#include <linux/spinlock.h>
#include <linux/rcupdate.h>
-/*
- * The end of the chain is marked with a special nulls marks which has
- * the following format:
- *
- * +-------+-----------------------------------------------------+-+
- * | Base | Hash |1|
- * +-------+-----------------------------------------------------+-+
- *
- * Base (4 bits) : Reserved to distinguish between multiple tables.
- * Specified via &struct rhashtable_params.nulls_base.
- * Hash (27 bits): Full hash (unmasked) of first element added to bucket
- * 1 (1 bit) : Nulls marker (always set)
- *
- * The remaining bits of the next pointer remain unused for now.
- */
#define RHT_BASE_BITS 4
#define RHT_HASH_BITS 27
#define RHT_BASE_SHIFT RHT_HASH_BITS
-
-/* Base bits plus 1 bit for nulls marker */
#define RHT_HASH_RESERVED_SPACE (RHT_BASE_BITS + 1)
struct rhash_head {
struct rhash_head __rcu *next;
};
-/**
- * struct bucket_table - Table of hash buckets
- * @size: Number of hash buckets
- * @rehash: Current bucket being rehashed
- * @hash_rnd: Random seed to fold into hash
- * @locks_mask: Mask to apply before accessing locks[]
- * @locks: Array of spinlocks protecting individual buckets
- * @walkers: List of active walkers
- * @rcu: RCU structure for freeing the table
- * @future_tbl: Table under construction during rehashing
- * @buckets: size * hash buckets
- */
struct bucket_table {
unsigned int size;
unsigned int rehash;
struct rhash_head __rcu *buckets[] ____cacheline_aligned_in_smp;
};
-/**
- * struct rhashtable_compare_arg - Key for the function rhashtable_compare
- * @ht: Hash table
- * @key: Key to compare against
- */
struct rhashtable_compare_arg {
struct rhashtable *ht;
const void *key;
typedef int (*rht_obj_cmpfn_t)(struct rhashtable_compare_arg *arg,
const void *obj);
-struct rhashtable;
-
-/**
- * struct rhashtable_params - Hash table construction parameters
- * @nelem_hint: Hint on number of elements, should be 75% of desired size
- * @key_len: Length of key
- * @key_offset: Offset of key in struct to be hashed
- * @head_offset: Offset of rhash_head in struct to be hashed
- * @insecure_max_entries: Maximum number of entries (may be exceeded)
- * @max_size: Maximum size while expanding
- * @min_size: Minimum size while shrinking
- * @nulls_base: Base value to generate nulls marker
- * @insecure_elasticity: Set to true to disable chain length checks
- * @automatic_shrinking: Enable automatic shrinking of tables
- * @locks_mul: Number of bucket locks to allocate per cpu (default: 128)
- * @hashfn: Hash function (default: jhash2 if !(key_len % 4), or jhash)
- * @obj_hashfn: Function to hash object
- * @obj_cmpfn: Function to compare key with object
- */
struct rhashtable_params {
size_t nelem_hint;
size_t key_len;
rht_obj_cmpfn_t obj_cmpfn;
};
-/**
- * struct rhashtable - Hash table handle
- * @tbl: Bucket table
- * @nelems: Number of elements in table
- * @key_len: Key length for hashfn
- * @elasticity: Maximum chain length before rehash
- * @p: Configuration parameters
- * @run_work: Deferred worker to expand/shrink asynchronously
- * @mutex: Mutex to protect current/future table swapping
- * @lock: Spin lock to protect walker list
- */
struct rhashtable {
struct bucket_table __rcu *tbl;
atomic_t nelems;
spinlock_t lock;
};
-/**
- * struct rhashtable_walker - Hash table walker
- * @list: List entry on list of walkers
- * @tbl: The table that we were walking over
- */
struct rhashtable_walker {
struct list_head list;
struct bucket_table *tbl;
};
-/**
- * struct rhashtable_iter - Hash table iterator, fits into netlink cb
- * @ht: Table to iterate through
- * @p: Current pointer
- * @walker: Associated rhashtable walker
- * @slot: Current slot
- * @skip: Number of entries to skip in slot
- */
-struct rhashtable_iter {
- struct rhashtable *ht;
- struct rhash_head *p;
- struct rhashtable_walker *walker;
- unsigned int slot;
- unsigned int skip;
-};
-
static inline unsigned long rht_marker(const struct rhashtable *ht, u32 hash)
{
return NULLS_MARKER(ht->p.nulls_base + hash);
rht_key_hashfn(ht, tbl, ptr + params.key_offset, params);
}
-/**
- * rht_grow_above_75 - returns true if nelems > 0.75 * table-size
- * @ht: hash table
- * @tbl: current table
- */
static inline bool rht_grow_above_75(const struct rhashtable *ht,
const struct bucket_table *tbl)
{
(!ht->p.max_size || tbl->size < ht->p.max_size);
}
-/**
- * rht_shrink_below_30 - returns true if nelems < 0.3 * table-size
- * @ht: hash table
- * @tbl: current table
- */
static inline bool rht_shrink_below_30(const struct rhashtable *ht,
const struct bucket_table *tbl)
{
tbl->size > ht->p.min_size;
}
-/**
- * rht_grow_above_100 - returns true if nelems > table-size
- * @ht: hash table
- * @tbl: current table
- */
static inline bool rht_grow_above_100(const struct rhashtable *ht,
const struct bucket_table *tbl)
{
(!ht->p.max_size || tbl->size < ht->p.max_size);
}
-/**
- * rht_grow_above_max - returns true if table is above maximum
- * @ht: hash table
- * @tbl: current table
- */
static inline bool rht_grow_above_max(const struct rhashtable *ht,
const struct bucket_table *tbl)
{
atomic_read(&ht->nelems) >= ht->p.insecure_max_entries;
}
-/* The bucket lock is selected based on the hash and protects mutations
- * on a group of hash buckets.
