_elts,
322 unsigned int entry_size)
323{
324 struct tracing_map_array *a;
325 unsigned int i;
326
327 a = kzalloc(sizeof(*a), GFP_KERNEL);
328 if (!a)
329 return NULL;
330
331 a->entry_size_shift = fls(roundup_pow_of_two(entry_size) - 1);
332 a->entries_per_page = PAGE_SIZE / (1 << a->entry_size_shift);
333 a->n_pages = n_elts / a->entries_per_page;
334 if (!a->n_pages)
335 a->n_pages = 1;
336 a->entry_shift = fls(a->entries_per_page) - 1;
337 a->entry_mask = (1 << a->entry_shift) - 1;
338
339 a->pages = kcalloc(a->n_pages, sizeof(void *), GFP_KERNEL);
340 if (!a->pages)
341 goto free;
342
343 for (i = 0; i < a->n_pages; i++) {
344 a->pages[i] = (void *)get_zeroed_page(GFP_KERNEL);
345 if (!a->pages[i])
346 goto free;
347 kmemleak_alloc(a->pages[i], PAGE_SIZE, 1, GFP_KERNEL);
348 }
349 out:
350 return a;
351 free:
352 tracing_map_array_free(a);
353 a = NULL;
354
355 goto out;
356}
357
358static void tracing_map_elt_clear(struct tracing_map_elt *elt)
359{
360 unsigned i;
361
362 for (i = 0; i < elt->map->n_fields; i++)
363 if (elt->fields[i].cmp_fn == tracing_map_cmp_atomic64)
364 atomic64_set(&elt->fields[i].sum, 0);
365
366 for (i = 0; i < elt->map->n_vars; i++) {
367 atomic64_set(&elt->vars[i], 0);
368 elt->var_set[i] = false;
369 }
370
371 if (elt->map->ops && elt->map->ops->elt_clear)
372 elt->map->ops->elt_clear(elt);
373}
374
375static void tracing_map_elt_init_fields(struct tracing_map_elt *elt)
376{
377 unsigned int i;
378
379 tracing_map_elt_clear(elt);
380
381 for (i = 0; i < elt->map->n_fields; i++) {
382 elt->fields[i].cmp_fn = elt->map->fields[i].cmp_fn;
383
384 if (elt->fields[i].cmp_fn != tracing_map_cmp_atomic64)
385 elt->fields[i].offset = elt->map->fields[i].offset;
386 }
387}
388
389static void tracing_map_elt_free(struct tracing_map_elt *elt)
390{
391 if (!elt)
392 return;
393
394 if (elt->map->ops && elt->map->ops->elt_free)
395 elt->map->ops->elt_free(elt);
396 kfree(elt->fields);
397 kfree(elt->vars);
398 kfree(elt->var_set);
399 kfree(elt->key);
400 kfree(elt);
401}
402
403static struct tracing_map_elt *tracing_map_elt_alloc(struct tracing_map *map)
404{
405 struct tracing_map_elt *elt;
406 int err = 0;
407
408 elt = kzalloc(sizeof(*elt), GFP_KERNEL);
409 if (!elt)
410 return ERR_PTR(-ENOMEM);
411
412 elt->map = map;
413
414 elt->key = kzalloc(map->key_size, GFP_KERNEL);
415 if (!elt->key) {
416 err = -ENOMEM;
417 goto free;
418 }
419
420 elt->fields = kcalloc(map->n_fields, sizeof(*elt->fields), GFP_KERNEL);
421 if (!elt->fields) {
422 err = -ENOMEM;
423 goto free;
424 }
425
426 elt->vars = kcalloc(map->n_vars, sizeof(*elt->vars), GFP_KERNEL);
427 if (!elt->vars) {
428 err = -ENOMEM;
429 goto free;
430 }
431
432 elt->var_set = kcalloc(map->n_vars, sizeof(*elt->var_set), GFP_KERNEL);
433 if (!elt->var_set) {
434 err = -ENOMEM;
435 goto free;
436 }
437
438 tracing_map_elt_init_fields(elt);
439
440 if (map->ops && map->ops->elt_alloc) {
441 err = map->ops->elt_alloc(elt);
442 if (err)
443 goto free;
444 }
445 return elt;
446 free:
447 tracing_map_elt_free(elt);
448
449 return ERR_PTR(err);
450}
451
452static struct tracing_map_elt *get_free_elt(struct tracing_map *map)
