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Diffstat (limited to 'module/spl/spl-tsd.c')
| -rw-r--r-- | module/spl/spl-tsd.c | 638 |
1 files changed, 638 insertions, 0 deletions
diff --git a/module/spl/spl-tsd.c b/module/spl/spl-tsd.c new file mode 100644 index 000000000..0581e1b2e --- /dev/null +++ b/module/spl/spl-tsd.c @@ -0,0 +1,638 @@ +/*****************************************************************************\ + * Copyright (C) 2010 Lawrence Livermore National Security, LLC. + * Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER). + * Written by Brian Behlendorf <[email protected]>. + * UCRL-CODE-235197 + * + * This file is part of the SPL, Solaris Porting Layer. + * For details, see <http://github.com/behlendorf/spl/>. + * + * The SPL is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License as published by the + * Free Software Foundation; either version 2 of the License, or (at your + * option) any later version. + * + * The SPL is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + * for more details. + * + * You should have received a copy of the GNU General Public License along + * with the SPL. If not, see <http://www.gnu.org/licenses/>. + ***************************************************************************** + * Solaris Porting Layer (SPL) Thread Specific Data Implementation. + * + * Thread specific data has implemented using a hash table, this avoids + * the need to add a member to the task structure and allows maximum + * portability between kernels. This implementation has been optimized + * to keep the tsd_set() and tsd_get() times as small as possible. + * + * The majority of the entries in the hash table are for specific tsd + * entries. These entries are hashed by the product of their key and + * pid because by design the key and pid are guaranteed to be unique. + * Their product also has the desirable properly that it will be uniformly + * distributed over the hash bins providing neither the pid nor key is zero. + * Under linux the zero pid is always the init process and thus won't be + * used, and this implementation is careful to never to assign a zero key. + * By default the hash table is sized to 512 bins which is expected to + * be sufficient for light to moderate usage of thread specific data. + * + * The hash table contains two additional type of entries. They first + * type is entry is called a 'key' entry and it is added to the hash during + * tsd_create(). It is used to store the address of the destructor function + * and it is used as an anchor point. All tsd entries which use the same + * key will be linked to this entry. This is used during tsd_destory() to + * quickly call the destructor function for all tsd associated with the key. + * The 'key' entry may be looked up with tsd_hash_search() by passing the + * key you wish to lookup and DTOR_PID constant as the pid. + * + * The second type of entry is called a 'pid' entry and it is added to the + * hash the first time a process set a key. The 'pid' entry is also used + * as an anchor and all tsd for the process will be linked to it. This + * list is using during tsd_exit() to ensure all registered destructors + * are run for the process. The 'pid' entry may be looked up with + * tsd_hash_search() by passing the PID_KEY constant as the key, and + * the process pid. Note that tsd_exit() is called by thread_exit() + * so if your using the Solaris thread API you should not need to call + * tsd_exit() directly. + * +\*****************************************************************************/ + +#include <sys/kmem.h> +#include <sys/thread.h> +#include <sys/tsd.h> +#include <spl-debug.h> + +#ifdef DEBUG_SUBSYSTEM +#undef DEBUG_SUBSYSTEM +#endif + +#define DEBUG_SUBSYSTEM SS_TSD +#define DEBUG_SUBSYSTEM SS_TSD + +typedef struct tsd_hash_bin { + spinlock_t hb_lock; + struct hlist_head hb_head; +} tsd_hash_bin_t; + +typedef struct tsd_hash_table { + spinlock_t ht_lock; + uint_t ht_bits; + uint_t ht_key; + tsd_hash_bin_t *ht_bins; +} tsd_hash_table_t; + +typedef struct tsd_hash_entry { + uint_t he_key; + pid_t he_pid; + dtor_func_t he_dtor; + void *he_value; + struct hlist_node he_list; + struct list_head he_key_list; + struct list_head he_pid_list; +} tsd_hash_entry_t; + +static tsd_hash_table_t *tsd_hash_table = NULL; + + +/* + * tsd_hash_search - searches hash table for tsd_hash_entry + * @table: hash table + * @key: search key + * @pid: search pid + */ +static tsd_hash_entry_t * +tsd_hash_search(tsd_hash_table_t *table, uint_t key, pid_t pid) +{ + struct hlist_node *node; + tsd_hash_entry_t *entry; + tsd_hash_bin_t *bin; + ulong_t hash; + SENTRY; + + hash = hash_long((ulong_t)key * (ulong_t)pid, table->ht_bits); + bin = &table->ht_bins[hash]; + spin_lock(&bin->hb_lock); + hlist_for_each_entry(entry, node, &bin->hb_head, he_list) { + if ((entry->he_key == key) && (entry->he_pid == pid)) { + spin_unlock(&bin->hb_lock); + SRETURN(entry); + } + } + + spin_unlock(&bin->hb_lock); + SRETURN(NULL); +} + +/* + * tsd_hash_dtor - call the destructor and free all entries on the list + * @work: list of hash entries + * + * For a list of entries which have all already been removed from the + * hash call their registered destructor then free the associated memory. + */ +static void +tsd_hash_dtor(struct hlist_head *work) +{ + tsd_hash_entry_t *entry; + SENTRY; + + while (!hlist_empty(work)) { + entry = hlist_entry(work->first, tsd_hash_entry_t, he_list); + hlist_del(&entry->he_list); + + if (entry->he_dtor && entry->he_pid != DTOR_PID) + entry->he_dtor(entry->he_value); + + kmem_free(entry, sizeof(tsd_hash_entry_t)); + } + + SEXIT; +} + +/* + * tsd_hash_add - adds an entry to hash table + * @table: hash table + * @key: search key + * @pid: search pid + * + * The caller is responsible for ensuring the unique key/pid do not + * already exist in the hash table. This possible because all entries + * are thread specific thus a concurrent thread will never attempt to + * add this key/pid. Because multiple bins must be checked to add + * links to the dtor and pid entries the entire table is locked. + */ +static int +tsd_hash_add(tsd_hash_table_t *table, uint_t key, pid_t pid, void *value) +{ + tsd_hash_entry_t *entry, *dtor_entry, *pid_entry; + tsd_hash_bin_t *bin; + ulong_t hash; + int rc = 0; + SENTRY; + + ASSERT3P(tsd_hash_search(table, key, pid), ==, NULL); + + /* New entry allocate structure, set value, and add to hash */ + entry = kmem_alloc(sizeof(tsd_hash_entry_t), KM_SLEEP); + if (entry == NULL) + SRETURN(ENOMEM); + + entry->he_key = key; + entry->he_pid = pid; + entry->he_value = value; + INIT_HLIST_NODE(&entry->he_list); + INIT_LIST_HEAD(&entry->he_key_list); + INIT_LIST_HEAD(&entry->he_pid_list); + + spin_lock(&table->ht_lock); + + /* Destructor entry must exist for all valid keys */ + dtor_entry = tsd_hash_search(table, entry->he_key, DTOR_PID); + ASSERT3P(dtor_entry, !=, NULL); + entry->he_dtor = dtor_entry->he_dtor; + + /* Process entry must exist for all valid processes */ + pid_entry = tsd_hash_search(table, PID_KEY, entry->he_pid); + ASSERT3P(pid_entry, !