tools/perf/util/threads.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include "threads.h"
   3 #include "machine.h"
   4 #include "thread.h"
   5
   6 static struct threads_table_entry *threads__table(struct threads *threads, pid_t tid)
   7 {
   8         /* Cast it to handle tid == -1 */
   9         return &threads->table[(unsigned int)tid % THREADS__TABLE_SIZE];
  10 }
  11
  12 static size_t key_hash(long key, void *ctx __maybe_unused)
  13 {
  14         /* The table lookup removes low bit entropy, but this is just ignored here. */
  15         return key;
  16 }
  17
  18 static bool key_equal(long key1, long key2, void *ctx __maybe_unused)
  19 {
  20         return key1 == key2;
  21 }
  22
  23 void threads__init(struct threads *threads)
  24 {
  25         for (int i = 0; i < THREADS__TABLE_SIZE; i++) {
  26                 struct threads_table_entry *table = &threads->table[i];
  27
  28                 hashmap__init(&table->shard, key_hash, key_equal, NULL);
  29                 init_rwsem(&table->lock);
  30                 table->last_match = NULL;
  31         }
  32 }
  33
  34 void threads__exit(struct threads *threads)
  35 {
  36         threads__remove_all_threads(threads);
  37         for (int i = 0; i < THREADS__TABLE_SIZE; i++) {
  38                 struct threads_table_entry *table = &threads->table[i];
  39
  40                 hashmap__clear(&table->shard);
  41                 exit_rwsem(&table->lock);
  42         }
  43 }
  44
  45 size_t threads__nr(struct threads *threads)
  46 {
  47         size_t nr = 0;
  48
  49         for (int i = 0; i < THREADS__TABLE_SIZE; i++) {
  50                 struct threads_table_entry *table = &threads->table[i];
  51
  52                 down_read(&table->lock);
  53                 nr += hashmap__size(&table->shard);
  54                 up_read(&table->lock);
  55         }
  56         return nr;
  57 }
  58
  59 /*
  60  * Front-end cache - TID lookups come in blocks,
  61  * so most of the time we dont have to look up
  62  * the full rbtree:
  63  */
  64 static struct thread *__threads_table_entry__get_last_match(struct threads_table_entry *table,
  65                                                             pid_t tid)
  66 {
  67         struct thread *th, *res = NULL;
  68
  69         th = table->last_match;
  70         if (th != NULL) {
  71                 if (thread__tid(th) == tid)
  72                         res = thread__get(th);
  73         }
  74         return res;
  75 }
  76
  77 static void __threads_table_entry__set_last_match(struct threads_table_entry *table,
  78                                                   struct thread *th)
  79 {
  80         thread__put(table->last_match);
  81         table->last_match = thread__get(th);
  82 }
  83
  84 static void threads_table_entry__set_last_match(struct threads_table_entry *table,
  85                                                 struct thread *th)
  86 {
  87         down_write(&table->lock);
  88         __threads_table_entry__set_last_match(table, th);
  89         up_write(&table->lock);
  90 }
  91
  92 struct thread *threads__find(struct threads *threads, pid_t tid)
  93 {
  94         struct threads_table_entry *table  = threads__table(threads, tid);
  95         struct thread *res;
  96
  97         down_read(&table->lock);
  98         res = __threads_table_entry__get_last_match(table, tid);
  99         if (!res) {
 100                 if (hashmap__find(&table->shard, tid, &res))
 101                         res = thread__get(res);
 102         }
 103         up_read(&table->lock);
 104         if (res)
 105                 threads_table_entry__set_last_match(table, res);
 106         return res;
 107 }
 108
 109 struct thread *threads__findnew(struct threads *threads, pid_t pid, pid_t tid, bool *created)
 110 {
 111         struct threads_table_entry *table  = threads__table(threads, tid);
 112         struct thread *res = NULL;
 113
 114         *created = false;
 115         down_write(&table->lock);
 116         res = thread__new(pid, tid);
 117         if (res) {
 118                 if (hashmap__add(&table->shard, tid, res)) {
 119                         /* Add failed. Assume a race so find other entry. */
 120                         thread__put(res);
 121                         res = NULL;
 122                         if (hashmap__find(&table->shard, tid, &res))
 123                                 res = thread__get(res);
 124                 } else {
 125                         res = thread__get(res);
 126                         *created = true;
 127                 }
 128                 if (res)
 129                         __threads_table_entry__set_last_match(table, res);
 130         }
 131         up_write(&table->lock);
 132         return res;
 133 }
 134
 135 void threads__remove_all_threads(struct threads *threads)
 136 {
 137         for (int i = 0; i < THREADS__TABLE_SIZE; i++) {
 138                 struct threads_table_entry *table = &threads->table[i];
 139                 struct hashmap_entry *cur, *tmp;
 140                 size_t bkt;
 141
 142                 down_write(&table->lock);
 143                 __threads_table_entry__set_last_match(table, NULL);
 144                 hashmap__for_each_entry_safe(&table->shard, cur, tmp, bkt) {
 145                         struct thread *old_value;
 146
 147                         hashmap__delete(&table->shard, cur->key, /*old_key=*/NULL, &old_value);
 148                         thread__put(old_value);
 149                 }
 150                 up_write(&table->lock);
 151         }
 152 }
 153
 154 void threads__remove(struct threads *threads, struct thread *thread)
 155 {
 156         struct threads_table_entry *table  = threads__table(threads, thread__tid(thread));
 157         struct thread *old_value;
 158
 159         down_write(&table->lock);
 160         if (table->last_match && RC_CHK_EQUAL(table->last_match, thread))
 161                 __threads_table_entry__set_last_match(table, NULL);
 162
 163         hashmap__delete(&table->shard, thread__tid(thread), /*old_key=*/NULL, &old_value);
 164         thread__put(old_value);
 165         up_write(&table->lock);
 166 }
 167
 168 int threads__for_each_thread(struct threads *threads,
 169                              int (*fn)(struct thread *thread, void *data),
 170                              void *data)
 171 {
 172         for (int i = 0; i < THREADS__TABLE_SIZE; i++) {
 173                 struct threads_table_entry *table = &threads->table[i];
 174                 struct hashmap_entry *cur;
 175                 size_t bkt;
 176
 177                 down_read(&table->lock);
 178                 hashmap__for_each_entry(&table->shard, cur, bkt) {
 179                         int rc = fn((struct thread *)cur->pvalue, data);
 180
 181                         if (rc != 0) {
 182                                 up_read(&table->lock);
 183                                 return rc;
 184                         }
 185                 }
 186                 up_read(&table->lock);
 187         }
 188         return 0;
 189
 190 }