FreeBSD/Linux Kernel Cross Reference
sys/contrib/openzfs/module/os/linux/spl/spl-tsd.c

     /*
      *  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.
      *
      *  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_destroy() 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 <linux/hash.h>
    
    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 = NULL;
           tsd_hash_entry_t *entry;
           tsd_hash_bin_t *bin;
           ulong_t hash;
   
           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(node, &bin->hb_head) {
                   entry = list_entry(node, tsd_hash_entry_t, he_list);
                   if ((entry->he_key == key) && (entry->he_pid == pid)) {
                           spin_unlock(&bin->hb_lock);
                           return (entry);
                   }
           }
   
           spin_unlock(&bin->hb_lock);
           return (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;
   
           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));
           }
   }
   
   /*
    * 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;
   
           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_PUSHPAGE);
           if (entry == NULL)
                   return (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);
   
           return (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;
   
           ASSERT3P(table, !=, NULL);
   
           /* Allocate entry to be used as a destructor for this key */
           entry = kmem_alloc(sizeof (tsd_hash_entry_t), KM_PUSHPAGE);
           if (entry == NULL)
                   return (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);
                           return (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);
   
           return (0);
   }
   
   /*
    * tsd_hash_add_pid - adds a process entry to the hash table
    * @table: hash table
    * @pid: search pid
    *
    * For every process there 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;
   
           /* Allocate entry to be used as the process reference */
           entry = kmem_alloc(sizeof (tsd_hash_entry_t), KM_PUSHPAGE);
           if (entry == NULL)
                   return (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);
   
           return (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)
   {
           hlist_del(&entry->he_list);
           list_del_init(&entry->he_key_list);
           list_del_init(&entry->he_pid_list);
   }
   
   /*
    * 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);
   
           table = kmem_zalloc(sizeof (tsd_hash_table_t), KM_SLEEP);
           if (table == NULL)
                   return (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));
                   return (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;
   
           return (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;
   
           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));
   }
   
   /*
    * tsd_remove_entry - remove a tsd entry for this thread
    * @entry: entry to remove
    *
    * Remove the thread specific data @entry for this thread.
    * If this is the last entry for this thread, also remove the PID entry.
    */
   static void
   tsd_remove_entry(tsd_hash_entry_t *entry)
   {
           HLIST_HEAD(work);
           tsd_hash_table_t *table;
           tsd_hash_entry_t *pid_entry;
           tsd_hash_bin_t *pid_entry_bin, *entry_bin;
           ulong_t hash;
   
           table = tsd_hash_table;
           ASSERT3P(table, !=, NULL);
           ASSERT3P(entry, !=, NULL);
   
           spin_lock(&table->ht_lock);
   
           hash = hash_long((ulong_t)entry->he_key *
               (ulong_t)entry->he_pid, table->ht_bits);
           entry_bin = &table->ht_bins[hash];
   
           /* save the possible pid_entry */
           pid_entry = list_entry(entry->he_pid_list.next, tsd_hash_entry_t,
               he_pid_list);
   
           /* remove entry */
           spin_lock(&entry_bin->hb_lock);
           tsd_hash_del(table, entry);
           hlist_add_head(&entry->he_list, &work);
           spin_unlock(&entry_bin->hb_lock);
   
           /* if pid_entry is indeed pid_entry, then remove it if it's empty */
           if (pid_entry->he_key == PID_KEY &&
               list_empty(&pid_entry->he_pid_list)) {
                   hash = hash_long((ulong_t)pid_entry->he_key *
                       (ulong_t)pid_entry->he_pid, table->ht_bits);
                   pid_entry_bin = &table->ht_bins[hash];
   
                   spin_lock(&pid_entry_bin->hb_lock);
                   tsd_hash_del(table, pid_entry);
                   hlist_add_head(&pid_entry->he_list, &work);
                   spin_unlock(&pid_entry_bin->hb_lock);
           }
   
           spin_unlock(&table->ht_lock);
   
           tsd_hash_dtor(&work);
   }
   
   /*
    * 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;
           /* mark remove if value is NULL */
           boolean_t remove = (value == NULL);
   
           table = tsd_hash_table;
           pid = curthread->pid;
           ASSERT3P(table, !=, NULL);
   
           if ((key == 0) || (key > TSD_KEYS_MAX))
                   return (EINVAL);
   
