From 488fb86ee91d3b1182c2e30a9f9b45da14eda46f Mon Sep 17 00:00:00 2001 From: Herbert Xu Date: Fri, 20 Mar 2015 21:56:59 +1100 Subject: rhashtable: Make rhashtable_init params argument const This patch marks the rhashtable_init params argument const as there is no reason to modify it since we will always make a copy of it in the rhashtable. This patch also fixes a bug where we don't actually round up the value of min_size unless it is less than HASH_MIN_SIZE. Signed-off-by: Herbert Xu Acked-by: Thomas Graf Signed-off-by: David S. Miller --- lib/rhashtable.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) (limited to 'lib') diff --git a/lib/rhashtable.c b/lib/rhashtable.c index e75c48d9d82f..e0a9d59f80d6 100644 --- a/lib/rhashtable.c +++ b/lib/rhashtable.c @@ -870,7 +870,7 @@ out: } EXPORT_SYMBOL_GPL(rhashtable_walk_stop); -static size_t rounded_hashtable_size(struct rhashtable_params *params) +static size_t rounded_hashtable_size(const struct rhashtable_params *params) { return max(roundup_pow_of_two(params->nelem_hint * 4 / 3), (unsigned long)params->min_size); @@ -919,7 +919,8 @@ static size_t rounded_hashtable_size(struct rhashtable_params *params) * .obj_hashfn = my_hash_fn, * }; */ -int rhashtable_init(struct rhashtable *ht, struct rhashtable_params *params) +int rhashtable_init(struct rhashtable *ht, + const struct rhashtable_params *params) { struct bucket_table *tbl; size_t size; @@ -946,7 +947,7 @@ int rhashtable_init(struct rhashtable *ht, struct rhashtable_params *params) if (params->max_size) ht->p.max_size = rounddown_pow_of_two(params->max_size); - ht->p.min_size = max(params->min_size, HASH_MIN_SIZE); + ht->p.min_size = max(ht->p.min_size, HASH_MIN_SIZE); if (params->locks_mul) ht->p.locks_mul = roundup_pow_of_two(params->locks_mul); -- cgit From 02fd97c3d4a8a14e222b0021c366db7041d28743 Mon Sep 17 00:00:00 2001 From: Herbert Xu Date: Fri, 20 Mar 2015 21:57:00 +1100 Subject: rhashtable: Allow hash/comparison functions to be inlined This patch deals with the complaint that we make indirect function calls on the fast paths unnecessarily in rhashtable. We resolve it by moving the fast paths into inline functions that take struct rhashtable_param (which obviously must be the same set of parameters supplied to rhashtable_init) as an argument. The only remaining indirect call is to obj_hashfn (or key_hashfn it obj_hashfn is unset) on the rehash as well as the insert-during- rehash slow path. This patch also extends the support of vairable-length keys to include those where the key is fixed but scattered in the object. For example, in netlink we want to key off the namespace and the portid but they're not next to each other. This patch does this by directly using the object hash function as the indicator of whether the key is accessible or not. It also adds a new function obj_cmpfn to compare a key against an object. This means that the caller no longer needs to supply explicit compare functions. All this is done in a backwards compatible manner so no existing users are affected until they convert to the new interface. Signed-off-by: Herbert Xu Signed-off-by: David S. Miller --- lib/rhashtable.c | 163 +++++++++++++++++-------------------------------------- 1 file changed, 50 insertions(+), 113 deletions(-) (limited to 'lib') diff --git a/lib/rhashtable.c b/lib/rhashtable.c index e0a9d59f80d6..d1d23fb58525 100644 --- a/lib/rhashtable.c +++ b/lib/rhashtable.c @@ -1,13 +1,13 @@ /* * Resizable, Scalable, Concurrent Hash Table * + * Copyright (c) 2015 Herbert Xu * Copyright (c) 2014-2015 Thomas Graf * Copyright (c) 2008-2014 Patrick McHardy * - * Based on the following paper: - * https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf - * * Code partially derived from nft_hash + * Rewritten with rehash code from br_multicast plus single list + * pointer as suggested by Josh Triplett * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as @@ -30,53 +30,11 @@ #define HASH_MIN_SIZE 4U #define BUCKET_LOCKS_PER_CPU 128UL -/* Base bits plus 1 bit for nulls marker */ -#define HASH_RESERVED_SPACE (RHT_BASE_BITS + 1) - -/* 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 spinlock_t *bucket_lock(const struct bucket_table *tbl, u32 hash) -{ - return &tbl->locks[hash & tbl->locks_mask]; -} - -static void *rht_obj(const struct rhashtable *ht, const struct rhash_head *he) -{ - return (void *) he - ht->p.head_offset; -} - -static u32 rht_bucket_index(const struct bucket_table *tbl, u32 hash) -{ - return (hash >> HASH_RESERVED_SPACE) & (tbl->size - 1); -} - -static u32 key_hashfn(struct rhashtable *ht, const struct bucket_table *tbl, - const void *key) -{ - return rht_bucket_index(tbl, ht->p.hashfn(key, ht->p.key_len, - tbl->hash_rnd)); -} - static u32 head_hashfn(struct rhashtable *ht, const struct bucket_table *tbl, const struct rhash_head *he) { - const char *ptr = rht_obj(ht, he); - - return likely(ht->p.key_len) ? - key_hashfn(ht, tbl, ptr + ht->p.key_offset) : - rht_bucket_index(tbl, ht->p.obj_hashfn(ptr, tbl->hash_rnd)); + return rht_head_hashfn(ht, tbl, he, ht->p); } #ifdef CONFIG_PROVE_LOCKING @@ -90,7 +48,7 @@ EXPORT_SYMBOL_GPL(lockdep_rht_mutex_is_held); int lockdep_rht_bucket_is_held(const struct bucket_table *tbl, u32 hash) { - spinlock_t *lock = bucket_lock(tbl, hash); + spinlock_t *lock = rht_bucket_lock(tbl, hash); return (debug_locks) ? lockdep_is_held(lock) : 1; } @@ -178,32 +136,6 @@ static struct bucket_table *bucket_table_alloc(struct rhashtable *ht, return tbl; } -/** - * rht_grow_above_75 - returns true if nelems > 0.75 * table-size - * @ht: hash table - * @tbl: current table - */ -static bool rht_grow_above_75(const struct rhashtable *ht, - const struct bucket_table *tbl) -{ - /* Expand table when exceeding 75% load */ - return atomic_read(&ht->nelems) > (tbl->size / 4 * 3) && - (!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 bool rht_shrink_below_30(const struct rhashtable *ht, - const struct bucket_table *tbl) -{ - /* Shrink table beneath 30% load */ - return atomic_read(&ht->nelems) < (tbl->size * 3 / 10) && - tbl->size > ht->p.min_size; -} - static int rhashtable_rehash_one(struct rhashtable *ht, unsigned old_hash) { struct bucket_table *old_tbl = rht_dereference(ht->tbl, ht); @@ -230,7 +162,7 @@ static int rhashtable_rehash_one(struct rhashtable *ht, unsigned old_hash) new_hash = head_hashfn(ht, new_tbl, entry); - new_bucket_lock = bucket_lock(new_tbl, new_hash); + new_bucket_lock = rht_bucket_lock(new_tbl, new_hash); spin_lock_nested(new_bucket_lock, SINGLE_DEPTH_NESTING); head = rht_dereference_bucket(new_tbl->buckets[new_hash], @@ -255,7 +187,7 @@ static void rhashtable_rehash_chain(struct rhashtable *ht, unsigned old_hash) struct bucket_table *old_tbl = rht_dereference(ht->tbl, ht); spinlock_t *old_bucket_lock; - old_bucket_lock = bucket_lock(old_tbl, old_hash); + old_bucket_lock = rht_bucket_lock(old_tbl, old_hash); spin_lock_bh(old_bucket_lock); while (!rhashtable_rehash_one(ht, old_hash)) @@ -376,6 +308,37 @@ unlock: mutex_unlock(&ht->mutex); } +int rhashtable_insert_slow(struct rhashtable *ht, const void *key, + struct rhash_head *obj, + struct bucket_table *tbl) +{ + struct rhash_head *head; + unsigned hash; + int err = -EEXIST; + + hash = head_hashfn(ht, tbl, obj); + spin_lock_nested(rht_bucket_lock(tbl, hash), SINGLE_DEPTH_NESTING); + + if (key && rhashtable_lookup_fast(ht, key, ht->p)) + goto exit; + + err = 0; + + head = rht_dereference_bucket(tbl->buckets[hash], tbl, hash); + + RCU_INIT_POINTER(obj->next, head); + + rcu_assign_pointer(tbl->buckets[hash], obj); + + atomic_inc(&ht->nelems); + +exit: + spin_unlock(rht_bucket_lock(tbl, hash)); + + return err; +} +EXPORT_SYMBOL_GPL(rhashtable_insert_slow); + static bool __rhashtable_insert(struct rhashtable *ht, struct rhash_head *obj, bool (*compare)(void *, void *), void *arg) { @@ -390,7 +353,7 @@ static bool __rhashtable_insert(struct rhashtable *ht, struct rhash_head *obj, old_tbl = rht_dereference_rcu(ht->tbl, ht); hash = head_hashfn(ht, old_tbl, obj); - old_lock = bucket_lock(old_tbl, hash); + old_lock = rht_bucket_lock(old_tbl, hash); spin_lock_bh(old_lock); @@ -403,7 +366,8 @@ static bool __rhashtable_insert(struct rhashtable *ht, struct rhash_head *obj, tbl = rht_dereference_rcu(old_tbl->future_tbl, ht) ?: old_tbl; if (tbl != old_tbl) { hash = head_hashfn(ht, tbl, obj); - spin_lock_nested(bucket_lock(tbl, hash), SINGLE_DEPTH_NESTING); + spin_lock_nested(rht_bucket_lock(tbl, hash), + SINGLE_DEPTH_NESTING); } if (compare && @@ -430,7 +394,7 @@ static bool __rhashtable_insert(struct rhashtable *ht, struct rhash_head *obj, exit: if (tbl != old_tbl) - spin_unlock(bucket_lock(tbl, hash)); + spin_unlock(rht_bucket_lock(tbl, hash)); spin_unlock_bh(old_lock); @@ -471,7 +435,7 @@ static bool __rhashtable_remove(struct rhashtable *ht, bool ret = false; hash = head_hashfn(ht, tbl, obj); - lock = bucket_lock(tbl, hash); + lock = rht_bucket_lock(tbl, hash); spin_lock_bh(lock); @@ -537,19 +501,6 @@ bool rhashtable_remove(struct rhashtable *ht, struct rhash_head *obj) } EXPORT_SYMBOL_GPL(rhashtable_remove); -struct rhashtable_compare_arg { - struct rhashtable *ht; - const void *key; -}; - -static bool rhashtable_compare(void *ptr, void *arg) -{ - struct rhashtable_compare_arg *x = arg; - struct rhashtable *ht = x->ht; - - return !memcmp(ptr + ht->p.key_offset, x->key, ht->p.key_len); -} - /** * rhashtable_lookup - lookup key in hash table * @ht: hash table @@ -565,14 +516,7 @@ static bool rhashtable_compare(void *ptr, void *arg) */ void *rhashtable_lookup(struct rhashtable *ht, const void *key) { - struct rhashtable_compare_arg arg = { - .ht = ht, - .key = key, - }; - - BUG_ON(!ht->p.key_len); - - return rhashtable_lookup_compare(ht, key, &rhashtable_compare, &arg); + return rhashtable_lookup_fast(ht, key, ht->p); } EXPORT_SYMBOL_GPL(rhashtable_lookup); @@ -591,7 +535,8 @@ EXPORT_SYMBOL_GPL(rhashtable_lookup); * Returns the first entry on which the compare function returned true. */ void *rhashtable_lookup_compare(struct rhashtable *ht, const void *key, - bool (*compare)(void *, void *), void *arg) + bool (*compare)(void *, void *), + void *arg) { const struct bucket_table *tbl; struct rhash_head *he; @@ -601,7 +546,7 @@ void *rhashtable_lookup_compare(struct rhashtable *ht, const void *key, tbl = rht_dereference_rcu(ht->tbl, ht); restart: - hash = key_hashfn(ht, tbl, key); + hash = rht_key_hashfn(ht, tbl, key, ht->p); rht_for_each_rcu(he, tbl, hash) { if (!compare(rht_obj(ht, he), arg)) continue; @@ -643,15 +588,7 @@ EXPORT_SYMBOL_GPL(rhashtable_lookup_compare); */ bool rhashtable_lookup_insert(struct rhashtable *ht, struct rhash_head *obj) { - struct rhashtable_compare_arg arg = { - .ht = ht, - .key = rht_obj(ht, obj) + ht->p.key_offset, - }; - - BUG_ON(!ht->p.key_len); - - return rhashtable_lookup_compare_insert(ht, obj, &rhashtable_compare, - &arg); + return rhashtable_lookup_insert_fast(ht, obj, ht->p); } EXPORT_SYMBOL_GPL(rhashtable_lookup_insert); @@ -927,8 +864,8 @@ int rhashtable_init(struct rhashtable *ht, size = HASH_DEFAULT_SIZE; - if ((params->key_len && !params->hashfn) || - (!params->key_len && !params->obj_hashfn)) + if ((!(params->key_len && params->hashfn) && !params->obj_hashfn) || + (params->obj_hashfn && !params->obj_cmpfn)) return -EINVAL; if (params->nulls_base && params->nulls_base < (1U << RHT_BASE_SHIFT)) -- cgit From b182aa6e967e8272a3ba718a89697f661915be7a Mon Sep 17 00:00:00 2001 From: Herbert Xu Date: Fri, 20 Mar 2015 21:57:04 +1100 Subject: test_rhashtable: Use inlined rhashtable interface This patch converts test_rhashtable to the inlined rhashtable interface. Signed-off-by: Herbert Xu Signed-off-by: David S. Miller --- lib/test_rhashtable.c | 33 +++++++++++++++++++-------------- 1 file changed, 19 insertions(+), 14 deletions(-) (limited to 'lib') diff --git a/lib/test_rhashtable.c b/lib/test_rhashtable.c index 2bc403d8f9ee..a2ba6adb60a2 100644 --- a/lib/test_rhashtable.c +++ b/lib/test_rhashtable.c @@ -38,6 +38,16 @@ struct test_obj { struct rhash_head node; }; +static const struct rhashtable_params test_rht_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, + .max_size = 2, /* we expand/shrink manually here */ + .nulls_base = (3U << RHT_BASE_SHIFT), +}; + static int __init test_rht_lookup(struct rhashtable *ht) { unsigned int i; @@ -47,7 +57,7 @@ static int __init test_rht_lookup(struct rhashtable *ht) bool expected = !(i % 2); u32 key = i; - obj = rhashtable_lookup(ht, &key); + obj = rhashtable_lookup_fast(ht, &key, test_rht_params); if (expected && !obj) { pr_warn("Test failed: Could not find key %u\n", key); @@ -133,7 +143,11 @@ static int __init test_rhashtable(struct rhashtable *ht) obj->ptr = TEST_PTR; obj->value = i * 2; - rhashtable_insert(ht, &obj->node); + err = rhashtable_insert_fast(ht, &obj->node, test_rht_params); + if (err) { + kfree(obj); + goto error; + } } rcu_read_lock(); @@ -173,10 +187,10 @@ static int __init test_rhashtable(struct rhashtable *ht) for (i = 0; i < TEST_ENTRIES; i++) { u32 key = i * 2; - obj = rhashtable_lookup(ht, &key); + obj = rhashtable_lookup_fast(ht, &key, test_rht_params); BUG_ON(!obj); - rhashtable_remove(ht, &obj->node); + rhashtable_remove_fast(ht, &obj->node, test_rht_params); kfree(obj); } @@ -195,20 +209,11 @@ static struct rhashtable ht; static int __init test_rht_init(void) { - 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, - .max_size = 2, /* we expand/shrink manually here */ - .nulls_base = (3U << RHT_BASE_SHIFT), - }; int err; pr_info("Running resizable hashtable tests...