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Linux/kernel/trace/tracing_map.c

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  1 /*
  2  * tracing_map - lock-free map for tracing
  3  *
  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.
  8  *
  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.
 13  *
 14  * Copyright (C) 2015 Tom Zanussi <tom.zanussi@linux.intel.com>
 15  *
 16  * tracing_map implementation inspired by lock-free map algorithms
 17  * originated by Dr. Cliff Click:
 18  *
 19  * http://www.azulsystems.com/blog/cliff/2007-03-26-non-blocking-hashtable
 20  * http://www.azulsystems.com/events/javaone_2007/2007_LockFreeHash.pdf
 21  */
 22 
 23 #include <linux/vmalloc.h>
 24 #include <linux/jhash.h>
 25 #include <linux/slab.h>
 26 #include <linux/sort.h>
 27 
 28 #include "tracing_map.h"
 29 #include "trace.h"
 30 
 31 /*
 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.
 35  */
 36 
 37 /**
 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
 42  *
 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.
 46  */
 47 void tracing_map_update_sum(struct tracing_map_elt *elt, unsigned int i, u64 n)
 48 {
 49         atomic64_add(n, &elt->fields[i].sum);
 50 }
 51 
 52 /**
 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
 56  *
 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
 60  * up.
 61  *
 62  * Return: The sum associated with field i for elt.
 63  */
 64 u64 tracing_map_read_sum(struct tracing_map_elt *elt, unsigned int i)
 65 {
 66         return (u64)atomic64_read(&elt->fields[i].sum);
 67 }
 68 
 69 /**
 70  * tracing_map_set_var - Assign a tracing_map_elt's variable field
 71  * @elt: The tracing_map_elt
 72  * @i: The index of the given variable associated with the tracing_map_elt
 73  * @n: The value to assign
 74  *
 75  * Assign n to variable i associated with the specified tracing_map_elt
 76  * instance.  The index i is the index returned by the call to
 77  * tracing_map_add_var() when the tracing map was set up.
 78  */
 79 void tracing_map_set_var(struct tracing_map_elt *elt, unsigned int i, u64 n)
 80 {
 81         atomic64_set(&elt->vars[i], n);
 82         elt->var_set[i] = true;
 83 }
 84 
 85 /**
 86  * tracing_map_var_set - Return whether or not a variable has been set
 87  * @elt: The tracing_map_elt
 88  * @i: The index of the given variable associated with the tracing_map_elt
 89  *
 90  * Return true if the variable has been set, false otherwise.  The
 91  * index i is the index returned by the call to tracing_map_add_var()
 92  * when the tracing map was set up.
 93  */
 94 bool tracing_map_var_set(struct tracing_map_elt *elt, unsigned int i)
 95 {
 96         return elt->var_set[i];
 97 }
 98 
 99 /**
100  * tracing_map_read_var - Return the value of a tracing_map_elt's variable field
101  * @elt: The tracing_map_elt
102  * @i: The index of the given variable associated with the tracing_map_elt
103  *
104  * Retrieve the value of the variable i associated with the specified
105  * tracing_map_elt instance.  The index i is the index returned by the
106  * call to tracing_map_add_var() when the tracing map was set
107  * up.
108  *
109  * Return: The variable value associated with field i for elt.
110  */
111 u64 tracing_map_read_var(struct tracing_map_elt *elt, unsigned int i)
112 {
113         return (u64)atomic64_read(&elt->vars[i]);
114 }
115 
116 /**
117  * tracing_map_read_var_once - Return and reset a tracing_map_elt's variable field
118  * @elt: The tracing_map_elt
119  * @i: The index of the given variable associated with the tracing_map_elt
120  *
121  * Retrieve the value of the variable i associated with the specified
122  * tracing_map_elt instance, and reset the variable to the 'not set'
123  * state.  The index i is the index returned by the call to
124  * tracing_map_add_var() when the tracing map was set up.  The reset
125  * essentially makes the variable a read-once variable if it's only
126  * accessed using this function.
127  *
128  * Return: The variable value associated with field i for elt.
