--- /dev/null
+/*****************************************************************************\
+ * Copyright (C) 2010 Lawrence Livermore National Security, LLC.
+ * Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
+ * Written by Brian Behlendorf <behlendorf1@llnl.gov>.
+ * 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;
+}
projects / zfs / commitdiff