\n"); - err = rhashtable_init(&ht, ¶ms); + err = rhashtable_init(&ht, &test_rht_params); if (err < 0) { pr_warn("Test failed: Unable to initialize hashtable: %d\n", err); -- cgit From dc0ee268d85026530720d8c874716287b7ede25b Mon Sep 17 00:00:00 2001 From: Herbert Xu Date: Fri, 20 Mar 2015 21:57:06 +1100 Subject: rhashtable: Rip out obsolete out-of-line interface Now that all rhashtable users have been converted over to the inline interface, this patch removes the unused out-of-line interface. Signed-off-by: Herbert Xu Signed-off-by: David S. Miller --- lib/rhashtable.c | 284 ------------------------------------------------------- 1 file changed, 284 deletions(-) (limited to 'lib') diff --git a/lib/rhashtable.c b/lib/rhashtable.c index d1d23fb58525..83cfedd6612a 100644 --- a/lib/rhashtable.c +++ b/lib/rhashtable.c @@ -339,290 +339,6 @@ exit: } EXPORT_SYMBOL_GPL(rhashtable_insert_slow); -static bool __rhashtable_insert(struct rhashtable *ht, struct rhash_head *obj, - bool (*compare)(void *, void *), void *arg) -{ - struct bucket_table *tbl, *old_tbl; - struct rhash_head *head; - bool no_resize_running; - unsigned hash; - spinlock_t *old_lock; - bool success = true; - - rcu_read_lock(); - - old_tbl = rht_dereference_rcu(ht->tbl, ht); - hash = head_hashfn(ht, old_tbl, obj); - old_lock = rht_bucket_lock(old_tbl, hash); - - spin_lock_bh(old_lock); - - /* Because we have already taken the bucket lock in old_tbl, - * if we find that future_tbl is not yet visible then that - * guarantees all other insertions of the same entry will - * also grab the bucket lock in old_tbl because until the - * rehash completes ht->tbl won't be changed. - */ - tbl = rht_dereference_rcu(old_tbl->future_tbl, ht) ?: old_tbl; - if (tbl != old_tbl) { - hash = head_hashfn(ht, tbl, obj); - spin_lock_nested(rht_bucket_lock(tbl, hash), - SINGLE_DEPTH_NESTING); - } - - if (compare && - rhashtable_lookup_compare(ht, rht_obj(ht, obj) + ht->p.key_offset, - compare, arg)) { - success = false; - goto exit; - } - - no_resize_running = tbl == old_tbl; - - head = rht_dereference_bucket(tbl->buckets[hash], tbl, hash); - - if (rht_is_a_nulls(head)) - INIT_RHT_NULLS_HEAD(obj->next, ht, hash); - else - RCU_INIT_POINTER(obj->next, head); - - rcu_assign_pointer(tbl->buckets[hash], obj); - - atomic_inc(&ht->nelems); - if (no_resize_running && rht_grow_above_75(ht, tbl)) - schedule_work(&ht->run_work); - -exit: - if (tbl != old_tbl) - spin_unlock(rht_bucket_lock(tbl, hash)); - - spin_unlock_bh(old_lock); - - rcu_read_unlock(); - - return success; -} - -/** - * rhashtable_insert - insert object into hash table - * @ht: hash table - * @obj: pointer to hash head inside object - * - * 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(). - */ -void rhashtable_insert(struct rhashtable *ht, struct rhash_head *obj) -{ - __rhashtable_insert(ht, obj, NULL, NULL); -} -EXPORT_SYMBOL_GPL(rhashtable_insert); - -static bool __rhashtable_remove(struct rhashtable *ht, - struct bucket_table *tbl, - struct rhash_head *obj) -{ - struct rhash_head __rcu **pprev; - struct rhash_head *he; - spinlock_t * lock; - unsigned hash; - bool ret = false; - - hash = head_hashfn(ht, tbl, obj); - lock = rht_bucket_lock(tbl, hash); - - spin_lock_bh(lock); - - pprev = &tbl->buckets[hash]; - rht_for_each(he, tbl, hash) { - if (he != obj) { - pprev = &he->next; - continue; - } - - rcu_assign_pointer(*pprev, obj->next); - ret = true; - break; - } - - spin_unlock_bh(lock); - - return ret; -} - -/** - * rhashtable_remove - remove object from hash table - * @ht: hash table - * @obj: pointer to hash head inside object - * - * 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. - * - * The caller must ensure that no concurrent table mutations occur. It is - * however valid to have concurrent lookups if they are RCU protected. - */ -bool rhashtable_remove(struct rhashtable *ht, struct rhash_head *obj) -{ - struct bucket_table *tbl; - bool ret; - - 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 (!