129  */
130 u64 tracing_map_read_var_once(struct tracing_map_elt *elt, unsigned int i)
131 {
132         elt->var_set[i] = false;
133         return (u64)atomic64_read(&elt->vars[i]);
134 }
135 
136 int tracing_map_cmp_string(void *val_a, void *val_b)
137 {
138         char *a = val_a;
139         char *b = val_b;
140 
141         return strcmp(a, b);
142 }
143 
144 int tracing_map_cmp_none(void *val_a, void *val_b)
145 {
146         return 0;
147 }
148 
149 static int tracing_map_cmp_atomic64(void *val_a, void *val_b)
150 {
151         u64 a = atomic64_read((atomic64_t *)val_a);
152         u64 b = atomic64_read((atomic64_t *)val_b);
153 
154         return (a > b) ? 1 : ((a < b) ? -1 : 0);
155 }
156 
157 #define DEFINE_TRACING_MAP_CMP_FN(type)                                 \
158 static int tracing_map_cmp_##type(void *val_a, void *val_b)             \
159 {                                                                       \
160         type a = *(type *)val_a;                                        \
161         type b = *(type *)val_b;                                        \
162                                                                         \
163         return (a > b) ? 1 : ((a < b) ? -1 : 0);                        \
164 }
165 
166 DEFINE_TRACING_MAP_CMP_FN(s64);
167 DEFINE_TRACING_MAP_CMP_FN(u64);
168 DEFINE_TRACING_MAP_CMP_FN(s32);
169 DEFINE_TRACING_MAP_CMP_FN(u32);
170 DEFINE_TRACING_MAP_CMP_FN(s16);
171 DEFINE_TRACING_MAP_CMP_FN(u16);
172 DEFINE_TRACING_MAP_CMP_FN(s8);
173 DEFINE_TRACING_MAP_CMP_FN(u8);
174 
175 tracing_map_cmp_fn_t tracing_map_cmp_num(int field_size,
176                                          int field_is_signed)
177 {
178         tracing_map_cmp_fn_t fn = tracing_map_cmp_none;
179 
180         switch (field_size) {
181         case 8:
182                 if (field_is_signed)
183                         fn = tracing_map_cmp_s64;
184                 else
185                         fn = tracing_map_cmp_u64;
186                 break;
187         case 4:
188                 if (field_is_signed)
189                         fn = tracing_map_cmp_s32;
190                 else
191                         fn = tracing_map_cmp_u32;
192                 break;
193         case 2:
194                 if (field_is_signed)
195                         fn = tracing_map_cmp_s16;
196                 else
197                         fn = tracing_map_cmp_u16;
198                 break;
199         case 1:
200                 if (field_is_signed)
201                         fn = tracing_map_cmp_s8;
202                 else
203                         fn = tracing_map_cmp_u8;
204                 break;
205         }
206 
207         return fn;
208 }
209 
210 static int tracing_map_add_field(struct tracing_map *map,
211                                  tracing_map_cmp_fn_t cmp_fn)
212 {
213         int ret = -EINVAL;
214 
215         if (map->n_fields < TRACING_MAP_FIELDS_MAX) {
216                 ret = map->n_fields;
217                 map->fields[map->n_fields++].cmp_fn = cmp_fn;
218         }
219 
220         return ret;
221 }
222 
223 /**
224  * tracing_map_add_sum_field - Add a field describing a tracing_map sum
225  * @map: The tracing_map
226  *
227  * Add a sum field to the key and return the index identifying it in
228  * the map and associated tracing_map_elts.  This is the index used
229  * for instance to update a sum for a particular tracing_map_elt using
230  * tracing_map_update_sum() or reading it via tracing_map_read_sum().
231  *
232  * Return: The index identifying the field in the map and associated
233  * tracing_map_elts, or -EINVAL on error.
234  */
235 int tracing_map_add_sum_field(struct tracing_map *map)
236 {
237         return tracing_map_add_field(map, tracing_map_cmp_atomic64);
238 }
239 
240 /**
241  * tracing_map_add_var - Add a field describing a tracing_map var
242  * @map: The tracing_map
243  *
244  * Add a var to the map and return the index identifying it in the map
245  * and associated tracing_map_elts.  This is the index used for
246  * instance to update a var for a particular tracing_map_elt using
247  * tracing_map_update_var() or reading it via tracing_map_read_var().
248  *
249  * Return: The index identifying the var in the map and associated
250  * tracing_map_elts, or -EINVAL on error.
251  */
252 int tracing_map_add_var(struct tracing_map *map)
253 {
254         int ret = -EINVAL;
255 
256         if (map->n_vars < TRACING_MAP_VARS_MAX)
257                 ret = map->n_vars++;
258 
259         return ret;
260 }
261 
262 /**
263  * tracing_map_add_key_field - Add a field describing a tracing_map key
264  * @map: The tracing_map
265  * @offset: The offset within the key
266  * @cmp_fn: The comparison function that will be used to sort on the key
267  *
268  * Let the map know there is a key and that if it's used as a sort key
269  * to use cmp_fn.