453{
454 struct tracing_map_elt *elt = NULL;
455 int idx;
456
457 idx = atomic_inc_return(&map->next_elt);
458 if (idx < map->max_elts) {
459 elt = *(TRACING_MAP_ELT(map->elts, idx));
460 if (map->ops && map->ops->elt_init)
461 map->ops->elt_init(elt);
462 }
463
464 return elt;
465}
466
467static void tracing_map_free_elts(struct tracing_map *map)
468{
469 unsigned int i;
470
471 if (!map->elts)
472 return;
473
474 for (i = 0; i < map->max_elts; i++) {
475 tracing_map_elt_free(*(TRACING_MAP_ELT(map->elts, i)));
476 *(TRACING_MAP_ELT(map->elts, i)) = NULL;
477 }
478
479 tracing_map_array_free(map->elts);
480 map->elts = NULL;
481}
482
483static int tracing_map_alloc_elts(struct tracing_map *map)
484{
485 unsigned int i;
486
487 map->elts = tracing_map_array_alloc(map->max_elts,
488 sizeof(struct tracing_map_elt *));
489 if (!map->elts)
490 return -ENOMEM;
491
492 for (i = 0; i < map->max_elts; i++) {
493 *(TRACING_MAP_ELT(map->elts, i)) = tracing_map_elt_alloc(map);
494 if (IS_ERR(*(TRACING_MAP_ELT(map->elts, i)))) {
495 *(TRACING_MAP_ELT(map->elts, i)) = NULL;
496 tracing_map_free_elts(map);
497
498 return -ENOMEM;
499 }
500 }
501
502 return 0;
503}
504
505static inline bool keys_match(void *key, void *test_key, unsigned key_size)
506{
507 bool match = true;
508
509 if (memcmp(key, test_key, key_size))
510 match = false;
511
512 return match;
513}
514
515static inline struct tracing_map_elt *
516__tracing_map_insert(struct tracing_map *map, void *key, bool lookup_only)
517{
518 u32 idx, key_hash, test_key;
519 int dup_try = 0;
520 struct tracing_map_entry *entry;
521 struct tracing_map_elt *val;
522
523 key_hash = jhash(key, map->key_size, 0);
524 if (key_hash == 0)
525 key_hash = 1;
526 idx = key_hash >> (32 - (map->map_bits + 1));
527
528 while (1) {
529 idx &= (map->map_size - 1);
530 entry = TRACING_MAP_ENTRY(map->map, idx);
531 test_key = entry->key;
532
533 if (test_key && test_key == key_hash) {
534 val = READ_ONCE(entry->val);
535 if (val &&
536 keys_match(key, val->key, map->key_size)) {
537 if (!lookup_only)
538 atomic64_inc(&map->hits);
539 return val;
540 } else if (unlikely(!val)) {
541 /*
542 * The key is present. But, val (pointer to elt
543 * struct) is still NULL. which means some other
544 * thread is in the process of inserting an
545 * element.
546 *
547 * On top of that, it's key_hash is same as the
548 * one being inserted right now. So, it's
549 * possible that the element has the same
550 * key as well.
551 */
552
553 dup_try++;
554 if (dup_try > map->map_size) {
555 atomic64_inc(&map->drops);
556 break;
557 }
558 continue;
559 }
560 }
561
562 if (!test_key) {
563 if (lookup_only)
564 break;
565
566 if (!cmpxchg(&entry->key, 0, key_hash)) {
567 struct tracing_map_elt *elt;
568
569 elt = get_free_elt(map);
570 if (!elt) {
571 atomic64_inc(&map->drops);
572 entry->key = 0;
573 break;
574 }
575
576 memcpy(elt->key, key, map->key_size);
577 entry->val = elt;
578 atomic64_inc(&map->hits);
579
580 return entry->val;
581 } else {
582 /*
583 * cmpxchg() failed. Loop around once
584 * more to check what key was inserted.
