aboutsummaryrefslogtreecommitdiffstatshomepage
path: root/lib/rhashtable.c
diff options
context:
space:
mode:
Diffstat (limited to 'lib/rhashtable.c')
-rw-r--r--lib/rhashtable.c372
1 files changed, 167 insertions, 205 deletions
diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index bc2d0d80d1f9..057919164e23 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -484,16 +484,24 @@ static void rht_deferred_worker(struct work_struct *work)
{
struct rhashtable *ht;
struct bucket_table *tbl;
+ struct rhashtable_walker *walker;
ht = container_of(work, struct rhashtable, run_work);
mutex_lock(&ht->mutex);
+ if (ht->being_destroyed)
+ goto unlock;
+
tbl = rht_dereference(ht->tbl, ht);
+ list_for_each_entry(walker, &ht->walkers, list)
+ walker->resize = true;
+
if (ht->p.grow_decision && ht->p.grow_decision(ht, tbl->size))
rhashtable_expand(ht);
else if (ht->p.shrink_decision && ht->p.shrink_decision(ht, tbl->size))
rhashtable_shrink(ht);
+unlock:
mutex_unlock(&ht->mutex);
}
@@ -818,6 +826,164 @@ exit:
}
EXPORT_SYMBOL_GPL(rhashtable_lookup_compare_insert);
+/**
+ * rhashtable_walk_init - Initialise an iterator
+ * @ht: Table to walk over
+ * @iter: Hash table Iterator
+ *
+ * This function prepares a hash table walk.
+ *
+ * Note that if you restart a walk after rhashtable_walk_stop you
+ * may see the same object twice. Also, you may miss objects if
+ * there are removals in between rhashtable_walk_stop and the next
+ * call to rhashtable_walk_start.
+ *
+ * For a completely stable walk you should construct your own data
+ * structure outside the hash table.
+ *
+ * This function may sleep so you must not call it from interrupt
+ * context or with spin locks held.
+ *
+ * You must call rhashtable_walk_exit if this function returns
+ * successfully.
+ */
+int rhashtable_walk_init(struct rhashtable *ht, struct rhashtable_iter *iter)
+{
+ iter->ht = ht;
+ iter->p = NULL;
+ iter->slot = 0;
+ iter->skip = 0;
+
+ iter->walker = kmalloc(sizeof(*iter->walker), GFP_KERNEL);
+ if (!iter->walker)
+ return -ENOMEM;
+
+ mutex_lock(&ht->mutex);
+ list_add(&iter->walker->list, &ht->walkers);
+ mutex_unlock(&ht->mutex);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(rhashtable_walk_init);
+
+/**
+ * rhashtable_walk_exit - Free an iterator
+ * @iter: Hash table Iterator
+ *
+ * This function frees resources allocated by rhashtable_walk_init.
+ */
+void rhashtable_walk_exit(struct rhashtable_iter *iter)
+{
+ mutex_lock(&iter->ht->mutex);
+ list_del(&iter->walker->list);
+ mutex_unlock(&iter->ht->mutex);
+ kfree(iter->walker);
+}
+EXPORT_SYMBOL_GPL(rhashtable_walk_exit);
+
+/**
+ * rhashtable_walk_start - Start a hash table walk
+ * @iter: Hash table iterator
+ *
+ * Start a hash table walk. Note that we take the RCU lock in all
+ * cases including when we return an error. So you must always call
+ * rhashtable_walk_stop to clean up.
+ *
+ * Returns zero if successful.
+ *
+ * Returns -EAGAIN if resize event occured. Note that the iterator
+ * will rewind back to the beginning and you may use it immediately
+ * by calling rhashtable_walk_next.
+ */
+int rhashtable_walk_start(struct rhashtable_iter *iter)
+{
+ rcu_read_lock();
+
+ if (iter->walker->resize) {
+ iter->slot = 0;
+ iter->skip = 0;
+ iter->walker->resize = false;
+ return -EAGAIN;
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(rhashtable_walk_start);
+
+/**
+ * rhashtable_walk_next - Return the next object and advance the iterator
+ * @iter: Hash table iterator
+ *
+ * Note that you must call rhashtable_walk_stop when you are finished
+ * with the walk.
+ *
+ * Returns the next object or NULL when the end of the table is reached.
+ *
+ * Returns -EAGAIN if resize event occured. Note that the iterator
+ * will rewind back to the beginning and you may continue to use it.