- *
- * A maximum of tbl->size/2 bucket locks is allocated. This ensures that
- * a single lock always covers both buckets which may both contains
- * entries which link to the same bucket of the old table during resizing.
- * This allows to simplify the locking as locking the bucket in both
- * tables during resize always guarantee protection.
- *
- * IMPORTANT: When holding the bucket lock of both the old and new table
- * during expansions and shrinking, the old bucket lock must always be
- * acquired first.
- */
static inline spinlock_t *rht_bucket_lock(const struct bucket_table *tbl,
unsigned int hash)
{
return &tbl->locks[hash & tbl->locks_mask];
}
-#ifdef CONFIG_PROVE_LOCKING
-int lockdep_rht_mutex_is_held(struct rhashtable *ht);
-int lockdep_rht_bucket_is_held(const struct bucket_table *tbl, u32 hash);
-#else
-static inline int lockdep_rht_mutex_is_held(struct rhashtable *ht)
-{
- return 1;
-}
-
-static inline int lockdep_rht_bucket_is_held(const struct bucket_table *tbl,
- u32 hash)
-{
- return 1;
-}
-#endif /* CONFIG_PROVE_LOCKING */
+int rhashtable_insert_rehash(struct rhashtable *, struct bucket_table *);
+struct bucket_table *rhashtable_insert_slow(struct rhashtable *,
+ const void *,
+ struct rhash_head *,
+ struct bucket_table *);
-int rhashtable_init(struct rhashtable *ht,
- const struct rhashtable_params *params);
+int rhashtable_init(struct rhashtable *, const struct rhashtable_params *);
+void rhashtable_destroy(struct rhashtable *);
-struct bucket_table *rhashtable_insert_slow(struct rhashtable *ht,
- const void *key,
- struct rhash_head *obj,
- struct bucket_table *old_tbl);
-int rhashtable_insert_rehash(struct rhashtable *ht, struct bucket_table *tbl);
-
-int rhashtable_walk_init(struct rhashtable *ht, struct rhashtable_iter *iter,
- gfp_t gfp);
-void rhashtable_walk_exit(struct rhashtable_iter *iter);
-int rhashtable_walk_start(struct rhashtable_iter *iter) __acquires(RCU);
-void *rhashtable_walk_next(struct rhashtable_iter *iter);
-void rhashtable_walk_stop(struct rhashtable_iter *iter) __releases(RCU);
-
-void rhashtable_free_and_destroy(struct rhashtable *ht,
- void (*free_fn)(void *ptr, void *arg),
- void *arg);
-void rhashtable_destroy(struct rhashtable *ht);
-
-#define rht_dereference(p, ht) \
- rcu_dereference_protected(p, lockdep_rht_mutex_is_held(ht))
-
-#define rht_dereference_rcu(p, ht) \
- rcu_dereference_check(p, lockdep_rht_mutex_is_held(ht))
-
-#define rht_dereference_bucket(p, tbl, hash) \
- rcu_dereference_protected(p, lockdep_rht_bucket_is_held(tbl, hash))
-
-#define rht_dereference_bucket_rcu(p, tbl, hash) \
- rcu_dereference_check(p, lockdep_rht_bucket_is_held(tbl, hash))
+#define rht_dereference(p, ht) rcu_dereference(p)
+#define rht_dereference_rcu(p, ht) rcu_dereference(p)
+#define rht_dereference_bucket(p, tbl, hash) rcu_dereference(p)
+#define rht_dereference_bucket_rcu(p, tbl, hash) rcu_dereference(p)
#define rht_entry(tpos, pos, member) \
({ tpos = container_of(pos, typeof(*tpos), member); 1; })
-/**
- * rht_for_each_continue - continue iterating over hash chain
- * @pos: the &struct rhash_head to use as a loop cursor.