585 */
586 dup_try++;
587 continue;
588 }
589 }
590
591 idx++;
592 }
593
594 return NULL;
595}
596
597/**
598 * tracing_map_insert - Insert key and/or retrieve val from a tracing_map
599 * @map: The tracing_map to insert into
600 * @key: The key to insert
601 *
602 * Inserts a key into a tracing_map and creates and returns a new
603 * tracing_map_elt for it, or if the key has already been inserted by
604 * a previous call, returns the tracing_map_elt already associated
605 * with it. When the map was created, the number of elements to be
606 * allocated for the map was specified (internally maintained as
607 * 'max_elts' in struct tracing_map), and that number of
608 * tracing_map_elts was created by tracing_map_init(). This is the
609 * pre-allocated pool of tracing_map_elts that tracing_map_insert()
610 * will allocate from when adding new keys. Once that pool is
611 * exhausted, tracing_map_insert() is useless and will return NULL to
612 * signal that state. There are two user-visible tracing_map
613 * variables, 'hits' and 'drops', which are updated by this function.
614 * Every time an element is either successfully inserted or retrieved,
615 * the 'hits' value is incremented. Every time an element insertion
616 * fails, the 'drops' value is incremented.
617 *
618 * This is a lock-free tracing map insertion function implementing a
619 * modified form of Cliff Click's basic insertion algorithm. It
620 * requires the table size be a power of two. To prevent any
621 * possibility of an infinite loop we always make the internal table
622 * size double the size of the requested table size (max_elts * 2).
623 * Likewise, we never reuse a slot or resize or delete elements - when
624 * we've reached max_elts entries, we simply return NULL once we've
625 * run out of entries. Readers can at any point in time traverse the
626 * tracing map and safely access the key/val pairs.
627 *
628 * Return: the tracing_map_elt pointer val associated with the key.
629 * If this was a newly inserted key, the val will be a newly allocated
630 * and associated tracing_map_elt pointer val. If the key wasn't
631 * found and the pool of tracing_map_elts has been exhausted, NULL is
632 * returned and no further insertions will succeed.
633 */
634struct tracing_map_elt *tracing_map_insert(struct tracing_map *map, void *key)
635{
636 return __tracing_map_insert(map, key, false);
637}
638
639/**
640 * tracing_map_lookup - Retrieve val from a tracing_map
641 * @map: The tracing_map to perform the lookup on
642 * @key: The key to look up
643 *
644 * Looks up key in tracing_map and if found returns the matching
645 * tracing_map_elt. This is a lock-free lookup; see
646 * tracing_map_insert() for details on tracing_map and how it works.
647 * Every time an element is retrieved, the 'hits' value is
648 * incremented. There is one user-visible tracing_map variable,
649 * 'hits', which is updated by this function. Every time an element
650 * is successfully retrieved, the 'hits' value is incremented. The
651 * 'drops' value is never updated by this function.
652 *
653 * Return: the tracing_map_elt pointer val associated with the key.
654 * If the key wasn't found, NULL is returned.
655 */
656struct tracing_map_elt *tracing_map_lookup(struct tracing_map *map, void *key)
657{
658 return __tracing_map_insert(map, key, true);
659}
660
661/**
662 * tracing_map_destroy - Destroy a tracing_map
663 * @map: The tracing_map to destroy
664 *
665 * Frees a tracing_map along with its associated array of
666 * tracing_map_elts.
667 *
668 * Callers should make sure there are no readers or writers actively
669 * reading or inserting into the map before calling this.
