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// SPDX-License-Identifier: GPL-2.0
#include "threads.h"
#include "machine.h"
#include "thread.h"
static struct threads_table_entry *threads__table(struct threads *threads, pid_t tid)
{
/* Cast it to handle tid == -1 */
return &threads->table[(unsigned int)tid % THREADS__TABLE_SIZE];
}
static size_t key_hash(long key, void *ctx __maybe_unused)
{
/* The table lookup removes low bit entropy, but this is just ignored here. */
return key;
}
static bool key_equal(long key1, long key2, void *ctx __maybe_unused)
{
return key1 == key2;
}
void threads__init(struct threads *threads)
{
for (int i = 0; i < THREADS__TABLE_SIZE; i++) {
struct threads_table_entry *table = &threads->table[i];
hashmap__init(&table->shard, key_hash, key_equal, NULL);
init_rwsem(&table->lock);
table->last_match = NULL;
}
}
void threads__exit(struct threads *threads)
{
threads__remove_all_threads(threads);
for (int i = 0; i < THREADS__TABLE_SIZE; i++) {
struct threads_table_entry *table = &threads->table[i];
hashmap__clear(&table->shard);
exit_rwsem(&table->lock);
}
}
size_t threads__nr(struct threads *threads)
{
size_t nr = 0;
for (int i = 0; i < THREADS__TABLE_SIZE; i++) {
struct threads_table_entry *table = &threads->table[i];
down_read(&table->lock);
nr += hashmap__size(&table->shard);
up_read(&table->lock);
}
return nr;
}
/*
* Front-end cache - TID lookups come in blocks,
* so most of the time we dont have to look up
* the full rbtree:
*/
static struct thread *__threads_table_entry__get_last_match(struct threads_table_entry *table,
pid_t tid)
{
struct thread *th, *res = NULL;
th = table->last_match;
if (th != NULL) {
if (thread__tid(th) == tid)
res = thread__get(th);
}
return res;
}
static void __threads_table_entry__set_last_match(struct threads_table_entry *table,
struct thread *th)
{
thread__put(table->last_match);
table->last_match = thread__get(th);
}
static void threads_table_entry__set_last_match(struct threads_table_entry *table,
struct thread *th)
{
down_write(&table->lock);
__threads_table_entry__set_last_match(table, th);
up_write(&table->lock);
}
struct thread *threads__find(struct threads *threads, pid_t tid)
{
struct threads_table_entry *table = threads__table(threads, tid);
struct thread *res;
down_read(&table->lock);
res = __threads_table_entry__get_last_match(table, tid);
if (!res) {
if (hashmap__find(&table->shard, tid, &res))
res = thread__get(res);
}
up_read(&table->lock);
if (res)
threads_table_entry__set_last_match(table, res);
return res;
}
struct thread *threads__findnew(struct threads *threads, pid_t pid, pid_t tid, bool *created)
{
struct threads_table_entry *table = threads__table(threads, tid);
struct thread *res = NULL;
*created = false;
down_write(&table->lock);
res = thread__new(pid, tid);
if (res) {
if (hashmap__add(&table->shard, tid, res)) {
/* Add failed. Assume a race so find other entry. */
thread__put(res);
res = NULL;
if (hashmap__find(&table->shard, tid, &res))
res = thread__get(res);
} else {
res = thread__get(res);
*created = true;
}
if (res)
__threads_table_entry__set_last_match(table, res);
}
up_write(&table->lock);
return res;
}
void threads__remove_all_threads(struct threads *threads)
{
for (int i = 0; i < THREADS__TABLE_SIZE; i++) {
struct threads_table_entry *table = &threads->table[i];
struct hashmap_entry *cur, *tmp;
size_t bkt;
down_write(&table->lock);
__threads_table_entry__set_last_match(table, NULL);
hashmap__for_each_entry_safe(&table->shard, cur, tmp, bkt) {
struct thread *old_value;
hashmap__delete(&table->shard, cur->key, /*old_key=*/NULL, &old_value);
thread__put(old_value);
}
up_write(&table->lock);
}
}
void threads__remove(struct threads *threads, struct thread *thread)
{
struct threads_table_entry *table = threads__table(threads, thread__tid(thread));
struct thread *old_value;
down_write(&table->lock);
if (table->last_match && RC_CHK_EQUAL(table->last_match, thread))
__threads_table_entry__set_last_match(table, NULL);
hashmap__delete(&table->shard, thread__tid(thread), /*old_key=*/NULL, &old_value);
thread__put(old_value);
up_write(&table->lock);
}
int threads__for_each_thread(struct threads *threads,
int (*fn)(struct thread *thread, void *data),
void *data)
{
for (int i = 0; i < THREADS__TABLE_SIZE; i++) {
struct threads_table_entry *table = &threads->table[i];
struct hashmap_entry *cur;
size_t bkt;
down_read(&table->lock);
hashmap__for_each_entry(&table->shard, cur, bkt) {
int rc = fn((struct thread *)cur->pvalue, data);
if (rc != 0) {
up_read(&table->lock);
return rc;
}
}
up_read(&table->lock);
}
return 0;
}
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