- * @head: the previous &struct rhash_head to continue from
- * @tbl: the &struct bucket_table
- * @hash: the hash value / bucket index
- */
#define rht_for_each_continue(pos, head, tbl, hash) \
for (pos = rht_dereference_bucket(head, tbl, hash); \
!rht_is_a_nulls(pos); \
pos = rht_dereference_bucket((pos)->next, tbl, hash))
-/**
- * rht_for_each - iterate over hash chain
- * @pos: the &struct rhash_head to use as a loop cursor.
- * @tbl: the &struct bucket_table
- * @hash: the hash value / bucket index
- */
#define rht_for_each(pos, tbl, hash) \
rht_for_each_continue(pos, (tbl)->buckets[hash], tbl, hash)
-/**
- * rht_for_each_entry_continue - continue iterating over hash chain
- * @tpos: the type * to use as a loop cursor.
- * @pos: the &struct rhash_head to use as a loop cursor.
- * @head: the previous &struct rhash_head to continue from
- * @tbl: the &struct bucket_table
- * @hash: the hash value / bucket index
- * @member: name of the &struct rhash_head within the hashable struct.
- */
-#define rht_for_each_entry_continue(tpos, pos, head, tbl, hash, member) \
- for (pos = rht_dereference_bucket(head, tbl, hash); \
- (!rht_is_a_nulls(pos)) && rht_entry(tpos, pos, member); \
- pos = rht_dereference_bucket((pos)->next, tbl, hash))
-
-/**
- * rht_for_each_entry - iterate over hash chain of given type
- * @tpos: the type * to use as a loop cursor.
- * @pos: the &struct rhash_head to use as a loop cursor.
- * @tbl: the &struct bucket_table
- * @hash: the hash value / bucket index
- * @member: name of the &struct rhash_head within the hashable struct.
- */
-#define rht_for_each_entry(tpos, pos, tbl, hash, member) \
- rht_for_each_entry_continue(tpos, pos, (tbl)->buckets[hash], \
- tbl, hash, member)
-
-/**
- * rht_for_each_entry_safe - safely iterate over hash chain of given type
- * @tpos: the type * to use as a loop cursor.
- * @pos: the &struct rhash_head to use as a loop cursor.
- * @next: the &struct rhash_head to use as next in loop cursor.
- * @tbl: the &struct bucket_table
- * @hash: the hash value / bucket index
- * @member: name of the &struct rhash_head within the hashable struct.
- *
- * This hash chain list-traversal primitive allows for the looped code to
- * remove the loop cursor from the list.
- */
-#define rht_for_each_entry_safe(tpos, pos, next, tbl, hash, member) \
- for (pos = rht_dereference_bucket((tbl)->buckets[hash], tbl, hash), \
- next = !rht_is_a_nulls(pos) ? \
- rht_dereference_bucket(pos->next, tbl, hash) : NULL; \
- (!rht_is_a_nulls(pos)) && rht_entry(tpos, pos, member); \
- pos = next, \
- next = !rht_is_a_nulls(pos) ? \
- rht_dereference_bucket(pos->next, tbl, hash) : NULL)
-
-/**
- * rht_for_each_rcu_continue - continue iterating over rcu hash chain
- * @pos: the &struct rhash_head to use as a loop cursor.
- * @head: the previous &struct rhash_head to continue from
- * @tbl: the &struct bucket_table
- * @hash: the hash value / bucket index
- *
- * This hash chain list-traversal primitive may safely run concurrently with
- * the _rcu mutation primitives such as rhashtable_insert() as long as the
- * traversal is guarded by rcu_read_lock().
- */
#define rht_for_each_rcu_continue(pos, head, tbl, hash) \
for (({barrier(); }), \
pos = rht_dereference_bucket_rcu(head, tbl, hash); \
!rht_is_a_nulls(pos); \
pos = rcu_dereference_raw(pos->next))
-/**
- * rht_for_each_rcu - iterate over rcu hash chain
- * @pos: the &struct rhash_head to use as a loop cursor.
- * @tbl: the &struct bucket_table
- * @hash: the hash value / bucket index
- *
- * This hash chain list-traversal primitive may safely run concurrently with
- * the _rcu mutation primitives such as rhashtable_insert() as long as the
- * traversal is guarded by rcu_read_lock().