670 */
671void tracing_map_destroy(struct tracing_map *map)
672{
673 if (!map)
674 return;
675
676 tracing_map_free_elts(map);
677
678 tracing_map_array_free(map->map);
679 kfree(map);
680}
681
682/**
683 * tracing_map_clear - Clear a tracing_map
684 * @map: The tracing_map to clear
685 *
686 * Resets the tracing map to a cleared or initial state. The
687 * tracing_map_elts are all cleared, and the array of struct
688 * tracing_map_entry is reset to an initialized state.
689 *
690 * Callers should make sure there are no writers actively inserting
691 * into the map before calling this.
692 */
693void tracing_map_clear(struct tracing_map *map)
694{
695 unsigned int i;
696
697 atomic_set(&map->next_elt, -1);
698 atomic64_set(&map->hits, 0);
699 atomic64_set(&map->drops, 0);
700
701 tracing_map_array_clear(map->map);
702
703 for (i = 0; i < map->max_elts; i++)
704 tracing_map_elt_clear(*(TRACING_MAP_ELT(map->elts, i)));
705}
706
707static void set_sort_key(struct tracing_map *map,
708 struct tracing_map_sort_key *sort_key)
709{
710 map->sort_key = *sort_key;
711}
712
713/**
714 * tracing_map_create - Create a lock-free map and element pool
715 * @map_bits: The size of the map (2 ** map_bits)
716 * @key_size: The size of the key for the map in bytes
717 * @ops: Optional client-defined tracing_map_ops instance
718 * @private_data: Client data associated with the map
719 *
720 * Creates and sets up a map to contain 2 ** map_bits number of
721 * elements (internally maintained as 'max_elts' in struct
722 * tracing_map). Before using, map fields should be added to the map
723 * with tracing_map_add_sum_field() and tracing_map_add_key_field().
724 * tracing_map_init() should then be called to allocate the array of
725 * tracing_map_elts, in order to avoid allocating anything in the map
726 * insertion path. The user-specified map size reflects the maximum
727 * number of elements that can be contained in the table requested by
728 * the user - internally we double that in order to keep the table
729 * sparse and keep collisions manageable.
730 *
731 * A tracing_map is a special-purpose map designed to aggregate or
732 * 'sum' one or more values associated with a specific object of type
733 * tracing_map_elt, which is attached by the map to a given key.
734 *
735 * tracing_map_create() sets up the map itself, and provides
736 * operations for inserting tracing_map_elts, but doesn't allocate the
737 * tracing_map_elts themselves, or provide a means for describing the
738 * keys or sums associated with the tracing_map_elts. All
739 * tracing_map_elts for a given map have the same set of sums and
740 * keys, which are defined by the client using the functions
741 * tracing_map_add_key_field() and tracing_map_add_sum_field(). Once
742 * the fields are defined, the pool of elements allocated for the map
743 * can be created, which occurs when the client code calls
744 * tracing_map_init().
745 *
746 * When tracing_map_init() returns, tracing_map_elt elements can be
747 * inserted into the map using tracing_map_insert(). When called,
748 * tracing_map_insert() grabs a free tracing_map_elt from the pool, or
749 * finds an existing match in the map and in either case returns it.
750 * The client can then use tracing_map_update_sum() and
751 * tracing_map_read_sum() to update or read a given sum field for the
752 * tracing_map_elt.
753 *
754 * The client can at any point retrieve and traverse the current set
755 * of inserted tracing_map_elts in a tracing_map, via
756 * tracing_map_sort_entries(). Sorting can be done on any field,
757 * including keys.
758 *
759 * See tracing_map.h for a description of tracing_map_ops.
760 *
761 * Return: the tracing_map pointer if successful, ERR_PTR if not.