270  *
271  * A key can be a subset of a compound key; for that purpose, the
272  * offset param is used to describe where within the the compound key
273  * the key referenced by this key field resides.
274  *
275  * Return: The index identifying the field in the map and associated
276  * tracing_map_elts, or -EINVAL on error.
277  */
278 int tracing_map_add_key_field(struct tracing_map *map,
279                               unsigned int offset,
280                               tracing_map_cmp_fn_t cmp_fn)
281 
282 {
283         int idx = tracing_map_add_field(map, cmp_fn);
284 
285         if (idx < 0)
286                 return idx;
287 
288         map->fields[idx].offset = offset;
289 
290         map->key_idx[map->n_keys++] = idx;
291 
292         return idx;
293 }
294 
295 void tracing_map_array_clear(struct tracing_map_array *a)
296 {
297         unsigned int i;
298 
299         if (!a->pages)
300                 return;
301 
302         for (i = 0; i < a->n_pages; i++)
303                 memset(a->pages[i], 0, PAGE_SIZE);
304 }
305 
306 void tracing_map_array_free(struct tracing_map_array *a)
307 {
308         unsigned int i;
309 
310         if (!a)
311                 return;
312 
313         if (!a->pages)
314                 goto free;
315 
316         for (i = 0; i < a->n_pages; i++) {
317                 if (!a->pages[i])
318                         break;
319                 free_page((unsigned long)a->pages[i]);
320         }
321 
322         kfree(a->pages);
323 
324  free:
325         kfree(a);
326 }
327 
328 struct tracing_map_array *tracing_map_array_alloc(unsigned int n_elts,
329                                                   unsigned int entry_size)
330 {
331         struct tracing_map_array *a;
332         unsigned int i;
333 
334         a = kzalloc(sizeof(*a), GFP_KERNEL);
335         if (!a)
336                 return NULL;
337 
338         a->entry_size_shift = fls(roundup_pow_of_two(entry_size) - 1);
339         a->entries_per_page = PAGE_SIZE / (1 << a->entry_size_shift);
340         a->n_pages = n_elts / a->entries_per_page;
341         if (!a->n_pages)
342                 a->n_pages = 1;
343         a->entry_shift = fls(a->entries_per_page) - 1;
344         a->entry_mask = (1 << a->entry_shift) - 1;
345 
346         a->pages = kcalloc(a->n_pages, sizeof(void *), GFP_KERNEL);
347         if (!a->pages)
348                 goto free;
349 
350         for (i = 0; i < a->n_pages; i++) {
351                 a->pages[i] = (void *)get_zeroed_page(GFP_KERNEL);
352                 if (!a->pages[i])
353                         goto free;
354         }
355  out:
356         return a;
357  free:
358         tracing_map_array_free(a);
359         a = NULL;
360 
361         goto out;
362 }
363 
364 static void tracing_map_elt_clear(struct tracing_map_elt *elt)
365 {
366         unsigned i;
367 
368         for (i = 0; i < elt->map->n_fields; i++)
369                 if (elt->fields[i].cmp_fn == tracing_map_cmp_atomic64)
370                         atomic64_set(&elt->fields[i].sum, 0);
371 
372         for (i = 0; i < elt->map->n_vars; i++) {
373                 atomic64_set(&elt->vars[i], 0);
374                 elt->var_set[i] = false;
375         }
376 
377         if (elt->map->ops && elt->map->ops->elt_clear)
378                 elt->map->ops->elt_clear(elt);
379 }
380 
381 static void tracing_map_elt_init_fields(struct tracing_map_elt *elt)
382 {
383         unsigned int i;
384 
385         tracing_map_elt_clear(elt);
386 
387         for (i = 0; i < elt->map->n_fields; i++) {
388                 elt->fields[i].cmp_fn = elt->map->fields[i].cmp_fn;
389 
390                 if (elt->fields[i].cmp_fn != tracing_map_cmp_atomic64)
391                         elt->fields[i].offset = elt->map->fields[i].offset;
392         }
393 }
394 
395 static void tracing_map_elt_free(struct tracing_map_elt *elt)
396 {
397         if (!elt)
398                 return;
399 
400         if (elt->map->ops && elt->map->ops->elt_free)
401                 elt->map->ops->elt_free(elt);
402         kfree(elt->fields);
403         kfree(elt->vars);
404         kfree(elt->var_set);
405         kfree(elt->key);
406         kfree(elt);
407 }
408 
409 static struct tracing_map_elt *tracing_map_elt_alloc(struct tracing_map *map)
410 {
411         struct tracing_map_elt *elt;
412         int err = 0;
413 
414         elt = kzalloc(sizeof(*elt), GFP_KERNEL);
415         if (!elt)
416                 return ERR_PTR(-ENOMEM);
417 
418         elt->map = map;