- */
#define rht_for_each_rcu(pos, tbl, hash) \
rht_for_each_rcu_continue(pos, (tbl)->buckets[hash], tbl, hash)
-/**
- * rht_for_each_entry_rcu_continue - continue iterating over rcu hash chain
- * @tpos: the type * to use as a loop cursor.
- * @pos: the &struct rhash_head to use as a loop cursor.
- * @head: the previous &struct rhash_head to continue from
- * @tbl: the &struct bucket_table
- * @hash: the hash value / bucket index
- * @member: name of the &struct rhash_head within the hashable struct.
- *
- * This hash chain list-traversal primitive may safely run concurrently with
- * the _rcu mutation primitives such as rhashtable_insert() as long as the
- * traversal is guarded by rcu_read_lock().
- */
#define rht_for_each_entry_rcu_continue(tpos, pos, head, tbl, hash, member) \
for (({barrier(); }), \
pos = rht_dereference_bucket_rcu(head, tbl, hash); \
(!rht_is_a_nulls(pos)) && rht_entry(tpos, pos, member); \
pos = rht_dereference_bucket_rcu(pos->next, tbl, hash))
-/**
- * rht_for_each_entry_rcu - iterate over rcu hash chain of given type
- * @tpos: the type * to use as a loop cursor.
- * @pos: the &struct rhash_head to use as a loop cursor.
- * @tbl: the &struct bucket_table
- * @hash: the hash value / bucket index
- * @member: name of the &struct rhash_head within the hashable struct.
- *
- * This hash chain list-traversal primitive may safely run concurrently with
- * the _rcu mutation primitives such as rhashtable_insert() as long as the
- * traversal is guarded by rcu_read_lock().
- */
#define rht_for_each_entry_rcu(tpos, pos, tbl, hash, member) \
rht_for_each_entry_rcu_continue(tpos, pos, (tbl)->buckets[hash],\
tbl, hash, member)
return memcmp(ptr + ht->p.key_offset, arg->key, ht->p.key_len);
}
-/**
- * rhashtable_lookup_fast - search hash table, inlined version
- * @ht: hash table
- * @key: the pointer to the key
- * @params: hash table parameters
- *
- * Computes the hash value for the key and traverses the bucket chain looking
- * for a entry with an identical key. The first matching entry is returned.
- *
- * Returns the first entry on which the compare function returned true.
- */
static inline void *rhashtable_lookup_fast(
struct rhashtable *ht, const void *key,
const struct rhashtable_params params)
return NULL;
}
-/* Internal function, please use rhashtable_insert_fast() instead */
static inline int __rhashtable_insert_fast(
struct rhashtable *ht, const void *key, struct rhash_head *obj,
const struct rhashtable_params params)
return err;
}
-/**
- * rhashtable_insert_fast - insert object into hash table
- * @ht: hash table
- * @obj: pointer to hash head inside object
- * @params: hash table parameters
- *
- * Will take a per bucket spinlock to protect against mutual mutations
- * on the same bucket. Multiple insertions may occur in parallel unless
- * they map to the same bucket lock.
- *
- * It is safe to call this function from atomic context.
- *
- * Will trigger an automatic deferred table resizing if the size grows
- * beyond the watermark indicated by grow_decision() which can be passed
- * to rhashtable_init().
- */
-static inline int rhashtable_insert_fast(
- struct rhashtable *ht, struct rhash_head *obj,
- const struct rhashtable_params params)
-{
- return __rhashtable_insert_fast(ht, NULL, obj, params);
-}
-
-/**
- * rhashtable_lookup_insert_fast - lookup and insert object into hash table
- * @ht: hash table
- * @obj: pointer to hash head inside object
- * @params: hash table parameters
- *
- * Locks down the bucket chain in both the old and new table if a resize
- * is in progress to ensure that writers can't remove from the old table
- * and can't insert to the new table during the atomic operation of search
- * and insertion. Searches for duplicates in both the old and new table if
- * a resize is in progress.
- *
- * This lookup function may only be used for fixed key hash table (key_len
- * parameter set). It will BUG() if used inappropriately.
- *
- * It is safe to call this function from atomic context.
- *
- * Will trigger an automatic deferred table resizing if the size grows
- * beyond the watermark indicated by grow_decision() which can be passed
- * to rhashtable_init().