762 */
763struct tracing_map *tracing_map_create(unsigned int map_bits,
764 unsigned int key_size,
765 const struct tracing_map_ops *ops,
766 void *private_data)
767{
768 struct tracing_map *map;
769 unsigned int i;
770
771 if (map_bits < TRACING_MAP_BITS_MIN ||
772 map_bits > TRACING_MAP_BITS_MAX)
773 return ERR_PTR(-EINVAL);
774
775 map = kzalloc(sizeof(*map), GFP_KERNEL);
776 if (!map)
777 return ERR_PTR(-ENOMEM);
778
779 map->map_bits = map_bits;
780 map->max_elts = (1 << map_bits);
781 atomic_set(&map->next_elt, -1);
782
783 map->map_size = (1 << (map_bits + 1));
784 map->ops = ops;
785
786 map->private_data = private_data;
787
788 map->map = tracing_map_array_alloc(map->map_size,
789 sizeof(struct tracing_map_entry));
790 if (!map->map)
791 goto free;
792
793 map->key_size = key_size;
794 for (i = 0; i < TRACING_MAP_KEYS_MAX; i++)
795 map->key_idx[i] = -1;
796 out:
797 return map;
798 free:
799 tracing_map_destroy(map);
800 map = ERR_PTR(-ENOMEM);
801
802 goto out;
803}
804
805/**
806 * tracing_map_init - Allocate and clear a map's tracing_map_elts
807 * @map: The tracing_map to initialize
808 *
809 * Allocates a clears a pool of tracing_map_elts equal to the
810 * user-specified size of 2 ** map_bits (internally maintained as
811 * 'max_elts' in struct tracing_map). Before using, the map fields
812 * should be added to the map with tracing_map_add_sum_field() and
813 * tracing_map_add_key_field(). tracing_map_init() should then be
814 * called to allocate the array of tracing_map_elts, in order to avoid
815 * allocating anything in the map insertion path. The user-specified
816 * map size reflects the max number of elements requested by the user
817 * - internally we double that in order to keep the table sparse and
818 * keep collisions manageable.
819 *
820 * See tracing_map.h for a description of tracing_map_ops.
821 *
822 * Return: the tracing_map pointer if successful, ERR_PTR if not.
823 */
824int tracing_map_init(struct tracing_map *map)
825{
826 int err;
827
828 if (map->n_fields < 2)
829 return -EINVAL; /* need at least 1 key and 1 val */
830
831 err = tracing_map_alloc_elts(map);
832 if (err)
833 return err;
834
835 tracing_map_clear(map);
836
837 return err;
838}
839
840static int cmp_entries_dup(const void *A, const void *B)
841{
842 const struct tracing_map_sort_entry *a, *b;
843 int ret = 0;
844
845 a = *(const struct tracing_map_sort_entry **)A;
846 b = *(const struct tracing_map_sort_entry **)B;
847
848 if (memcmp(a->key, b->key, a->elt->map->key_size))
849 ret = 1;
850
851 return ret;
852}
853
854static int cmp_entries_sum(const void *A, const void *B)
855{
856 const struct tracing_map_elt *elt_a, *elt_b;
857 const struct tracing_map_sort_entry *a, *b;
858 struct tracing_map_sort_key *sort_key;
859 struct tracing_map_field *field;
860 tracing_map_cmp_fn_t cmp_fn;
861 void *val_a, *val_b;
862 int ret = 0;
863
864 a = *(const struct tracing_map_sort_entry **)A;
865 b = *(const struct tracing_map_sort_entry **)B;
866
867 elt_a = a->elt;
868 elt_b = b->elt;
869
870 sort_key = &elt_a->map->sort_key;
871
872 field = &elt_a->fields[sort_key->field_idx];
873 cmp_fn = field->cmp_fn;
874
875 val_a = &elt_a->fields[sort_key->field_idx].sum;
876 val_b = &elt_b->fields[sort_key->field_idx].sum;
877
878 ret = cmp_fn(val_a, val_b);
879 if (sort_key->descending)
880 ret = -ret;
881
882 return ret;
883}
884
885static int cmp_entries_key(const void *A, const void *B)
886{
887 const struct tracing_map_elt *elt_a, *elt_b;
888 const struct tracing_map_sort_entry *a, *b;
889 struct tracing_map_sort_key *sort_key;
890 struct tracing_map_field *field;
891 tracing_map_cmp_fn_t cmp_fn;
892 void *val_a, *val_b;
893 int ret = 0;
894
895 a = *(const struct tracing_map_sort_entry **)A;
896 b = *(const struct tracing_map_sort_entry **)B;
897
898 elt_a = a->elt;
899 elt_b = b->elt;
900
901 sort_key = &elt_a->map->sort_key;
902
903 field = &elt_a->fields[sort_key->field_idx];
904
905 cmp_fn = field->cmp_fn;
906
907 val_a = elt_a->key + field->offset;
908 val_b = elt_b->key + field->offset;
909
910 ret = cmp_fn(val_a, val_b);
911 if (sort_key->descending)
912 ret = -ret;
913
914 return ret;
915}
916
917static void destroy_sort_entry(struct tracing_map_sort_entry *entry)
918{
919 if (!entry)
920 return;
921
922 if (entry->elt_copied)
923 tracing_map_elt_free(entry->elt);
924
925 kfree(entry);
926}
927
928/**
929 * tracing_map_destroy_sort_entries - Destroy an array of sort entries
930 * @entries: The entries to destroy
931 * @n_entries: The number of entries in the array
932 *
933 * Destroy the elements returned by a tracing_map_sort_entries() call.