419 
420         elt->key = kzalloc(map->key_size, GFP_KERNEL);
421         if (!elt->key) {
422                 err = -ENOMEM;
423                 goto free;
424         }
425 
426         elt->fields = kcalloc(map->n_fields, sizeof(*elt->fields), GFP_KERNEL);
427         if (!elt->fields) {
428                 err = -ENOMEM;
429                 goto free;
430         }
431 
432         elt->vars = kcalloc(map->n_vars, sizeof(*elt->vars), GFP_KERNEL);
433         if (!elt->vars) {
434                 err = -ENOMEM;
435                 goto free;
436         }
437 
438         elt->var_set = kcalloc(map->n_vars, sizeof(*elt->var_set), GFP_KERNEL);
439         if (!elt->var_set) {
440                 err = -ENOMEM;
441                 goto free;
442         }
443 
444         tracing_map_elt_init_fields(elt);
445 
446         if (map->ops && map->ops->elt_alloc) {
447                 err = map->ops->elt_alloc(elt);
448                 if (err)
449                         goto free;
450         }
451         return elt;
452  free:
453         tracing_map_elt_free(elt);
454 
455         return ERR_PTR(err);
456 }
457 
458 static struct tracing_map_elt *get_free_elt(struct tracing_map *map)
459 {
460         struct tracing_map_elt *elt = NULL;
461         int idx;
462 
463         idx = atomic_inc_return(&map->next_elt);
464         if (idx < map->max_elts) {
465                 elt = *(TRACING_MAP_ELT(map->elts, idx));
466                 if (map->ops && map->ops->elt_init)
467                         map->ops->elt_init(elt);
468         }
469 
470         return elt;
471 }
472 
473 static void tracing_map_free_elts(struct tracing_map *map)
474 {
475         unsigned int i;
476 
477         if (!map->elts)
478                 return;
479 
480         for (i = 0; i < map->max_elts; i++) {
481                 tracing_map_elt_free(*(TRACING_MAP_ELT(map->elts, i)));
482                 *(TRACING_MAP_ELT(map->elts, i)) = NULL;
483         }
484 
485         tracing_map_array_free(map->elts);
486         map->elts = NULL;
487 }
488 
489 static int tracing_map_alloc_elts(struct tracing_map *map)
490 {
491         unsigned int i;
492 
493         map->elts = tracing_map_array_alloc(map->max_elts,
494                                             sizeof(struct tracing_map_elt *));
495         if (!map->elts)
496                 return -ENOMEM;
497 
498         for (i = 0; i < map->max_elts; i++) {
499                 *(TRACING_MAP_ELT(map->elts, i)) = tracing_map_elt_alloc(map);
500                 if (IS_ERR(*(TRACING_MAP_ELT(map->elts, i)))) {
501                         *(TRACING_MAP_ELT(map->elts, i)) = NULL;
502                         tracing_map_free_elts(map);
503 
504                         return -ENOMEM;
505                 }
506         }
507 
508         return 0;
509 }
510 
511 static inline bool keys_match(void *key, void *test_key, unsigned key_size)
512 {
513         bool match = true;
514 
515         if (memcmp(key, test_key, key_size))
516                 match = false;
517 
518         return match;
519 }
520 
521 static inline struct tracing_map_elt *
522 __tracing_map_insert(struct tracing_map *map, void *key, bool lookup_only)
523 {
524         u32 idx, key_hash, test_key;
525         int dup_try = 0;
526         struct tracing_map_entry *entry;
527         struct tracing_map_elt *val;
528 
529         key_hash = jhash(key, map->key_size, 0);
530         if (key_hash == 0)
531                 key_hash = 1;
532         idx = key_hash >> (32 - (map->map_bits + 1));
533 
534         while (1) {
535                 idx &= (map->map_size - 1);
536                 entry = TRACING_MAP_ENTRY(map->map, idx);
537                 test_key = entry->key;
538 
539                 if (test_key && test_key == key_hash) {
540                         val = READ_ONCE(entry->val);
541                         if (val &&
542                             keys_match(key, val->key, map->key_size)) {
543                                 if (!lookup_only)
544                                         atomic64_inc(&map->hits);
545                                 return val;
546                         } else if (unlikely(!val)) {
547                                 /*
548                                  * The key is present. But, val (pointer to elt
549                                  * struct) is still NULL. which means some other
550                                  * thread is in the process of inserting an
551                                  * element.