+ */
+void *rhashtable_walk_next(struct rhashtable_iter *iter)
+{
+ const struct bucket_table *tbl;
+ struct rhashtable *ht = iter->ht;
+ struct rhash_head *p = iter->p;
+ void *obj = NULL;
+
+ tbl = rht_dereference_rcu(ht->tbl, ht);
+
+ if (p) {
+ p = rht_dereference_bucket_rcu(p->next, tbl, iter->slot);
+ goto next;
+ }
+
+ for (; iter->slot < tbl->size; iter->slot++) {
+ int skip = iter->skip;
+
+ rht_for_each_rcu(p, tbl, iter->slot) {
+ if (!skip)
+ break;
+ skip--;
+ }
+
+next:
+ if (!rht_is_a_nulls(p)) {
+ iter->skip++;
+ iter->p = p;
+ obj = rht_obj(ht, p);
+ goto out;
+ }
+
+ iter->skip = 0;
+ }
+
+ iter->p = NULL;
+
+out:
+ if (iter->walker->resize) {
+ iter->p = NULL;
+ iter->slot = 0;
+ iter->skip = 0;
+ iter->walker->resize = false;
+ return ERR_PTR(-EAGAIN);
+ }
+
+ return obj;
+}
+EXPORT_SYMBOL_GPL(rhashtable_walk_next);
+
+/**
+ * rhashtable_walk_stop - Finish a hash table walk
+ * @iter: Hash table iterator
+ *
+ * Finish a hash table walk.
+ */
+void rhashtable_walk_stop(struct rhashtable_iter *iter)
+{
+ rcu_read_unlock();
+ iter->p = NULL;
+}
+EXPORT_SYMBOL_GPL(rhashtable_walk_stop);
+
static size_t rounded_hashtable_size(struct rhashtable_params *params)
{
return max(roundup_pow_of_two(params->nelem_hint * 4 / 3),
@@ -890,6 +1056,7 @@ int rhashtable_init(struct rhashtable *ht, struct rhashtable_params *params)
memset(ht, 0, sizeof(*ht));
mutex_init(&ht->mutex);
memcpy(&ht->p, params, sizeof(*params));
+ INIT_LIST_HEAD(&ht->walkers);
if (params->locks_mul)
ht->p.locks_mul = roundup_pow_of_two(params->locks_mul);
@@ -935,208 +1102,3 @@ void rhashtable_destroy(struct rhashtable *ht)
mutex_unlock(&ht->mutex);
}
EXPORT_SYMBOL_GPL(rhashtable_destroy);
-
-/**************************************************************************
- * Self Test
- **************************************************************************/
-
-#ifdef CONFIG_TEST_RHASHTABLE
-
-#define TEST_HT_SIZE 8
-#define TEST_ENTRIES 2048
-#define TEST_PTR ((void *) 0xdeadbeef)
-#define TEST_NEXPANDS 4
-
-struct test_obj {
- void *ptr;
- int value;
- struct rhash_head node;
-};
-
-static int __init test_rht_lookup(struct rhashtable *ht)
-{
- unsigned int i;
-
- for (i = 0; i < TEST_ENTRIES * 2; i++) {
- struct test_obj *obj;
- bool expected = !(i % 2);
- u32 key = i;
-
- obj = rhashtable_lookup(ht, &key);
-
- if (expected && !obj) {
- pr_warn("Test failed: Could not find key %u\n", key);
- return -ENOENT;
- } else if (!expected && obj) {
- pr_warn("Test failed: Unexpected entry found for key %u\n",
- key);
- return -EEXIST;
- } else if (expected && obj) {
- if (obj->ptr != TEST_PTR || obj->value != i) {
- pr_warn("Test failed: Lookup value mismatch %p!=%p, %u!=%u\n",
- obj->ptr, TEST_PTR, obj->value, i);
- return -EINVAL;
- }
- }
- }
-
- return 0;
-}
-
-static void test_bucket_stats(struct rhashtable *ht, bool quiet)
-{
- unsigned int cnt, rcu_cnt, i, total = 0;
- struct rhash_head *pos;
- struct test_obj *obj;
- struct bucket_table *tbl;
-
- tbl = rht_dereference_rcu(ht->tbl, ht);
- for (i = 0; i < tbl->size; i++) {
- rcu_cnt = cnt = 0;
-
- if (!quiet)
- pr_info(" [%#4x/%zu]", i, tbl->size);
-
