NetLabel: Consolidate the LSM domain mapping/hashing locks

Currently we use two separate spinlocks to protect both the hash/mapping table
and the default entry.  This could be considered a bit foolish because it adds
complexity without offering any real performance advantage.  This patch
removes the dedicated default spinlock and protects the default entry with the
hash/mapping table spinlock.

Signed-off-by: Paul Moore <paul.moore@hp.com>
Signed-off-by: James Morris <jmorris@namei.org>

diff --git a/net/netlabel/netlabel_domainhash.c b/net/netlabel/netlabel_domainhash.c
index 1f8f7ac..9a8ea01 100644 (file)
--- a/net/netlabel/netlabel_domainhash.c
+++ b/net/netlabel/netlabel_domainhash.c
@@ -54,9 +54,6 @@ struct netlbl_domhsh_tbl {
  * hash table should be okay */
 static DEFINE_SPINLOCK(netlbl_domhsh_lock);
 static struct netlbl_domhsh_tbl *netlbl_domhsh = NULL;
-
-/* Default domain mapping */
-static DEFINE_SPINLOCK(netlbl_domhsh_def_lock);
 static struct netlbl_dom_map *netlbl_domhsh_def = NULL;
 
 /*
@@ -239,24 +236,22 @@ int netlbl_domhsh_add(struct netlbl_dom_map *entry,
        INIT_RCU_HEAD(&entry->rcu);
 
        rcu_read_lock();
+       spin_lock(&netlbl_domhsh_lock);
        if (entry->domain != NULL) {
                bkt = netlbl_domhsh_hash(entry->domain);
-               spin_lock(&netlbl_domhsh_lock);
                if (netlbl_domhsh_search(entry->domain) == NULL)
                        list_add_tail_rcu(&entry->list,
                                    &rcu_dereference(netlbl_domhsh)->tbl[bkt]);
                else
                        ret_val = -EEXIST;
-               spin_unlock(&netlbl_domhsh_lock);
        } else {
                INIT_LIST_HEAD(&entry->list);
-               spin_lock(&netlbl_domhsh_def_lock);
                if (rcu_dereference(netlbl_domhsh_def) == NULL)
                        rcu_assign_pointer(netlbl_domhsh_def, entry);
                else
                        ret_val = -EEXIST;
-               spin_unlock(&netlbl_domhsh_def_lock);
        }
+       spin_unlock(&netlbl_domhsh_lock);
        audit_buf = netlbl_audit_start_common(AUDIT_MAC_MAP_ADD, audit_info);
        if (audit_buf != NULL) {
                audit_log_format(audit_buf,
@@ -337,23 +332,16 @@ int netlbl_domhsh_remove(const char *domain, struct netlbl_audit *audit_info)
                                           entry->domain);
                break;
        }
-       if (entry != rcu_dereference(netlbl_domhsh_def)) {
-               spin_lock(&netlbl_domhsh_lock);
-               if (entry->valid) {
-                       entry->valid = 0;
+       spin_lock(&netlbl_domhsh_lock);
+       if (entry->valid) {
+               entry->valid = 0;
+               if (entry != rcu_dereference(netlbl_domhsh_def))
                        list_del_rcu(&entry->list);
-                       ret_val = 0;
-               }
-               spin_unlock(&netlbl_domhsh_lock);
-       } else {
-               spin_lock(&netlbl_domhsh_def_lock);
-               if (entry->valid) {
-                       entry->valid = 0;
+               else
                        rcu_assign_pointer(netlbl_domhsh_def, NULL);
-                       ret_val = 0;
-               }
-               spin_unlock(&netlbl_domhsh_def_lock);
+               ret_val = 0;
        }
+       spin_unlock(&netlbl_domhsh_lock);
 
        audit_buf = netlbl_audit_start_common(AUDIT_MAC_MAP_DEL, audit_info);
        if (audit_buf != NULL) {