552                                  *
553                                  * On top of that, it's key_hash is same as the
554                                  * one being inserted right now. So, it's
555                                  * possible that the element has the same
556                                  * key as well.
557                                  */
558 
559                                 dup_try++;
560                                 if (dup_try > map->map_size) {
561                                         atomic64_inc(&map->drops);
562                                         break;
563                                 }
564                                 continue;
565                         }
566                 }
567 
568                 if (!test_key) {
569                         if (lookup_only)
570                                 break;
571 
572                         if (!cmpxchg(&entry->key, 0, key_hash)) {
573                                 struct tracing_map_elt *elt;
574 
575                                 elt = get_free_elt(map);
576                                 if (!elt) {
577                                         atomic64_inc(&map->drops);
578                                         entry->key = 0;
579                                         break;
580                                 }
581 
582                                 memcpy(elt->key, key, map->key_size);
583                                 entry->val = elt;
584                                 atomic64_inc(&map->hits);
585 
586                                 return entry->val;
587                         } else {
588                                 /*
589                                  * cmpxchg() failed. Loop around once
590                                  * more to check what key was inserted.
591                                  */
592                                 dup_try++;
593                                 continue;
594                         }
595                 }
596 
597                 idx++;
598         }
599 
600         return NULL;
601 }
602 
603 /**
604  * tracing_map_insert - Insert key and/or retrieve val from a tracing_map
605  * @map: The tracing_map to insert into
606  * @key: The key to insert
607  *
608  * Inserts a key into a tracing_map and creates and returns a new
609  * tracing_map_elt for it, or if the key has already been inserted by
610  * a previous call, returns the tracing_map_elt already associated
611  * with it.  When the map was created, the number of elements to be
612  * allocated for the map was specified (internally maintained as
613  * 'max_elts' in struct tracing_map), and that number of
614  * tracing_map_elts was created by tracing_map_init().  This is the
615  * pre-allocated pool of tracing_map_elts that tracing_map_insert()
616  * will allocate from when adding new keys.  Once that pool is
617  * exhausted, tracing_map_insert() is useless and will return NULL to
618  * signal that state.  There are two user-visible tracing_map
619  * variables, 'hits' and 'drops', which are updated by this function.
620  * Every time an element is either successfully inserted or retrieved,
621  * the 'hits' value is incrememented.  Every time an element insertion
622  * fails, the 'drops' value is incremented.
623  *
624  * This is a lock-free tracing map insertion function implementing a
625  * modified form of Cliff Click's basic insertion algorithm.  It
626  * requires the table size be a power of two.  To prevent any
627  * possibility of an infinite loop we always make the internal table
628  * size double the size of the requested table size (max_elts * 2).
629  * Likewise, we never reuse a slot or resize or delete elements - when
630  * we've reached max_elts entries, we simply return NULL once we've
631  * run out of entries.  Readers can at any point in time traverse the
632  * tracing map and safely access the key/val pairs.
633  *
634  * Return: the tracing_map_elt pointer val associated with the key.
635  * If this was a newly inserted key, the val will be a newly allocated
636  * and associated tracing_map_elt pointer val.  If the key wasn't
637  * found and the pool of tracing_map_elts has been exhausted, NULL is
638  * returned and no further insertions will succeed.
639  */
640 struct tracing_map_elt *tracing_map_insert(struct tracing_map *map, void *key)
641 {
642         return __tracing_map_insert(map, key, false);
643 }
644 
645 /**
646  * tracing_map_lookup - Retrieve val from a tracing_map
647  * @map: The tracing_map to perform the lookup on
648  * @key: The key to look up
649  *
650  * Looks up key in tracing_map and if found returns the matching
651  * tracing_map_elt.  This is a lock-free lookup; see
652  * tracing_map_insert() for details on tracing_map and how it works.