- */
static inline int rhashtable_lookup_insert_fast(
struct rhashtable *ht, struct rhash_head *obj,
const struct rhashtable_params params)
params);
}
-/**
- * rhashtable_lookup_insert_key - search and insert object to hash table
- * with explicit key
- * @ht: hash table
- * @key: key
- * @obj: pointer to hash head inside object
- * @params: hash table parameters
- *
- * Locks down the bucket chain in both the old and new table if a resize
- * is in progress to ensure that writers can't remove from the old table
- * and can't insert to the new table during the atomic operation of search
- * and insertion. Searches for duplicates in both the old and new table if
- * a resize is in progress.
- *
- * Lookups may occur in parallel with hashtable mutations and resizing.
- *
- * Will trigger an automatic deferred table resizing if the size grows
- * beyond the watermark indicated by grow_decision() which can be passed
- * to rhashtable_init().
- *
- * Returns zero on success.
- */
-static inline int rhashtable_lookup_insert_key(
- struct rhashtable *ht, const void *key, struct rhash_head *obj,
- const struct rhashtable_params params)
-{
- BUG_ON(!ht->p.obj_hashfn || !key);
-
- return __rhashtable_insert_fast(ht, key, obj, params);
-}
-
-/* Internal function, please use rhashtable_remove_fast() instead */
static inline int __rhashtable_remove_fast(
struct rhashtable *ht, struct bucket_table *tbl,
struct rhash_head *obj, const struct rhashtable_params params)
return err;
}
-/**
- * rhashtable_remove_fast - remove object from hash table
- * @ht: hash table
- * @obj: pointer to hash head inside object
- * @params: hash table parameters
- *
- * Since the hash chain is single linked, the removal operation needs to
- * walk the bucket chain upon removal. The removal operation is thus
- * considerable slow if the hash table is not correctly sized.
- *
- * Will automatically shrink the table via rhashtable_expand() if the
- * shrink_decision function specified at rhashtable_init() returns true.
- *
- * Returns zero on success, -ENOENT if the entry could not be found.
- */
static inline int rhashtable_remove_fast(
struct rhashtable *ht, struct rhash_head *obj,
const struct rhashtable_params params)
return err;
}
-/* Internal function, please use rhashtable_replace_fast() instead */
-static inline int __rhashtable_replace_fast(
- struct rhashtable *ht, struct bucket_table *tbl,
- struct rhash_head *obj_old, struct rhash_head *obj_new,
- const struct rhashtable_params params)
-{
- struct rhash_head __rcu **pprev;
- struct rhash_head *he;
- spinlock_t *lock;
- unsigned int hash;
- int err = -ENOENT;
-
- /* Minimally, the old and new objects must have same hash
- * (which should mean identifiers are the same).
- */
- hash = rht_head_hashfn(ht, tbl, obj_old, params);
- if (hash != rht_head_hashfn(ht, tbl, obj_new, params))
- return -EINVAL;
-
- lock = rht_bucket_lock(tbl, hash);
-
- spin_lock_bh(lock);
-
- pprev = &tbl->buckets[hash];
- rht_for_each(he, tbl, hash) {
- if (he != obj_old) {
- pprev = &he->next;
- continue;
- }
-
- rcu_assign_pointer(obj_new->next, obj_old->next);
- rcu_assign_pointer(*pprev, obj_new);
- err = 0;
- break;
- }
-
- spin_unlock_bh(lock);
-
- return err;
-}
-
-/**
- * rhashtable_replace_fast - replace an object in hash table
- * @ht: hash table
- * @obj_old: pointer to hash head inside object being replaced
- * @obj_new: pointer to hash head inside object which is new
- * @params: hash table parameters
- *
- * Replacing an object doesn't affect the number of elements in the hash table
- * or bucket, so we don't need to worry about shrinking or expanding the
- * table here.
- *
- * Returns zero on success, -ENOENT if the entry could not be found,
- * -EINVAL if hash is not the same for the old and new objects.
- */
-static inline int rhashtable_replace_fast(
- struct rhashtable *ht, struct rhash_head *obj_old,
- struct rhash_head *obj_new,
- const struct rhashtable_params params)
-{
- struct bucket_table *tbl;
- int err;
-
- rcu_read_lock();
-
- tbl = rht_dereference_rcu(ht->tbl, ht);
-
- /* Because we have already taken (and released) the bucket
- * lock in old_tbl, if we find that future_tbl is not yet
- * visible then that guarantees the entry to still be in
- * the old tbl if it exists.
- */
- while ((err = __rhashtable_replace_fast(ht, tbl, obj_old,
- obj_new, params)) &&
- (tbl = rht_dereference_rcu(tbl->future_tbl, ht)))
- ;
-
- rcu_read_unlock();
-
- return err;
-}
-
#endif /* _LINUX_RHASHTABLE_H */
projects / bcachefs-tools-debian / blobdiff