diff options
Diffstat (limited to 'include/linux/rhashtable.h')
-rw-r--r-- | include/linux/rhashtable.h | 466 |
1 files changed, 11 insertions, 455 deletions
diff --git a/include/linux/rhashtable.h b/include/linux/rhashtable.h index e5b35edd..f3faea17 100644 --- a/include/linux/rhashtable.h +++ b/include/linux/rhashtable.h @@ -30,44 +30,15 @@ #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; @@ -82,11 +53,6 @@ struct bucket_table { 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; @@ -97,25 +63,6 @@ typedef u32 (*rht_obj_hashfn_t)(const void *data, u32 len, u32 seed); 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; @@ -133,17 +80,6 @@ struct rhashtable_params { 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; @@ -155,32 +91,11 @@ struct rhashtable { 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); @@ -255,11 +170,6 @@ static inline unsigned int rht_head_hashfn( 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) { @@ -268,11 +178,6 @@ static inline bool rht_grow_above_75(const struct rhashtable *ht, (!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) { @@ -281,11 +186,6 @@ static inline bool rht_shrink_below_30(const struct rhashtable *ht, 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) { @@ -293,11 +193,6 @@ static inline bool rht_grow_above_100(const struct rhashtable *ht, (!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) { @@ -305,206 +200,52 @@ static inline bool rht_grow_above_max(const struct rhashtable *ht, 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) @@ -518,17 +259,6 @@ static inline int rhashtable_compare(struct rhashtable_compare_arg *arg, 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) @@ -566,7 +296,6 @@ restart: 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) @@ -658,50 +387,6 @@ out: 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) @@ -714,38 +399,6 @@ static inline int rhashtable_lookup_insert_fast( 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) @@ -778,21 +431,6 @@ static inline int __rhashtable_remove_fast( 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) @@ -827,86 +465,4 @@ out: 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 */ |