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Make tsd_set(key, NULL) remove the tsd entry for current thread

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To prevent leaking tsd entries, we make tsd_set(key, NULL) remove the tsd
entry for the current thread. This is alright since tsd_get() returns NULL
when the entry doesn't exist.

Signed-off-by: Chunwei Chen <tuxoko@gmail.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #443
This commit is contained in:
Chunwei Chen 2015-04-02 01:50:48 +08:00 committed by Brian Behlendorf
parent d3c677bcd3
commit 3d39d0afab
1 changed files with 63 additions and 0 deletions
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63
module/spl/spl-tsd.c
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@ -391,6 +391,60 @@ tsd_hash_table_fini(tsd_hash_table_t *table)
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
@ -409,6 +463,8 @@ tsd_set(uint_t key, void *value)
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;
@ -421,9 +477,16 @@ tsd_set(uint_t key, void *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) {