653  * Every time an element is retrieved, the 'hits' value is
654  * incrememented.  There is one user-visible tracing_map variable,
655  * 'hits', which is updated by this function.  Every time an element
656  * is successfully retrieved, the 'hits' value is incrememented.  The
657  * 'drops' value is never updated by this function.
658  *
659  * Return: the tracing_map_elt pointer val associated with the key.
660  * If the key wasn't found, NULL is returned.
661  */
662 struct tracing_map_elt *tracing_map_lookup(struct tracing_map *map, void *key)
663 {
664         return __tracing_map_insert(map, key, true);
665 }
666 
667 /**
668  * tracing_map_destroy - Destroy a tracing_map
669  * @map: The tracing_map to destroy
670  *
671  * Frees a tracing_map along with its associated array of
672  * tracing_map_elts.
673  *
674  * Callers should make sure there are no readers or writers actively
675  * reading or inserting into the map before calling this.
676  */
677 void tracing_map_destroy(struct tracing_map *map)
678 {
679         if (!map)
680                 return;
681 
682         tracing_map_free_elts(map);
683 
684         tracing_map_array_free(map->map);
685         kfree(map);
686 }
687 
688 /**
689  * tracing_map_clear - Clear a tracing_map
690  * @map: The tracing_map to clear
691  *
692  * Resets the tracing map to a cleared or initial state.  The
693  * tracing_map_elts are all cleared, and the array of struct
694  * tracing_map_entry is reset to an initialized state.
695  *
696  * Callers should make sure there are no writers actively inserting
697  * into the map before calling this.
698  */
699 void tracing_map_clear(struct tracing_map *map)
700 {
701         unsigned int i;
702 
703         atomic_set(&map->next_elt, -1);
704         atomic64_set(&map->hits, 0);
705         atomic64_set(&map->drops, 0);
706 
707         tracing_map_array_clear(map->map);
708 
709         for (i = 0; i < map->max_elts; i++)
710                 tracing_map_elt_clear(*(TRACING_MAP_ELT(map->elts, i)));
711 }
712 
713 static void set_sort_key(struct tracing_map *map,
714                          struct tracing_map_sort_key *sort_key)
715 {
716         map->sort_key = *sort_key;
717 }
718 
719 /**
720  * tracing_map_create - Create a lock-free map and element pool
721  * @map_bits: The size of the map (2 ** map_bits)
722  * @key_size: The size of the key for the map in bytes
723  * @ops: Optional client-defined tracing_map_ops instance
724  * @private_data: Client data associated with the map
725  *
726  * Creates and sets up a map to contain 2 ** map_bits number of
727  * elements (internally maintained as 'max_elts' in struct
728  * tracing_map).  Before using, map fields should be added to the map
729  * with tracing_map_add_sum_field() and tracing_map_add_key_field().
730  * tracing_map_init() should then be called to allocate the array of
731  * tracing_map_elts, in order to avoid allocating anything in the map
732  * insertion path.  The user-specified map size reflects the maximum
733  * number of elements that can be contained in the table requested by
734  * the user - internally we double that in order to keep the table
735  * sparse and keep collisions manageable.
736  *
737  * A tracing_map is a special-purpose map designed to aggregate or
738  * 'sum' one or more values associated with a specific object of type
739  * tracing_map_elt, which is attached by the map to a given key.
740  *
741  * tracing_map_create() sets up the map itself, and provides
742  * operations for inserting tracing_map_elts, but doesn't allocate the
743  * tracing_map_elts themselves, or provide a means for describing the
744  * keys or sums associated with the tracing_map_elts.  All
745  * tracing_map_elts for a given map have the same set of sums and
746  * keys, which are defined by the client using the functions
747  * tracing_map_add_key_field() and tracing_map_add_sum_field().  Once
748  * the fields are defined, the pool of elements allocated for the map
749  * can be created, which occurs when the client code calls
750  * tracing_map_init().
751  *
752  * When tracing_map_init() returns, tracing_map_elt elements can be
753  * inserted into the map using tracing_map_insert().  When called,
754  * tracing_map_insert() grabs a free tracing_map_elt from the pool, or
755  * finds an existing match in the map and in either case returns it.
756  * The client can then use tracing_map_update_sum() and
757  * tracing_map_read_sum() to update or read a given sum field for the
758  * tracing_map_elt.
759  *
760  * The client can at any point retrieve and traverse the current set
761  * of inserted tracing_map_elts in a tracing_map, via
762  * tracing_map_sort_entries().  Sorting can be done on any field,
763  * including keys.