=, NULL); + + hash = hash_long((ulong_t)key * (ulong_t)pid, table->ht_bits); + bin = &table->ht_bins[hash]; + spin_lock(&bin->hb_lock); + + /* Add to the hash, key, and pid lists */ + hlist_add_head(&entry->he_list, &bin->hb_head); + list_add(&entry->he_key_list, &dtor_entry->he_key_list); + list_add(&entry->he_pid_list, &pid_entry->he_pid_list); + + spin_unlock(&bin->hb_lock); + spin_unlock(&table->ht_lock); + + SRETURN(rc); +} + +/* + * tsd_hash_add_key - adds a destructor entry to the hash table + * @table: hash table + * @keyp: search key + * @dtor: key destructor + * + * For every unique key there is a single entry in the hash which is used + * as anchor. All other thread specific entries for this key are linked + * to this anchor via the 'he_key_list' list head. On return they keyp + * will be set to the next available key for the hash table. + */ +static int +tsd_hash_add_key(tsd_hash_table_t *table, uint_t *keyp, dtor_func_t dtor) +{ + tsd_hash_entry_t *tmp_entry, *entry; + tsd_hash_bin_t *bin; + ulong_t hash; + int keys_checked = 0; + SENTRY; + + ASSERT3P(table, !=, NULL); + + /* Allocate entry to be used as a destructor for this key */ + entry = kmem_alloc(sizeof(tsd_hash_entry_t), KM_SLEEP); + if (entry == NULL) + SRETURN(ENOMEM); + + /* Determine next available key value */ + spin_lock(&table->ht_lock); + do { + /* Limited to TSD_KEYS_MAX concurrent unique keys */ + if (table->ht_key++ > TSD_KEYS_MAX) + table->ht_key = 1; + + /* Ensure failure when all TSD_KEYS_MAX keys are in use */ + if (keys_checked++ >= TSD_KEYS_MAX) { + spin_unlock(&table->ht_lock); + SRETURN(ENOENT); + } + + tmp_entry = tsd_hash_search(table, table->ht_key, DTOR_PID); + } while (tmp_entry); + + /* Add destructor entry in to hash table */ + entry->he_key = *keyp = table->ht_key; + entry->he_pid = DTOR_PID; + entry->he_dtor = dtor; + entry->he_value = NULL; + INIT_HLIST_NODE(&entry->he_list); + INIT_LIST_HEAD(&entry->he_key_list); + INIT_LIST_HEAD(&entry->he_pid_list); + + hash = hash_long((ulong_t)*keyp * (ulong_t)DTOR_PID, table->ht_bits); + bin = &table->ht_bins[hash]; + spin_lock(&bin->hb_lock); + + hlist_add_head(&entry->he_list, &bin->hb_head); + + spin_unlock(&bin->hb_lock); + spin_unlock(&table->ht_lock); + + SRETURN(0); +} + +/* + * tsd_hash_add_pid - adds a process entry to the hash table + * @table: hash table + * @pid: search pid + * + * For every process these is a single entry in the hash which is used + * as anchor. All other thread specific entries for this process are + * linked to this anchor via the 'he_pid_list' list head. + */ +static int +tsd_hash_add_pid(tsd_hash_table_t *table, pid_t pid) +{ + tsd_hash_entry_t *entry; + tsd_hash_bin_t *bin; + ulong_t hash; + SENTRY; + + /* Allocate entry to be used as the process reference */ + entry = kmem_alloc(sizeof(tsd_hash_entry_t), KM_SLEEP); + if (entry == NULL) + SRETURN(ENOMEM); + + spin_lock(&table->ht_lock); + entry->he_key = PID_KEY; + entry->he_pid = pid; + entry->he_dtor = NULL; + entry->he_value = NULL; + INIT_HLIST_NODE(&entry->he_list); + INIT_LIST_HEAD(&entry->he_key_list); + INIT_LIST_HEAD(&entry->he_pid_list); + + hash = hash_long((ulong_t)PID_KEY * (ulong_t)pid, table->ht_bits); + bin = &table->ht_bins[hash]; + spin_lock(&bin->hb_lock); + + hlist_add_head(&entry->he_list, &bin->hb_head); + + spin_unlock(&bin->hb_lock); + spin_unlock(&table->ht_lock); + + SRETURN(0); +} + +/* + * tsd_hash_del - delete an entry from hash table, key, and pid lists + * @table: hash table + * @key: search key + * @pid: search pid + */ +static void +tsd_hash_del(tsd_hash_table_t *table, tsd_hash_entry_t *entry) +{ + SENTRY; + + ASSERT(spin_is_locked(&table->ht_lock)); + hlist_del(&entry->he_list); + list_del_init(&entry->he_key_list); + list_del_init(&entry->he_pid_list); + + SEXIT; +} + +/* + * tsd_hash_table_init - allocate a hash