(ret = __rhashtable_remove(ht, tbl, obj)) && - (tbl = rht_dereference_rcu(tbl->future_tbl, ht))) - ; - - if (ret) { - atomic_dec(&ht->nelems); - if (rht_shrink_below_30(ht, tbl)) - schedule_work(&ht->run_work); - } - - rcu_read_unlock(); - - return ret; -} -EXPORT_SYMBOL_GPL(rhashtable_remove); - -/** - * rhashtable_lookup - lookup key in hash table - * @ht: hash table - * @key: pointer to key - * - * 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. - * - * This lookup function may only be used for fixed key hash table (key_len - * parameter set). It will BUG() if used inappropriately. - * - * Lookups may occur in parallel with hashtable mutations and resizing. - */ -void *rhashtable_lookup(struct rhashtable *ht, const void *key) -{ - return rhashtable_lookup_fast(ht, key, ht->p); -} -EXPORT_SYMBOL_GPL(rhashtable_lookup); - -/** - * rhashtable_lookup_compare - search hash table with compare function - * @ht: hash table - * @key: the pointer to the key - * @compare: compare function, must return true on match - * @arg: argument passed on to compare function - * - * Traverses the bucket chain behind the provided hash value and calls the - * specified compare function for each entry. - * - * Lookups may occur in parallel with hashtable mutations and resizing. - * - * Returns the first entry on which the compare function returned true. - */ -void *rhashtable_lookup_compare(struct rhashtable *ht, const void *key, - bool (*compare)(void *, void *), - void *arg) -{ - const struct bucket_table *tbl; - struct rhash_head *he; - u32 hash; - - rcu_read_lock(); - - tbl = rht_dereference_rcu(ht->tbl, ht); -restart: - hash = rht_key_hashfn(ht, tbl, key, ht->p); - rht_for_each_rcu(he, tbl, hash) { - if (!compare(rht_obj(ht, he), arg)) - continue; - rcu_read_unlock(); - return rht_obj(ht, he); - } - - /* Ensure we see any new tables. */ - smp_rmb(); - - tbl = rht_dereference_rcu(tbl->future_tbl, ht); - if (unlikely(tbl)) - goto restart; - rcu_read_unlock(); - - return NULL; -} -EXPORT_SYMBOL_GPL(rhashtable_lookup_compare); - -/** - * rhashtable_lookup_insert - lookup and insert object into hash table - * @ht: hash table - * @obj: pointer to hash head inside object - * - * 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(). - */ -bool rhashtable_lookup_insert(struct rhashtable *ht, struct rhash_head *obj) -{ - return rhashtable_lookup_insert_fast(ht, obj, ht->p); -} -EXPORT_SYMBOL_GPL(rhashtable_lookup_insert); - -/** - * rhashtable_lookup_compare_insert - search and insert object to hash table - * with compare function - * @ht: hash table - * @obj: pointer to hash head inside object - * @compare: compare function, must return true on match - * @arg: argument passed on to compare function - * - * 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(). - */ -bool rhashtable_lookup_compare_insert(struct rhashtable *ht, - struct rhash_head *obj, - bool (*compare)(void *, void *), - void *arg) -{ - BUG_ON(!ht->p.key_len); - - return __rhashtable_insert(ht, obj, compare, arg); -} -EXPORT_SYMBOL_GPL(rhashtable_lookup_compare_insert); - /** * rhashtable_walk_init - Initialise an iterator * @ht: Table to walk over -- cgit