764  *
765  * See tracing_map.h for a description of tracing_map_ops.
766  *
767  * Return: the tracing_map pointer if successful, ERR_PTR if not.
768  */
769 struct tracing_map *tracing_map_create(unsigned int map_bits,
770                                        unsigned int key_size,
771                                        const struct tracing_map_ops *ops,
772                                        void *private_data)
773 {
774         struct tracing_map *map;
775         unsigned int i;
776 
777         if (map_bits < TRACING_MAP_BITS_MIN ||
778             map_bits > TRACING_MAP_BITS_MAX)
779                 return ERR_PTR(-EINVAL);
780 
781         map = kzalloc(sizeof(*map), GFP_KERNEL);
782         if (!map)
783                 return ERR_PTR(-ENOMEM);
784 
785         map->map_bits = map_bits;
786         map->max_elts = (1 << map_bits);
787         atomic_set(&map->next_elt, -1);
788 
789         map->map_size = (1 << (map_bits + 1));
790         map->ops = ops;
791 
792         map->private_data = private_data;
793 
794         map->map = tracing_map_array_alloc(map->map_size,
795                                            sizeof(struct tracing_map_entry));
796         if (!map->map)
797                 goto free;
798 
799         map->key_size = key_size;
800         for (i = 0; i < TRACING_MAP_KEYS_MAX; i++)
801                 map->key_idx[i] = -1;
802  out:
803         return map;
804  free:
805         tracing_map_destroy(map);
806         map = ERR_PTR(-ENOMEM);
807 
808         goto out;
809 }
810 
811 /**
812  * tracing_map_init - Allocate and clear a map's tracing_map_elts
813  * @map: The tracing_map to initialize
814  *
815  * Allocates a clears a pool of tracing_map_elts equal to the
816  * user-specified size of 2 ** map_bits (internally maintained as
817  * 'max_elts' in struct tracing_map).  Before using, the map fields
818  * should be added to the map with tracing_map_add_sum_field() and
819  * tracing_map_add_key_field().  tracing_map_init() should then be
820  * called to allocate the array of tracing_map_elts, in order to avoid
821  * allocating anything in the map insertion path.  The user-specified
822  * map size reflects the max number of elements requested by the user
823  * - internally we double that in order to keep the table sparse and
824  * keep collisions manageable.
825  *
826  * See tracing_map.h for a description of tracing_map_ops.
827  *
828  * Return: the tracing_map pointer if successful, ERR_PTR if not.
829  */
830 int tracing_map_init(struct tracing_map *map)
831 {
832         int err;
833 
834         if (map->n_fields < 2)
835                 return -EINVAL; /* need at least 1 key and 1 val */
836 
837         err = tracing_map_alloc_elts(map);
838         if (err)
839                 return err;
840 
841         tracing_map_clear(map);
842 
843         return err;
844 }
845 
846 static int cmp_entries_dup(const struct tracing_map_sort_entry **a,
847                            const struct tracing_map_sort_entry **b)
848 {
849         int ret = 0;
850 
851         if (memcmp((*a)->key, (*b)->key, (*a)->elt->map->key_size))
852                 ret = 1;
853 
854         return ret;
855 }
856 
857 static int cmp_entries_sum(const struct tracing_map_sort_entry **a,
858                            const struct tracing_map_sort_entry **b)
859 {
860         const struct tracing_map_elt *elt_a, *elt_b;
861         struct tracing_map_sort_key *sort_key;
862         struct tracing_map_field *field;
863         tracing_map_cmp_fn_t cmp_fn;
864         void *val_a, *val_b;
865         int ret = 0;
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 
885 static int cmp_entries_key(const struct tracing_map_sort_entry **a,
886                            const struct tracing_map_sort_entry **b)
887 {
888         const struct tracing_map_elt *elt_a, *elt_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         elt_a = (*a)->elt;
896         elt_b = (*b)->elt;
897 
898         sort_key = &elt_a->map->sort_key;
899 
900         field = &elt_a->fields[sort_key->field_idx];
901 
902         cmp_fn = field->cmp_fn;
903 
904         val_a = elt_a->key + field->offset;
905         val_b = elt_b->key + field->offset;
906 
907         ret = cmp_fn(val_a, val_b);
908         if (sort_key->descending)
909                 ret = -ret;
910 
911         return ret;
912 }
913 
914 static void destroy_sort_entry(struct tracing_map_sort_entry *entry)
915 {
916         if (!entry)
917                 return;
918 
919         if (entry->elt_copied)
920                 tracing_map_elt_free(entry->elt);
921 
922         kfree(entry);
923 }
924 
925 /**
926  * tracing_map_destroy_sort_entries - Destroy an array of sort entries
927  * @entries: The entries to destroy
928  * @n_entries: The number of entries in the array
929  *
930  * Destroy the elements returned by a tracing_map_sort_entries() call.
