#define HASH_MIN_SIZE 4U
#define BUCKET_LOCKS_PER_CPU 32UL
-union nested_table {
- union nested_table __rcu *table;
- struct rhash_head __rcu *bucket;
-};
-
static u32 head_hashfn(struct rhashtable *ht,
const struct bucket_table *tbl,
const struct rhash_head *he)
/* Never allocate more than 0.5 locks per bucket */
size = min_t(unsigned int, size, tbl->size >> 1);
- if (tbl->nest)
- size = min(size, 1U << tbl->nest);
-
if (sizeof(spinlock_t) != 0) {
tbl->locks = NULL;
#ifdef CONFIG_NUMA
return 0;
}
-static void nested_table_free(union nested_table *ntbl, unsigned int size)
-{
- const unsigned int shift = PAGE_SHIFT - ilog2(sizeof(void *));
- const unsigned int len = 1 << shift;
- unsigned int i;
-
- ntbl = rcu_dereference_raw(ntbl->table);
- if (!ntbl)
- return;
-
- if (size > len) {
- size >>= shift;
- for (i = 0; i < len; i++)
- nested_table_free(ntbl + i, size);
- }
-
- kfree(ntbl);
-}
-
-static void nested_bucket_table_free(const struct bucket_table *tbl)
-{
- unsigned int size = tbl->size >> tbl->nest;
- unsigned int len = 1 << tbl->nest;
- union nested_table *ntbl;
- unsigned int i;
-
- ntbl = (union nested_table *)rcu_dereference_raw(tbl->buckets[0]);
-
- for (i = 0; i < len; i++)
- nested_table_free(ntbl + i, size);
-
- kfree(ntbl);
-}
-
static void bucket_table_free(const struct bucket_table *tbl)
{
- if (tbl->nest)
- nested_bucket_table_free(tbl);
-
if (tbl)
kvfree(tbl->locks);
bucket_table_free(container_of(head, struct bucket_table, rcu));
}
-static union nested_table *nested_table_alloc(struct rhashtable *ht,
- union nested_table __rcu **prev,
- unsigned int shifted,
- unsigned int nhash)
-{
- union nested_table *ntbl;
- int i;
-
- ntbl = rcu_dereference(*prev);
- if (ntbl)
- return ntbl;
-
- ntbl = kzalloc(PAGE_SIZE, GFP_ATOMIC);
-
- if (ntbl && shifted) {
- for (i = 0; i < PAGE_SIZE / sizeof(ntbl[0].bucket); i++)
- INIT_RHT_NULLS_HEAD(ntbl[i].bucket, ht,
- (i << shifted) | nhash);
- }
-
- rcu_assign_pointer(*prev, ntbl);
-
- return ntbl;
-}
-
-static struct bucket_table *nested_bucket_table_alloc(struct rhashtable *ht,
- size_t nbuckets,
- gfp_t gfp)
-{
- const unsigned int shift = PAGE_SHIFT - ilog2(sizeof(void *));
- struct bucket_table *tbl;
- size_t size;
-
- if (nbuckets < (1 << (shift + 1)))
- return NULL;
-
- size = sizeof(*tbl) + sizeof(tbl->buckets[0]);
-
- tbl = kzalloc(size, gfp);
- if (!tbl)
- return NULL;
-
- if (!nested_table_alloc(ht, (union nested_table __rcu **)tbl->buckets,
- 0, 0)) {
- kfree(tbl);
- return NULL;
- }
-
- tbl->nest = (ilog2(nbuckets) - 1) % shift + 1;
-
- return tbl;
-}
-
static struct bucket_table *bucket_table_alloc(struct rhashtable *ht,
size_t nbuckets,
gfp_t gfp)
tbl = kzalloc(size, gfp | __GFP_NOWARN | __GFP_NORETRY);
if (tbl == NULL && gfp == GFP_KERNEL)
tbl = vzalloc(size);
-
- size = nbuckets;
-
- if (tbl == NULL && gfp != GFP_KERNEL) {
- tbl = nested_bucket_table_alloc(ht, nbuckets, gfp);
- nbuckets = 0;
- }
if (tbl == NULL)
return NULL;
- tbl->size = size;
+ tbl->size = nbuckets;
if (alloc_bucket_locks(ht, tbl, gfp) < 0) {
bucket_table_free(tbl);
struct bucket_table *old_tbl = rht_dereference(ht->tbl, ht);
struct bucket_table *new_tbl = rhashtable_last_table(ht,
rht_dereference_rcu(old_tbl->future_tbl, ht));
- struct rhash_head __rcu **pprev = rht_bucket_var(old_tbl, old_hash);
- int err = -EAGAIN;
+ struct rhash_head __rcu **pprev = &old_tbl->buckets[old_hash];
+ int err = -ENOENT;
struct rhash_head *head, *next, *entry;
spinlock_t *new_bucket_lock;
unsigned int new_hash;