- rht_for_each_entry_rcu(obj, pos, tbl, i, node) {
- cnt++;
- total++;
- if (!quiet)
- pr_cont(" [%p],", obj);
- }
-
- rht_for_each_entry_rcu(obj, pos, tbl, i, node)
- rcu_cnt++;
-
- if (rcu_cnt != cnt)
- pr_warn("Test failed: Chain count mismach %d != %d",
- cnt, rcu_cnt);
-
- if (!quiet)
- pr_cont("\n [%#x] first element: %p, chain length: %u\n",
- i, tbl->buckets[i], cnt);
- }
-
- pr_info(" Traversal complete: counted=%u, nelems=%u, entries=%d\n",
- total, atomic_read(&ht->nelems), TEST_ENTRIES);
-
- if (total != atomic_read(&ht->nelems) || total != TEST_ENTRIES)
- pr_warn("Test failed: Total count mismatch ^^^");
-}
-
-static int __init test_rhashtable(struct rhashtable *ht)
-{
- struct bucket_table *tbl;
- struct test_obj *obj;
- struct rhash_head *pos, *next;
- int err;
- unsigned int i;
-
- /*
- * Insertion Test:
- * Insert TEST_ENTRIES into table with all keys even numbers
- */
- pr_info(" Adding %d keys\n", TEST_ENTRIES);
- for (i = 0; i < TEST_ENTRIES; i++) {
- struct test_obj *obj;
-
- obj = kzalloc(sizeof(*obj), GFP_KERNEL);
- if (!obj) {
- err = -ENOMEM;
- goto error;
- }
-
- obj->ptr = TEST_PTR;
- obj->value = i * 2;
-
- rhashtable_insert(ht, &obj->node);
- }
-
- rcu_read_lock();
- test_bucket_stats(ht, true);
- test_rht_lookup(ht);
- rcu_read_unlock();
-
- for (i = 0; i < TEST_NEXPANDS; i++) {
- pr_info(" Table expansion iteration %u...\n", i);
- mutex_lock(&ht->mutex);
- rhashtable_expand(ht);
- mutex_unlock(&ht->mutex);
-
- rcu_read_lock();
- pr_info(" Verifying lookups...\n");
- test_rht_lookup(ht);
- rcu_read_unlock();
- }
-
- for (i = 0; i < TEST_NEXPANDS; i++) {
- pr_info(" Table shrinkage iteration %u...\n", i);
- mutex_lock(&ht->mutex);
- rhashtable_shrink(ht);
- mutex_unlock(&ht->mutex);
-
- rcu_read_lock();
- pr_info(" Verifying lookups...\n");
- test_rht_lookup(ht);
- rcu_read_unlock();
- }
-
- rcu_read_lock();
- test_bucket_stats(ht, true);
- rcu_read_unlock();
-
- pr_info(" Deleting %d keys\n", TEST_ENTRIES);
- for (i = 0; i < TEST_ENTRIES; i++) {
- u32 key = i * 2;
-
- obj = rhashtable_lookup(ht, &key);
- BUG_ON(!obj);
-
- rhashtable_remove(ht, &obj->node);
- kfree(obj);
- }
-
- return 0;
-
-error:
- tbl = rht_dereference_rcu(ht->tbl, ht);
- for (i = 0; i < tbl->size; i++)
- rht_for_each_entry_safe(obj, pos, next, tbl, i, node)
- kfree(obj);
-
- return err;
-}
-
-static int __init test_rht_init(void)
-{
- struct rhashtable ht;
- struct rhashtable_params params = {
- .nelem_hint = TEST_HT_SIZE,
- .head_offset = offsetof(struct test_obj, node),
- .key_offset = offsetof(struct test_obj, value),
- .key_len = sizeof(int),
- .hashfn = jhash,
- .nulls_base = (3U << RHT_BASE_SHIFT),
- .grow_decision = rht_grow_above_75,
- .shrink_decision = rht_shrink_below_30,
- };
- int err;
-
- pr_info("Running resizable hashtable tests...\n");
-
- err = rhashtable_init(&ht, &params);
- if (err < 0) {
- pr_warn("Test failed: Unable to initialize hashtable: %d\n",
- err);
- return err;
- }
-
- err = test_rhashtable(&ht);
-
- rhashtable_destroy(&ht);
-
- return err;
-}
-
-subsys_initcall(test_rht_init);
-
-#endif /* CONFIG_TEST_RHASHTABLE */
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.