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>

1 files changed, 9 insertions, 21 deletions

diff --git a/net/netlabel/netlabel_domainhash.c b/net/netlabel/netlabel_domainhash.c
index 1f8f7ace790e..9a8ea0195c4f 100644
--- 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) {