- if (new_tbl->nest)
- goto out;
-
- err = -ENOENT;
-
rht_for_each(entry, old_tbl, old_hash) {
err = 0;
next = rht_dereference_bucket(entry->next, old_tbl, old_hash);
return err;
}
-static int rhashtable_rehash_chain(struct rhashtable *ht,
+static void rhashtable_rehash_chain(struct rhashtable *ht,
unsigned int old_hash)
{
struct bucket_table *old_tbl = rht_dereference(ht->tbl, ht);
spinlock_t *old_bucket_lock;
- int err;
old_bucket_lock = rht_bucket_lock(old_tbl, old_hash);
spin_lock_bh(old_bucket_lock);
- while (!(err = rhashtable_rehash_one(ht, old_hash)))
+ while (!rhashtable_rehash_one(ht, old_hash))
;
-
- if (err == -ENOENT) {
- old_tbl->rehash++;
- err = 0;
- }
+ old_tbl->rehash++;
spin_unlock_bh(old_bucket_lock);
-
- return err;
}
static int rhashtable_rehash_attach(struct rhashtable *ht,
struct bucket_table *new_tbl;
struct rhashtable_walker *walker;
unsigned int old_hash;
- int err;
new_tbl = rht_dereference(old_tbl->future_tbl, ht);
if (!new_tbl)
return 0;
- for (old_hash = 0; old_hash < old_tbl->size; old_hash++) {
- err = rhashtable_rehash_chain(ht, old_hash);
- if (err)
- return err;
- }
+ for (old_hash = 0; old_hash < old_tbl->size; old_hash++)
+ rhashtable_rehash_chain(ht, old_hash);
/* Publish the new table pointer. */
rcu_assign_pointer(ht->tbl, new_tbl);
return rht_dereference(new_tbl->future_tbl, ht) ? -EAGAIN : 0;
}
-static int rhashtable_rehash_alloc(struct rhashtable *ht,
- struct bucket_table *old_tbl,
- unsigned int size)
+/**
+ * rhashtable_expand - Expand hash table while allowing concurrent lookups
+ * @ht: the hash table to expand
+ *
+ * A secondary bucket array is allocated and the hash entries are migrated.
+ *
+ * This function may only be called in a context where it is safe to call
+ * synchronize_rcu(), e.g. not within a rcu_read_lock() section.
+ *
+ * The caller must ensure that no concurrent resizing occurs by holding
+ * ht->mutex.
+ *
+ * It is valid to have concurrent insertions and deletions protected by per
+ * bucket locks or concurrent RCU protected lookups and traversals.
+ */
+static int rhashtable_expand(struct rhashtable *ht)
{
- struct bucket_table *new_tbl;
+ struct bucket_table *new_tbl, *old_tbl = rht_dereference(ht->tbl, ht);
int err;
ASSERT_RHT_MUTEX(ht);
- new_tbl = bucket_table_alloc(ht, size, GFP_KERNEL);
+ old_tbl = rhashtable_last_table(ht, old_tbl);
+
+ new_tbl = bucket_table_alloc(ht, old_tbl->size * 2, GFP_KERNEL);
if (new_tbl == NULL)
return -ENOMEM;
*/
static int rhashtable_shrink(struct rhashtable *ht)
{
- struct bucket_table *old_tbl = rht_dereference(ht->tbl, ht);
+ struct bucket_table *new_tbl, *old_tbl = rht_dereference(ht->tbl, ht);
unsigned int nelems = atomic_read(&ht->nelems);
unsigned int size = 0;
+ int err;
+
+ ASSERT_RHT_MUTEX(ht);
if (nelems)
size = roundup_pow_of_two(nelems * 3 / 2);
if (rht_dereference(old_tbl->future_tbl, ht))
return -EEXIST;
- return rhashtable_rehash_alloc(ht, old_tbl, size);
+ new_tbl = bucket_table_alloc(ht, size, GFP_KERNEL);
+ if (new_tbl == NULL)
+ return -ENOMEM;
+
+ err = rhashtable_rehash_attach(ht, old_tbl, new_tbl);
+ if (err)
+ bucket_table_free(new_tbl);
+
+ return err;
}
static void rht_deferred_worker(struct work_struct *work)
tbl = rhashtable_last_table(ht, tbl);
if (rht_grow_above_75(ht, tbl))
- err = rhashtable_rehash_alloc(ht, tbl, tbl->size * 2);
+ rhashtable_expand(ht);
else if (ht->p.automatic_shrinking && rht_shrink_below_30(ht, tbl))
- err = rhashtable_shrink(ht);
- else if (tbl->nest)