934 */
935void tracing_map_destroy_sort_entries(struct tracing_map_sort_entry **entries,
936 unsigned int n_entries)
937{
938 unsigned int i;
939
940 for (i = 0; i < n_entries; i++)
941 destroy_sort_entry(entries[i]);
942
943 vfree(entries);
944}
945
946static struct tracing_map_sort_entry *
947create_sort_entry(void *key, struct tracing_map_elt *elt)
948{
949 struct tracing_map_sort_entry *sort_entry;
950
951 sort_entry = kzalloc(sizeof(*sort_entry), GFP_KERNEL);
952 if (!sort_entry)
953 return NULL;
954
955 sort_entry->key = key;
956 sort_entry->elt = elt;
957
958 return sort_entry;
959}
960
961static void detect_dups(struct tracing_map_sort_entry **sort_entries,
962 int n_entries, unsigned int key_size)
963{
964 unsigned int total_dups = 0;
965 int i;
966 void *key;
967
968 if (n_entries < 2)
969 return;
970
971 sort(sort_entries, n_entries, sizeof(struct tracing_map_sort_entry *),
972 (int (*)(const void *, const void *))cmp_entries_dup, NULL);
973
974 key = sort_entries[0]->key;
975 for (i = 1; i < n_entries; i++) {
976 if (!memcmp(sort_entries[i]->key, key, key_size)) {
977 total_dups++;
978 continue;
979 }
980 key = sort_entries[i]->key;
981 }
982
983 WARN_ONCE(total_dups > 0,
984 "Duplicates detected: %d\n", total_dups);
985}
986
987static bool is_key(struct tracing_map *map, unsigned int field_idx)
988{
989 unsigned int i;
990
991 for (i = 0; i < map->n_keys; i++)
992 if (map->key_idx[i] == field_idx)
993 return true;
994 return false;
995}
996
997static void sort_secondary(struct tracing_map *map,
998 const struct tracing_map_sort_entry **entries,
999 unsigned int n_entries,
1000 struct tracing_map_sort_key *primary_key,
1001 struct tracing_map_sort_key *secondary_key)
1002{
1003 int (*primary_fn)(const void *, const void *);
1004 int (*secondary_fn)(const void *, const void *);
1005 unsigned i, start = 0, n_sub = 1;
1006
1007 if (is_key(map, primary_key->field_idx))
1008 primary_fn = cmp_entries_key;
1009 else
1010 primary_fn = cmp_entries_sum;
1011
1012 if (is_key(map, secondary_key->field_idx))
1013 secondary_fn = cmp_entries_key;
1014 else
1015 secondary_fn = cmp_entries_sum;
1016
1017 for (i = 0; i < n_entries - 1; i++) {
1018 const struct tracing_map_sort_entry **a = &entries[i];
1019 const struct tracing_map_sort_entry **b = &entries[i + 1];
1020
1021 if (primary_fn(a, b) == 0) {
1022 n_sub++;
1023 if (i < n_entries - 2)
1024 continue;
1025 }
1026
1027 if (n_sub < 2) {
1028 start = i + 1;
1029 n_sub = 1;
1030 continue;
1031 }
1032
1033 set_sort_key(map, secondary_key);
1034 sort(&entries[start], n_sub,
1035 sizeof(struct tracing_map_sort_entry *),
1036 (int (*)(const void *, const void *))secondary_fn, NULL);
1037 set_sort_key(map, primary_key);
1038
1039 start = i + 1;
1040 n_sub = 1;
1041 }
1042}
1043
1044/**
1045 * tracing_map_sort_entries - Sort the current set of tracing_map_elts in a map
1046 * @map: The tracing_map
1047 * @sort_keys: The sort key to use for sorting
1048 * @n_sort_keys: hitcount, always have at least one
1049 * @sort_entries: outval: pointer to allocated and sorted array of entries
1050 *
1051 * tracing_map_sort_entries() sorts the current set of entries in the
1052 * map and returns the list of tracing_map_sort_entries containing
1053 * them to the client in the sort_entries param. The client can
1054 * access the struct tracing_map_elt element of interest directly as
1055 * the 'elt' field of a returned struct tracing_map_sort_entry object.