           /* Entry already exists in hash table update value */
           entry = tsd_hash_search(table, key, pid);
           if (entry) {
                   entry->he_value = value;
                   /* remove the entry */
                   if (remove)
                           tsd_remove_entry(entry);
                   return (0);
           }
   
           /* don't create entry if value is NULL */
           if (remove)
                   return (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)
                           return (rc);
           }
   
           rc = tsd_hash_add(table, key, pid, value);
           return (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;
   
           ASSERT3P(tsd_hash_table, !=, NULL);
   
           if ((key == 0) || (key > TSD_KEYS_MAX))
                   return (NULL);
   
           entry = tsd_hash_search(tsd_hash_table, key, curthread->pid);
           if (entry == NULL)
                   return (NULL);
   
           return (entry->he_value);
   }
   EXPORT_SYMBOL(tsd_get);
   
   /*
    * tsd_get_by_thread - get thread specific data for specified thread
    * @key: lookup key
    * @thread: thread to lookup
    *
    * 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_by_thread(uint_t key, kthread_t *thread)
   {
           tsd_hash_entry_t *entry;
   
           ASSERT3P(tsd_hash_table, !=, NULL);
   
           if ((key == 0) || (key > TSD_KEYS_MAX))
                   return (NULL);
   
           entry = tsd_hash_search(tsd_hash_table, key, thread->pid);
           if (entry == NULL)
                   return (NULL);
   
           return (entry->he_value);
   }
   EXPORT_SYMBOL(tsd_get_by_thread);
   
   /*
    * 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)
   {
           ASSERT3P(keyp, !=, NULL);
           if (*keyp)
                   return;
   
           (void) tsd_hash_add_key(tsd_hash_table, keyp, dtor);
   }
   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;
           tsd_hash_bin_t *dtor_entry_bin, *entry_bin;
           ulong_t hash;
   
           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);
                   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);
   
                   hash = hash_long((ulong_t)entry->he_key *
                       (ulong_t)entry->he_pid, table->ht_bits);
                   entry_bin = &table->ht_bins[hash];
   
                   spin_lock(&entry_bin->hb_lock);
                   tsd_hash_del(table, entry);
                   hlist_add_head(&entry->he_list, &work);
                   spin_unlock(&entry_bin->hb_lock);
           }
   
           hash = hash_long((ulong_t)dtor_entry->he_key *
               (ulong_t)dtor_entry->he_pid, table->ht_bits);
           dtor_entry_bin = &table->ht_bins[hash];
   
           spin_lock(&dtor_entry_bin->hb_lock);
           tsd_hash_del(table, dtor_entry);
           hlist_add_head(&dtor_entry->he_list, &work);
           spin_unlock(&dtor_entry_bin->hb_lock);
           spin_unlock(&table->ht_lock);
   
           tsd_hash_dtor(&work);
           *keyp = 0;
   }
   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;
           tsd_hash_bin_t *pid_entry_bin, *entry_bin;
           ulong_t hash;
   
           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);
                   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 list 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);
   
                   hash = hash_long((ulong_t)entry->he_key *
                       (ulong_t)entry->he_pid, table->ht_bits);
                   entry_bin = &table->ht_bins[hash];
   
                   spin_lock(&entry_bin->hb_lock);
                   tsd_hash_del(table, entry);
                   hlist_add_head(&entry->he_list, &work);
                   spin_unlock(&entry_bin->hb_lock);
           }
   
           hash = hash_long((ulong_t)pid_entry->he_key *
               (ulong_t)pid_entry->he_pid, table->ht_bits);
           pid_entry_bin = &table->ht_bins[hash];
   
           spin_lock(&pid_entry_bin->hb_lock);
           tsd_hash_del(table, pid_entry);
           hlist_add_head(&pid_entry->he_list, &work);
           spin_unlock(&pid_entry_bin->hb_lock);
           spin_unlock(&table->ht_lock);
   
           tsd_hash_dtor(&work);
   }
   EXPORT_SYMBOL(tsd_exit);
   
   int
   spl_tsd_init(void)
   {
           tsd_hash_table = tsd_hash_table_init(TSD_HASH_TABLE_BITS_DEFAULT);
           if (tsd_hash_table == NULL)
                   return (-ENOMEM);
   
           return (0);
   }
   
   void
   spl_tsd_fini(void)
   {
           tsd_hash_table_fini(tsd_hash_table);
           tsd_hash_table = NULL;
   }

Cache object: 8122fe9e03719e7f10c2b42f8bf552d1