table + * @bits: hash table size + * + * A hash table with 2^bits bins will be created, it may not be resized + * after the fact and must be free'd with tsd_hash_table_fini(). + */ +static tsd_hash_table_t * +tsd_hash_table_init(uint_t bits) +{ + tsd_hash_table_t *table; + int hash, size = (1 << bits); + SENTRY; + + table = kmem_zalloc(sizeof(tsd_hash_table_t), KM_SLEEP); + if (table == NULL) + SRETURN(NULL); + + table->ht_bins = kmem_zalloc(sizeof(tsd_hash_bin_t) * size, KM_SLEEP); + if (table->ht_bins == NULL) { + kmem_free(table, sizeof(tsd_hash_table_t)); + SRETURN(NULL); + } + + for (hash = 0; hash < size; hash++) { + spin_lock_init(&table->ht_bins[hash].hb_lock); + INIT_HLIST_HEAD(&table->ht_bins[hash].hb_head); + } + + spin_lock_init(&table->ht_lock); + table->ht_bits = bits; + table->ht_key = 1; + + SRETURN(table); +} + +/* + * tsd_hash_table_fini - free a hash table + * @table: hash table + * + * Free a hash table allocated by tsd_hash_table_init(). If the hash + * table is not empty this function will call the proper destructor for + * all remaining entries before freeing the memory used by those entries. + */ +static void +tsd_hash_table_fini(tsd_hash_table_t *table) +{ + HLIST_HEAD(work); + tsd_hash_bin_t *bin; + tsd_hash_entry_t *entry; + int size, i; + SENTRY; + + ASSERT3P(table, !=, NULL); + spin_lock(&table->ht_lock); + for (i = 0, size = (1 << table->ht_bits); i < size; i++) { + bin = &table->ht_bins[i]; + spin_lock(&bin->hb_lock); + while (!hlist_empty(&bin->hb_head)) { + entry = hlist_entry(bin->hb_head.first, + tsd_hash_entry_t, he_list); + tsd_hash_del(table, entry); + hlist_add_head(&entry->he_list, &work); + } + spin_unlock(&bin->hb_lock); + } + spin_unlock(&table->ht_lock); + + tsd_hash_dtor(&work); + kmem_free(table->ht_bins, sizeof(tsd_hash_bin_t)*(1<<table->ht_bits)); + kmem_free(table, sizeof(tsd_hash_table_t)); + + SEXIT; +} + +/* + * tsd_set - set thread specific data + * @key: lookup key + * @value: value to set + * + * Caller must prevent racing tsd_create() or tsd_destroy(), protected + * from racing tsd_get() or tsd_set() because it is thread specific. + * This function has been optimized to be fast for the update case. + * When setting the tsd initially it will be slower due to additional + * required locking and potential memory allocations. + */ +int +tsd_set(uint_t key, void *value) +{ + tsd_hash_table_t *table; + tsd_hash_entry_t *entry; + pid_t pid; + int rc; + SENTRY; + + table = tsd_hash_table; + pid = curthread->pid; + ASSERT3P(table, !=, NULL); + + if ((key == 0) || (key > TSD_KEYS_MAX)) + SRETURN(EINVAL); + + /* Entry already exists in hash table update value */ + entry = tsd_hash_search(table, key, pid); + if (entry) { + entry->he_value = value; + SRETURN(0); + } + + /* Add a process entry to the hash if not yet exists */ + entry = tsd_hash_search(table, PID_KEY, pid); + if (entry == NULL) { + rc = tsd_hash_add_pid(table, pid); + if (rc) + SRETURN(rc); + } + + rc = tsd_hash_add(table, key, pid, value); + SRETURN(rc); +} +EXPORT_SYMBOL(tsd_set); + +/* + * tsd_get - get thread specific data + * @key: lookup key + * + * Caller must prevent racing tsd_create() or tsd_destroy(). This + * implementation is designed to be fast and scalable, it does not + * lock the entire table only a single hash bin. + */ +void * +tsd_get(uint_t key) +{ + tsd_hash_entry_t *entry; + SENTRY; + + ASSERT3P(tsd_hash_table, !