1 files changed, 19 insertions, 10 deletions

diff --git a/net/netlabel/netlabel_domainhash.c b/net/netlabel/netlabel_domainhash.c
index 0bfeaab88ef5..d37b7f80fa37 100644
--- a/net/netlabel/netlabel_domainhash.c
+++ b/net/netlabel/netlabel_domainhash.c
@@ -35,6 +35,7 @@
 #include <linux/spinlock.h>
 #include <linux/string.h>
 #include <linux/audit.h>
+#include <linux/slab.h>
 #include <net/netlabel.h>
 #include <net/cipso_ipv4.h>
 #include <asm/bug.h>
@@ -50,9 +51,12 @@ struct netlbl_domhsh_tbl {
 };
 
 /* Domain hash table */
-/* XXX - updates should be so rare that having one spinlock for the entire
- * hash table should be okay */
+/* updates should be so rare that having one spinlock for the entire hash table
+ * should be okay */
 static DEFINE_SPINLOCK(netlbl_domhsh_lock);
+#define netlbl_domhsh_rcu_deref(p) \
+        rcu_dereference_check(p, rcu_read_lock_held() || \
+                                 lockdep_is_held(&netlbl_domhsh_lock))
 static struct netlbl_domhsh_tbl *netlbl_domhsh = NULL;
 static struct netlbl_dom_map *netlbl_domhsh_def = NULL;
 
@@ -106,7 +110,8 @@ static void netlbl_domhsh_free_entry(struct rcu_head *entry)
  * Description:
  * This is the hashing function for the domain hash table, it returns the
  * correct bucket number for the domain.  The caller is responsibile for
- * calling the rcu_read_[un]lock() functions.
+ * ensuring that the hash table is protected with either a RCU read lock or the
+ * hash table lock.
  *
  */
 static u32 netlbl_domhsh_hash(const char *key)
@@ -120,7 +125,7 @@ static u32 netlbl_domhsh_hash(const char *key)
 
         for (iter = 0, val = 0, len = strlen(key); iter < len; iter++)
                 val = (val << 4 | (val >> (8 * sizeof(u32) - 4))) ^ key[iter];
-        return val & (rcu_dereference(netlbl_domhsh)->size - 1);
+        return val & (netlbl_domhsh_rcu_deref(netlbl_domhsh)->size - 1);
 }
 
 /**
@@ -130,7 +135,8 @@ static u32 netlbl_domhsh_hash(const char *key)
  * Description:
  * Searches the domain hash table and returns a pointer to the hash table
  * entry if found, otherwise NULL is returned.  The caller is responsibile for
- * the rcu hash table locks (i.e. the caller much call rcu_read_[un]lock()).
+ * ensuring that the hash table is protected with either a RCU read lock or the
+ * hash table lock.
  *
  */
 static struct netlbl_dom_map *netlbl_domhsh_search(const char *domain)
@@ -141,7 +147,7 @@ static struct netlbl_dom_map *netlbl_domhsh_search(const char *domain)
 
         if (domain != NULL) {
                 bkt = netlbl_domhsh_hash(domain);
-                bkt_list = &rcu_dereference(netlbl_domhsh)->tbl[bkt];
+                bkt_list = &netlbl_domhsh_rcu_deref(netlbl_domhsh)->tbl[bkt];
                 list_for_each_entry_rcu(iter, bkt_list, list)
                         if (iter->valid && strcmp(iter->domain, domain) == 0)
                                 return iter;
@@ -159,8 +165,8 @@ static struct netlbl_dom_map *netlbl_domhsh_search(const char *domain)
  * Searches the domain hash table and returns a pointer to the hash table
  * entry if an exact match is found, if an exact match is not present in the
  * hash table then the default entry is returned if valid otherwise NULL is
- * returned.  The caller is responsibile for the rcu hash table locks
- * (i.e. the caller much call rcu_read_[un]lock()).
+ * returned.  The caller is responsibile ensuring that the hash table is
+ * protected with either a RCU read lock or the hash table lock.
  *
  */
 static struct netlbl_dom_map *netlbl_domhsh_search_def(const char *domain)
@@ -169,7 +175,7 @@ static struct netlbl_dom_map *netlbl_domhsh_search_def(const char *domain)
 
         entry = netlbl_domhsh_search(domain);
         if (entry == NULL) {
-                entry = rcu_dereference(netlbl_domhsh_def);
+                entry = netlbl_domhsh_rcu_deref(netlbl_domhsh_def);
                 if (entry != NULL && !entry->valid)
                         entry = NULL;
         }
@@ -306,8 +312,11 @@ int netlbl_domhsh_add(struct netlbl_dom_map *entry,
         struct netlbl_af6list *tmp6;
 #endif /* IPv6 */
 
+        /* XXX - we can remove this RCU read lock as the spinlock protects the
+         *       entire function, but before we do we need to fixup the
+         *       netlbl_af[4,6]list RCU functions to do "the right thing" with
+         *       respect to rcu_dereference() when only a spinlock is held. */
         rcu_read_lock();
-
         spin_lock(&netlbl_domhsh_lock);
         if (entry->domain != NULL)
                 entry_old = netlbl_domhsh_search(entry->domain);