1056 *
1057 * The sort_key has only two fields: idx and descending. 'idx' refers
1058 * to the index of the field added via tracing_map_add_sum_field() or
1059 * tracing_map_add_key_field() when the tracing_map was initialized.
1060 * 'descending' is a flag that if set reverses the sort order, which
1061 * by default is ascending.
1062 *
1063 * The client should not hold on to the returned array but should use
1064 * it and call tracing_map_destroy_sort_entries() when done.
1065 *
1066 * Return: the number of sort_entries in the struct tracing_map_sort_entry
1067 * array, negative on error
1068 */
1069int tracing_map_sort_entries(struct tracing_map *map,
1070 struct tracing_map_sort_key *sort_keys,
1071 unsigned int n_sort_keys,
1072 struct tracing_map_sort_entry ***sort_entries)
1073{
1074 int (*cmp_entries_fn)(const void *, const void *);
1075 struct tracing_map_sort_entry *sort_entry, **entries;
1076 int i, n_entries, ret;
1077
1078 entries = vmalloc(array_size(sizeof(sort_entry), map->max_elts));
1079 if (!entries)
1080 return -ENOMEM;
1081
1082 for (i = 0, n_entries = 0; i < map->map_size; i++) {
1083 struct tracing_map_entry *entry;
1084
1085 entry = TRACING_MAP_ENTRY(map->map, i);
1086
1087 if (!entry->key || !entry->val)
1088 continue;
1089
1090 entries[n_entries] = create_sort_entry(entry->val->key,
1091 entry->val);
1092 if (!entries[n_entries++]) {
1093 ret = -ENOMEM;
1094 goto free;
1095 }
1096 }
1097
1098 if (n_entries == 0) {
1099 ret = 0;
1100 goto free;
1101 }
1102
1103 if (n_entries == 1) {
1104 *sort_entries = entries;
1105 return 1;
1106 }
1107
1108 detect_dups(entries, n_entries, map->key_size);
1109
1110 if (is_key(map, sort_keys[0].field_idx))
1111 cmp_entries_fn = cmp_entries_key;
1112 else
1113 cmp_entries_fn = cmp_entries_sum;
1114
1115 set_sort_key(map, &sort_keys[0]);
1116
1117 sort(entries, n_entries, sizeof(struct tracing_map_sort_entry *),
1118 (int (*)(const void *, const void *))cmp_entries_fn, NULL);
1119
1120 if (n_sort_keys > 1)
1121 sort_secondary(map,
1122 (const struct tracing_map_sort_entry **)entries,
1123 n_entries,
1124 &sort_keys[0],
1125 &sort_keys[1]);
1126
1127 *sort_entries = entries;
1128
1129 return n_entries;
1130 free:
1131 tracing_map_destroy_sort_entries(entries, n_entries);
1132
1133 return ret;
1134}