=, NULL); + + if ((key == 0) || (key > TSD_KEYS_MAX)) + SRETURN(NULL); + + entry = tsd_hash_search(tsd_hash_table, key, curthread->pid); + if (entry == NULL) + SRETURN(NULL); + + SRETURN(entry->he_value); +} +EXPORT_SYMBOL(tsd_get); + +/* + * tsd_create - create thread specific data key + * @keyp: lookup key address + * @dtor: destructor called during tsd_destroy() or tsd_exit() + * + * Provided key must be set to 0 or it assumed to be already in use. + * The dtor is allowed to be NULL in which case no additional cleanup + * for the data is performed during tsd_destroy() or tsd_exit(). + * + * Caller must prevent racing tsd_set() or tsd_get(), this function is + * safe from racing tsd_create(), tsd_destroy(), and tsd_exit(). + */ +void +tsd_create(uint_t *keyp, dtor_func_t dtor) +{ + SENTRY; + + ASSERT3P(keyp, !=, NULL); + if (*keyp) { + SEXIT; + return; + } + + (void)tsd_hash_add_key(tsd_hash_table, keyp, dtor); + + SEXIT; +} +EXPORT_SYMBOL(tsd_create); + +/* + * tsd_destroy - destroy thread specific data + * @keyp: lookup key address + * + * Destroys the thread specific data on all threads which use this key. + * + * Caller must prevent racing tsd_set() or tsd_get(), this function is + * safe from racing tsd_create(), tsd_destroy(), and tsd_exit(). + */ +void +tsd_destroy(uint_t *keyp) +{ + HLIST_HEAD(work); + tsd_hash_table_t *table; + tsd_hash_entry_t *dtor_entry, *entry; + SENTRY; + + table = tsd_hash_table; + ASSERT3P(table, !=, NULL); + + spin_lock(&table->ht_lock); + dtor_entry = tsd_hash_search(table, *keyp, DTOR_PID); + if (dtor_entry == NULL) { + spin_unlock(&table->ht_lock); + SEXIT; + return; + } + + /* + * All threads which use this key must be linked off of the + * DTOR_PID entry. They are removed from the hash table and + * linked in to a private working list to be destroyed. + */ + while (!list_empty(&dtor_entry->he_key_list)) { + entry = list_entry(dtor_entry->he_key_list.next, + tsd_hash_entry_t, he_key_list); + ASSERT3U(dtor_entry->he_key, ==, entry->he_key); + ASSERT3P(dtor_entry->he_dtor, ==, entry->he_dtor); + tsd_hash_del(table, entry); + hlist_add_head(&entry->he_list, &work); + } + + tsd_hash_del(table, dtor_entry); + hlist_add_head(&dtor_entry->he_list, &work); + spin_unlock(&table->ht_lock); + + tsd_hash_dtor(&work); + *keyp = 0; + + SEXIT; +} +EXPORT_SYMBOL(tsd_destroy); + +/* + * tsd_exit - destroys all thread specific data for this thread + * + * Destroys all the thread specific data for this thread. + * + * Caller must prevent racing tsd_set() or tsd_get(), this function is + * safe from racing tsd_create(), tsd_destroy(), and tsd_exit(). + */ +void +tsd_exit(void) +{ + HLIST_HEAD(work); + tsd_hash_table_t *table; + tsd_hash_entry_t *pid_entry, *entry; + SENTRY; + + table = tsd_hash_table; + ASSERT3P(table, !=, NULL); + + spin_lock(&table->ht_lock); + pid_entry = tsd_hash_search(table, PID_KEY, curthread->pid); + if (pid_entry == NULL) { + spin_unlock(&table->ht_lock); + SEXIT; + return; + } + + /* + * All keys associated with this pid must be linked off of the + * PID_KEY entry. They are removed from the hash table and + * linked in to a private working to be destroyed. + */ + while (!list_empty(&pid_entry->he_pid_list)) { + entry = list_entry(pid_entry->he_pid_list.next, + tsd_hash_entry_t, he_pid_list); + ASSERT3U(pid_entry->he_pid, ==, entry->he_pid); + tsd_hash_del(table, entry); + hlist_add_head(&entry->he_list, &work); + } + + tsd_hash_del(table, pid_entry); + hlist_add_head(&pid_entry->he_list, &work); + spin_unlock(&table->ht_lock); + + tsd_hash_dtor(&work); + + SEXIT; +} +EXPORT_SYMBOL(tsd_exit); + +int tsd_init(void) +{ + SENTRY; + + tsd_hash_table = tsd_hash_table_init(TSD_HASH_TABLE_BITS_DEFAULT); + if (tsd_hash_table == NULL) + SRETURN(1); + + SRETURN(0); +} + +void tsd_fini(void) +{ + SENTRY; + tsd_hash_table_fini(tsd_hash_table); + tsd_hash_table = NULL; + SEXIT; +} |