931  */
932 void tracing_map_destroy_sort_entries(struct tracing_map_sort_entry **entries,
933                                       unsigned int n_entries)
934 {
935         unsigned int i;
936 
937         for (i = 0; i < n_entries; i++)
938                 destroy_sort_entry(entries[i]);
939 
940         vfree(entries);
941 }
942 
943 static struct tracing_map_sort_entry *
944 create_sort_entry(void *key, struct tracing_map_elt *elt)
945 {
946         struct tracing_map_sort_entry *sort_entry;
947 
948         sort_entry = kzalloc(sizeof(*sort_entry), GFP_KERNEL);
949         if (!sort_entry)
950                 return NULL;
951 
952         sort_entry->key = key;
953         sort_entry->elt = elt;
954 
955         return sort_entry;
956 }
957 
958 static void detect_dups(struct tracing_map_sort_entry **sort_entries,
959                       int n_entries, unsigned int key_size)
960 {
961         unsigned int dups = 0, total_dups = 0;
962         int i;
963         void *key;
964 
965         if (n_entries < 2)
966                 return;
967 
968         sort(sort_entries, n_entries, sizeof(struct tracing_map_sort_entry *),
969              (int (*)(const void *, const void *))cmp_entries_dup, NULL);
970 
971         key = sort_entries[0]->key;
972         for (i = 1; i < n_entries; i++) {
973                 if (!memcmp(sort_entries[i]->key, key, key_size)) {
974                         dups++; total_dups++;
975                         continue;
976                 }
977                 key = sort_entries[i]->key;
978                 dups = 0;
979         }
980 
981         WARN_ONCE(total_dups > 0,
982                   "Duplicates detected: %d\n", total_dups);
983 }
984 
985 static bool is_key(struct tracing_map *map, unsigned int field_idx)
986 {
987         unsigned int i;
988 
989         for (i = 0; i < map->n_keys; i++)
990                 if (map->key_idx[i] == field_idx)
991                         return true;
992         return false;
993 }
994 
995 static void sort_secondary(struct tracing_map *map,
996                            const struct tracing_map_sort_entry **entries,
997                            unsigned int n_entries,
998                            struct tracing_map_sort_key *primary_key,
999                            struct tracing_map_sort_key *secondary_key)
1000 {
1001         int (*primary_fn)(const struct tracing_map_sort_entry **,
1002                           const struct tracing_map_sort_entry **);
1003         int (*secondary_fn)(const struct tracing_map_sort_entry **,
1004                             const struct tracing_map_sort_entry **);
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_key: The sort key to use for sorting
1048  * @sort_entries: outval: pointer to allocated and sorted array of entries
1049  *
1050  * tracing_map_sort_entries() sorts the current set of entries in the
1051  * map and returns the list of tracing_map_sort_entries containing
1052  * them to the client in the sort_entries param.  The client can
1053  * access the struct tracing_map_elt element of interest directly as
1054  * the 'elt' field of a returned struct tracing_map_sort_entry object.
1055  *
1056  * The sort_key has only two fields: idx and descending.  'idx' refers
1057  * to the index of the field added via tracing_map_add_sum_field() or
1058  * tracing_map_add_key_field() when the tracing_map was initialized.
1059  * 'descending' is a flag that if set reverses the sort order, which
1060  * by default is ascending.
1061  *
1062  * The client should not hold on to the returned array but should use
1063  * it and call tracing_map_destroy_sort_entries() when done.
1064  *
1065  * Return: the number of sort_entries in the struct tracing_map_sort_entry
1066  * array, negative on error
1067  */
1068 int tracing_map_sort_entries(struct tracing_map *map,
1069                              struct tracing_map_sort_key *sort_keys,
1070                              unsigned int n_sort_keys,
1071                              struct tracing_map_sort_entry ***sort_entries)
1072 {
1073         int (*cmp_entries_fn)(const struct tracing_map_sort_entry **,
1074                               const struct tracing_map_sort_entry **);
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 }
1135 

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