- err = rhashtable_rehash_alloc(ht, tbl, tbl->size);
+ rhashtable_shrink(ht);
- if (!err)
- err = rhashtable_rehash_table(ht);
+ err = rhashtable_rehash_table(ht);
mutex_unlock(&ht->mutex);
int elasticity;
elasticity = ht->elasticity;
- pprev = rht_bucket_var(tbl, hash);
- rht_for_each_continue(head, *pprev, tbl, hash) {
+ pprev = &tbl->buckets[hash];
+ rht_for_each(head, tbl, hash) {
struct rhlist_head *list;
struct rhlist_head *plist;
struct rhash_head *obj,
void *data)
{
- struct rhash_head __rcu **pprev;
struct bucket_table *new_tbl;
struct rhash_head *head;
if (unlikely(rht_grow_above_100(ht, tbl)))
return ERR_PTR(-EAGAIN);
- pprev = rht_bucket_insert(ht, tbl, hash);
- if (!pprev)
- return ERR_PTR(-ENOMEM);
-
- head = rht_dereference_bucket(*pprev, tbl, hash);
+ head = rht_dereference_bucket(tbl->buckets[hash], tbl, hash);
RCU_INIT_POINTER(obj->next, head);
if (ht->rhlist) {
RCU_INIT_POINTER(list->next, NULL);
}
- rcu_assign_pointer(*pprev, obj);
+ rcu_assign_pointer(tbl->buckets[hash], obj);
atomic_inc(&ht->nelems);
if (rht_grow_above_75(ht, tbl))
void (*free_fn)(void *ptr, void *arg),
void *arg)
{
- struct bucket_table *tbl;
+ const struct bucket_table *tbl;
unsigned int i;
cancel_work_sync(&ht->run_work);
for (i = 0; i < tbl->size; i++) {
struct rhash_head *pos, *next;
- for (pos = rht_dereference(*rht_bucket(tbl, i), ht),
+ for (pos = rht_dereference(tbl->buckets[i], ht),
next = !rht_is_a_nulls(pos) ?
rht_dereference(pos->next, ht) : NULL;
!rht_is_a_nulls(pos);
return rhashtable_free_and_destroy(ht, NULL, NULL);
}
EXPORT_SYMBOL_GPL(rhashtable_destroy);
-
-struct rhash_head __rcu **rht_bucket_nested(const struct bucket_table *tbl,
- unsigned int hash)
-{
- const unsigned int shift = PAGE_SHIFT - ilog2(sizeof(void *));
- static struct rhash_head __rcu *rhnull =
- (struct rhash_head __rcu *)NULLS_MARKER(0);
- unsigned int index = hash & ((1 << tbl->nest) - 1);
- unsigned int size = tbl->size >> tbl->nest;
- unsigned int subhash = hash;
- union nested_table *ntbl;
-
- ntbl = (union nested_table *)rcu_dereference_raw(tbl->buckets[0]);
- ntbl = rht_dereference_bucket(ntbl[index].table, tbl, hash);
- subhash >>= tbl->nest;
-
- while (ntbl && size > (1 << shift)) {
- index = subhash & ((1 << shift) - 1);
- ntbl = rht_dereference_bucket(ntbl[index].table, tbl, hash);
- size >>= shift;
- subhash >>= shift;
- }
-
- if (!ntbl)
- return &rhnull;
-
- return &ntbl[subhash].bucket;
-
-}
-EXPORT_SYMBOL_GPL(rht_bucket_nested);
-
-struct rhash_head __rcu **rht_bucket_nested_insert(struct rhashtable *ht,
- struct bucket_table *tbl,
- unsigned int hash)
-{
- const unsigned int shift = PAGE_SHIFT - ilog2(sizeof(void *));
- unsigned int index = hash & ((1 << tbl->nest) - 1);
- unsigned int size = tbl->size >> tbl->nest;
- union nested_table *ntbl;
- unsigned int shifted;
- unsigned int nhash;
-
- ntbl = (union nested_table *)rcu_dereference_raw(tbl->buckets[0]);
- hash >>= tbl->nest;
- nhash = index;
- shifted = tbl->nest;
- ntbl = nested_table_alloc(ht, &ntbl[index].table,
- size <= (1 << shift) ? shifted : 0, nhash);
-
- while (ntbl && size > (1 << shift)) {
- index = hash & ((1 << shift) - 1);
- size >>= shift;
- hash >>= shift;
- nhash |= index << shifted;
- shifted += shift;
- ntbl = nested_table_alloc(ht, &ntbl[index].table,
- size <= (1 << shift) ? shifted : 0,
- nhash);
- }
-
- if (!ntbl)
- return NULL;
-
- return &ntbl[hash].bucket;
-
-}
-EXPORT_SYMBOL_GPL(rht_bucket_nested_insert);
projects / mirror_ubuntu-zesty-kernel.git / blobdiff